JP2008058336A - Optical element - Google Patents

Abstract

An optical element capable of detecting necessary and sufficient reflected light from a part of the outer surface of a molded optical element without requiring a new manufacturing process is provided.
An optical element includes an optically effective portion and a frame portion adjacent to the optically effective portion. On at least one surface of the optical element 1, the frame portion 1 b includes a plurality of planes that are not on the same plane and have different surface roughness. This makes it possible to selectively detect only the reflected light from the plane portion having a small surface roughness. In addition, it is easy to process a plurality of flat surfaces that are not on the same plane with different surface roughnesses by processing the corresponding surfaces of a molding die used for molding optical elements to a predetermined surface roughness. Therefore, a new manufacturing process is not required.
[Selection] Figure 1

Description

  The present invention relates to an optical element used for an optical head of a DVD, an optical recording apparatus for a computer or the like.

Conventionally, optical elements such as optical pickup devices for optical recording devices, such as optical discs, and storage lenses for music information, video information storage or computer data storage devices as known for CDs (compact discs) or DVDs are known. It has been. A plastic lens is frequently used as the optical element. When incorporating a lens into these pickups, it is necessary to detect the tilt of the lens and the required correction amount. In order to realize this, Patent Document 1 discloses the following method. That is, a flat portion having a normal line parallel to the optical axis of the lens is provided on the lens, and a reflecting portion that reflects only light in a predetermined wavelength band is formed on the flat portion. Then, the reflected light from the reflecting portion is detected to detect the tilt of the lens and the necessary correction amount.
JP 2001-34991 A

  In the conventional method described above, it is necessary to sequentially form an aluminum film and a dielectric film on the planar portion of the optical element (lens) to form a reflective portion, which increases the number of optical element manufacturing steps. In addition, when the outer peripheral portion outside the optically effective portion of the optical element has a complicated shape, it is difficult to form the film at a desired position.

  The present invention solves the above-described problems in the prior art and detects necessary and sufficient reflected light from a part of the outer surface of the optical element after molding without requiring a new manufacturing process. An object of the present invention is to provide an optical element capable of satisfying the requirements.

  In order to achieve the above object, the present invention has the following configuration.

  The optical element of the present invention is an optical element including an optically effective portion and a frame portion adjacent to the optically effective portion, and the frame portions have a surface roughness of at least one surface of the optical element. A plurality of planes that are not on the same plane are provided.

  According to the first optical element, it is possible to selectively detect only the reflected light from the plane portion having a small surface roughness. In addition, a plurality of planes that are not on the same plane with different surface roughnesses can be easily obtained by processing the corresponding surfaces of a molding die used for molding an optical element to a predetermined surface roughness. Therefore, a new manufacturing process is not required.

  In the first optical element, it is preferable that any of the plurality of planes not on the same plane is orthogonal to the optical axis of the optical element. As a result, the plane portion having the smaller surface roughness can be used as the reflecting surface, and the plane portion having the larger surface roughness can be used as the contact surface for holding the optical element on the holder.

  The second optical element of the present invention is an optical element comprising an optically effective portion and a frame portion adjacent to the optically effective portion, wherein the frame portion is the optical element on at least one surface of the optical element. It is characterized by having a flat portion having a surface roughness Ra of 0.1 μm or less, which is orthogonal to the optical axis of the element.

  According to the second optical element, it is possible to detect reflected light from a flat surface portion having a surface roughness Ra of 0.1 μm or less. In addition, the flat portion having such surface roughness can be easily formed by processing the corresponding surface of the molding die used for molding the optical element to a predetermined surface roughness. It does not require a simple manufacturing process.

  In the second optical element, on at least one surface of the optical element, the frame portion has a plurality of plane portions orthogonal to the optical axis of the optical element, and one of the plane portions is a surface. It is preferable that the roughness Ra is the planar portion having a size of 0.1 μm or less, and the surface roughness Ra of the remaining planar portions is larger than 0.1 μm. Thereby, only the reflected light from the plane part with surface roughness Ra of 0.1 μm or less can be selectively detected. Therefore, accurate detection can be performed.

  The third optical element of the present invention is an optical element comprising an optically effective portion and a frame portion adjacent to the optically effective portion, wherein the frame portion is the optical element on at least one surface of the optical element. The planar portion having the largest area among a plurality of planes not on the same plane orthogonal to the optical axis of the element is an optical reflecting surface.

  According to the third optical element, it is possible to detect the reflected light from the plane portion having the largest area. Moreover, since such a plane part can be easily formed by setting a corresponding surface of a molding die used for molding an optical element to a predetermined dimension, a new manufacturing process is not required. .

  Said 3rd optical element WHEREIN: The surface roughness Ra of the said 1st plane part is 0.1 micrometer or less among said several plane parts, The surface roughness of the remaining plane parts except the said 1st plane part It is preferable that Ra is larger than 0.1 μm. Thereby, it is possible to selectively detect only the reflected light from the first flat portion having the largest area and the surface roughness Ra of 0.1 μm or less. Therefore, accurate detection can be performed.

  A fourth optical element of the present invention is an optical element including an optically effective portion and a frame portion adjacent to the optically effective portion, and the frame portion is flush with at least one surface of the optical element. It has a plurality of surfaces that are not on top, and one of the plurality of surfaces is a plane part orthogonal to the optical axis of the optical element, and the rest are all inclined surfaces that are inclined with respect to the optical axis It is characterized by that.

  According to the fourth optical element, it is possible to selectively detect only the reflected light from the plane portion orthogonal to the optical axis of the optical element. In addition, such flat portions and inclined surfaces can be easily formed by setting the directions of the corresponding surfaces of the molding die used for molding the optical element to predetermined directions, so that new manufacturing is possible. No process is required.

  The fifth optical element of the present invention is an optical element having an optically effective portion and a frame portion adjacent to the optically effective portion, and the surface roughness is the same on at least one surface of the optical element. A plurality of planes that are not on a plane are provided, and a plane closest to the optically effective portion is an optical reflecting surface.

  According to the fifth optical element, the plane closest to the optically effective portion has less surface waviness than the other planes, and sufficient reflected light can be obtained as the optical reflecting surface. Since the object can be achieved by using the plane closest to the optically effective portion, no new manufacturing process is required.

  A sixth optical element of the present invention is an optical element comprising an optically effective portion and a frame portion adjacent to the optically effective portion, wherein the frame portion is the optical element on at least one surface of the optical element. It has a plurality of surfaces which are not on the same plane perpendicular to the optical axis of the element, and the radial dimension of one of the plane portions is 0.1 mm or more.

  According to the sixth optical element, it is possible to detect the reflected light from the plane portion having a radial dimension of 0.1 mm or more. Moreover, since such a plane part can be easily formed by setting a corresponding surface of a molding die used for molding an optical element to a predetermined dimension, a new manufacturing process is not required. .

  Said 6th optical element WHEREIN: The radial direction dimension of the remaining plane parts except said 1 plane part whose radial dimension is 0.1 mm or more among these several plane parts are all 0.1 mm. It is preferable that it is less than. As a result, it is possible to detect only the reflected light from the flat surface having a radial dimension of 0.1 mm or more. Therefore, accurate detection can be performed.

  Said 1st-6th optical element WHEREIN: It is preferable to have the part which resin or glass which is a material of an optical element exposed in the said plane part. Thereby, since a plane part can be used as a reflective surface without providing a reflective film, an optical element capable of detecting reflected light without increasing the number of manufacturing steps can be provided.

  According to the optical element of the present invention, it is possible to detect necessary and sufficient reflected light from the flat part provided on the frame part of the optical element after molding without requiring a new manufacturing process. Therefore, for example, when performing tilt detection of an optical element in a tilt detection apparatus or evaluation of aberration of an optical element by an interferometer, accurate adjustment and evaluation can be performed using reflected light from a flat portion of the optical element. Become.

  The optical element of the present invention will be specifically described below with reference to the drawings.

(Embodiment 1)
An optical element according to Embodiment 1 of the present invention will be described with reference to FIGS.

  FIG. 1 is a sectional view of an optical element 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the optical element 1 includes an optically effective portion 1 a that exhibits an original function as an optical element when a light beam enters, and a frame portion 1 b that is formed adjacent to the outside. The optically effective portion 1a has optically effective surfaces 2 and 3 that face each other and have a predetermined shape so as to exert a predetermined optical action on an incident light beam. The frame portion 1b includes, in order from the optically effective surfaces 2 and 3 side toward the radially outer side, flat portions 4a and 4b, inclined surfaces 5a and 5b, and flat portions 6a and 6b, which are adjacent to each other. Yes.

  The plane portions 4 a and 4 b adjacent to the optically effective surfaces 2 and 3 are planes perpendicular to the optical center axis (hereinafter referred to as “optical axis”) of the optical element 1. The slopes 5a and 5b constitute a part of a conical surface. The flat portions 6a and 6b adjacent to the inclined surfaces 5a and 5b protrude in the optical axis direction from the optically effective surfaces 2 and 3, respectively, so that the optically effective surfaces 2 and 3 are damaged in the optical element manufacturing process. It is preventing. The plane portions 6a and 6b are planes perpendicular to the optical axis because they serve as contact surfaces with the lens holder when the optical element 1 is incorporated in the lens holder of the pickup. The frame portion 1b needs to be as large as possible because of the need for a bonding margin with the lens holder and the need to make a large gate opening for pouring the molten resin when molding the optical element 1 by injection molding. Is done. The flat portions 4a and 4b have a small surface roughness in order to increase the reflectance when light is incident. On the other hand, the flat portions 6a and 6b have a large surface roughness so that when light is incident, the light is irregularly reflected without being reflected in a specific direction.

  FIG. 2 is a schematic configuration diagram of the tilt detection device of the optical element 1. The tilt detection apparatus includes a light source 11 that emits a light beam, a pinhole plate 12 having a pinhole 12a, a collimator lens 13, a beam splitter 14, a collimator lens 15, and a light receiving element 16 made of, for example, a CCD. .

  The divergent light emitted from the light source 11 and passed through the pinhole 12 a of the pinhole plate 12 is converted into a parallel light beam by the collimator lens 13, reflected by the beam splitter 14, and incident on the optical element 1. Of the light incident on the optical element 1, the light incident on the flat portion 4 a of the frame portion 1 b enters the beam splitter 14. The light incident on the flat portion 4 a is reflected here, passes through the beam splitter 14, is guided to the light receiving element 16 by the collimating lens 15, and forms a single condensing spot on the light receiving element 16. The inclination of the optical element 1 can be detected by detecting the position of the condensed spot on the light receiving element 16. Accordingly, when the optical element 1 is assembled to the lens holder of the pickup, the inclination of the optical element 1 is corrected so that the position of the focused spot on the light receiving element 16 is at a predetermined position. Adhere to and fix. Accordingly, the optical element can be incorporated into the lens holder with a predetermined relative inclination.

  In the above description, the light incident on the flat surface portion 6a parallel to the flat surface portion 4a is irregularly reflected because the surface roughness is rough, so that a condensed spot is not substantially formed on the light receiving element 16. In addition, although light incident on the inclined surface 5a may be reflected here, similarly, a condensing spot is not substantially formed on the light receiving element 16. Therefore, it is possible to selectively detect only the reflected light from the flat surface portion 4a having a small surface roughness and use it for adjusting the tilt of the optical element 1.

  Further, in the aberration evaluation of the optical element 1 by the interferometer, the planar portion 4b is irradiated with laser light, tilt adjustment is performed using reflected light from the laser beam, and the optical element 1 is tilt-adjusted. By measuring the effective surface, it is possible to perform measurement evaluation with less error and less variation even in repeated measurement. Also in this case, the laser light incident on the flat surface portion 6b is irregularly reflected, and the light incident on the inclined surface 5b is reflected in different directions.

  As described above, the frame portion 1b of the optical element 1 of the present embodiment includes the flat portions 4a and 4b and the flat portions 6a and 6b orthogonal to the optical axis of the optical element 1, but the flat portion 4a, Since the surface roughness of 4b is smaller than that of the flat portions 6a and 6b, only the sufficient reflected light from the flat portions 4a and 4b is selectively used to detect the inclination of the optical element 1 and the aberration of the optical element by the interferometer. Evaluation can be made. The flat portions 4a and 4b and the flat portions 6a and 6b are surfaces from which the resin or glass that is the material of the optical element 1 is exposed, and it is not necessary to form a reflective film. Therefore, the plane portions 4a and 4b and the plane portions 6a and 6b can be easily formed by processing the corresponding surface of the molding die used for molding the optical element 1 to a predetermined surface roughness. No new manufacturing process is required.

  In addition, an antireflection film is formed on the optically effective portion in order to improve the transmittance, but it is necessary to devise so that the antireflection film is not formed on the optical reflection surfaces of the flat portions 4a and 4b. is there. Since the reflectance of the surface on which the antireflection film is formed is lowered, the light intensity of the spot image is lowered, and it is difficult to detect the inclination. However, the above-described problem can be solved by having a part of the optical reflecting surface where the resin or glass as the material of the optical element is exposed.

  In the first embodiment, the surface roughness of the entire surface of the flat portions 4a and 4b is reduced. However, only a portion of the surface roughness may be reduced, and in this case, the same effect as described above can be obtained. It is done.

(Embodiment 2)
FIG. 3 is a cross-sectional view of the optical element 1 according to Embodiment 2 of the present invention. The basic structure of the optical element 1 of the second embodiment is the same as that of the optical element of the first embodiment. The same components as those of the optical element 1 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  Similar to the optical element 1 shown in FIG. 1, the frame portion 1b includes, in order from the optically effective surfaces 2 and 3 toward the radially outer side, flat portions 4a and 4b, inclined surfaces 5a and 5b, and flat portions 6a and 6b. And have. The flat portions 4a and 4b and the flat portions 6a and 6b are orthogonal to the optical axis. As shown in FIG. 3, assuming that the widths of the planar portions 4a and 4b and the planar portions 6a and 6b in the radial direction are the widths 4A and 4B and the widths 6A and 6B, respectively, in the example of the second embodiment, 4A = 0.3 mm, 6A = 0.15 mm. Further, the surface roughness Ra = 0.08 μm of the flat surface portion 4a and the surface roughness Ra = 5 μm of the flat surface portion 6a were set.

  When the optical element 1 of the present embodiment is applied to the tilt detection apparatus shown in FIG. 2, the light incident on the optical element 1 is reflected by the optical effective surface 2 and the flat portion 4a. At this time, the light incident on the flat portion 6a is diffusely reflected and diffused because the surface roughness of the flat portion 6a is rough. The light reflected by the flat surface portion 4 a passes through the beam splitter 14 and is guided to the light receiving element 16 by the collimating lens 15, thereby forming a single condensing spot on the light receiving element 16. The inclination of the optical element 1 can be detected by detecting the position of the condensed spot on the light receiving element 16.

  Here, Table 1 shows how the condensing spot changes on the light receiving element 16 when the surface roughness Ra of the flat surface portion 4a is changed in the above embodiment.

  In Table 1, “◯” indicates that a good condensing spot is formed, “×” indicates that a condensing spot is not formed, and “Δ” indicates that the condensing spot is blurred. 1 indicates that trouble is detected in the inclination detection of 1.

  From the results in Table 1, it was found that a good light spot was obtained when the surface roughness Ra was 0.1 μm or less. In the above embodiment, since the surface roughness Ra of the flat portion 6a is 0.12 μm or more, the reflected light from the flat portion 6a may not form a condensing spot or may slightly form a condensing spot. However, since the amount of light is small compared to the focused spot by the reflected light on the flat surface portion 4a, the level is ignored.

  When there are a plurality of plane portions that are not on the same plane orthogonal to the optical axis, the surface roughness Ra of all the plurality of plane portions can be set to 0.1 μm or less. For example, in the above example, both the surface roughness Ra of the flat portion 4a and the flat portion 6a can be set to 0.1 μm or less. In this case, it is necessary to form one condensing spot in which each reflected light from the plane part 4a and the plane part 6a is common. However, if the perpendicularity of each of the plane part 4a and the plane part 6a with respect to the optical axis does not match, the spot image may be distorted or enlarged, and a problem may occur in tilt detection. Therefore, the surface for obtaining the reflected light is preferably one surface.

  Further, when the surface roughness Ra of each of the flat surface portion 4a and the flat surface portion 6a is set to 0.1 μm, when one flat surface portion is shielded and the other spot image is evaluated, it approaches the optical effective portion 1a. The spot image on the flat surface portion 4a was condensed as compared with that on the flat surface portion 6a, which was good. From our experiments, it has been clarified that as the distance from the optically effective part increases and the outer peripheral part is approached, undulation is likely to occur in the flat part. There is a difference in the focused spot image depending on the size of this undulation, and therefore, it is desirable that the plane portion closest to the optically effective portion of the optical element with less undulation of the plane portion is the optical reflecting surface.

  Even if there is only one surface for obtaining reflected light, if the flatness is poor, the spot image may be similarly distorted or enlarged. Therefore, the surface for obtaining the reflected light may be limited to a specific region where a predetermined flatness can be ensured. However, if the area of the surface for obtaining the reflection surface is too small, the amount of reflected light is insufficient and the condensing spot cannot be clearly seen. Therefore, generally, as described above, when the frame portion has a plurality of plane portions perpendicular to the optical axis, the surface roughness Ra of the plane portion having the largest area is set to 0.1 μm or less and used as a reflection surface. In addition, it is preferable that the surface roughness Ra of the other flat portion is larger than 0.1 μm (more preferably 0.14 μm or more).

  Further, in the aberration evaluation of the optical element 1 by the interferometer, the tilt of the optical element is adjusted using the reflected light from the optical element 1 when measurement is performed by irradiating the optical effective surface 3 with laser light. At this time, in the above example, since the width 4B> width 6B in the surface of the frame portion 1b on the optical effective surface 3 side, the surface roughness Ra of the flat portion 4b is 0.08 μm, and the surface roughness of the flat portion 6b. Ra was 3 μm. When laser light is irradiated, the tilt of the optical element 1 is adjusted using the reflected light from the flat surface portion 4b, and the tilt of the optical element 1 is adjusted, and then the optical effective surface is measured, thereby producing an error. Therefore, measurement evaluation with little variation even in repeated measurement is possible.

  As described above, the frame 1b of the optical element 1 according to the second embodiment includes the flat portions 4a and 4b and the flat portions 6a and 6b orthogonal to the optical axis, and the surface roughness Ra of the flat portions 4a and 4b. Is 0.1 μm or less, the surface roughness Ra of the flat portions 6a and 6b is larger than 0.1 μm, and the area of the flat portions 4a and 4b is larger than the area of the flat portions 6a and 6b, so that no reflective film is provided. The tilt detection of the optical element 1 and the aberration evaluation of the optical element by the interferometer can be performed by selectively using only the sufficient reflected light from the flat portions 4a and 4b. Such flat portions 4a and 4b are easily formed by processing the corresponding surface of the molding die used for molding the optical element 1 to a predetermined surface roughness and setting the dimensions appropriately. As a result, a new manufacturing process is not required.

(Embodiment 3)
FIG. 4 is a cross-sectional view of the optical element 1 according to Embodiment 3 of the present invention. The basic structure of the optical element 1 of the present embodiment is the same as that of the optical element of the first embodiment. The same components as those of the optical element 1 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  In the optical element 1 according to Embodiment 3, the surfaces 6a and 6b are inclined with respect to the optical axis, unlike the optical element shown in FIG. That is, in the frame portion 1b of the optical element 1 shown in FIG. 4, the plane portions 4a and 4b are planes orthogonal to the optical axis, and the other surfaces 5a, 6a, 5b and 6b are inclined with respect to the optical axis. ing.

  When the optical element 1 of the third embodiment is applied to the tilt detection apparatus shown in FIG. 2, the light incident on the optical element 1 is reflected by the optical effective surface 2, the flat portion 4a, and the inclined surfaces 5a and 6a. At this time, the reflected light from the flat surface portion 4 a passes through the beam splitter 14 and is guided to the light receiving element 16 by the collimating lens 15, thereby forming a single condensing spot on the light receiving element 16. The inclination of the optical element 1 can be detected by detecting the position of the condensed spot on the light receiving element 16.

  On the other hand, the reflected light from the inclined surfaces 5 a and 6 a does not substantially form a condensing spot on the light receiving element 16.

  Therefore, as in the first embodiment, the optical element 1 can be incorporated into the lens holder with a predetermined relative inclination.

  Further, in the aberration evaluation of the optical element 1 by the interferometer, the planar portion 4b is irradiated with laser light, tilt adjustment is performed using reflected light from the laser beam, and the optical element 1 is tilt-adjusted. By measuring the effective surface, it is possible to perform measurement evaluation with less error and less variation even in repeated measurement.

  As described above, the frame portion 1b of the optical element 1 according to the third embodiment includes the plane portions 4a and 4b orthogonal to the optical axis of the optical element 1, and the inclined surfaces 5a and 6a inclined with respect to the optical axis. 5b and 6b, without using a reflection film, selectively using only sufficient reflected light from the flat portions 4a and 4b, and detecting the inclination of the optical element 1 and evaluating the aberration of the optical element using an interferometer. It can be performed. Such flat portions 4a and 4b and inclined surfaces 5a, 6a, 5b and 6b can be easily formed by processing a molding die used for molding the optical element 1 into a predetermined shape. It does not require a simple manufacturing process.

(Embodiment 4)
FIG. 5 is a cross-sectional view of the optical element 1 according to Embodiment 4 of the present invention. The basic structure of the optical element 1 of the fifth embodiment is the same as that of the optical element of the first embodiment. The same components as those of the optical element 1 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  The optical element 1 according to the fifth embodiment has flat portions 4a, 6a, 8a and flat portions 4b, 6b, 8b orthogonal to the optical axis in the frame portion 1b.

  When the tilt detection apparatus shown in FIG. 2 is used to irradiate the optical element with laser light and perform tilt adjustment using reflected light from the flat surface, the light is condensed when the radial width of the flat surface is changed. Table 2 shows how the spots change.

  In Table 2, “◯” indicates that the condensing spot has a sufficient amount of light, “×” indicates that the condensing spot cannot be clearly confirmed due to insufficient amount of light, and “△” indicates the condensing spot. Although the amount of light that can be confirmed is not sufficient, each indicates that the tilt detection of the optical element 1 is hindered.

  From Table 2, it was found that if the radial width of the flat portion is 0.1 mm or more, the amount of reflected light can be sufficiently secured, and the focused spot becomes good.

  Therefore, in the embodiment, when the radial widths of the plane portions 4a, 6a, 8a, 4b, 6b, and 8b constituting the frame portion 1b are 4A, 6A, 8A, 4B, 6B, and 8B in order, 4A = 0. 25 mm, 6A = 0.08 mm, 8A = 0.05 mm, 4B = 0.22 mm, 6B = 0.07 mm, and 8B = 0.05 mm.

  A sufficient amount of reflected light is obtained from the flat portions 4a and 4b having a radial width of 0.1 mm or more, and the amount of reflected light from the other flat portions 6a, 8a, 6b, and 8b is insufficient and substantially ignored. It is possible.

  Therefore, in the tilt detection apparatus shown in FIG. 2, when detecting the position of the focused spot on the light receiving element 16, the tilt of the optical element 1 is detected using only the reflected light from the flat portion 4a. Can do. This makes it possible to bond the optical element 1 while correcting the tilt of the optical element 1 when the optical element 1 is assembled to the lens holder of the pickup.

  Further, in the aberration evaluation of the optical element 1 by the interferometer, the planar portion 4b is irradiated with laser light, tilt adjustment is performed using reflected light from the laser beam, and the optical element 1 is tilt-adjusted. By measuring the effective surface, it is possible to perform measurement evaluation with less error and less variation even in repeated measurement.

  As described above, the frame portion 1b of the optical element 1 according to the fourth embodiment includes the annular plane portions 4a, 6a, 8a orthogonal to the optical axis of the optical element 1, and the annular plane portions 4b, 6b, 8b, of which the radial dimension of the plane parts 4a and 4b is 0.1 mm or more, and the radial dimension of the plane parts 6a, 8a, 6b and 8b is less than 0.1 mm.

  Therefore, it is possible to detect the inclination of the optical element 1 and evaluate the aberration of the optical element by the interferometer by selectively using only the sufficiently reflected light from the flat portions 4a and 4b without providing a reflective film. Such flat portions 4a and 4b can be easily formed by setting each portion of a molding die used for molding the optical element 1 to a predetermined size, and thus no new manufacturing process is required.

  In said Embodiment 1-4, although reflective surface 4a, 4b was formed in both surfaces of the frame part 1b, you may form the reflective surface 4a or the reflective surface 4b only in one surface.

  In addition, the optical element of the present invention may simultaneously include two or more of the forms shown in the first to fourth embodiments. Moreover, the one surface and the other surface of the optical element may have different forms.

  The present invention is capable of attaching an optical element with high accuracy in an optical head of various optical disk devices including a DVD and a CD.

Sectional drawing of the optical element of Embodiment 1 of this invention Schematic configuration diagram of optical element tilt detection device Sectional drawing of the optical element of Embodiment 2 of this invention Sectional drawing of the optical element of Embodiment 3 of this invention Sectional drawing of the optical element of Embodiment 4 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical element 1a Optical effective part 1b Frame part 2, 3 Optical effective surface 4a, 4b Plane part 5a, 5b Slope 11 Light source 12a Pinhole 12 Pinhole plate 13 Collimating lens 14 Beam splitter 15 Collimating lens 16 Light receiving element

Claims (11)

An optical element including an optically effective portion and a frame portion adjacent to the optically effective portion, wherein the frame portions are not on the same plane having different surface roughnesses on at least one surface of the optical element. An optical element comprising a flat surface. 2. The optical element according to claim 1, wherein each of the plurality of planar portions is orthogonal to the optical axis of the optical element. An optical element comprising an optically effective portion and a frame portion adjacent to the optically effective portion, wherein at least one surface of the optical element, the frame portion is orthogonal to the optical axis of the optical element. And an optical element having a planar portion with a surface roughness Ra of 0.1 μm or less. On at least one surface of the optical element, the frame portion is orthogonal to the optical axis of the optical element, and the surface roughness Ra of one of the plurality of planes not on the same plane is 0.1 μm. 4. The optical element according to claim 3, wherein the surface roughness Ra of the remaining flat portions is greater than 0.1 μm. An optical element comprising an optically effective portion and a frame portion adjacent to the optically effective portion, wherein a plurality of the frame portions are orthogonal to the optical axis of the optical element on at least one surface of the optical element. An optical element, wherein the planar portion having the largest area among the plurality of planar portions is an optical reflecting surface. The surface roughness Ra of the plane portion having the largest area among the plurality of plane portions is 0.1 μm or less, and the surface roughness Ra of the remaining plane portions is larger than 0.1 μm. The optical element described. An optical element comprising an optically effective part and a frame part adjacent to the optically effective part, wherein at least one surface of the optical element has a plurality of surfaces that are not on the same plane, Of the plurality of surfaces, one is a plane portion orthogonal to the optical axis of the optical element, and the rest are slopes inclined with respect to the optical axis. An optical element including an optically effective portion and a frame portion adjacent to the optically effective portion, and at least one surface of the optical element includes a plurality of planes that are not on the same plane and have different surface roughness. An optical element characterized in that a plane closest to the optically effective portion is an optical reflecting surface. An optical element comprising an optically effective part and a frame part adjacent to the optically effective part, wherein the frame part is the same on at least one surface of the optical element that is orthogonal to the optical axis of the optical element. An optical element having a plurality of flat portions not on a flat surface, wherein one of the plurality of flat portions has a radial dimension of 0.1 mm or more. 10. The radial dimension of the remaining planar portions excluding the one planar portion having a radial dimension of 0.1 mm or more among the plurality of planar portions is less than 0.1 mm. Optical element. The optical element according to any one of claims 1 to 10, wherein the planar portion has a portion where a resin or glass that is a material of the optical element is exposed.

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