WO2008035685A1

WO2008035685A1 - Polarization measuring device

Info

Publication number: WO2008035685A1
Application number: PCT/JP2007/068113
Authority: WO
Inventors: Susumu Takahashi
Original assignee: Olympus Medical Systems Corporation
Priority date: 2006-09-19
Filing date: 2007-09-19
Publication date: 2008-03-27
Also published as: JPWO2008035685A1; JP5011302B2

Abstract

A polarization measuring device includes: a polarized light projection unit (1); a polarized light reception unit (2); and a transmission optical system (4) which collects the polarized light from the polarized light projection unit (1) so as to apply it to a plane under test (3), collects the light reflected by the plane under test (3), and introduces it to the polarized light reception unit (2). The transmission optical system (4) includes an optical axis of the polarized light applied from the polarized light projection unit (1) to the plane under test (3) and an optical axis of the light reflected from the plane under test (3) and introduced to the polarized light reception unit (2) which are arranged symmetrically about a center axis O of the same optical system and configured so that they intersect at least once. The polarized light projection unit (1) includes an intensity distribution uniformizing optical system (1c) for uniformizing the intensity distribution of the light emitted from a light source (1a). A light flux cross section of a predetermined range at a pupil position (1d) of the intensity distribution uniformizing optical system (1c) is projected to the plane under test (3).

Description

Specification

Polarimeter

Technical field

The present invention relates to a polarization measuring device.

Background art

A polarization measuring device is a device that irradiates a test surface with polarized light, receives reflected light, and measures a change in the polarization state of the received light. Used to detect the physical properties of!

FIG. 1 is an explanatory diagram showing an example of a basic configuration of a conventional polarization measuring device. For convenience, an optical member such as a lens for condensing (imaging) light on a predetermined surface is omitted.

[0004] The polarization measuring apparatus has a light source 51 and a polarizer 52 as a polarization projection unit on one optical path for projecting polarized light onto the test surface 53, and reflected from the test surface 53. On the other optical path for receiving light, an analyzer 54 and a photodetector 55 are provided as polarized light receiving parts.

[0005] Then, polarized light is incident on the test surface obliquely through the light source 51 and the polarizer 52, and the reflected light from the test surface 3 is incident on the analyzer 54, and the polarized light that has passed through the analyzer 54 Is detected by the photodetector 55, and changes in the polarization state due to reflection on the surface 53 to be detected are detected based on the measurement values obtained by the photodetector 55, and various physical properties of the specimen are detected based on the changes. (For example, absorption coefficient, film thickness, refractive index, etc.) (changes) can be detected.

[0006] For example, the relative reference position of the polarizer 52 and the analyzer 54 is determined in advance, and the polarizer 52 and the analyzer 54 are rotated around the respective optical axes when measuring the test object. The relative angle between the polarizer 52 and the analyzer 54 at which the intensity received by the optical detector 55 is minimum or maximum is detected, and the physical properties (changes) of the test object are determined from the relative angle. To detect.

[0007] Further, for example, a voltage control liquid crystal retarder (not shown) is further provided on the reflection optical path between the test surface 53 and the analyzer 54, and the voltage of the voltage control liquid crystal retarder is adjusted to adjust the analyzer 54. After that, the minimum value of the intensity received by the photodetector 55 is obtained, and various physical properties (changes) of the test object are detected from the voltage at that time.

As such a conventional polarization measuring apparatus, for example, as described in JP-A-2001-296182 There is a device.

However, in the conventional polarization measuring device, an optical system for condensing the polarized light and irradiating the test surface, and the reflected light from the test surface are collected and applied to the photodetector. Since the optical systems for guiding are arranged on separate optical paths, the optical path spreads in the direction of incidence and reflection with respect to the surface to be measured, resulting in an increase in size and a large space for the equipment. The space was narrowed. In such an apparatus, measurement must be performed in a state where the test object is fixed, and the use of the polarization state in the industrial product such as measurement of the film thickness or birefringence of the industrial crystal material is unavoidable. It was limited to measuring changes.

[0010] In addition, in the conventional polarization measuring device, the power of light emitting elements such as LD and LED is used as an illumination light source. However, these light emitting elements are not configured so that the light emitting points have a uniform shape. For this reason, if the configuration is such that the image of the light emission point is formed on the test surface, the intensity distribution of the illumination light varies greatly depending on the site of the test surface at the irradiation position, and the accuracy of the measured value deteriorates. It is easy to end up. In addition, since the irradiation area on the surface to be measured is small, a stable measurement value cannot be obtained because the relative area of dirt and dust on the surface to be measured is large. Furthermore, if the irradiation area on the test surface is small, the position adjustment between the test surface and the illumination light source, which is easily affected by the relative displacement between the test surface and the light emitting unit, becomes complicated. was there.

[0011] Therefore, an object of the present invention is to provide a polarization measuring device that can be remarkably reduced in size as compared with conventional polarization measuring devices and that can be easily expanded to applications other than industrial use.

Another object of the present invention is to provide a polarization measuring device that can improve measurement accuracy and perform stable measurement, and can eliminate the complexity of position adjustment between the surface to be measured and the illumination light source. It is to provide.

Disclosure of the invention

[0013] In order to achieve the above object, a polarization measuring device according to the present invention condenses the polarized light from the polarization projection unit, the polarization light receiving unit, and the polarization projection unit and irradiates the surface to be examined. A transmission optical system that condenses the light reflected by the surface and guides the light to the polarized light receiving unit, and the transmission optical system includes an optical axis of polarized light that irradiates the test surface from the polarized light projection unit, and the test target. The optical axis of the light reflected by the surface and guided to the polarized light receiving unit is symmetrically arranged with respect to the central axis of the same optical system. And is configured to intersect at least once.

In the polarization measuring apparatus of the present invention, the surface to be examined is irradiated from the polarization projection unit arranged symmetrically with respect to the central axis of the transmission optical system at the pupil position of the intensity distribution uniformizing optical system. It is preferable to include an elongated slit extending in a direction perpendicular to the same virtual plane including the optical axis of polarized light to be reflected and the optical axis of light reflected by the test surface and guided to the polarized light receiving unit. .

In the polarization measuring device of the present invention, the polarization projection unit is configured as a telecentric optical system at least on the emission side, and the polarization light receiving unit is separated from the polarization projection unit in the transmission optical system. An imaging optical system for forming an image at a position where the optical axis of polarized light irradiating the test surface and the optical axis of light reflected by the test surface and guided to the polarized light receiving unit intersect with the light receiving device Preferred to have! / ,.

[0016] Further, the polarization measuring device according to the present invention includes a polarization projection unit having a light source and a polarizer, a polarization light receiving unit having an analyzer and a light receiving device, and condensing the polarized light from the polarization projection unit. A transmission optical system that irradiates the surface and collects light reflected by the test surface and guides it to the polarized light receiving unit, and the transmission optical system irradiates the test surface from the polarized light projection unit The optical axis of polarized light and the optical axis of the light reflected by the test surface and guided to the polarized light receiving unit are arranged symmetrically with respect to the central axis of the same optical system and intersect at least once. The polarization projection unit includes an intensity distribution equalizing optical system that equalizes an intensity distribution of light emitted from the light source, and a light beam having a predetermined range at a pupil position of the intensity distribution equalizing optical system. The cross section is projected onto the test surface.

[0017] In the polarization measuring apparatus of the present invention, the transmission optical system emits the polarized light from the polarization projection unit so as to irradiate the surface to be measured obliquely, and is reflected on the surface to be measured. It is preferable to have a tip optical system configured to allow incident light to enter the inside. Further, in the polarization measuring device of the present invention, the tip optical system includes an irradiation light total reflection surface that totally reflects the light incident on the test surface toward the test surface, and is reflected by the test surface and enters the test light. It is preferable to be composed of a prism having a reflection light total reflection surface that totally reflects light!

[0018] In the polarization measuring device of the present invention, the transmission optical system is more than the tip optical system. And an optical axis of polarized light that irradiates the test surface from the polarized light projection unit at a position away from the test surface, and an optical axis of light that is reflected by the test surface and guided to the polarized light receiving unit. At least once, and configured so as to be parallel to the central axis of the transmission optical system, and the tip optical system is configured to make the incident light incident so that the polarized light from the polarization projection unit enters perpendicularly. A surface, an irradiation light total reflection surface that totally reflects light incident inside from the irradiation light incident surface toward the test surface, and an irradiation light that vertically emits the light totally reflected by the irradiation light total reflection surface An exit surface, a reflected light incident surface that vertically enters light reflected by the test surface, a reflected light total reflection surface that totally reflects light incident inside from the reflected light incident surface, and the reflected light total reflection And a reflected light exit surface for emitting the light totally reflected by the surface vertically. Has been Shi favored, Ru of Les,.

[0019] In the polarization measuring device of the present invention, the transmission optical system irradiates the test surface from the polarization projection unit at a position farther from the test surface than the tip optical system. And the optical axis of the light that is reflected by the test surface and guided to the polarized light receiving unit are inclined with respect to the central axis of the transmission optical system, and the tip optical system is The irradiation light total reflection surface that totally reflects the light incident on the inner surface toward the test surface, and the reflected light total reflection surface that reflects the light incident on the test surface and total reflection. It is preferable that it is composed of a prism.

[0020] In the polarization measuring apparatus of the present invention, the transmission optical system irradiates the test surface from the polarization projection unit at a position farther from the test surface than the tip optical system. And the optical axis of the light that is reflected by the test surface and guided to the polarized light receiving unit are inclined with respect to the central axis of the transmission optical system, and the tip optical system is The irradiation light total reflection surface that totally reflects the light incident inside from the irradiation light incident surface toward the test surface, and the irradiation light emission surface that vertically emits the light totally reflected by the irradiation light total reflection surface And a reflected light incident surface for vertically incidence of light reflected by the test surface, and a reflected light total reflection surface for totally reflecting light incident on the inside from the reflected light incident surface. It is preferable that

In the polarization measuring device of the present invention, the transmission optical system irradiates the test surface from the polarization projection unit at a position farther from the test surface than the tip optical system. An optical axis of polarized light that is reflected by the surface to be measured and guided to the polarized light receiving unit is inclined with respect to the central axis of the transmission optical system, and the tip optical An irradiation light incident surface on which the polarized light from the polarization projection unit is incident vertically; an irradiation light total reflection surface that totally reflects light incident on the irradiation light incident surface force toward the test surface; Irradiation light exit surface for emitting the light totally reflected by the illumination light total reflection surface vertically, reflected light entrance surface for allowing the light reflected by the test surface to enter vertically, and from the reflected light entrance surface to the inside It is preferable that the prism is constituted by a prism having a reflected light total reflection surface that totally reflects incident light, and a reflected light emission surface that vertically emits light totally reflected by the reflected light total reflection surface.

In the polarization measuring device of the present invention, the prism has a side total reflection prism having the irradiation light total reflection surface and the reflection light total reflection surface on side surfaces symmetrical to a central axis of the transmission optical system. It is preferable to be.

In the polarization measuring device of the present invention, an irradiation light total reflection surface that totally reflects incident irradiation light and a reflection light total reflection surface that totally reflects incident reflection light are respectively provided in the transmission optical system. It is preferable to have it at a plurality of locations on the side surface symmetrical to the central axis.

[0024] Further, in the polarization measuring apparatus of the present invention, it is preferable that the prism is made of a crystalline material.

In the polarization measuring device of the present invention, it is preferable that the prism is arranged so that the crystalline C-axis is parallel to the central axis direction of the transmission optical system.

In the polarization measuring apparatus of the present invention, it is preferable that the prism is arranged so that the crystalline C-axis is perpendicular to the central axis direction of the transmission optical system.

[0027] In the polarization measuring device of the present invention, the transmission optical system further applies polarization to the surface to be inspected from the polarization projection unit to the polarization projection unit side and the polarization light receiving unit side. It is preferable to have a relay optical system that crosses the optical axis of the light beam and the optical axis of the light reflected by the test surface and guided to the polarized light receiving unit.

[0028] According to the polarization measuring device of the present invention, it can be remarkably reduced in size compared to the conventional polarization measuring device, and for non-industrial uses, for example, medical uses such as inspection of tooth surface conditions, for example, However, it is easy to expand the application for use as an analytical instrument such as DNA chip inspection, etc., but it is possible to improve the measurement accuracy and perform stable measurement. A polarization measuring device that can eliminate the complication of the position adjustment can be obtained.

Brief Description of Drawings

FIG. 1 is an explanatory diagram showing an example of a basic configuration of a polarization measuring device of a conventional polarization measuring device.

FIG. 2 is a conceptual diagram showing a basic configuration of the polarization measuring device of the present invention.

FIG. 3 is a cross-sectional view along the optical axis showing the overall configuration of the polarization measuring apparatus according to the first embodiment of the present invention.

[FIG. 4] FIG. 4 is a conceptual diagram showing an enlarged configuration of a main part of FIG.

FIG. 5 is a cross-sectional view along the optical axis showing the overall configuration of the polarization measuring apparatus according to the second embodiment of the present invention.

FIG. 6 is a conceptual diagram showing a partially enlarged configuration of the main part of FIG.

FIG. 7 is an explanatory view showing a modification of the tip optical system in the polarization measuring device of the second embodiment.

FIG. 8 is an explanatory view showing another modification of the tip optical system in the polarization measuring device of the second embodiment.

[FIG. 9] FIGS. 9 (a) and 9 (b) are images of light emission points when a light emitting element such as an LD or LED is used as the light source of the polarization measuring device of the present invention shown in FIGS. It is explanatory drawing which shows the shape of.

[FIG. 10] FIG. 10 shows a configuration of the polarization measuring device of the present invention shown in FIGS. 2 to 5 when the image of the light emitting point as shown in FIG. 9 (b) is formed on the surface to be measured. FIG. 3 is an explanatory diagram conceptually showing the size of a relative area of dirt or dust on a test surface with respect to an image of a light emitting point.

FIG. 11 is a conceptual diagram showing a basic configuration of a polarization measuring apparatus according to a third embodiment of the present invention.

[FIG. 12] FIG. 12 shows the size of the image of the optical cross section at the pupil position of the intensity uniformizing optical system in the polarization measuring device shown in FIG. 11 in comparison with the size of the image of the light emitting point shown in FIG. It is an explanatory diagram.

FIG. 13 is a cross-sectional view along the optical axis showing the overall configuration of the polarization measuring apparatus according to the fourth embodiment of the present invention. FIG. 14 is a conceptual diagram showing an enlarged configuration of a main part of a transmission optical system in the polarization measuring device of FIG.

FIG. 15 is an explanatory diagram showing the path of light reflected by the test surface when the distance (working distance) from the test surface is different in the polarization measuring device of the fourth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Prior to the description of the embodiments, the function and effect of the present invention will be described.

FIG. 2 is a conceptual diagram showing a basic configuration of the polarization measuring apparatus of the present invention. The polarization measuring device of the present invention condenses the polarized light from the polarization projection unit 1, the polarization light receiving unit 2, and the polarization projection unit 1 in a spot shape and irradiates the test surface 3 and reflects it on the test surface 3. It has a transmission optical system 4 that collects the reflected light in the form of a spot and guides it to the polarized light receiving unit 2.

[0032] The polarization projection unit 1 includes a light source la and a polarizer lb such as a polarizing plate that converts light emitted from the light source la into predetermined polarization and a polarization beam splitter that transmits only predetermined polarization. A configuration is employed and configured to project polarized light.

The polarization light receiving unit 2 employs a conventionally known optical configuration including, for example, an analyzer 2 a such as a polarizing beam splitter or a rotatable analyzer plate and a light receiving device 2 b such as a photodetector,

The change of the polarization state of the light reflected at 3 can be detected. Note that the polarization projection unit 1 and the polarization light receiving unit 2 are not limited to the configuration shown in FIG. 2, and are conventionally employed in a polarization measuring apparatus.

A characteristic configuration of the present invention resides in the transmission optical system 4.

Unlike the conventional polarization measuring device disclosed in Japanese Patent Laid-Open No. 2001-296182, the polarization measuring device of the present invention includes a transmission optical system 4 in which the optical path of projection light and the optical path of reflected light are provided in a common optical system. Provided.

In order to project polarized light with a minimum spot onto the surface to be measured, it is necessary to collect the polarized light through an optical system. In addition, since this type of polarization measuring device projects polarized light obliquely onto the surface to be measured, the optical path of the projected light and the reflected light on the surface to be measured passes through a position off the central axis in the common optical system. .

Therefore, in the polarization measuring apparatus of the present invention, the transmission optical system 4 is irradiated from the polarization projection unit 1 to the test surface 3 in order to provide the optical path of the projection light and the optical path of the reflected light in a common optical system. Polarized light The axis and the optical axis of the light reflected from the test surface 3 and guided to the polarized light receiving unit 2 are arranged symmetrically with respect to the central axis O of the same optical system.

[0037] In addition, in order to collect the polarized light via the transmission optical system in which the optical path of the projection light and the optical path of the reflected light are provided as separate optical paths with the central axis of the same optical system being symmetrical, Since it is necessary to bend in a direction that intersects the axis, it is necessary to cross these optical paths at least once.

Therefore, in the polarization measuring device of the present invention, the optical axis of the polarized light irradiated from the polarization projection unit 1 to the test surface 3 and the optical axis of the light reflected by the test surface 3 and guided to the polarization light receiving unit 2 Are configured to cross at least once.

With this configuration, the optical path used for the projection light and the reflected light can be configured in an elongated shape, and it is not necessary to widen the optical path in the direction of incidence and reflection with respect to the test surface. In particular, the space used for the optical path of the projection light and the reflected light can be reduced in size. As a result, the application can be easily expanded to non-industrial uses, for example, medical uses such as inspection of the surface condition of teeth, and uses as analysis devices such as inspection of DNA chips.

[0039] Further, in the polarization measuring device of the present invention, the polarized light from the polarization projection unit 1 is emitted so as to irradiate the test surface 3 obliquely, and the light reflected by the test surface 3 is internally introduced. The transmission optical system 4 is equipped with a tip optical system (not shown in FIG. 2) configured to be incident. Specifically, the tip optical system includes an irradiation light total reflection surface that totally reflects light incident on the test surface toward the test surface, and a reflection that reflects light incident on the test surface after being reflected by the test surface. And a prism having a light total reflection surface.

[0040] As described above, when the prism having the irradiation light total reflection surface and the reflection light total reflection surface is provided as the tip optical system, the optical path used for the projection light and the reflection light is elongated while being covered. The surface can be irradiated obliquely at a large incident angle, and the same function as that of a conventional polarization measuring device can be easily exhibited.

[0041] In the polarization measuring apparatus of the present invention, it is preferable that the incident surface of the tip optical system is perpendicular to the incident light, and the exit surface is perpendicular to the emitted light. In this way, the incident angle and reflection angle with respect to the surface to be measured are determined only by the irradiation light total reflection surface and reflection light total reflection surface. Since it is not necessary to consider the light refraction at the entrance surface and the exit surface of the tip optical system, it is possible to measure the polarization state with high accuracy and little light loss on the surface to be measured.

Yes

Hereinafter, embodiments of the polarization measuring apparatus of the present invention will be described with reference to the drawings.

FIG. 3 is a cross-sectional view along the optical axis showing the overall configuration of the polarization measuring apparatus according to the first embodiment of the present invention. The polarization measuring apparatus according to the first embodiment condenses the polarized light from the polarization projection unit 1, the polarization light receiving unit 2, and the polarization projection unit 2 in a spot shape or a slit shape and irradiates the surface 3 to be examined. It has a transmission optical system 4 that condenses the light reflected by the surface 3 in a spot shape or slit shape and guides it to the polarized light receiving unit 2.

[0044] The polarization projection unit 1 may have any configuration as long as it can project linearly polarized light in the form of a spot or slit.

The polarization detector 2 may have any configuration as long as it can detect a change in polarization state.

[0045] The transmission optical system 4 includes a lens 41 that converts the polarized light from the polarization projection unit 1 into a parallel light beam, and a condensing lens that condenses the parallel light of the lens 41 force and projects it onto the test surface 3. 42 and a tip optical system 43. In addition, the transmission optical system 4 is an optical system in which the optical axis of the polarized light irradiated from the polarization projection unit 1 to the test surface 3 is the same as the optical axis of the light reflected by the test surface 3 and guided to the polarization light receiving unit 2. It is configured to be arranged symmetrically with respect to the central axis O of the system. Further, the transmission optical system 4 includes a lens 41 having an optical axis of polarized light radiated from the polarization projection unit 1 to the test surface 3 and an optical axis of light reflected from the test surface 3 and guided to the polarization light receiving unit 2. And a converging lens 42 so as to intersect once.

In FIG. 3, CP is an optical axis of polarized light radiated from the polarization projection unit 1 to the test surface 3 and an optical axis of light reflected by the test surface 3 and guided to the polarization light receiving unit 2. The crossing position is shown.

FIG. 4 is an enlarged conceptual diagram showing the configuration of the main part of FIG. In FIG. 4, for convenience, the polarization projection unit 1 is conceptually shown as having a polarizer 1A, and the polarization light receiving unit 2 is branched by a polarization beam splitter 2A and a polarization beam splitter 2A. This is conceptually shown as a configuration having photodetectors 2B1 and 2B2 arranged in the optical path. Of course, the polarization projection unit 1, polarization receiver The optical unit 2 may have the same configuration as in FIG.

The optical axis of polarized light that exits the condensing lens 42 and enters the tip optical system 43 is parallel to the central axis O of the transmission optical system 4. Further, the optical axis of the light that exits from the tip optical system 43 and enters the condenser lens 42 is also parallel to the central axis O of the transmission optical system 4. The tip optical system 43 includes an irradiation light incident surface 43a, an irradiation light total reflection surface 43b, an irradiation light output surface 43c, a reflected light incident surface 43d, a reflected light total reflection surface 43e, and a reflected light output surface 43f. It consists of a prism.

The irradiation light incident surface 43 a is arranged perpendicular to the central axis O of the transmission optical system 4. The polarized light emitted from the polarization projection unit 1 and passed through the lens 41 and the condenser lens 42 is vertically incident. The irradiation light total reflection surface 43b is configured to totally reflect the light incident inside from the irradiation light incident surface 43a toward the test surface 3. The irradiation light exit surface 43c is configured to emit vertically the light totally reflected by the irradiation light total reflection surface 43b. The reflected light incident surface 43d is configured so that the light reflected by the test surface 3 is incident vertically. The reflected light total reflection surface 43e is configured to totally reflect the light incident on the inside from the reflected light incident surface 43d. The reflected light emitting surface 43f is provided at a position symmetrical to the central axis O of the transmission optical system 4 on the same plane as the irradiated light incident surface 43a, and vertically emits the light totally reflected by the reflected light total reflection surface 43e. It is configured to let you.

[0050] According to the polarization measuring apparatus of the first embodiment configured as described above, the polarization from the polarization projection unit 1 is bent in the optical path via the lens 41 of the transmission optical system 4, and is transmitted to the lens 42. Incident light is incident on the irradiation light incident surface 43 a of the prism 43 perpendicularly while being condensed through the condenser lens 42. The polarized light incident on the irradiation light incident surface 43a is totally reflected toward the test surface 3 by the irradiation light total reflection surface 43b. The light totally reflected by the irradiation light total reflection surface 43b is emitted vertically through the irradiation light emission surface 43c, and is incident at a predetermined incident angle at the position intersecting with the central axis O of the transmission optical system 4 ′ on the test surface 3. Incident at.

[0051] The light reflected by the surface to be inspected 3 travels along the optical path opposite to the irradiation light with the central axis O of the transmission optical system 4 as symmetric. That is, the light reflected by the test surface 3 enters the reflected light incident surface 43d of the prism 43 vertically. The light incident inside from the reflected light incident surface 43d is totally reflected by the reflected light total reflection surface 43e. At this time, the optical axis of the light totally reflected by the reflected light total reflection surface 43e is the transmission optical Parallel to the central axis O of system 4. Further, the light totally reflected by the reflected light total reflection surface 43e is emitted vertically through the reflected light emission surface 43f and enters the condenser lens. The light incident on the condensing lens 42 is incident on the lens 41 with its optical path bent. At this time, the optical axis of the polarized light irradiated from the polarized light projection unit 1 to the test surface 3 and the optical axis of the light reflected by the test surface 3 and guided to the polarized light receiving unit 2 intersect at the intersection position CP. The light incident on the lens 41 is collected at the intermediate image position S12. The light condensed at the intermediate imaging position S12 enters the polarization light receiving unit 2 and the polarization state is detected via the polarization light reception unit 2.

Therefore, according to the polarization measuring apparatus of the first embodiment, the transmission optical system 4 is configured in an elongated shape by providing the optical path used for the projection light and the reflected light in the same transmission optical system 4. Since it is not necessary to widen the optical path in the incident and reflection directions with respect to the surface to be measured, the space used for the optical path of the projection light and the reflected light can be significantly reduced as compared with the conventional polarization measuring device. As a result, the application can be easily expanded to non-industrial uses, for example, medical uses such as inspection of tooth surface conditions, and uses as analysis devices such as DNA chip inspection.

[0053] Since the prism 43 having the irradiation light total reflection surface 43b and the reflected light total reflection surface 43e is provided as the tip optical system, the optical path used for the projection light and the reflection light is elongated, It is possible to irradiate the test surface obliquely at a large incident angle, and it becomes easy to exert the same function as a conventional polarization measuring device.

[0054] Further, the irradiation light incident surface 43a and the reflected light incident surface 43d of the prism 43 are configured to be perpendicular to the incident light, respectively, and the irradiation light emission surface 43c and the reflected light emission surface 43f are arranged. Are configured to be perpendicular to the emitted light. For this reason, the incident angle and the reflection angle with respect to the test surface 3 can be determined only by the irradiation light total reflection surface 43b and the reflection light total reflection surface 43e, and on the incident surface and the output surface of the prism 43 which is the tip optical system. Since it is not necessary to consider the refraction of light, it is possible to measure the polarization state of the surface 3 to be measured with high accuracy and with little light loss.

Note that the prism 43 can be made of quartz. The prism 43 can also be made of a crystalline material. In that case, the prism 43 is preferably arranged so that the crystalline C-axis is parallel to the direction of the central axis O of the transmission optical system 4. Or The prism 43 may be arranged so that the crystalline C axis is perpendicular to the central axis O direction of the transmission optical system 4. By doing so, since the polarization direction and the crystal axis can be made to coincide with each other, it is possible to measure the polarization state with higher accuracy and less light loss.

[0056] In addition, in the polarization measuring device of the first embodiment shown in Figs. 2 and 3, the transmission optical system 4 is further polarized and projected onto the polarization projection unit 1 side and the polarization light receiving unit 2 side according to the application. One or more relay optical systems are provided to cross the optical axis of the polarized light radiated from the part 1 to the test surface 3 and the optical axis of the light reflected from the test surface 3 and guided to the polarized light receiving part 2 and long. An optical system may be configured.

FIG. 5 is a cross-sectional view taken along the optical axis showing the overall configuration of the polarization measuring apparatus which is a force and a second embodiment of the present invention. The polarization measuring apparatus of the second embodiment condenses the polarized light from the polarization projection unit 1, the polarization light receiving unit 2, and the polarization projection unit 2 in a spot shape and irradiates the test surface 3 with the test surface 3. It has a transmission optical system 4 'that collects the reflected light in a spot shape and guides it to the polarized light receiving unit 2.

The configurations of the polarization projection unit 1 and the polarization light receiving unit 2 are the same as those in the first embodiment shown in FIG.

[0059] The transmission optical system 4 'includes a relay optical system including a lens 41', a lens 42 ', and a lens 43', a lens 44, a lens 45, a lens 46, and a tip optical system 47. Is configured with

[0060] The transmission optical system 4 'includes an optical axis of polarized light radiated from the polarization projection unit 1 to the test surface 3, and an optical axis of light reflected by the test surface 3 and guided to the polarization light receiving unit 2. Are arranged symmetrically with respect to the central axis O of the same optical system. Further, the transmission optical system 4 ′ includes a lens having an optical axis of polarized light radiated from the polarization projection unit 1 to the test surface 3 and an optical axis of light reflected from the test surface 3 and guided to the polarization light receiving unit 2. It is configured to intersect two times in total, once through 44 ′, 45 ′, 46 ′ and the tip optical system 47 ′, and once through the relay optical system. In FIG. 5, reference numeral 48 'denotes a holding frame for holding the lenses 44', 45 ', 46', and 49 'denotes a lens barrel that holds the relay optical system and the holding frame 48'. CP1 and CP2 indicate positions where the optical axis of the polarized light irradiated from the polarization projection unit 1 to the test surface 3 intersects with the optical axis of the light reflected by the test surface 3 and guided to the polarized light receiving unit 2. ing.

FIG. 6 is a conceptual diagram showing a partially enlarged configuration of the main part of FIG. The relay optical system is The polarized light condensed at the intermediate imaging position SI 1 is condensed at the intermediate imaging position S21. The lenses 44 ', 45', 46 'are optical paths so as to be inclined with respect to the central axis O of the transmission optical system so as to project the polarized light condensed at the intermediate imaging position S21 onto the test surface 3. Is bent and emitted toward the tip optical system 47 ′.

[0062] The tip optical system 47 'includes an irradiation light incident surface 47a', an irradiation light total reflection surface 47b ', and an irradiation light emission surface.

47c ′, a reflected light incident surface 47d ′, a reflected light total reflection surface 47e ′, and a side surface reflecting prism having a reflected light exit surface 47f ′.

[0063] The irradiation light incident surface 47a 'is arranged perpendicular to the central axis O of the transmission optical system 4'.

The polarized light emitted from the polarization projection unit 1 and incident through the relay optical system and the lenses 44 ′, 45 ′, and 46 ′ is incident obliquely. The irradiation light total reflection surface 47b ′ is configured to totally reflect the light incident inside from the irradiation light incident surface 47a ′ toward the test surface 3. The irradiation light exit surface 47c ′ is arranged perpendicular to the central axis O of the transmission optical system 4 ′. The light totally reflected by the irradiated light total reflection surface 47b ′ is configured to be emitted obliquely. The reflected light incident surface 47d ′ is provided at a position symmetrical to the central axis O of the transmission optical system 4 ′ in the same plane as the irradiation light total reflection surface 47c ′, and obliquely enters the light reflected by the test surface 3. It is configured to shoot. The reflected light total reflection surface 47e ′ is provided on the side surface symmetrical to the irradiation light total reflection surface 47b ′ and the central axis O of the transmission optical system 4 ′. It is configured to reflect. The reflected light exit surface 47f ′ is symmetric with respect to the central axis O of the transmission optical system 4 ′ in the same plane as the incident light incident surface 47a ′, and is provided near or substantially at the same position as the irradiated light incident surface 47a ′. It is configured so that the light totally reflected by the reflected light total reflection surface 47e 'is emitted obliquely!

In the examples of FIGS. 5 and 6, the irradiation light incident surface 47a ′ and the reflected light emission surface 47f ′ are overlapped at the same position, and the position force of the overlapped surface is detected from the polarization projection unit 1. This is a position CP1 where the optical axis of the polarized light irradiating the surface 3 intersects the optical axis of the light reflected by the surface 3 to be detected and guided to the polarized light receiving unit 2.

[0065] The irradiation light incident surface 47a 'and the reflected light emission surface 47f' are not overlapped at the same position, and the optical axis of polarized light irradiating the surface 3 to be measured from the polarization projection unit 1 and the surface to be measured Position CP1 where the optical axis of the light reflected by 3 and guided to the polarized light receiving section 2 intersects is located inside or outside the tip optical system 47 ′. Configured to do! /, Even! /.

[0066] According to the polarization measuring apparatus of the second embodiment configured as described above, the polarization from the polarization projection unit 1 is collected at the intermediate imaging position S21 via the relay optical system of the transmission optical system 4 '. After shining, it enters the lens 43 ′ at a position off the central axis O of the transmission optical system 4 ′. The light incident on the lens 43 ′ is obliquely incident on the irradiation light incident surface 47a ′ of the prism 47 ′ while being condensed through the lenses 44 ′ and 45 ′. The polarized light incident on the irradiation light incident surface 47a ′ is refracted by a predetermined amount to reach the irradiation light total reflection surface 47b ′, and is totally reflected toward the test surface 3 by the irradiation light total reflection surface 47b ′. The light totally reflected by the irradiation light total reflection surface 47 is emitted obliquely through the irradiation light emission surface 47c ′, refracted by a predetermined amount, and intersects the central axis O of the transmission optical system 4 ′ on the test surface 3. It is incident at a predetermined angle of incidence.

[0067] The light reflected by the surface to be inspected 3 travels in the direction opposite to the irradiation light with the central axis O of the transmission optical system 4 'as symmetric. That is, the light reflected by the test surface 3 is obliquely incident on the reflected light incident surface 47d ′ of the prism 47 ′. The light incident on the reflected light incident surface 47d ′ is refracted by a predetermined amount, reaches the reflected light total reflection surface 47e ′, and is totally reflected by the reflected light total reflection surface 47e ′. Further, the light totally reflected by the reflected light total reflection surface 47e ′ is emitted obliquely through the reflected light emission surface 47f ′, refracted by a predetermined amount, and enters the lens 46 ′. At this time, the optical axis of the polarized light irradiated from the polarized light projection unit 1 to the test surface 3 and the optical axis of the light reflected by the test surface 3 and guided to the polarized light receiving unit 2 intersect at the intersection position CP1. The light incident on the lens 46 'passes through the lenses 45' and 44 'and is collected at the intermediate image position S22. The light condensed at the intermediate imaging position S22 is condensed at the intermediate imaging position S12 via the relay optical system. At this time, the optical axis of the polarization irradiated from the polarization projection unit 1 to the test surface 3 and the optical axis of the light reflected by the test surface 3 and guided to the polarization light receiving unit 2 intersect at the intersection position CP2. . The light collected at the intermediate imaging position S 12 enters the polarization light receiving unit 2, and the polarization state is detected via the polarization light reception unit 2.

Therefore, according to the polarization measuring device of the second embodiment, the optical path used for the projection light and the reflected light is provided in the same transmission optical system 4 ′, so that the transmission optical system 4 ′ is elongated. Since the optical path does not need to be widened in the direction of incidence and reflection on the surface to be measured, the space used for the optical path of the projected light and reflected light can be significantly reduced compared to conventional polarization measuring devices. . As a result, for non-industrial applications, for example, inspection of tooth surface conditions, etc. Applications can be easily expanded for medical use, for example, as an analytical device such as DNA chip inspection.

[0069] Further, as the tip optical system, the side surface reflecting prism 47 'having the irradiation light total reflection surface 47b' and the reflection light total reflection surface 47e 'is provided. While the optical path used for reflected light is elongated, it can be irradiated obliquely at a large incident angle with respect to the surface to be measured, and functions similar to those of a conventional polarization measuring device can be easily exhibited.

[0070] Note that the prism 47 'can be made of quartz. The prism 47 'can be made of a crystalline material. In that case, it is preferable that the prism 47 ′ is arranged so that the crystalline C-axis is parallel to the direction of the central axis O of the transmission optical system 4 ′. Alternatively, the prism 47 ′ may be arranged so that the crystalline C axis is perpendicular to the central axis O direction of the transmission optical system 4 ′. By doing so, the polarization direction and the crystal axis cannot be made coincident, but inside the prism 47 ', the optical path of the polarized light that irradiates the test surface 3 and the optical path of the light reflected by the test surface 3 Therefore, it is possible to measure the polarization state with higher accuracy and reliability.

In the polarization measuring device of the second embodiment shown in FIG. 5, the transmission optical system 4 ′ is provided from the polarization projection unit 1 to the test surface 3 on the polarization projection unit 1 side and the polarization light receiving unit 2 side. Although the relay optical system is configured to cross the optical axis of the polarized light to be irradiated and the optical axis of the light reflected by the test surface 3 and guided to the polarized light receiving unit 2, the transmission optical system 4 ′ has such a configuration. The relay optical system may not be provided. Alternatively, the transmission optical system 4 ′ may be provided with a plurality of such relay optical systems depending on the application to form a long optical system.

[0072] Further, as a tip optical system used in the polarization measuring device of the second embodiment, instead of the side reflecting prism 4 7 ', as shown in FIG. The reflected light total reflection surface 47bl ", 47b2" and the reflected light total reflection surface 47el ", 47e2" which totally reflects the incident reflected light. May be used as the side reflecting prisms 47 "having a plurality of side faces symmetrical to the central axis O of the transmission optical system 4 '. The light exit surface 47c ", the reflected light entrance surface 47d", and the reflected light exit surface 47f "are the illumination light entrance surface 47a ', the illumination light exit surface 47c', and the reflected light entrance surface of the side reflecting prism 47 'shown in FIG. 47d ' Thus, the configuration is almost the same as that of the reflected light emitting surface 47f ′. In FIG. 7, CP11, CP12, and CP13 indicate the optical axis of the polarized light irradiated from the polarization projection unit 1 to the test surface 3, and the light reflected from the test surface 3 and guided to the polarization light receiving unit 2. The position where the axis intersects is shown.

[0073] If the side reflecting prism 47 "is used, the thinned tip optical system can be made long in the direction of the central axis O of the transmission optical system 4 ', and it is difficult to make a space around the test surface 3 It is advantageous for the measurement of the case.

[0074] Further, as a tip optical system used in the polarization measuring device of the second embodiment, instead of the side reflecting prism 47 ', it is internally reflected a plurality of times (as shown in FIG. 8, three times for convenience) as shown in FIG. Thus, the incident light total reflection surface 47b ", 47b2" ', 47b3 "' that totally reflects the incident illumination light and the reflected light total reflection surface 47el" ', 47e2 "', Polarized light incident on the transmission optical system 4 ′ at an angle with respect to the central axis O of the transmission optical system 4 ′. Light total reflection surface 4 7b3 "'Irradiated light exit surface 47c"' that emits light that is totally reflected by light, and reflected light entrance surface 47d "'that makes light reflected by the test surface 3 enter vertically A side reflecting prism having a reflected light emitting surface 47f "'that vertically emits the light totally reflected by the light total reflecting surface 47e3"' may be used.

[0075] If the side reflecting prism 47 "'is used, the entrance surface of the tip optical system is perpendicular to the incident light, the exit surface is perpendicular to the exit light, and the incident angle and reflection angle with respect to the test surface 3 are It is determined only by the irradiation light total reflection surface and the reflection light total reflection surface, and it is not necessary to consider the light refraction at the entrance surface and the exit surface of the tip optical system. The polarization state can be measured.

By the way, in the polarization measuring apparatus of the present invention described above, when a light emitting element such as LD or LED is used as the light source la, the light emitting element is, for example, as shown in FIGS. 9 (a) and 9 (b). The light emitting points are not configured to have a uniform shape. For this reason, in the above-described polarization measuring device according to the present invention, when the light emission point image is formed on the test surface, a large difference occurs in the light intensity distribution depending on the part of the test surface at the irradiation position. The accuracy of the measured value of reflected light is likely to deteriorate. In addition, since the irradiation area on the test surface is small, stable measurements can be obtained as the relative area of dirt and dust on the test surface increases as shown in Fig. 10. I can't. Furthermore, if the irradiation area on the test surface is small, the position adjustment between the test surface and the illumination light source, which is greatly affected by the relative displacement between the test surface and the light emitting unit, becomes complicated.

Therefore, the present applicant has conceived a polarization measuring device in which the following configuration is added to the configuration of the polarization measuring device according to the present invention.

FIG. 11 is a conceptual diagram showing the basic configuration of this improved polarization measuring device according to the present invention, and FIG. 12 is an optical cross section at the pupil position of the intensity uniformizing optical system in the polarization measuring device shown in FIG. FIG. 10 is an explanatory diagram showing the size of the image in comparison with the size of the image of the light emitting point shown in FIG. Note that the same components as those of the polarization measuring apparatus shown in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted.

In this improved polarization measuring apparatus, the polarization projection unit 1 is configured to have an intensity distribution uniformizing optical system lc that uniformizes the intensity distribution of light emitted from the light source la. Further, the light beam cross-sectional force S in a predetermined range at the pupil position I d of the intensity distribution uniformizing optical system lc is projected onto the test surface 3. In this way, even if the intensity distribution on the light emitting surface of the light source la is non-uniform, the test surface 3 is irradiated with light of uniform intensity, improving the accuracy of the measurement values obtained from the irradiated surface. Therefore, stable measurement can be performed.

[0080] Further, as shown in FIG. 12, since the irradiation area on the test surface 3 is enlarged, a stable measurement value can be obtained as the relative area of dirt and dust on the test surface 3 is reduced, Furthermore, even if there is a relative positional shift between the test surface 3 and the light emitting part, it becomes difficult to be affected, and the position adjustment between the test surface 3 and the light source la becomes easy.

In addition, the polarization measuring device of the present invention is directed from the polarization projection unit 1 arranged symmetrically with the central axis of the transmission optical system 4 to the test surface 3 at the pupil position Id of the intensity distribution uniformizing optical system lc. The direction perpendicular to the same virtual plane including the optical axis of the polarized light to be irradiated and the optical axis of the light reflected from the surface 3 to be detected and guided to the polarization receiver 2 (in FIG. Elongate slit Id, extending in the direction).

As described above, in the polarization measuring device, the polarized light is projected obliquely with respect to the test surface. For this reason, the reflected light from the test surface is also reflected obliquely. That is, in the transmission optical system 4 shown in FIG. 11, the outgoing light (that is, illumination light) and the incident light (that is, the reflection from the test surface 3) with respect to the surface 3 to be measured. (Irradiation) has a predetermined angle. At this time, along the same virtual plane including the optical axis of the polarized light irradiated from the polarization projection unit 1 to the test surface 3 and the optical axis of the light reflected by the test surface 3 and guided to the polarized light receiving unit 2, the center If the light beam illuminating the test surface 3 in a direction perpendicular to the axis O greatly expands, it cannot be emitted from the irradiation light exit surface of the transmission optical system 4 toward the test surface 3 and is reflected internally. Of the light reflected from the surface 3 to be measured, light that cannot enter the reflected light incident surface of the transmission optical system 4 is generated, and these lights enter the polarization receiver 2 and become flare, ghost, etc. It may cause the S / N ratio to deteriorate.

Therefore, when projecting a light beam cross section within a predetermined range at the pupil position Id of the intensity distribution uniformizing optical system lc onto the test surface 3, the emitted light (that is, illumination light) and the incident light with respect to the test surface 3 It is desirable to make the light beam cross-section in a shape that takes into account the angle of the reflected light (that is, the reflected light from the test surface 3).

Therefore, in the polarization measuring apparatus of the present invention, the polarization projection unit 1 is arranged at the pupil position Id of the intensity distribution uniformizing optical system lc symmetrically with the central axis O of the transmission optical system 4 to the test surface 3. Direction perpendicular to the same imaginary plane including the optical axis of the polarized light irradiating and the optical axis of the light reflected from the surface 3 to be detected and guided to the polarization receiver 2 (in FIG. 1, perpendicular to the paper surface) Elongate slits Id 'extending in the same direction.

In this way, the optical axis of the polarization irradiated from the polarization projection unit 1 to the test surface 3 and the optical axis of the light reflected from the test surface 3 and guided to the polarization light receiving unit 2 are the same. Since the illumination light does not spread in a direction along the virtual plane and perpendicular to the central axis O, the outgoing light (that is, the illumination light) and the incident light (that is, the illumination light from the test surface 3). As shown in Fig. 12, the illumination area for the test surface 3 can be expanded as much as possible and the noise-generating parts such as flares and ghosts can be cut without being affected by the angle of the reflected light). / N ratio is high! /, Brightness and polarization are detected.

In actual polarization measurement, the distance (working distance) between the test surface 3 and the front end surface of the transmission optical system 4 may vary. However, if the working distance varies, the imaging position of the reflected light may deviate from the light receiving device of the polarized light receiving unit 2, and the received light detection intensity may be uneven.

Therefore, in the polarization measuring device of the present invention, the polarization projection unit 1 is at least on the output side. The light receiving unit 2 is configured as a recentric optical system, and the polarized light receiving unit 2 is reflected by the optical axis of the polarized light irradiated from the polarized light projecting unit 1 to the test surface 3 and the test surface 3 in the transmission optical system 4 and reflected by the polarized light receiving unit 2. An image forming optical system 2c that forms an image of a position CP at which the optical axis of the light guided to the light receiving device 2b is formed.

In this way, even if the distance (working distance) from the test surface 3 is different for each measurement, any reflected light reflected by the test surface 3 is at the position CP in the transmission optical system 4. It forms an image and enters parallel to the imaging optical system 2c. At this time, the position CP is conjugate with the light receiving surface of the light receiving device 2b, and the image at the position P is formed on the light receiving device 2b via the imaging optical system 2c. For this reason, it is possible to detect a stable polarization state without causing unevenness in the received light detection intensity.

Hereinafter, a third embodiment of the polarization measuring device of the present invention will be described with reference to the drawings.

FIG. 13 is a cross-sectional view taken along the optical axis showing the overall configuration of the polarization measuring apparatus according to the third embodiment of the present invention. In the figure, the same symbols are used for the same members and portions as in the first embodiment. The polarization measuring apparatus according to the third embodiment is configured to collect the polarized light from the polarization projection unit 1, the polarization light receiving unit 2, and the polarization projection unit 2 and irradiate the test surface 3 with the light reflected by the test surface 3. It has a transmission optical system 4 that collects the light and guides it to the polarized light receiver 2.

The polarization projection unit 1 includes a light source la, a polarizer lb, an intensity distribution uniformizing optical system lc, and a slit Id ′, and is configured as a telecentric optical system on the exit side.

The polarizer lb includes a polarizing plate that converts light emitted from the light source la into predetermined polarization, a polarizing beam splitter that transmits only predetermined polarization, and the like.

[0093] The intensity distribution uniformizing optical system lc is composed of, for example, a condenser lens and has a function of uniformizing the intensity distribution of the light emitted from the light source la.

[0094] The slit Id 'is an optical axis of polarized light that irradiates the test surface 3 from the polarization projection unit 1 arranged symmetrically with respect to the central axis of the transmission optical system 4 at the pupil position Id of the intensity distribution uniformizing optical system lc. And a direction perpendicular to the same imaginary plane including the optical axis of the light reflected from the surface 3 to be measured and guided to the polarized light receiving unit 2 (in FIG. 13, the direction perpendicular to the paper surface). Is formed into an elongated shape

Then, the polarization projection unit 1 includes the slit Id ′ at the pupil position Id of the intensity distribution uniformizing optical system lc. The cross-sectional force of the light beam is configured to be projected onto the test surface 3.

Further, the polarization detection unit 2 includes an analyzer 2a, a light receiving device 2b, and an imaging optical system 2c.

The analyzer 2a is composed of, for example, a polarizing beam splitter or a rotatable analyzer plate.

[0098] The light receiving device 2b is configured by a photodetector or the like, detects a change in the polarization state due to reflection on the surface 3 to be detected from the intensity value of the received polarized light, and detects the detection based on the change. It is configured so that various physical properties of the object can be detected. If the analyzer 2a and the light receiving device 2b can detect the polarization state of the light reflected by the surface 3 to be detected, they are used in conventional polarization measuring devices! It is good even if you use a misaligned one.

In the transmission optical system 4, the imaging optical system 2c is an optical axis of polarized light that is irradiated from the polarization projection unit 1 to the test surface 3, and the light that is reflected by the test surface 3 and guided to the polarization light receiving unit 2. An image of a position CP where the axis intersects is formed on the light receiving device 2b.

[0100] The transmission optical system 4 includes a lens 41 that condenses the parallel light beam from the polarization projection unit 1 at the position CP, and a lens 42 that projects the light from the lens 41 into the test surface 3 as a parallel light beam. And a tip optical system 43.

[0101] The transmission optical system 4 includes an optical axis of polarized light radiated from the polarization projection unit 1 to the test surface 3, and an optical axis of light reflected by the test surface 3 and guided to the polarization light receiving unit 2. It is configured to be arranged symmetrically with respect to the central axis O of the same optical system!

[0102] Further, the transmission optical system 4 includes an optical axis of polarized light radiated from the polarization projection unit 1 to the test surface 3, and an optical axis of light reflected by the test surface 3 and guided to the polarization light receiving unit 2. It is configured to cross once at the position CP via the lens 41 and the lens 42! /.

FIG. 14 is a conceptual diagram showing an enlarged configuration of a main part of the transmission optical system 4 in the polarization measuring device of FIG. The optical axis of the polarized light that exits the lens 42 and enters the tip optical system 43 is parallel to the central axis O of the transmission optical system 4. Further, the optical axis of the light emitted from the tip optical system 43 and incident on the lens 42 is also parallel to the central axis O of the transmission optical system 4.

The leading optical system 43 includes an irradiation light incident surface 43a, an irradiation light total reflection surface 43b, an irradiation light emission surface 43c, a reflected light incident surface 43d, a reflected light total reflection surface 43e, and a reflected light emission. It consists of a prism with face 43f. [0105] The irradiation light incident surface 43a is arranged perpendicular to the central axis O of the transmission optical system 4. The polarized light emitted from the polarization projection unit 1 and passed through the lenses 41 and 42 is vertically incident. The irradiation light total reflection surface 43b is configured to totally reflect the light incident inside from the irradiation light incident surface 43a toward the test surface 3. The irradiation light exit surface 43c is configured to emit vertically the light totally reflected by the irradiation light total reflection surface 43b. The reflected light incident surface 43d is configured so that the light reflected by the test surface 3 is incident vertically. The reflected light total reflection surface 43e is configured to totally reflect the light incident inside from the reflected light incident surface 43d. The reflected light exit surface 43f is provided at a position symmetrical to the central axis O of the transmission optical system 4 in the same plane as the irradiated light incident surface 43a, and vertically reflects the light totally reflected by the reflected light total reflection surface 43e. It is comprised so that it may radiate | emit.

According to the polarization measuring device of the first embodiment configured as described above, the light emitted from the light source la in the polarization projection unit 1 is parallel through the condenser lens as the intensity distribution uniformizing optical system lc. After being converted into a light beam and converted into a predetermined linearly polarized light through the polarizer lb, it is emitted as an elongated flat light beam extending in a direction perpendicular to the paper surface through the slit Id ′.

[0107] The polarized light from the polarization projection unit 1 is bent in the optical path through the lens 41 of the transmission optical system 4 and enters the lens 42, and then enters the irradiation light incident surface 43a of the prism 43 through the lens 42. Incident vertically. The polarized light incident on the irradiation light incident surface 43a is totally reflected toward the test surface 3 by the irradiation light total reflection surface 43b. The light totally reflected by the irradiation light total reflection surface 43b is emitted vertically via the irradiation light emission surface 43c, and at a predetermined incident angle at a position intersecting the central axis O of the transmission optical system 4 ′ on the test surface 3. Incident.

[0108] The light reflected by the surface to be inspected 3 travels along the optical path opposite to the irradiation light with the central axis O of the transmission optical system 4 as symmetric. That is, the light reflected by the test surface 3 enters the reflected light incident surface 43d of the prism 43 vertically. The light incident inside from the reflected light incident surface 43d is totally reflected by the reflected light total reflection surface 43e. At this time, the optical axis of the light totally reflected by the reflected light total reflection surface 43e is parallel to the central axis O of the transmission optical system 4. Further, the light totally reflected by the reflected light total reflection surface 43e is emitted vertically through the reflected light emission surface 43f and enters the lens 42. The light incident on the lens 42 is incident on the lens 41 with its optical path bent. At this time, the polarization projection unit 1 The optical axis of polarized light applied to the test surface 3 and the optical axis of the light reflected by the test surface 3 and guided to the polarized light receiving unit 2 intersect at the intersection position CP. The light incident on the lens 41 enters the polarized light receiving unit 2 in the form of a parallel light beam.

The light incident on the polarized light receiving unit 2 is imaged on the light receiving device 2b via the imaging lens 2c. In addition, only predetermined linearly polarized light is transmitted through the analyzer 2a in the middle. The light receiving device 2b detects changes in the polarization state due to reflection on the test surface 3 from the intensity value of the received polarized light, and detects various physical properties of the test object based on the changes.

[0110] At this time, according to the polarization measuring apparatus of the third embodiment, the polarization projection unit 1 is configured to have the intensity distribution uniformizing optical system lc that uniformizes the intensity distribution of the light emitted from the light source la, Further, since the light beam cross-sectional force S in the predetermined range at the pupil position Id of the intensity distribution uniformizing optical system lc is projected onto the test surface 3, even if the intensity distribution on the light emitting surface of the light source la is non-uniform The test surface 3 is irradiated with light of uniform intensity, and the accuracy of the measurement values obtained from the irradiated surface is improved, and stable measurement can be performed.

[0111] Further, as shown in FIG. 12, the irradiation area on the test surface 3 is enlarged, so that a stable measurement value can be obtained as the relative area of dirt and dust on the test surface 3 is reduced. Furthermore, even if there is a relative positional shift between the test surface 3 and the light emitting portion, it becomes difficult to be affected, and the position adjustment between the test surface 3 and the light source la becomes easy.

In addition, according to the polarization measuring apparatus of the third embodiment, the polarization projection unit 1 arranged symmetrically with respect to the central axis of the transmission optical system 4 is examined at the pupil position Id of the intensity distribution uniformizing optical system lc. The direction perpendicular to the same virtual plane including the optical axis of the polarized light irradiating the surface 3 and the optical axis of the light reflected from the test surface 3 and guided to the polarized light receiving unit 2 (in FIG. (Elongated perpendicular direction) is provided with an elongated slit Id ', so that the polarization optical axis irradiates from the polarization projection unit 1 to the test surface 3 and the polarized light receiving unit reflected by the test surface 3 Since the illumination light does not spread in the direction perpendicular to the central axis O along the same virtual plane including the optical axis of the light guided to 2, the emitted light (that is, the illumination light) to the test surface 3 and As shown in Fig. 12, which is not affected by the angle of incident light (ie, reflected light from the test surface 3), the illumination area for the test surface 3 is expanded as much as possible. In addition, it is possible to cut out noise-generating parts such as flare and ghost, and it is possible to detect low brightness and polarization with high S / N ratio. [0113] Also, according to the polarization measuring apparatus of the third embodiment, the polarization projection unit 1 is configured as a telecentric optical system at least on the emission side, and the polarization light receiving unit 2 is a polarization projection unit in the transmission optical system 4. The image of the position CP where the optical axis of the polarized light radiated from 1 to the test surface 3 intersects the optical axis of the light reflected by the test surface 3 and guided to the polarization receiver 2 is formed on the light receiving device 2b. Since the image optical system 2c is included, for example, as shown in FIG. 15, even if the distance (working distance) from the test surface 3 differs for each measurement, any reflected light reflected by the test surface 3 An image is formed at the position CP in the transmission optical system 4 and enters the imaging optical system 2c in parallel. At this time, the position CP is conjugate with the light receiving surface of the light receiving device 2b, and the image at the position P is formed on the light receiving device 2b via the imaging optical system 2c. For this reason, even if the working distance changes, the image of the slit Id 'does not move, so even if there is uneven sensitivity within the light receiving surface of the light receiving device 2b, it is possible to detect a stable polarization state without being affected by it. Become.

[0114] In addition to the above-described effects, the polarization measuring device of the third embodiment has various functions and effects described in relation to the polarization measuring device of the first embodiment.

Therefore, according to the polarization measuring device of the third embodiment, it can be remarkably miniaturized as compared with the conventional polarization measuring device, and for non-industrial uses, for example, medical examination such as inspection of tooth surface condition. For example, it can be easily expanded for use as an analytical device such as DNA chip inspection, and it is possible to perform stable measurement with improved measurement accuracy. Thus, a polarization measuring device that can eliminate the complication of the positional adjustment is obtained.

Further, in the polarization measuring device of the third embodiment shown in FIGS. 11 and 13, the transmission optical system 4 is further provided on the polarization projection unit 1 side and the polarization light receiving unit 2 side according to the application. A long optical system is provided with one or more relay optical systems that cross the optical axis of polarized light radiated from 1 to the test surface 3 and the optical axis of the light reflected from the test surface 3 and guided to the polarized light receiving unit 2. You may configure the system.

Industrial applicability

[0117] The polarization measuring device of the present invention can be used in an engineering field in which a change in physical properties is required in real time, a medical field in which, for example, a dental surface condition is required, or a DNA chip. This is useful in the biological field where testing is required.

Claims

The scope of the claims

[1] A polarized light projecting unit, a polarized light receiving unit, and the polarized light receiving unit condensing the polarized light of the polarized light projecting unit force to irradiate the test surface and collecting the light reflected by the test surface. A transmission optical system that leads to

The transmission optical system has an optical system in which an optical axis of polarized light irradiating the test surface from the polarized light projection unit and an optical axis of light reflected by the test surface and guided to the polarized light receiving unit are the same. A polarization measuring device, characterized in that the polarization measuring device is arranged symmetrically with respect to the central axis, and is configured to intersect at least once.

[2] A polarization projection unit having a light source and a polarizer, a polarization light reception unit having an analyzer and a light receiving device, and condensing the polarized light from the polarization projection unit and irradiating the test surface, A transmission optical system that condenses the reflected light and guides it to the polarized light receiving unit,

The optical system in which the transmission optical system irradiates the test surface from the polarized light projection unit and the optical axis of the light reflected by the test surface and guided to the polarized light receiving unit are the same optical system The polarization projection unit has an intensity distribution homogenizing optical system that equalizes the intensity distribution of the light emitted from the light source, And

A polarization measuring apparatus characterized in that a light beam cross section within a predetermined range at a pupil position of the intensity distribution uniformizing optical system is projected onto the test surface.

[3] The optical axis of polarized light irradiating the test surface from the polarization projection unit disposed symmetrically with the central axis of the transmission optical system at the pupil position of the intensity distribution uniformizing optical system and the test surface 3. An elongated slit extending in a direction perpendicular to the same imaginary plane including the optical axis of the light reflected and guided to the polarized light receiving unit. Polarization measuring device.

[4] The polarization projection unit is configured as a telecentric optical system at least on the emission side, and the polarization light receiving unit includes an optical axis of polarized light that irradiates the test surface from the polarization projection unit in the transmission optical system, and The imaging optical system that forms an image on the light receiving device at a position where the optical axis of the light reflected by the test surface and guided to the polarized light receiving unit intersects the light receiving device. The polarization measuring device according to 1.

[5] The transmission optical system is

It has a tip optical system configured to emit the polarized light from the polarization projection unit so as to irradiate the test surface obliquely and to make the light reflected by the test surface enter inside. The polarization measuring device according to any one of claims 1 to 4, wherein

[6] The tip optical system is

Irradiation light total reflection surface that totally reflects the light incident on the test surface toward the test surface;

6. The polarization measuring device according to claim 5, wherein the polarization measuring device comprises a prism having a reflected light total reflection surface that reflects the light reflected by the test surface and totally reflects the light incident on the test surface.

[7] The transmission optical system is reflected by the test surface and an optical axis of polarized light irradiating the test surface from the polarization projection unit at a position farther from the test surface than the tip optical system. The optical axis of the light guided to the polarized light receiving unit is configured to be parallel to the central axis of the transmission optical system after intersecting at least once.

The tip optical system is

An irradiation light incident surface on which polarized light from the polarization projection unit is vertically incident;

An irradiation light total reflection surface that totally reflects light incident inside from the irradiation light incident surface toward the test surface; and an irradiation light emission surface that vertically emits the light totally reflected by the irradiation light total reflection surface; A reflected light incident surface on which the light reflected by the test surface is incident vertically;

A reflected light total reflection surface that totally reflects light incident inside from the reflected light incident surface; and a reflected light output surface that vertically emits light totally reflected by the reflected light total reflection surface. The polarization measuring device according to claim 5, wherein

[8] The transmission optical system is reflected by the test surface and an optical axis of polarized light radiated from the polarization projection unit to the test surface at a position farther from the test surface than the tip optical system. The optical axis of the light guided to the polarized light receiving unit is inclined with respect to the central axis of the transmission optical system,

The tip optical system is

Irradiation light total reflection surface that totally reflects the light incident on the test surface toward the test surface; 6. The polarization measuring device according to claim 5, wherein the polarization measuring device comprises a prism having a reflected light total reflection surface that reflects the light reflected by the test surface and totally reflects the light incident on the test surface.

[9] The transmission optical system is reflected by the test surface and an optical axis of polarized light radiated from the polarization projection unit to the test surface at a position farther from the test surface than the tip optical system. The optical axis of the light guided to the polarized light receiving unit is inclined with respect to the central axis of the transmission optical system,

The tip optical system is

An irradiation light total reflection surface that totally reflects light incident inside from the irradiation light incident surface toward the test surface; and an irradiation light emission surface that emits light totally reflected by the irradiation light total reflection surface vertically. A reflected light incident surface on which the light reflected by the test surface is incident vertically;

6. The polarization measuring device according to claim 5, comprising: a prism having: a reflected light total reflection surface that totally reflects light incident inside from the reflected light incident surface.

[10] The transmission optical system is reflected by the test surface and an optical axis of polarized light radiated from the polarization projection unit to the test surface at a position farther from the test surface than the tip optical system. The optical axis of the light guided to the polarized light receiving unit is inclined with respect to the central axis of the transmission optical system,

The tip optical system is

[11] The prism includes the transmission light system including the irradiation light total reflection surface and the reflected light total reflection surface. 11. The polarization measuring device according to claim 8, wherein the polarization measuring device is a side total reflection prism having a side surface symmetrical to the central axis.

[12] The irradiation light total reflection surface that totally reflects incident irradiation light and the reflection light total reflection surface that totally reflects incident reflection light are provided at a plurality of positions on side surfaces symmetrical to the central axis of the transmission optical system. 12. The polarization measuring device according to claim 11, wherein:

[13] The polarization measuring device according to any one of [6] to [12], wherein the prism is made of a crystalline material.

14. The polarization measuring apparatus according to claim 13, wherein the prism is arranged so that the crystalline C-axis is parallel to a central axis direction of the transmission optical system.

15. The polarization measuring device according to claim 13, wherein the prism is arranged so that the crystalline C-axis is perpendicular to a central axis direction of the transmission optical system.

[16] Further, the transmission optical system reflects the optical axis of polarized light irradiating the test surface from the polarization projection unit to the polarization projection unit side and the polarization light receiving unit side, and the test surface. 16. The polarization measuring device according to claim 1, further comprising a relay optical system that intersects an optical axis of light guided to the polarization light receiving unit.

[17] A projecting unit, a light receiving unit, and a transmission optical system that collects light from the projecting unit and irradiates the test surface and collects light reflected by the test surface and guides it to the light receiving unit Have

In the transmission optical system, the optical axis of the light irradiated from the projection unit to the test surface and the optical axis of the light reflected by the test surface and guided to the light receiving unit are the center of the same optical system. A polarization measuring device, characterized in that it is arranged symmetrically with an axis and is configured to intersect at least once.

[18] A projection unit having a light source, a polarized light receiving unit having an analyzer and a light receiving device, and condensing the light from the projection unit to irradiate the test surface and reflecting the light reflected by the test surface A transmission optical system that focuses the light and guides it to the polarized light receiving unit;

The optical axis of the light that the transmission optical system irradiates from the projection unit onto the test surface and the optical axis of the light that is reflected by the test surface and guided to the polarized light receiving unit are the same optical system. Arranged symmetrically with respect to the central axis and configured to intersect at least once, The projection unit has an intensity distribution uniformizing optical system that uniformizes the intensity distribution of light emitted from the light source, and