JP2000304521A - Angle meter and polarimeter using it - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a goniometer capable of measuring a rotation angle of a rotating body such as a worm gear with high accuracy regardless of the mechanical accuracy thereof, and an optical rotation using the same. To provide a total. SOLUTION: The optical path length X1 to be detected is changed with the rotation of a rotating body 138, and the interference light L between the test light L3 and the reference light L2 is changed.
4, a photodetector 144 that photoelectrically converts a change in the intensity of the interference light L4, and a change in the intensity of the interference light L4 obtained by the photodetector 144, the rotation angle β of the rotating body 138 is determined. The counting means 146 for obtaining the change amount information of the test light path length X1 corresponding thereto, and the conversion means 148 for obtaining the rotation angle β of the rotating body 138 from the change amount information of the test light path length X1.
And a goniometer characterized by comprising:

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a goniometer and a polarimeter using the goniometer, and more particularly to a rotation angle measurement by an interferometer.

[0002]

2. Description of the Related Art Conventionally, to adjust the angle of various members,
For example, a rotating body such as a worm gear combining a worm and a worm wheel is used. For example, if you fix a member that adjusts the angle to almost the center of the worm wheel,
Since the worm wheel is rotated by rotating the worm, the member can be rotated integrally with the rotation of the worm wheel.

In order to properly perform such angle adjustment, it is necessary to accurately grasp the rotation angle of a rotating body such as a worm wheel and then adjust the angle. Here, since the mechanical accuracy of the worm and the worm wheel is measured independently, conventionally, the rotation angle obtained by combining such a worm and the worm wheel is not estimated from the respective mechanical accuracy. However, in order to measure a very small angle with high accuracy, a method is used in which a correction value is obtained by an angle standard device combining an angle standard prism and an autocollimator, and the estimated value of the rotation angle is calibrated by the correction value. Can be

By the way, various organic substances have the property of rotating the plane of polarization of linearly polarized light, and by measuring the angle of rotation, identification of the substance or identification of the optical isomer can be performed. FIG. 1 shows a general schematic configuration of a polarimeter for measuring such an optical rotation angle.

[0005] A lens 12 is provided in front of the sodium (Na) lamp 10 in the light emission direction, and a light beam converted into a parallel beam by the lens 12 passes through a polarizer 14 provided in front of the lens 12. The light beam that has passed through the polarizer 14 becomes linearly polarized light in a predetermined vibration direction. Then, it passes through a Faraday cell 16 installed further forward. The Faraday cell 16 is formed of a coil wound in multiple layers, and an oscillation circuit for passing an alternating current through the coil is provided.

[0006] The linearly polarized light is applied to the Faraday cell 16.
Modulates the deflection direction. The luminous flux leaving the Faraday cell 16 is applied to a flow cell 20 filled with a sample.
After passing through the filled sample, the light passes through an analyzer 22 installed further forward. The light beam that has passed through the analyzer 22 is incident on a detector 24, which is the last member of the optical system. The detector 24 is constituted by, for example, a photomultiplier. The amplifier 26, the fHz amplifier 28, the synchronous rectifier circuit 30, and the voltage indicator 32 are used as an electric system portion for obtaining an optical rotation angle based on the electric signal obtained by the detector 24.

In the polarimeter, the analyzer 22 is installed with its angle adjusted so that the polarization direction of the polarizer 14 and the transmission axis direction of the analyzer 22 are orthogonal to each other. For example, a rotating body such as the worm gear is used. For example, as shown in FIG. 2, the analyzer 22 is fixed to a substantially central hole of the worm wheel 38 rotated by the worm 36. Also, in such a polarimeter, how to appropriately adjust the angle of the analyzer 22 is an important issue in order to improve the measurement accuracy of the optical rotation angle.

For this reason, the measurement of the rotation angle β of the analyzer 22 requires very high precision, but conventionally, the worm 36 is rotated to measure the rotation angle of the analyzer 22. The number of pulses of the pulse motor 40 is counted, the rotation angle of the analyzer 22 is converted from the count value, and the angle of the analyzer 22 is adjusted based on the obtained rotation angle.

[0009]

However, in the conventional angle measurement, the measurement accuracy of the rotation angle of the worm wheel 38 is limited to the worm 36 and the worm wheel 38.
Is highly dependent on the mechanical accuracy of the In particular, in the conventional goniometer, since the detected rotation angle signal is weak, a mechanical error between the worm 36 and the worm wheel 38 directly affects the measured value of the rotation angle.

For example, the measurement accuracy is determined by the worm wheel 3
8 in consideration of the mechanical error and the measurement reproducibility, when the diameter of the worm wheel 38 is 100 mm, ± 0.002 ° (± 1 ° or less), ± 0.2% (± 1 ° or more) ) And very high precision is required. The specifications of the worm wheel 38 are, for example, ± 0.001 ° (± 1.8 ° or less), α ± 0.1% (±
(1.8 ° or more), which requires very high accuracy.

As described above, in order to measure the optical rotation angle with higher accuracy, higher accuracy is required for the specification of a rotating body such as a worm gear, but it is necessary to improve the mechanical accuracy of the rotating body. However, the technique for improving the measurement accuracy of the rotation angle has reached the limit both technically and costly.

As described above, although there has been a strong demand for the development of a technique capable of measuring the rotation angle with higher precision, a technique for improving the measurement precision by improving the mechanical precision of the rotating body has been strongly desired. If used, it was virtually impossible for the reasons described above. The present invention has been made in view of the above-mentioned problems of the related art, and an object of the present invention is to provide a goniometer and a goniometer capable of measuring the rotation angle with high accuracy regardless of the mechanical accuracy of a rotating body such as a worm gear. To provide a polarimeter using the same.

[0013]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors to achieve the above object, as a result of measuring the rotation angle on the basis of the wavelength of light using light interference, By measuring the moving distance of the moving mirror according to the rotation angle of the rotating body with an interferometer and determining the rotation angle from the moving distance of the moving mirror, the mechanical movement of a rotating body such as a worm gear, which was extremely difficult It has been found that the measurement accuracy can be greatly improved regardless of the accuracy, and the present invention has been completed.

That is, the goniometer according to the present invention includes an interferometer, a photodetector, a counting means, and a converting means,
The method is characterized in that the amount of change in the length of the optical path under test according to the rotation angle of the rotating body is measured by an interferometer, and the rotation angle is obtained from the amount of change in the length of the optical path under test. Here, the interferometer changes the length of the optical path to be detected along with the rotation of the rotating body, and obtains interference light between the test light from the optical path to be tested and the reference light from the reference optical path. The photodetector photoelectrically converts a change in the intensity of the interference light obtained by the interferometer.

The counting means obtains information on the amount of change in the optical path length to be detected from the change in the intensity of the interference light obtained by the photodetector. The conversion means obtains the rotation angle of the rotating body from the information on the amount of change in the optical path length to be detected obtained by the counting means. In the goniometer, the counting means counts the number of lightness signals corresponding to the number of interference fringes obtained by photoelectrically detecting the change in the intensity of the interference light with the photodetector, thereby obtaining the light-receiving signal. It is preferable to obtain information on the amount of change in the detection path length.

In the goniometer, it is preferable that one of the rotating bodies rotates the other rotating body. In the goniometer, it is preferable that the rotating body is a worm having a worm whose rotation axes are substantially perpendicular to each other and a worm gear including a worm wheel, and the rotation angle of the worm wheel is preferably measured.

In the goniometer, the interferometer includes a light source, a splitting unit, a fixed mirror, a moving mirror, a combining unit, a wire winding shaft, and a wire. It is preferable that the moving mirror is moved by a distance corresponding to a rotation angle of the rotating body by the wire winding shaft winding or unwinding the wire with the rotation. Here, the light source emits coherent light.

Further, the dividing means divides the coherent light from the light source into two. The fixed mirror is fixed on the reference light path, and receives one split light from the splitting unit. The movable mirror is provided movably on the optical path to be detected, receives the other split light from the splitting unit, and obtains an optical path difference between the movable mirror and the reference optical path. The combining means combines the reflected light from the fixed mirror and the reflected light from the movable mirror to obtain interference light.

The wire winding shaft is provided on a concentric circle of the rotating body. The wire has one end provided on the wire winding shaft and the other end provided on the movable mirror. Also,
In the goniometer, the interferometer includes the light source, the splitting unit, the fixed mirror, the moving mirror, the synthesizing unit, and an arm, and the arm is rotated with the rotation of the rotating body. It is also preferable to move the movable mirror by a distance corresponding to the rotation angle of the rotating body by rotating the movable mirror side on the concentric circle with the rotating body.

Here, one end of the arm is provided on the worm wheel, and the other end is provided on the movable mirror. In the goniometer, the fixed mirror and / or the movable mirror are preferably corner cube mirrors. Further, it is preferable that the goniometer includes an angle information acquiring unit and a comparing unit.

Here, the angle information obtaining means is provided at one end of a rotation shaft of the one rotating body, and obtains rotation angle information of the rotating body. Further, the comparing means includes: rotation angle information of one of the rotating bodies obtained by the angle information obtaining means;
The rotation angle information of the other rotator obtained by the conversion means is compared. As the angle information acquiring means of the present invention, for example, a photoelectric rotary encoder or the like can be used.

In the goniometer, it is preferable that a drive unit is provided on the other end side of the rotating shaft of the rotating body with respect to the angle information collecting unit, and is capable of rotating the rotating body. As the driving means of the present invention, for example, a motor such as a stepping motor can be used. In order to achieve the above object, a polarimeter according to the present invention is characterized in that, in the goniometer according to the present invention, an analyzer is fixed on a concentric circle of the rotating body.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
One embodiment will be described.First embodiment  FIG. 3 shows a schematic structure of the goniometer according to the first embodiment of the present invention.
The results are shown. In the present embodiment, the rotation
A worm whose rotating axes O 'and O are at right angles to each other as a body
Worm gear consisting of 136 and worm wheel 138
And a hole in the center of the worm wheel 138
The inclination angle β of the polarimeter analyzer (not shown) fixed to
The case of obtaining is described. Corresponds to the prior art
Parts are denoted by reference numeral 100, and description thereof is omitted.

In the figure, the goniometer according to the present embodiment includes an interferometer 142, a photodetector 144, and a counting means 14.
6 and conversion means. The photodetector 144 photoelectrically converts the intensity change of the interference light L4 from the interferometer 142. The counting unit 146 includes, for example, a fringe counter, and obtains information on the amount of change in the optical path length X1 from the intensity change of the interference light obtained by the photodetector 144.

In this embodiment, in order to obtain information on the amount of change in the optical path length X1 to be detected, the counting means 146 corresponds to the number of interference fringes obtained by photoelectrically detecting the intensity change of the interference light L4. By counting the number of brightness signals, information on the amount of change in the test optical path length X1 is obtained. Here, in the present embodiment, the reference optical path length X1 and the reference optical path length X2 are based on the same optical path length when the rotation angle β is 0 °. As the change amount information of X1, information on an optical path difference (X1-X2) between the test optical path length X1 and the reference optical path length X2 is used.

The conversion means comprises, for example, a CPU 148 or the like, and the optical path difference (X
1-X2) The rotation angle β of the worm wheel 152 is obtained from the information. Thereby, the inclination angle β of the analyzer can be obtained. In the present embodiment, the interferometer 142
A rotary pulley 152 as a wire take-up shaft is provided on a concentric circle of the worm wheel 138, and one end of a wire 154 is fixed to the rotary pulley 152.
52 rotates to wind up the wire 154.

The other end of the wire 154 is fixed to a linearly movable slider (not shown), and the movable mirror 162 is fixed to the slider. Therefore, the worm wheel 1
When the rotary pulley 152 rotates with the rotation of 38,
By winding or unwinding the wire 154, the movable mirror 162 moves along the slider in the left-right direction in the figure by a distance corresponding to the rotation angle β of the worm wheel 138.

In this embodiment, the moving distance of the movable mirror 162 is obtained as the optical path difference (X1-X2). That is, the laser beam L1 which is the coherent light emitted from the light source 156
Is a beam splitter 1 that is a dividing unit and a combining unit.
The light beam L2 traveling to the fixed mirror 160 and the light beam L3 traveling to the movable mirror 162 are split by 58. Luminous flux L2
Are reflected and reflected by the fixed mirror 160 and again enter the beam splitter 158. The light beam L3 is incident and reflected by the movable mirror 162, and reenters the beam splitter 158.

The beam splitter 158 includes a fixed mirror 16
The reflected light beam L2 from 0 and the reflected light beam L3 from the movable mirror 162 are combined and interfered. Here, when the interference light L4 obtained in this manner rotates the worm wheel 138 and moves the movable mirror 162, light and dark are repeated in a sinusoidal wave. The intensity change of the interference light L4 is photoelectrically detected by the photodetector 144, and the number of brightness signals corresponding to the number of interference fringes is counted by the counting unit 146, thereby obtaining the optical path difference (X1-X2) information, That is, the moving distance of the movable mirror 162 according to the rotation angle of the worm wheel can be obtained.

The CPU 148 obtains the rotation angle β of the worm wheel 138 based on the optical path difference (X1-X2) information obtained by the counting means 146. As described above, in the present embodiment, when the worm 136 is rotated about the rotation axis O ′, the worm wheel 138 is rotated about the rotation axis O. Then, the movable mirror 162 moves along the slider by a distance corresponding to the rotation angle β of the worm wheel 152, and an optical path difference (X1-X2) is generated between the movable mirror 162 and the fixed mirror 160. This optical path difference information is obtained by the photodetector 144, the counting means 146, and the like as described above.

Therefore, as shown in FIG. 4, for example, reference information 163 indicating the relationship between the optical path difference (X1-X2) and the rotation angle β ° of the worm wheel 138 is stored in advance in the CP.
If it is obtained at U148 or the like, the interference light L4
Is detected by the photodetector 144, and the number of interference fringes (for example, a high pulse signal corresponding to a bright portion) is counted by the counting means 146, whereby the optical path difference (X
1-X2) By obtaining the information, the rotation angle β can be obtained by the CPU 148 based on such reference information 163.

As described above, according to the goniometer according to the present embodiment, the moving distance of the movable mirror 162 according to the rotation angle of the worm wheel 138 is measured by the interferometer 142, and based on the moving distance of the movable mirror 162, Since the rotation angle β of the worm wheel 138 is determined, the inclination angle β of the analyzer can be measured with high accuracy regardless of the mechanical accuracy of the rotating body such as the worm gear. In other words, since the rotation angle is determined based on the wavelength of light using the interference of light, the rotation angle of a rotating body such as a worm wheel, which has a mechanical accuracy that is not as high as that of a conventional device, can be measured with high accuracy. Therefore, the versatility of the device under test is improved.

In the above configuration, an example in which a plane mirror is used as the fixed mirror 160 and the movable mirror 162 has been described. However, the goniometer of the present invention is not limited to this.
Other reflecting mirrors such as corner cube mirrors can be used.

[0034]Second embodiment  FIG. 5 shows an outline of a goniometer according to a second embodiment of the present invention.
The configuration is shown. In addition, in the part corresponding to FIG.
Is added with reference numeral 100, and the description is omitted. This embodiment
Then, as shown in FIG. 5, in addition to the configuration shown in FIG.
At one end of the worm 236, for example, a photoelectric rotary
-Angle information acquisition means 264 such as an encoder is connected.
You.

Then, the number of pulses from the angle information obtaining means 264 is counted by the counting means 246, and the rotation angle information of the worm 236 can be obtained by the CPU 248 or the like based on the counted value. Therefore, the rotation angle information of the worm 236 thus obtained and the rotation angle information β of the worm wheel 238 obtained as described above are
For example, by making a comparison using a comparing unit such as the CPU 248, the rotation accuracy of the worm wheel 238 with respect to the rotation of the worm 236 can be directly measured.

Here, by providing a driving means 240 such as a stepping motor at the other end of the worm 236,
Worm wheel 2 for rotation of the worm 236
It is possible to continuously and automatically measure the rotation accuracy of the 38. Thereby, in the present embodiment, the worm 236 and the worm wheel 2 are compared with the first embodiment.
It becomes easy to verify the correlation between the mechanical accuracy and the rotational accuracy of the 38.
In the above-described configuration, an example in which a plane mirror is used as the fixed mirror 260 and the movable mirror 262 has been described. However, the angle meter according to the present invention is not limited to this, and another reflector such as a corner cube mirror is used. be able to.

[0037]Third embodiment  FIG. 6 shows an outline of a goniometer according to a third embodiment of the present invention.
The configuration is shown. The first and second embodiments of the present invention
The part corresponding to the form is indicated by adding reference numeral 100 and explained.
Is omitted. In the present embodiment, the fixed mirror 360 and
A corner cube mirror is used as the movable mirror 362.
You.

In FIG. 6, in the goniometer according to the present embodiment, a moving mirror 362 formed of a corner cube mirror is mounted on the surface of a worm wheel 338 at a position away from the center of rotation O by R. For this reason, in the present embodiment, the surface of the worm wheel 338 has a length R in the longitudinal direction.
Arm 366 having one end is provided, and the movable mirror 3 is provided on the other end.
62 are provided.

In this embodiment, when the worm wheel 338 is rotated, the movable mirror 362 is rotated with the rotation.
Move on R about the rotation axis O. The moving distance of the moving mirror 362 is obtained by the photodetector 344, the counting means 346, and the like, as in the first embodiment, and the rotation angle β is determined by the CPU 348 based on the obtained moving distance of the moving mirror 362. You can ask.

Here, in the present embodiment, the movable mirror 362 is moved on the R centered on the rotation axis O of the worm wheel 338 by the arm 366, but a general plane mirror is used as the movable mirror. Since the direction of the mirror surface is different on each R, the reflected light from the movable mirror may not be returned to the beam splitter 358 in some cases. In addition, if only the corner cube mirror is used, if the incident position of the split light L3 on the moving mirror 362 is different, the split light L3 is incident on a portion slightly shifted from the center depending on the incident position.

Accordingly, in the present embodiment, the fixed mirror 360 and the movable mirror 362 are used so that the reflected light L3 can be returned to the beam splitter 358 regardless of the incident position of the incident light L3 on the movable mirror 362. , A reflecting mirror 368 and a reflecting mirror 370 are provided at the subsequent stage of these corner cube mirrors.

As described above, according to the goniometer according to the present embodiment, similarly to the first embodiment, the worm wheel 3
The movement distance of the movable mirror 362 according to the rotation angle of the worm wheel 338 is measured by the interferometer 342, and the rotation angle β of the worm wheel 338 is determined from the movement distance. Regardless, the tilt angle of the analyzer can be measured with high accuracy.

Further, according to the present embodiment, the movable mirror is moved only by the arm 366 instead of the rotating pulley and the wire as in the first embodiment. The number can be reduced. This allows
It is also possible to significantly reduce the occurrence of defects at the connection parts of the components due to long-term use.

[0044]Fourth embodiment  FIG. 7 shows an outline of a goniometer according to a second embodiment of the present invention.
The configuration is shown. In addition, in the part corresponding to FIG.
Is added with reference numeral 100, and the description is omitted. In addition,
In the embodiment, the fixed mirror 460 and the movable mirror 462 are
Uses a cube mirror. In this embodiment,
In addition to the configuration shown in FIG.
For example, a photoelectric rotary encoder
And angle information acquiring means 464 such as a square.

The number of pulses from the angle information obtaining means 464 such as a photoelectric rotary encoder is counted by the counting means 4.
The rotation angle of the worm 436 can be obtained by the CPU 448 or the like based on the counted value.
Therefore, the rotation angle information of the worm 436 obtained in this way and the rotation angle information β of the worm wheel 438 obtained as described above are compared by comparison means such as the CPU 448, so that the The rotation accuracy of the worm wheel 438 with respect to rotation can be directly measured.

Here, by providing driving means 440 such as a stepping motor at the other end of the worm 436,
Worm wheel 438 against rotation of worm 436
It is possible to automatically measure the rotation angle continuously. Accordingly, in the present embodiment, the worm 436 and the worm wheel 438 are further compared with the third embodiment.
It is easy to verify the correlation between the mechanical accuracy and the rotational accuracy.

As described above, according to the goniometer according to the present embodiment, the moving distance of the movable mirror according to the rotation angle of the worm wheel is measured by the interferometer, and the rotation angle of the worm wheel is obtained from the moving distance information. Therefore, regardless of the mechanical accuracy of the worm gear, the inclination angle β of the analyzer provided on the concentric circle of the worm wheel can be measured with high accuracy.

Therefore, when the optical rotation of a micro sample such as biotechnology or a natural compound is measured with high sensitivity, even when a narrow angle range (for example, ± 15 °) is measured, the rotation angle β of the analyzer is measured. Can be measured directly by the interferometer, so that the measurement accuracy can be improved. As a result, the mechanical error of the worm gear does not affect the measured value, for example, when the diameter of the worm wheel is 100 m
If it is about m, a minimum detection angle of 0.00018 ° is possible. That is, assuming that the measurement reproducibility is 0 °,
The measurement accuracy is ± 0.00018 ° (± 15 ° or less).

As described above, in this embodiment, the number of lightness signals corresponding to the number of interference fringes obtained by photoelectrically detecting the intensity change of the interference light that repeats light and dark in a sine wave shape with the rotation of the rotating body. Is calculated by calculating the rotation angle of the rotating body. Therefore, when one stripe is converted into an angle, ± 0.00
Since the angle is 018 °, the accuracy is not deteriorated, and the accuracy can be greatly improved, for example, by about one digit as compared with the related art. Further, in the present embodiment, the accuracy of the worm gear is not required to be as high as the conventional one, so that the versatility for the object to be measured is improved.

In this embodiment, the rotation accuracy of the worm wheel with respect to the rotation of the worm can be directly measured by connecting angle information acquisition means such as a photoelectric rotary encoder to the rotation shaft of the worm. Becomes Here, by connecting a driving means such as a motor to the other end of the worm rotation shaft, it is possible to continuously and automatically measure the rotation angle of the worm wheel with respect to the rotation of the worm. This makes it easy to verify the correlation between the mechanical accuracy and the rotational accuracy of the worm and the worm wheel.

It should be noted that the goniometer of the present invention is not limited to the above-described configurations, but can be variously modified within the scope of the invention. For example, in each of the above configurations, an example was described in which a worm gear including a worm and a worm wheel was used as the rotating body. However, the present invention is not limited to this, and can be applied to other rotating bodies.

Further, in each of the above-described configurations, an example has been described in which the analyzer of the polarimeter is provided in the center hole of the worm wheel and the inclination angle of the analyzer is measured. However, the present invention is not limited to this. Instead, if a member whose rotation angle is to be measured is fixed on a concentric circle of the rotating body, the present invention can be applied to angle measurement of another member. In the third and fourth embodiments of the present invention, it is preferable to use a corner cube mirror as the movable mirror and the fixed mirror. However, the angle meter according to the present invention is not limited to this, and the If it can be obtained, other reflecting mirrors such as a plane mirror can be used.

Further, in the above-described embodiment, an example in which comparison means such as a CPU is provided has been described. However, the present invention is not limited to this, and a user may perform the same processing as the comparison means. Furthermore, in each of the above-described configurations, when the rotation angle is 0 °, the case where the test optical path length and the reference optical path length are the same optical path length is used as a reference, so that the moving distance of the movable mirror according to the rotational angle of the rotating body Although an example using the optical path difference between the test optical path length and the reference optical path length has been described above, the present invention is not limited to this, and an interference state different from the above state may be used as a reference.

[0054]

As described above, according to the goniometer according to the present invention, the interferometer measures the amount of change in the length of the optical path to be measured in accordance with the rotation angle of the rotator such as a worm wheel. Since the rotation angle is determined from the length change information, the rotation angle can be directly measured without being affected by the mechanical accuracy of the rotating body. Thereby, the reliability of the measured value is improved regardless of the mechanical accuracy of the rotating body. In particular, unlike the conventional method in which measurement is performed using an artificially manufactured scale or the like, the rotation angle is measured based on the wavelength of light using light interference, so that the measurement is close to an absolute measurement. Further, according to the goniometer according to the present invention, by providing the driving means at one end of the worm rotating shaft and the angle information obtaining means at the other end, the rotation angle of the worm wheel with respect to the rotation of the worm can be continuously adjusted. Automatic measurement becomes possible. This makes it easy to verify the correlation between the mechanical accuracy and the rotational accuracy of the worm and the worm wheel.
Further, according to the polarimeter according to the present invention, the angle meter according to the present invention as described above is used to measure the inclination angle of the analyzer fixed on the concentric circle of the rotating body such as the worm wheel. , Even for the small inclination angle of the analyzer,
Since the measurement can be performed with high accuracy, the angle of the analyzer can be more appropriately adjusted based on the measured value. This makes it possible to measure the optical rotation angle with higher accuracy as compared with a device without such a device.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a schematic configuration of a general polarimeter.

FIG. 2 is an explanatory diagram of a general installation state of an analyzer.

FIG. 3 is an explanatory diagram of a schematic configuration of a goniometer according to the first embodiment of the present invention.

FIG. 4 is an example showing a relationship between an optical path difference between a test optical path and a reference optical path obtained by the apparatus shown in FIG. 3 and a rotation angle of a worm wheel.

FIG. 5 is an explanatory diagram of a schematic configuration of a goniometer according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a schematic configuration of a goniometer according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram of a schematic configuration of a goniometer according to a fourth embodiment of the present invention.

[Explanation of symbols]

122 analyzer 136, 236, 336, 436 worm (rotating body) 138, 238, 338, 438 worm wheel (rotating body) 142, 242, 342, 442 interferometer 144, 244, 344, 444 light Detectors 146, 246, 346, 446: counting means 148, 248, 348, 448: CPU (conversion means) 160, 260, 360, 460: fixed mirror 162, 262, 362, 462: moving mirror

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Mutsumi Senuma 5F, 2967, Ishikawa-cho, Hachioji-shi, Tokyo F-term in Japan Nippon Bunko Co., Ltd. 2F065 AA39 BB16 CC05 DD03 FF52 GG04 JJ15 LL12 LL17 LL46 QQ51 2G059 AA10 EE05 EE09 GG01 HH02 JJ13 JJ19 JJ22 KK01 KK02 MM14

Claims (10)

[Claims] 1. An angle meter for measuring, using an interferometer, a rotation angle of a rotating body rotatable about a predetermined rotation axis, wherein a length of an optical path to be detected is changed with the rotation of the rotating body. An interferometer that obtains interference light between the test light from the detection path and the reference light from the reference light path, a photodetector that photoelectrically converts the intensity change of the interference light obtained by the interferometer, and the photodetector Counting means for obtaining information on a change in the length of the optical path to be detected in accordance with the rotation angle of the rotator from the intensity change of the obtained interference light; and information on the change in the optical path length to be detected obtained by the counting means. Conversion means for determining the rotation angle of the rotator, and measuring the amount of change in the optical path length of the test object in accordance with the rotation angle of the rotator with an interferometer to determine the rotation angle of the rotator. A goniometer characterized in that: 2. A goniometer according to claim 1, wherein said counting means calculates the number of brightness signals corresponding to the number of interference fringes obtained by photoelectrically detecting the intensity change of said interference light by said photodetector. A goniometer characterized in that information on the amount of change in the optical path length to be detected is obtained by counting. 3. The goniometer according to claim 1, wherein
The said rotary body rotates the other rotary body by one rotary body, The angle meter characterized by the above-mentioned. 4. The goniometer according to claim 3, wherein the rotating body is a worm whose rotating shafts are substantially perpendicular to each other, and a worm gear composed of a worm wheel, and measures the rotation angle of the worm wheel. Characteristic goniometer. 5. The goniometer according to claim 1, wherein the interferometer includes a light source that emits coherent light, a dividing unit that divides the coherent light from the light source into two, A fixed mirror fixed on a reference light path and receiving one of the divided lights from the splitting means, and movably provided on the test light path, receiving the other split light from the splitting means and receiving the reference light; A moving mirror for generating an optical path difference between the light path and a combining means for combining reflected light from the fixed mirror and reflected light from the moving mirror to obtain interference light, and provided on a concentric circle of the rotator. A wire winding shaft, one end of which is provided on the wire winding shaft, the other end of which includes a wire provided on the movable mirror,
An angle meter for moving the movable mirror by a distance corresponding to a rotation angle of the rotating body by winding or unwinding the wire by the wire winding shaft with rotation of the rotating body. . 6. The goniometer according to claim 1, wherein the interferometer includes a light source that emits coherent light, a dividing unit that divides the coherent light from the light source into two, A fixed mirror fixed on a reference light path and receiving one of the divided lights from the splitting means, and movably provided on the test light path, receiving the other split light from the splitting means and receiving the reference light; A movable mirror for producing an optical path difference between the movable mirror, an arm having one end provided on the rotating body and the other end provided on the movable mirror, reflected light from the fixed mirror, and reflected light from the movable mirror And a synthesizing means for obtaining interference light by synthesizing the moving mirror, and the moving mirror side of the arm rotates concentrically with the rotating body with the rotation of the rotating body, whereby the moving mirror is rotated. A goniometer that moves by a distance corresponding to the rotation angle of the body. 7. The goniometer according to claim 1, wherein said fixed mirror and / or movable mirror is a corner cube mirror. 8. The goniometer according to claim 1, provided at one end of a rotating shaft of said one rotating body, for obtaining rotation angle information of said rotating body;
And a comparing means for comparing the rotation angle information of one of the rotating bodies obtained by the angle information obtaining means with the rotation angle information of the other rotating body obtained by the converting means. Degree Ruler. 9. The goniometer according to claim 8, further comprising a driving means provided on the other end side of said one rotating body rotating shaft with respect to said angle information acquiring means, and capable of rotating said rotating body. Characteristic goniometer. 10. The polarimeter according to claim 1, wherein an analyzer is fixed on a concentric circle of the rotating body.