CN1719192A - Two-dimensional photoelectric self-collimation device and measurement method based on optical path multiplication compensation method - Google Patents

Abstract

The present invention relates to high precision 2-D photoelectric autocollimating equipment based on optical path multiplication compensation method. Said equipment successively includes laser light source, calibrated plate, main spectroscope, main CCD image sensor, collimating objective and measurement reflector. Besides, said invention also provides its measurement method and concrete steps.

Description

Two-dimensional photoelectric self-collimation device and measurement method based on optical path multiplication compensation method

technical field

The invention belongs to the technical field of precision instrument manufacturing and precision test and measurement, and in particular relates to a high-precision two-dimensional photoelectric self-collimation device and a measurement method for real-time compensation of the angular drift of light beams based on an optical path multiplication compensation method.

Background technique

With the continuous improvement and improvement of measurement technology, the development of modern high-precision measurement technology and azimuth targeting and tracking system has put forward higher and higher requirements for the measurement accuracy of small angles. Photoelectric autocollimator plays an irreplaceable role in small-angle precision measurement, high-precision aiming and positioning. It can be used as a component of optical measuring instruments such as goniometers and optical comparators, and can also be used alone in measuring instruments for optical Measurement, assembly and adjustment of aerospace instruments and attitude measurement of military aircraft.

In high-precision small-angle measurement, for a photoelectric autocollimator with a measurement uncertainty better than 0.5", the angular drift of the light source part of the beam is the main source of measurement error of the photoelectric autocollimator. When the light beam emitted by the light source exists When drifting, for example, the angular drift of the beam caused by the modification of the reflector in the cavity of the helium-neon laser resonator is: 10 ^-6 ~ 10 ^-7 rad, that is: 0.02″ ~ 0.2″ (1. Wandean. Laser reference high-precision measurement technology . National Defense Industry Press. June 1999; 2. Fang Zhongyan, Yin Chunyong, Liang Jinwen. Research on High-precision Laser Alignment Technology (1). Aeronautical Measurement Technology. 1997, 17(1): 3-6), if using If the spot center positioning method is used, the spot center received by the receiver will drift with the beam drift; if the profile center positioning method is adopted, the energy center of the spot received by the receiver and the geometric center of the profile will not coincide due to the beam drift, causing the deviation of the profile center. If the angle drift is not corrected or compensated, it will be directly fed back to the angle measurement error caused by the measurement result of a small angle, resulting in poor repeatability and stability of the instrument data. To further It is difficult to improve the measurement uncertainty only by improving the collimation accuracy of the beam itself, whether it is from the existing technology or the manufacturing level. The error separation and compensation technology, especially the dynamic compensation technology, is used to eliminate or compensate Correcting the angle measurement error caused by the angle drift provides an effective technical approach to realize high-precision small-angle measurement.

At present, the photoelectric autocollimator widely used in engineering, such as the 702 photoelectric autocollimator produced by the Beijing Metrology Instrument Factory of the National Metrology Bureau, has a measurement resolution of 0.1″ and a measurement uncertainty of 2″ within 10′ , within the range of any 4′～6′ in the center of the field of view is 0.5″ (Wu Jinxie. Geometric Quantity Precision Measurement Technology. Harbin Institute of Technology Press. September 1989). This measurement scheme measures a one-dimensional angle. For one-dimensional angle measurement, the instrument must be readjusted in this direction, resulting in cumbersome measurement process and poor data repeatability. At the same time, it will introduce artificial measurement error and mechanical return error; at the same time, the angular drift of the beam still exists, and the measurement uncertainty is difficult to improve. .

In order to overcome the shortcomings of poor repeatability caused by the secondary adjustment of the instrument when the photoelectric autocollimator measures the angles in two directions, improve the measurement resolution of the photoelectric autocollimator, and at the same time meet the requirements of real-time display and storage of data Many manufacturers and research institutes have developed photoelectric autocollimators that use high-precision CCD image sensors to measure two-dimensional angles. For example:

1. Photoelectric autocollimator of ELCOMAT vario type produced by ELCOMAT company in Germany. Using a high-precision CCD image sensor, by measuring the displacement of the center of the light spot received on the CCD image sensor to accurately measure the small angle change of the measuring mirror, the biaxial autocollimator of the product ELCOMAT vario 500T/D65 The technical index is: the measurement uncertainty is ±0.4″ within the measurement range of 24′ on the X axis and 18′ on the Y axis (Chinese operation manual for ELCOMAT vario dual-axis autocollimator of German MLLER-WEDEL company. 2004) ;

2. Patent 99242552.2 "Two-dimensional dynamic digital display autocollimator";

3. Patent 99254139.5 "Photoelectric Autocollimator";

4. Patent 200410032713.2 "Autocollimator".

Due to its good single directionality, high brightness and high stability, the laser beam is often used as a measurement standard and widely used in ultra-precision processing equipment and measurement equipment. Many scientific research institutes have developed laser light source and high-precision CCD image Photoelectric autocollimator with sensor measuring two-dimensional angle (1. Wu Xiuli. Laser autocollimator. Opto-Mechanical Information. 1994, Issue 08: 11-13; 2. Jiang Benhe, Chen Wenyi, Hu Wenfei, Hu Qingrong. Using laser Small-angle measurement system for collimation and CCD detection. Laser and Infrared. 1998, 28(4): 233-234+243; 3. Lin Yuchi, Zhang Ping, Zhao Meirong, Hong Xin. Semiconductor laser autocollimator for field use . Aeronautical Precision Manufacturing Technology. 2001, 37(3): 35-37; 4. Zhang Yaoyu, Zhang Minghui, Qiao Yanfeng. Research on a High-precision CCD Laser Self-collimation Measurement System. Optoelectronics Laser. 2003, 14(2) : 168-170; 5. Ma Fulu, Zhang Zhili, Zhou Zhaofa. Single linear array CCD straightness collimator based on M-type reticle. Optical Technology. 2002, 28(3): 224-225+227).

Due to the use of a laser light source and a high-precision CCD image sensor, the collimation of the beam, the measurement distance and the measurement resolution are improved while the automatic measurement of the two-dimensional angle is realized, and the data is displayed and stored in real time.

However, in practical applications, especially from the optical path, mechanical structure and measurement process, it can be seen that the above measurement schemes have the following shortcomings: since no error compensation or correction is used, the angular drift of the beam is not eliminated during the measurement process , and finally mixed with the angle measurement error caused in the measurement results, it directly leads to the poor measurement stability of the photoelectric autocollimator, and it is difficult to further improve the measurement uncertainty, which greatly limits the application range of the photoelectric autocollimator. This is the measurement scheme The insufficiency of itself is also an important problem that cannot be solved in the practical application of the current photoelectric autocollimator.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies existing in the above-mentioned existing photoelectric autocollimator measurement scheme, to provide a kind of two-dimensional photoelectric autocollimation device and measurement method based on the optical path multiplication compensation method, and obtain and measure through the front spectroscope The reference beam with the same characteristics of the measurement beam, the optical path multiplication device composed of two relatively parallel plane mirrors reflects the reference beam multiple times, prolongs the optical path of the reference beam, and enlarges the linear displacement corresponding to the beam angle drift , the front CCD image sensor monitors the angular drift of the beam in real time and dynamically compensates the angle measurement error caused by the angular drift of the beam, which can significantly improve the measurement stability and measurement accuracy of the two-dimensional photoelectric autocollimator.

The technical solution adopted by the present invention is: a two-dimensional photoelectric self-collimation device based on the optical path multiplication compensation method, including a laser light source, a reticle, a main beam splitter, a main CCD image sensor, a collimating objective lens, Measuring mirror, place a pre-beam splitter between the laser light source and the reticle to obtain a reference beam with exactly the same characteristics as the measurement beam, an optical path multiplier to reflect the reference beam multiple times, and a front CCD image sensor The angular drift of the light beam is monitored; the optical path multiplication device is composed of two plane mirrors placed relatively parallel.

The optical path multiplier also includes an additional flat mirror located in the path of the reference beam.

The optical path multiplier is composed of two right-angle prisms placed opposite to each other.

The optical path multiplier consists of two opposite rectangular prisms and an additional flat mirror located on the path of the reference beam. .

The optical path multiplication device is composed of a plurality of plane mirrors placed in parallel in pairs.

The optical path multiplier is composed of several pairs of plane mirrors placed in parallel and an additional plane mirror located on the path of the reference beam.

The present invention also provides a measurement method of a two-dimensional photoelectric self-collimation device based on an optical path multiplication compensation method, the measurement method comprising the following steps:

1. First adjust and fix the optical path multiplication device, and then calibrate the two-dimensional photoelectric self-collimation device;

2. The laser beam emitted by the laser light source is divided into two beams after passing through the pre-beam splitter: the transmitted beam becomes the measuring beam, and the reflected beam becomes the reference beam;

3. After the reference beam enters the optical path multiplication device, it is received by the front CCD image sensor after multiple reflections and becomes a reference signal;

4. After the measurement beam acquires the variation of the two-dimensional small angle of the measurement mirror, it is received by the main CCD image sensor and becomes a measurement signal;

5. The reference signal monitors and separates the angle drift of the beam, and real-time differential processing can dynamically compensate the angle measurement error caused by the angle drift, and accurately measure the change of the two-dimensional small angle of the measuring mirror:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>$

Here: θ is the variation of the two-dimensional small angle of the measuring mirror, d ₁ is the measurement signal in the main CCD image sensor

The amount of change in the central position of the spot formed on the detector, f is the equivalent focal length of the collimator objective lens, d ₀ is the reference signal at

The amount of change in the center position of the spot formed on the front CCD image sensor, L is the laser beam from the laser light source

The total equivalent optical distance to the front CCD image sensor.

The present invention has following characteristics and good effect:

1. A novel optical path multiplication device is used to improve the optical system, and the reference beam with the same characteristics as the measurement beam is obtained through the pre-beam splitter. After multiple reflections by the optical path multiplication device, the optical path of the reference beam is extended, and the beam angle is magnified. The linear displacement corresponding to the drift is easy to receive and monitor the subsequent CCD image sensor, which is one of the innovations different from the existing photoelectric self-collimation measurement technology;

2. In the design, the angular drift of the beam causes the reference signal and the measurement signal to change at the same time. Two CCD image sensors are used to obtain the angular drift of the beam and the two-dimensional angle change of the measuring mirror respectively, which can be separated and dynamically compensated in real time. The angle measurement error caused by the angular drift of the beam is the second innovation point different from the existing photoelectric self-collimation measurement technology;

3. The optical path multiplication optical structure is adopted, which realizes the miniaturization of the instrument volume while amplifying the linear displacement corresponding to the beam angle drift, and is easy to design as a portable device. This is an innovation different from the existing photoelectric self-collimation measurement technology point three;

4. This design scheme adopts a very simple structure. Adding an optical path multiplication device in the optical path can dynamically compensate the angle measurement error caused by the angular drift of the beam, and improve the measurement stability of the two-dimensional photoelectric autocollimator. It meets the needs of high-precision two-dimensional small-angle measurement, the measurement process and data processing are obviously simplified, and the practicability is strong.

Description of drawings

Fig. 1 is the structural representation of device of the present invention;

Fig. 2 is the structural representation of the optical path multiplication device that is made up of two plane mirrors placed relatively parallel and an additional plane mirror positioned on the reference beam path in the device of the present invention;

Fig. 3 a is the structural representation of the optical path multiplication device that is made up of two oppositely placed rectangular prisms in the device of the present invention;

Fig. 3 b is the structural representation of the optical path multiplication device that is made up of two rectangular prisms placed oppositely and an additional plane reflector positioned on the reference beam path in the device of the present invention;

Fig. 4 a is the structural representation of the optical path multiplication device that is made up of a plurality of plane mirrors placed in parallel in the device of the present invention;

Fig. 4b is a structural schematic diagram of an optical path multiplication device composed of a plurality of parallel plane reflectors in pairs and an additional plane reflector positioned on the reference beam path in the device of the present invention;

Fig. 5 is a schematic diagram of the optical path multiplication device used in the device of the present invention to amplify the linear displacement corresponding to the drift of the beam angle.

Detailed ways

The two-dimensional photoelectric self-collimation device and measurement method based on the optical path multiplication compensation method of the present invention are described in detail below in conjunction with the accompanying drawings:

As shown in Figure 1, the device of the present invention consists of a laser light source 1, a front beam splitter 2, a reticle 3, a main beam splitter 4, a main CCD image sensor 5, a collimating objective lens 6, a measuring mirror 7, and a front CCD The image sensor 8 and the optical path multiplication device 9 composed of the plane mirror 10 and the plane mirror 11 are constituted. The path of its light is as follows:

The beam emitted by the laser light source 1 is divided into two beams by the pre-beam splitter 2: the transmitted beam becomes the measuring beam, and the reflected beam becomes the reference beam with the same characteristics as the measuring beam. After the reference beam is incident into the optical path multiplication device 9, after multiple reflections by the plane mirror 10 and the plane mirror 11, the optical path of the reference beam is extended, and the linear displacement corresponding to the beam angle drift is amplified, which is pre-imaged by the CCD The sensor 8 receives it and becomes a reference signal; the measuring beam illuminates the reticle 3 located at the focus of the collimating objective lens 6, transmits through the main beam splitter 4, and after the collimating objective lens 6 converges, it is incident on the measurement placed on the measured object. Mirror 7, the light beam reflected by the measuring mirror 7 is converged by the collimating objective lens 6, reflected by the main beam splitter 4, and then imaged on the main CCD image sensor 5 to become a measurement signal, and the angular drift of the beam causes the reference signal and measurement The signal changes at the same time, combined with the principle of geometric optics and optical self-collimation, the reference signal monitors and separates the angle drift of the beam, and performs two-dimensional real-time differential processing to dynamically compensate the angle measurement error caused by the angle drift, and accurately measure The amount of variation of the two-dimensional small angle of the measuring reflector 7 is obtained:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>$

Here: θ is the variation of the two-dimensional small angle of measuring reflector 7, _d is the variation of the light spot center position that measurement signal forms on main CCD image sensor 5, f is the equivalent focal length of collimating objective lens 6, d ₀ is the amount of change in the spot center position formed by the reference signal on the front CCD image sensor 8, and L is the total equivalent optical path that the laser beam passes from the laser light source 1 to the front CCD image sensor 8.

The present invention improves the two-dimensional photoelectric autocollimator by placing a pre-beam splitter 2 between the laser light source 1 and the reticle 3 of the two-dimensional photoelectric autocollimator, and utilizing an optical path multiplication device 9 composed of two plane mirrors 10 and 11. The optical structure of the collimator. After the light beam emitted by the laser light source 1 is split by the pre-beam splitter 2, a reference beam with exactly the same characteristics as the measurement beam is obtained. The linear displacement corresponding to the beam angle drift is received by the front CCD image sensor 8 and dynamically monitored, and the angle measurement error caused by the angular drift is eliminated and suppressed by using error separation and dynamic compensation technology.

Referring to FIG. 2 , the optical path multiplication device 9 in the device of the present invention is composed of two relatively parallel plane mirrors 10 and 11 and an additional plane mirror 12 . An additional flat mirror 12 is arranged in the path of the reference beam. In this way, the optical path is reflected multiple times along the horizontal direction, which is relatively easy to adjust.

Referring to FIG. 3 a , the optical path multiplication device 9 in the device of the present invention is composed of two rectangular prisms 13 and 14 placed opposite to each other.

Referring to Fig. 3b, the optical path multiplication device 9 in the device of the present invention is composed of two opposite rectangular prisms 13 and 14 and an additional plane mirror 12 located on the path of the reference beam.

Referring to FIG. 4 a , the optical path multiplication device 9 in the device of the present invention is composed of a plurality of plane mirrors 15 , 16 , 17 , 18 , 19 , 20 , 21 and 22 placed in parallel in pairs.

Referring to Fig. 4 b, the optical path multiplication device 9 in the device of the present invention consists of a plurality of plane reflectors 15, 16, 17, 18, 19, 20, 21 and 22 placed in parallel in pairs and an additional plane positioned on the reference beam path mirror 12.

The method described in the present invention is described in detail below:

The present invention also provides a measurement method of a two-dimensional photoelectric self-collimation device based on an optical path multiplication compensation method, the measurement method comprising the following steps:

1. First of all, it is necessary to determine the distance between devices and the number of reflections of light beams between devices to obtain the total equivalent optical path L, and adjust the optical path multiplication device 9 according to the value of the total equivalent optical path L to realize laser Multiple reflections of the beam to increase the optical path and enlarge the linear displacement corresponding to the drift of the beam angle. After the adjustment, the optical path multiplying device 9 should be fixed, and then the two-dimensional photoelectric self-collimation device should be calibrated. After the calibration is completed, the use process The middle optical path multiplying device 9 is no longer adjusted;

2. When measuring, the laser beam emitted by the laser light source 1 is divided into two beams by the pre-beam splitter 2: the transmitted beam becomes the measuring beam, and the reflected beam becomes the reference beam with exactly the same characteristics as the measuring beam;

3. After the reference beam enters the optical path multiplication device 9, after multiple reflections, the optical path of the reference beam is extended, and the linear displacement corresponding to the drift of the beam angle is amplified, which is received by the front CCD image sensor 8 and becomes a reference signal. The central position of the light spot formed on the front CCD image sensor 8 is d ₀ ;

4. The measuring beam illuminates the reticle located at the focal point of the collimating objective lens 6, transmits through the main beam splitter 4, and after the collimating objective lens 6 converges, it is incident on the measuring mirror 7 placed on the measured object, and the measuring mirror 7. The light beam reflected back is converged by the collimating objective lens 6 again, and is imaged on the main CCD image sensor 5 after being reflected by the main beam splitter 4, and becomes a measurement signal, and the spot center position formed on the main CCD image sensor 5 is _d1 ;

5. The angular drift Δθ ₀ of the beam will cause the drift of the measurement result. The measurement result calculated from the measurement signal includes the two-dimensional small angular variation θ of the measuring mirror 7 and the angular drift Δθ ₀ of the beam. However, since this measurement scheme uses an optical path multiplier to amplify the linear displacement Δθ ₀ corresponding to the angular drift of the beam, and uses the front CCD image sensor 8 to receive it, the angular drift Δθ ₀ of the beam can be effectively monitored and separated, as shown in the figure As shown in 5, it can be obtained from the geometric relationship:

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>$

Here: d ₀ is the amount of change in the spot center position formed by the reference signal on the front CCD image sensor 8, and L is the total equivalent optical path that the laser beam passes from the laser light source 1 to the front CCD image sensor 8. Combining the principle of geometric optics and optical self-collimation, real-time differential processing can dynamically compensate the angle measurement error caused by the angle drift, and accurately measure the change of the two-dimensional small angle of the measuring mirror 7:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>$

Here: θ is the variation of the two-dimensional small angle of measuring reflector 7, _d is the variation of the light spot center position that measurement signal forms on main CCD image sensor 5, f is the equivalent focal length of collimating objective lens 6, d ₀ is the amount of change in the spot center position formed by the reference signal on the front CCD image sensor 8, and L is the total equivalent optical path that the laser beam passes from the laser light source 1 to the front CCD image sensor 8.

It can be seen that in the measurement results, the real-time differential processing of the reference signal and the measurement signal can separate and dynamically compensate the angle measurement error caused by the angular drift of the beam, without affecting the measurement results. The measurement stability and measurement uncertainty of the two-dimensional photoelectric autocollimator are improved, so that the measurement scheme realizes high-precision two-dimensional small-angle measurement.

Example 1:

For the two-dimensional photoelectric self-collimation device shown in Figure 1, the optical path multiplication device 9 is first adjusted, and here, the optical path multiplication device 9, as shown in Figure 1, is composed of two relatively parallel plane mirrors 10 and 11 After the adjustment, the optical path multiplication device 9 should be fixed, and then the two-dimensional photoelectric self-collimation device should be calibrated. After the calibration, the optical path multiplication device 9 will not be adjusted during use. When measuring, the laser beam emitted by the laser light source 1 is divided into two beams by the pre-beam splitter 2: the transmitted beam becomes the measuring beam, and the reflected beam becomes the reference beam with exactly the same characteristics as the measuring beam; the reference beam enters the optical path multiplication device After 9, the optical path multiplying device 9 reflects the reference beam multiple times, prolongs the optical path of the reference beam, and amplifies the linear displacement corresponding to the beam angle drift, which is received by the front CCD image sensor 8 and becomes a reference signal; The reticle located at the focal point of the collimating objective lens 6 is transmitted through the main beam splitter 4, and after being converged by the collimating objective lens 6, it is incident on the measuring mirror 7 placed on the measured object, and the light beam reflected by the measuring mirror 7 Convergence by the collimating objective lens 6, image on the main CCD image sensor 5 after being reflected by the main beam splitter 4, and become a measurement signal; the measurement result calculated by the measurement signal includes the two-dimensional small angle variation of the measurement mirror 7 θ and the angular drift of the beam Δθ ₀ , the reference signal monitors and separates the angular drift Δθ ₀ of the beam, combined with the principle of geometric optics and optical self-collimation, real-time differential processing can dynamically compensate the angular drift caused by the Angle measurement error, accurately measure the variation of the two-dimensional small angle of the measuring reflector 7:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>$

Here: θ is the variation of the two-dimensional small angle of measuring reflector 7, _d is the variation of the light spot center position that measurement signal forms on main CCD image sensor 5, f is the equivalent focal length of collimating objective lens 6, d ₀ is the amount of change in the spot center position formed by the reference signal on the front CCD image sensor 8, and L is the total equivalent optical path that the laser beam passes from the laser light source 1 to the front CCD image sensor 8.

In the present embodiment, the optical path multiplication device 9 is made up of two relatively parallel plane reflectors 10 and 11, and the two plane reflectors 10 and 11 are all made up of length: a=50mm, width: b=10mm, thickness It is: the surface of the flat crystal with d=5mm is finely ground and then coated with a high-reflection film. The surface roughness of the flat crystal is better than 0.08um. The reflectivity coefficient of the high-reflection film: R≥99%@632.8nm, two flat mirrors 10 The distance between and 11 is: D=40mm, the exit pupil diameter of the laser beam emitted by the laser light source is Φ5mm, after reflecting N=8 times between the two plane reflectors 10 and 11, it reaches the front CCD image sensor 8, and the laser beam The total equivalent optical path of the light beam from the laser light source 1 to the front CCD image sensor 8 is L=400mm. The experimental results show that the two-dimensional photoelectric self-collimation device can measure stably when the measurement resolution reaches 0.01″ The accuracy is better than 0.05″/h, and the measurement uncertainty is better than 0.05″, realizing high-precision two-dimensional small-angle measurement.

Example 2:

Two-dimensional photoelectric self-collimation device as shown in Figure 1, here, the optical path multiplication device 9 is made of two relatively parallel plane reflectors 10 and 11 as shown in Figure 2 and an additional plane positioned on the reference beam path mirror 12. The optical path multiplying device 9 reflects the reference beam multiple times, prolongs the optical path of the reference beam, and amplifies the linear displacement corresponding to the beam angle drift. Other components and working principles of this embodiment are the same as those of Embodiment 1.

Example 3:

The two-dimensional photoelectric self-collimation device shown in FIG. 1, here, the optical path multiplication device 9 is composed of two rectangular prisms 13 and 14 placed opposite each other as shown in FIG. 3a. The optical path multiplying device 9 reflects the reference beam multiple times, prolongs the optical path of the reference beam, and amplifies the linear displacement corresponding to the beam angle drift. Other components and working principles of this embodiment are the same as those of Embodiment 1.

Example 4:

Two-dimensional photoelectric self-collimation device as shown in Figure 1, here, the optical path multiplication device 9 is composed of two rectangular prisms 13 and 14 placed oppositely as shown in Figure 3 b and an additional plane reflector positioned on the reference beam path 12 compositions. The optical path multiplying device 9 reflects the reference beam multiple times, prolongs the optical path of the reference beam, and amplifies the linear displacement corresponding to the beam angle drift. Other components and working principles of this embodiment are the same as those of Embodiment 1.

Example 5:

Two-dimensional photoelectric self-collimation device as shown in Figure 1, here, the optical path multiplication device 9 is made of a plurality of plane reflectors 15,16,17,18,19,20 placed in parallel in pairs as shown in Figure 4a, Composed of 21 and 22. The optical path multiplying device 9 reflects the reference beam multiple times, prolongs the optical path of the reference beam, and amplifies the linear displacement corresponding to the beam angle drift. Other components and working principles of this embodiment are the same as those of Embodiment 1.

Embodiment 6:

Two-dimensional photoelectric self-collimation device as shown in Figure 1, here, the optical path multiplication device 9 is made of a plurality of plane reflectors 15,16,17,18,19,20 placed in parallel in pairs as shown in Figure 4b, 21 and 22 and an additional flat mirror 12 located in the path of the reference beam. The optical path multiplying device 9 reflects the reference beam multiple times, prolongs the optical path of the reference beam, and amplifies the linear displacement corresponding to the beam angle drift. Other components and working principles of this embodiment are the same as those of Embodiment 1.

Claims (7)

1. A two-dimensional photoelectric self-collimation device based on the optical path multiplication compensation method, comprising a laser light source, a reticle, a main beam splitter, a main CCD image sensor, a collimating objective lens, and a measuring mirror placed in sequence, characterized in that A pre-beam splitter is placed between the laser light source and the reticle to obtain a reference beam with exactly the same characteristics as the measurement beam, an optical path multiplier device performs multiple reflections on the reference beam, and a front-end CCD image sensor monitors the angular drift of the beam The amount is monitored; the optical path multiplication device is composed of two plane mirrors placed relatively parallel. 2. The device according to claim 1, characterized in that said optical path multiplication device further comprises an additional plane mirror located on the path of the reference beam. 3. The device according to claim 1, characterized in that said optical path multiplication device is composed of two opposite right-angle prisms. 4. The device according to claim 3, characterized in that said optical path multiplication device further comprises an additional plane mirror located on the path of the reference beam. 5. The device according to claim 1, characterized in that said optical path multiplication device is composed of a plurality of plane mirrors placed in parallel in pairs. 6. The device according to claim 5, characterized in that said optical path multiplication device further comprises an additional plane mirror located on the path of the reference beam. 7. A measurement method based on a two-dimensional photoelectric self-collimation device of the optical path multiplication compensation method, characterized in that said measurement method comprises the following steps: (1). First adjust and fix the optical path multiplication device, and then calibrate the two-dimensional photoelectric self-collimation device; (2). The laser beam emitted by the laser light source is divided into a transmitted beam and a reflected beam by the pre-beam splitter: the transmitted beam becomes the measuring beam, and the reflected beam becomes the reference beam; (3). After the reference beam enters the optical path multiplication device, it is received by the front CCD image sensor after multiple reflections and becomes a reference signal; (4). After the measurement beam acquires the variation of the two-dimensional small angle of the measurement mirror, it is received by the main CCD image sensor and becomes a measurement signal; (5). The reference signal monitors and separates the angle drift of the beam, and real-time differential processing can dynamically compensate the angle measurement error caused by the angle drift, and accurately measure the change of the two-dimensional small angle of the measuring mirror: $\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>$ Here: θ is the variation of the two-dimensional small angle of the measuring mirror, d ₁ is the variation of the spot center position formed by the measurement signal on the main CCD image sensor, f is the equivalent focal length of the collimating objective lens, and d ₀ is the reference The amount of change in the center position of the light spot formed by the signal on the front CCD image sensor is the total equivalent optical path of the laser beam from the laser light source to the front CCD image sensor.

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