JPS5987309A - Measuring device of inclination of face - Google Patents

Abstract

PURPOSE:To measure the inclination of a face independently of the refractive index, by providing a light beam source, biaxial actuator which makes the advance direction of the light beam orthogonal to each other, and a photodetector which detects the movement of the reflected light from an object to be measured. CONSTITUTION:A face inclination measuring device is provided with a laser light source 21, polarizing beam splitter 22, 1/4 wavelength plate 23, pivoting mirrors 24 and 25, 4-divided photodetector 27, etc. In this case, the deviation of the beam in the X direction and the Z direction appear as outputs A1-A3 and A2-A4. These two outputs are used to change the inclination of pivoting mirrors 24 and 25, and the control is so performed that the beam is placed in the center of the 4-divided photodetector 27. These inclinations are detected by the driving current of pivoting mirrors to detect the inclination of the face of a disc 26 to be measured, and thus, measurement is performed independently of the refractive index of the reflective face.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inclination measuring device for measuring the inclination of a plane having a mirror surface.

Configuration of a conventional example and its problems A conventional surface inclination measuring device will be explained by taking as an example the measurement of the surface inclination of an optical disk. FIG. 1 shows a conventional surface inclination measuring device. @1 In Figure 1, (1) is a disk, (2) is a turntable that fixes the disk, (3) is a motor for driving the turntable, (4) is a He-Re laser, and (5) is a turntable that fixes the disk.
) is the screen. The measurement method using this surface inclination measuring device is as follows. The origin is the point where the light reflected by the mirrored disk, whose surface has a zero inclination, forms an image on the screen. Next, place the disk to be measured (1) on the turntable (
Set it to 2) and the reflected light screen (5)! : , and measure the distance from the disk (1) to the screen (5). By setting the coordinate axes in the radial direction and the circumferential direction of the disk (1), the inclination of the surface at the measurement point can be measured independently in the radial direction and the circumferential direction.

This measurement method has the following problems because the incident light does not enter the disk (1) perpendicularly. Figure 2 shows how the laser is reflected on the disk. In the figure, Oυ is the mirror surface of the disk (the surface that reflects the light beam), and (2) is the mirror surface (
11) A transparent substance with a refractive index n covering the laser beam. Laser light incident on the surface of the disk at an incident angle θ1 passes through a substance with a refractive index n and is reflected by a mirror surface. The angle of incidence θ2 on this mirror surface αυ is expressed as −11 θ2=8In (−sin θ1) using θ1 and n. Therefore, there was a problem in that it was impossible to measure the incident angle θ2 unless the refractive index n was known.

OBJECTS OF THE INVENTION It is an object of the present invention to solve the problems of the prior art as described in section 2 and to provide an apparatus capable of measuring surface inclination regardless of the refractive index.

DESCRIPTION OF THE CONFIGURATION OF THE INVENTION In order to achieve the object, the present invention includes a light beam source, a 2111 actuator whose traveling directions of the light beams are orthogonal to each other, and a light source that can detect the movement of reflected light from an object to be measured. The actuator is controlled so that the incident light and the reflected light on the object to be measured always pass through the same path (so that the incident light always hits the object to be measured perpendicularly), and the control amount at this time is It is configured to measure the inclination of the surface of the object to be measured.

Examples In the following, the present invention will be explained using a pivoting mirror as a two-axis actuator, a quarter-wave plate and a polarizing beam splitter to separate incident light and reflected light, and a 4-split filter as a photodetector.・The measurement of the surface inclination of an optical disc using a Tetector will be explained as an example.

FIG. 3 is a configuration diagram of a surface inclination measuring device according to an embodiment of the present invention. Regarding the scolding figure 8, c! l) is a laser light source, C-
O is a polarizing beam splitter, φ) is a quarter wavelength plate, (・
φ is a pivoting mirror that can change the direction of the laser beam in the radial direction of the disk (C), and C is a pivoting mirror that can change the direction of the laser beam in the radial direction of the disk (C).
(g) is a pivoting mirror that can change the direction of the laser beam in the circumferential direction; (b) is a four-part photodetector; (c) is a turntable driving motor; and (4) is a turntable. The laser light emitted from the laser light source (1) changes its traveling direction from one direction to the -Y direction by a polarizing beam splitter. At this time, the laser beam is linearly polarized. This light is turned into circularly polarized light by the quarter-wave plate (c), and then the pivoting mirror (c) (1)
reflected by the light and reaches the disk).

The reflected light from the disk (A) is reflected again by two pivoting mirrors (E) (Incorporated) and passes through a 174 wavelength plate (
C), the circularly polarized light becomes linearly polarized light again, but the polarization direction is 90°l from the incident light! ll! Because of the J-turn, the traveling direction of the beam in the Y direction does not change at the polarizing beam splitter (c), and it reaches the four-split photodetector (c). The 4-split photodetector) is set in such a position that when a disk (e) whose surface has a zero inclination is set on the turntable (a), the reflected light will focus on the center of the disk (e). At this time, the laser beam is perpendicularly incident on the disk @.

The 4-split photodetector (b) is installed as shown in Figure 4, and when the pivoting ξler (c) is moved, a change appears in the output of A l - A 8, and A 2 - A
There is no change in the output of 4, and the pivoting mirror (
When c) is moved, a change appears in the output of A2-A4, but there is no change in the output of Al-AJ3.

The reflected light from the disk (e) whose inclination from the reference plane is θr in the radial direction and θ( in the circumferential direction at the measuring point) is 4.
The beam position of the split photodetector @t is the optical path length from the disk (E) to the 4-split photodetector (F)! Then, there is a shift of lθt in the two directions and lθr in the x direction. The deviation of the beam in the construction direction and the two directions is Al
-A3 and appears as the output of A2-A4. This 2
Using two outputs, pivoting mirror = (c) (b)
By changing the inclination of the photodetector, the beam is divided into four parts (b)
Control it so that it is centered. At this time, i-chair'7
The laser beam is perpendicularly incident on the ψ-kai. ■The tilts of the bivoting mirror of Omabi (c) are θr and θt, respectively.
If this inclination is detected, for example, using the drive current of a piphosotting mirror, then i? of the disk to be measured is equal to p? You can know the slope of M.

Also, in the installation method of the 4-split photodetector (b) shown in Figure @4, this is 90. ' If the lid is rotated and installed, the inclination of the disk (E) will be (AI + A2) - (
A-30A4) and (A1+, A4)-(A8+A2)
This method can also be implemented.

Furthermore, even if either one of the pivoting mirrors (c) or (c) is a fixed mirror, the light beam is incident on the disk at right angles, and the inclination in only one direction can be measured.

At this time, the photodetector can be replaced by a two-split photodetector.

Furthermore, a half mirror or a prism may be used instead of the pivoting mirror.

Effects of the Invention According to the inclination measuring device of the present invention, the following effects can be obtained. That is, since the light beam always enters the object to be measured vertically, even if the bell surface (reflecting surface) is covered with a material having a refractive index, measurement is possible regardless of the refractive index. Therefore, the error in the refractive index included in the measured value is I'
ll! It is also possible to measure the angle of incidence on the mirror surface of an object covered with a material whose refractive index is unknown.

The practical value of this invention is great.

[Brief explanation of the drawing]

Figure 1 shows a schematic diagram and configuration diagram of an example of a conventional surface inclination measuring device, and Figure 2 shows an example of a conventional surface inclination measuring device in which a light beam is directed onto an object whose mirror surface is covered with a material having a refractive index n. An explanatory diagram showing the state of incidence and reflection, Figure 8 is a configuration diagram of a surface inclination measuring device showing one embodiment of the present invention, and the fourth factor is a layout diagram of an example of installing a 4-split photodetector in the present invention. c! 1)... Laser light source, (2)... Polarizing beam splitter, Buddha... 1/4 wavelength plate, h m... Vibration mirror, (2)... Disk, @6I)・・・
・Four-division photo detector Fig. 1 Fig. 2 t 2 B 2 Fig. χ Fig. 4

Claims (1)

[Claims] 1. A light beam optical helix, an actuator that can change the traveling direction of the light beam in 2M directions orthogonal to each other, and a photodetector that can detect the movement of reflected light from the object to be measured. and controlling the actuator described above so that the incident light and the reflected light of the object to be measured always pass through the same path, and measuring the inclination of the surface of the object to be measured using the control amount at this time. An inclination measuring device configured as follows. 2. The surface inclination measuring device according to claim 1, wherein the two-axis actuator uses a prism or a prism. 8. The blood slope measuring device according to claim 1, wherein the incident light on the object to be measured and the light reflected from the object to be measured are separated by a polarizing beam splitter and a quarter wavelength plate. 4. Surface inclination measurement device according to claim 1 using a 4-split photodetector as a photodetector - 05. Either one of the two-axis actuators is fixed so that the light beam is always perpendicular to the object to be measured. The ml inclination measuring device according to claim 1, wherein the actuator is controlled so that the ml inclination is incident on the