阅读说明：本技术 基于波前校正的低像差高精度二维光电自准直方法与装置 (Low-aberration high-precision two-dimensional photoelectric auto-collimation method and device based on wavefront correction ) 是由 于洋 石剑 张玮煊 陈祥发 谭久彬 于 2021-07-30 设计创作，主要内容包括：本发明属于精密测试计量技术领域,提出一种基于波前校正的低像差高精度二维光电自准直方法与装置。本发明在传统自准直仪测量方法中增加光源光束相位补偿环节,该环节利用仪器内参考光路的波前畸变信息通过驱动变形镜补偿光源光束相位,实现对自准直仪光源出射光束角漂移的测量与补偿,减小像差,提高光学系统的成像质量与光斑定位精度,进而提高了自准直仪角度测量精度。同时引入该环节使自准直仪光源出射光束具有极高的光束质量和稳定性,进一步提高自准直仪角度测量的分辨力与稳定性。该方法使传统自准直仪具备纳弧度量级(5×10～(-)～(9)rad,即0.001″)的角度分辨力和亚微弧度量级(10～(-7)rad,即0.02″)的角度测量精度。本发明具有同等条件下,实现高分辨力、高精度、高稳定性兼顾的角度测量的技术优势,同时具备抗环境扰动和补偿扰动引起的误差的能力。(The invention belongs to the technical field of precision test and measurement, and provides a low-aberration high-precision two-dimensional photoelectric auto-collimation method and device based on wavefront correction. The invention adds a light source beam phase compensation link in the traditional autocollimator measurement method, and the link compensates the light source beam phase by driving a deformable mirror by utilizing the wavefront distortion information of a reference light path in the autocollimator, thereby realizing the measurement and compensation of the angular drift of the light beam emitted by the light source of the autocollimator, reducing the aberration, improving the light qualityThe imaging quality and the light spot positioning accuracy of the optical system further improve the angle measurement accuracy of the autocollimator. Meanwhile, the link is introduced, so that the emergent light beam of the light source of the autocollimator has extremely high light beam quality and stability, and the resolution and the stability of the angle measurement of the autocollimator are further improved. The method makes the traditional autocollimator have the magnitude of nano radian (5 multiplied by 10) ‑ 9 Angular resolution of rad, i.e., 0.001 ″) and sub-microradians (10 ″) ‑7 rad, i.e., 0.02 ") angular measurement accuracy. The method has the technical advantages of realizing angle measurement with high resolution, high precision and high stability under the same condition, and has the capabilities of resisting environmental disturbance and compensating errors caused by disturbance.)

1. The invention relates to a low-aberration high-precision two-dimensional photoelectric auto-collimation method based on wavefront correction, which is characterized in that a light source light beam phase correction link is added, and the method comprises the following steps:

a, fixing a plane reflector (5) on the surface of a measured object;

b, lightening the laser light source (1), and adjusting the positions of the measured object and the plane reflector (5) to enable the geometric center of a measuring beam spot image received by the image sensor (3) to be positioned at the center position of the sensor;

step c, the wavefront sensor (14) measures displacement information and wavefront information of the incident reference beam spot, and a measurement error caused by factors such as environmental disturbance and light source drift in the device measurement process is obtained as alpha₀And beta₀；

D, adjusting the wavefront phase difference of the surface shape compensation distortion of the deformable mirror (15) according to the reference beam wavefront information measured by the wavefront sensor (14), so that the measurement error introduced by factors such as environmental disturbance and light source drift in the instrument is 0;

step e, when the plane reflector (5) rotates along with the yaw angle and the pitch angle of the measured object, the image sensor (3) measures the displacement value of the light spot of the incident measuring light beam, wherein the distances of the light spot deviating from the center position of the image sensor are x1 and y1 respectively;

step f, calculating alpha according to x1 ═ f · tan (2 alpha) by using the measuring beam spot displacements x1 and y1, wherein alpha is an angle of a yaw angle generated by the measured object; β is calculated according to y1 ═ f · tan (2 β), where β is the angle at which the measured object produces a pitch angle.

2. The two-dimensional photoelectric auto-collimation method with low aberration and high precision based on wavefront correction as claimed in claim 1, characterized in that a correction link of a spatial light modulator (17) is added, comprising the following steps:

a, fixing a plane reflector (5) on the surface of a measured object;

b, lightening the laser light source (1), adjusting the positions of the measured object and the plane reflector (5), and enabling the geometric center of a measuring beam spot image received by the image sensor (3) to be in the center position of the sensor;

step c, the wavefront sensor (14) measures displacement information and wavefront information of the incident reference beam spot to obtain angle drift information alpha of the laser light source (1) in the device measuring process₀And beta₀；

D, adjusting the spatial light modulator (17) to enable the angular drift information of the laser light source (1) to be 0 all the time;

e, adjusting the surface shape of the deformable mirror (15) at any time according to the wavefront information of the reference beam measured by the wavefront sensor (14) again, and compensating the wavefront phase distortion of the measuring beam caused by long-distance air disturbance to enable the wave aberration of the measuring beam to be 0;

step f, when the plane reflector (5) rotates along with the yaw angle and the pitch angle of the measured object, the image sensor (3) measures the displacement value of the light spot of the incident measuring light beam, wherein the distances of the light spot deviating from the center position of the image sensor are x1 and y1 respectively;

step g, calculating alpha according to x1 ═ f · tan (2 alpha) by using the measuring beam spot displacements x1 and y1, wherein alpha is an angle of a yaw angle generated by the measured object; β is calculated according to y1 ═ f · tan (2 β), where β is the angle at which the measured object produces a pitch angle.

3. The two-dimensional photoelectric auto-collimation device with low aberration and high precision based on wavefront correction is characterized by comprising a laser light source (1), a first spectroscope (2), an image sensor (3), a collimation objective lens group (4), a plane mirror (5), a second convex lens (6), an aperture diaphragm (7), a first turning mirror (8), a second turning mirror (9), a first polarization spectroscope (10), a reference mirror (11), a second polarization spectroscope (12), a third convex lens (13), a wavefront sensor (14), a deformable mirror (15) and a deformable mirror driver (16);

after being collimated by a second convex lens (6), light emitted by the laser source (1) is reflected by a deformable mirror (15) and is incident on the small-hole diaphragm (7) in parallel; two beams of light emitted by using the aperture diaphragm (7) as an object plane are transmitted by the first spectroscope (2), reflected by the first turning mirror (8) and the second turning mirror (9) and vertically incident on the collimating objective lens group (4) to be collimated into parallel beams;

the parallel light beam is split into a transmission light beam and a reflection light beam by a first polarization beam splitter (10), and the polarization states are vertical to each other; the transmitted light beam is a measuring light beam and is vertically incident to the plane mirror (5); the reflected light beam is a reference light beam and is vertically incident to a reference reflector (11); the two light beams are respectively reflected by the reflecting mirrors and then return along the original path, and after being reflected by the first spectroscope (2), the reference light beam and the measuring light beam are separated by beam splitting of the second polarizing spectroscope (12); the measuring beam is transmitted and vertically incident to the image sensor (3) to acquire images, and the reference beam is reflected and transmitted by the third convex lens (13) to be changed into parallel light to be incident to the wavefront sensor (14) to acquire images;

the laser light source (1) is positioned at the focal plane of the second convex lens (6), and emergent light is parallel light;

the deformable mirror (15) is connected with the deformable mirror driver (16), is arranged between the second convex lens (6) and the small-hole diaphragm (7), and after light emitted by the laser light source (1) is collimated into parallel light through the second convex lens (6), is reflected by the deformable mirror (15) arranged at an inclined angle of 45 degrees and vertically enters the small-hole diaphragm (7); the deformable mirror driver (16) can control the surface shape of the deformable mirror (15), finely adjust the yaw angle and the pitch angle and adjust the direction of parallel light entering the aperture diaphragm (7);

the aperture diaphragm (7) is used as an object plane and is positioned at the equivalent focal plane of the collimating objective lens group (4);

the collimating objective lens group (4) consists of a first combined lens (42) and a second combined lens (43) to form a telephoto objective lens group, and the focal length of the telephoto objective lens group is far greater than that of the first combined lens (42);

the first combined lens (42) is formed by combining 2 or more lenses, and the centers of the lenses are on the same straight line; the first combined lens (42) has the same action effect of converging the light beam as the first convex lens (42); the first combined lens (42) is formed by combining a plurality of lenses and has smaller aberration and nonlinearity;

the second combined lens (43) is formed by combining 2 or more lenses, and the centers of the lenses are on the same straight line; the second combined lens (43) has the same effect of diverging the light beam as the concave lens; the second combined lens (43) is formed by combining a plurality of lenses and has smaller aberration and nonlinearity;

the third convex lens (13) is positioned at the right side of the convergent focus of the reflected light beam of the second polarizing beam splitter (12), the focus is positioned at the focal plane of the third convex lens (13), and the reference light beam is reflected by the second polarizing beam splitter (12), converged, diverged, transmitted by the third convex lens (13) and changed into a parallel light beam and merged into the central position of the wavefront sensor (14);

the first turning mirror (8) and the second turning mirror (9) are arranged in parallel, and a fixed small angle exists between the normal direction of the mirror surface and the main optical axis.

4. The two-dimensional photoelectric auto-collimation device with low aberration and high precision based on wavefront correction as claimed in claim 2 is characterized in that the second turning mirror (9) is removed, the deformable mirror (15), the deformable mirror driver (16) and the spatial light modulator (17) are added, meanwhile, the first polarization beam splitter (10), the reference mirror (11) are outside the instrument, and the plane mirror (5) are taken as the target to be measured together;

the spatial light modulator (17) is arranged between the second convex lens (6) and the small aperture diaphragm (7), and light emitted by the laser light source (1) is collimated into parallel light through the second convex lens (6) and then vertically enters the small aperture diaphragm (7); the spatial light modulator (17) can adjust the direction of parallel light entering the small aperture diaphragm (7);

the deformable mirror (15) is connected with a deformable mirror driver (16), and the deformable mirror driver (16) can control the surface shape of the reflecting surface of the deformable mirror (15); the deformable mirror (15) replaces the second turning mirror (9), and the position and the posture of the reflecting surface are not changed;

the combined target consists of a first polarizing beam splitter (10), a reference reflector (11) and a plane reflector (5), wherein the first polarizing beam splitter (10) and the reference reflector (11) do not change along with the deflection of the plane reflector (5).

Technical Field

The invention belongs to the technical field of precision test and measurement, and particularly relates to a low-aberration high-precision two-dimensional photoelectric auto-collimation method and device based on wavefront correction.

Background

With the continuous development of the fields of ultra-precision machining and manufacturing, large-scale equipment manufacturing, large scientific engineering and the like, an auto-collimation angle measurement technology which can realize high resolution, high precision and high stability in a large measurement range and has certain anti-interference capability on a measurement field is urgently required. The technology plays an important supporting role in the development of the field.

In the field of ultra-precision machining and manufacturing, the combination of the autocollimator, a plane mirror, a multi-surface prism and the like can measure the shape tolerance and the position tolerance of parts, and the angle resolution can reach 0.1 to 0.001; in the manufacturing and installation process of large equipment, the autocollimator is matched with a cooperative target, and the measurement distance can reach several meters or even dozens of meters; and (3) measuring the yaw angle and the pitch angle remotely in real time by using an autocollimator in an assembly workshop, so as to realize the monitoring of the equipment attitude. In the field of large scientific engineering, the autocollimator can be used for measuring the rotation precision of a large scientific instrument, the linear precision of linear motion and the relative attitude and position between the instruments. Furthermore, the application scenarios described above are not limited to detection room and laboratory environments. Limited by the target to be measured, a self-aligning instrument capable of performing real-time remote high-precision high-stability measurement in the manufacturing field, assembly shop or even field environment is needed.

The photoelectric autocollimator is based on the principle of optical autocollimation, and the conventional structure is shown in fig. 1, and the device comprises a laser light source 1, a first convex lens 41, a first spectroscope 2 and an image sensor 3. The light beam emitted from the laser light source 1 is collimated into a parallel light beam by the convex lens 41 and enters the reflection surface of the object 5. The light beam reflected from the reflecting surface of the object 5 is converged by the convex lens 41, and the light spot information is collected by the image sensor 3. The angular information of the measured object 5 can be calculated by using the position information of the light spot.

The autocollimator of the conventional structure has the following problems:

the collimator objective is a single lens, the focal length is about 500mm generally and is difficult to improve continuously, the limit displacement resolution of a common photoelectric sensor is between 30 and 50nm, and the autocollimator is difficult to realize angle measurement of the magnitude of the nano radian according to the measurement principle; the single-lens optical system has large aberration and large photoelectric sensor light spot positioning error, and the autocollimator is difficult to realize high-precision angle measurement; the light source of the autocollimator is generally a laser light source, and because of the light emitting mechanism, an emergent light beam has flat drift and angle drift, and the autocollimator is difficult to realize high-stability measurement; the structure does not have any compensation link, and is extremely easily influenced by external disturbance, for example, air disturbance under the long-distance measurement condition can cause the reflected light beam to have extra angle drift, and the measurement precision and the stability of the autocollimator are reduced.

In summary, the influence of various factors such as the hardware limitation, the sensitivity to the measurement environment, the influence of air disturbance and the like of the traditional photoelectric auto-receiving optical system and the sensor greatly limits the technical indexes and the use environment of the auto-collimator, and the task of measuring the nano-arc degree angle with long distance, high resolution, high precision and high stability is difficult to realize in a complex environment.

Disclosure of Invention

The invention aims to overcome the defects of the traditional structure autocollimator measuring method and device, realize angle measurement with high precision, high resolution and high stability, and provide a low-aberration high-precision two-dimensional photoelectric autocollimation method and device based on wavefront correction.

The invention relates to a low-aberration high-precision two-dimensional photoelectric auto-collimation method based on wavefront correction, which comprises the following steps of:

step a, light emitted by a laser light source forms collimated light beams through a convex lens, a deformable mirror, a diaphragm, a spectroscope, a deformable mirror, a plane mirror and a collimating objective lens group and then is emitted;

b, splitting the emergent light beam by a first polarization beam splitter in the instrument, wherein the transmitted light beam is incident on a measured reflector outside the instrument as a measuring light beam, is reflected and has two-dimensional angle change information of a measured target; wherein the reflected beam is incident on a reference reflector fixed in the instrument as a reference beam and returns in the original path;

c, returning the measuring beam and the reference beam along the original emergent light path until the measuring beam and the reference beam are split by the second polarizing beam splitter after being reflected by the first beam splitter; wherein the transmitted beam is a measuring beam received by the image sensor; wherein the reflected light beam is a reference light beam, and is converged into parallel light by the convex lens to be received by the wavefront sensor;

d, the wavefront sensor acquires the drift amount and wavefront phase information of the reference beam, and the controller calculates and provides a driving wavefront correction device to compensate the light source angle drift and phase distortion and reduce the aberration of the optical system;

step e, after the links of wavefront measurement and correction, measuring the displacement value of the light spot of the incident measuring light beam by the image sensor, wherein the distances of the light spot deviating from the central position of the image sensor are x1 and y1 respectively;

step f, calculating alpha according to x1, f · tan (2a) by using the spot displacements x1 and y1 of the measuring beams, wherein the alpha is an angle for generating a yaw angle of the measured object after compensation; and calculating beta according to y1 ═ f · tan (2 beta), wherein beta is an angle for generating a pitch angle of the measured object after compensation.

The wavefront correction device is a deformable mirror or a spatial light modulator, and has the function of correcting and compensating the light source angle drift and the wavefront phase distortion according to the measurement data of the wavefront sensor, so that the light beam quality is improved.

The invention relates to a low-aberration high-precision two-dimensional photoelectric auto-collimation device based on wavefront correction, which comprises the following contents:

the device comprises a laser light source, a first spectroscope, an image sensor, a first combined lens, a second combined lens, a plane reflector, a second convex lens, a deformable mirror driver, an aperture diaphragm, a first turning mirror, a second turning mirror, a first polarizing spectroscope, a reference reflector, a second polarizing spectroscope, a third convex lens and a wavefront sensor.

The light emitted by the laser source is collimated by the second convex lens and reflected by the deformable mirror, and then is incident to the aperture diaphragm; the aperture diaphragm is used as an object plane, and two beams of light emitted are transmitted by the first spectroscope, reflected by the first turning mirror and the second turning mirror and vertically incident on the collimating objective lens group to be collimated into parallel beams of light.

The parallel light beam is split into a transmission light beam and a reflection light beam by a first polarization beam splitter, and the polarization states are vertical to each other; the transmitted beam is a measuring beam and is vertically incident to the plane mirror; the reflected light beam is a reference light beam and is vertically incident to the reference reflector; the two light beams are respectively reflected by the reflecting mirrors and then return along the original path, and after being reflected by the first spectroscope, the reference light beam and the measuring light beam are separated by beam splitting of the second polarizing spectroscope; the measuring beam transmits and vertically enters the image sensor to collect imaging, and the reference beam is reflected and transmitted by the third convex lens to become parallel light to enter the wavefront sensor to collect imaging.

The laser light source is positioned at the focal plane of the second convex lens, and emergent light is parallel light;

the aperture diaphragm is used as an object plane and is positioned at the equivalent focal plane of the collimating objective lens group;

the collimating objective lens group consists of a first combined lens and a second combined lens to form a telephoto objective lens group, and the focal length of the telephoto objective lens group is far larger than that of the first convex lens, so that the limiting angle resolution of the autocollimator is improved;

the third convex lens is positioned on the right side of the convergence focus of the reflected light beam of the second polarizing beam splitter, the focus is positioned on the focal plane of the third convex lens, and the reference light beam is converged after being reflected by the second polarizing beam splitter, then is diverged and is transmitted by the third convex lens to become a parallel light beam and is merged into the central position of the sensor before the transmitted wave;

the first turning mirror and the second turning mirror are arranged in parallel and have a fixed small angle with the main optical axis.

Advantageous effects of the invention

The low-aberration high-precision two-dimensional photoelectric auto-collimation method based on wavefront correction provided by the invention adds a light source light beam phase compensation link in the traditional auto-collimation measuring method. The link utilizes wavefront distortion information of a reference light path in the instrument to compensate the phase of a light beam of a light source by driving a deformable mirror, so that the emergent light of the autocollimator is measured and regulated, the aberration is reduced, the imaging quality and the light spot positioning precision of an optical system are improved, and the angle measurement precision of the autocollimator is further improved. Meanwhile, the link is introduced, so that the emergent light beam of the light source of the autocollimator has extremely high light beam quality and stability, and the resolution and the stability of the angle measurement of the autocollimator are further improved. The method makes the traditional self-collimator possess the magnitude of nano radian (5 multiplied by 10)^-9Angular resolution of rad, i.e., 0.001 ″) and sub-microradians (10 ″)^-7rad, i.e., 0.02 ") angular measurement accuracy.

Compared with the traditional autocollimator structure, the low-aberration high-precision two-dimensional photoelectric autocollimator based on wavefront correction provided by the invention has the following advantages:

(1) a single collimating objective lens is replaced by a telephoto objective lens group, the focal length is enlarged, the aberration and the light path volume are reduced, and the extreme angle resolution of the system is improved to the magnitude of nanoradian under the same condition;

(2) the reference beam is introduced to realize the measurement and the regulation of the aberration of the optical system of the autocollimator, thereby improving the imaging quality of light spots, improving the positioning precision of the light spots and further improving the measurement precision and the stability of the autocollimator;

(3) the laser light source is replaced by the light which is subjected to phase correction and transmitted by the small-hole diaphragm to serve as the light source of the autocollimator, so that the measurement instability caused by the self-drifting of the light source is directly reduced;

(4) the turning mirror folds the long-focus light path of the system for two times, so that the volume of the device is reduced, the device is more suitable for a field measurement environment, and the influence of air disturbance on beam transmission caused by overlarge size of the device is avoided;

therefore, compared with the traditional self-aligning angle measuring device, the device has the technical advantages that under the same measuring range, the angle limit resolution reaches the magnitude of nanoradian, meanwhile, the angle measurement with high precision and high stability is realized, and the device has the capabilities of resisting environmental disturbance and compensating errors caused by disturbance.

Drawings

FIG. 1 is a schematic structural view of a conventional self-collimation angle measuring device;

FIG. 2 is a schematic structural diagram of a first embodiment of the low-aberration high-precision two-dimensional electro-optic auto-collimation method and apparatus based on wavefront correction according to the present invention;

FIG. 4 is a schematic structural diagram of a second embodiment of the low-aberration high-precision two-dimensional electro-optic auto-collimation method and apparatus based on wavefront correction according to the present invention;

fig. 3 is a schematic diagram of a collimator lens assembly formed by combining a first combined lens and a second combined lens according to an embodiment of the invention.

In the figure: 1 laser light source, 2 first spectroscope, 3 image sensor, 4 collimation objective lens group, 41 first convex lens, 42 first combined lens, 43 second combined lens, 5 plane reflector, 6 second convex lens, 7 aperture diaphragm, 8 first turning mirror, 9 second turning mirror, 10 first polarization spectroscope, 11 reference reflector, 12 second polarization spectroscope, 13 third convex lens, 14 wave front sensor, 15 deformable mirror, 16 deformable mirror driver, 17 spatial light modulator.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The following describes in further detail specific embodiments of the present invention with reference to the accompanying drawings.

Detailed description of the preferred embodiment

The embodiment is a two-dimensional photoelectric auto-collimation method and device with low aberration and high precision based on wavefront correction.

The two-dimensional photoelectric auto-collimation device with low aberration and high precision based on wavefront correction in the embodiment has a schematic structural diagram as shown in fig. 2.

The angle measuring device comprises a laser light source 1, a first spectroscope 2, an image sensor 3, a first combined lens 42, a second combined lens 43, a plane reflector 5, a second convex lens 6, an aperture diaphragm 7, a first turning mirror 8, a second turning mirror 9, a first polarizing spectroscope 10, a reference reflector 11, a second polarizing spectroscope 12, a third convex lens 13, a wavefront sensor 14, a deformable mirror 15 and a deformable mirror driver 16.

Light emitted by the laser source is collimated by the second convex lens 6 and reflected by the deformable mirror 15 and then parallelly enters the aperture diaphragm 7; two beams of light emitted by the aperture diaphragm 7 are transmitted by the first spectroscope 2, reflected by the first turning mirror 8 and the second turning mirror 9, and vertically incident on the collimating objective lens group 4 to be collimated into parallel beams.

The parallel light beam is split into a transmission light beam and a reflection light beam by a first polarization beam splitter 10, and the polarization states are vertical to each other; the transmitted beam is a measuring beam and is vertically incident to the plane mirror 5; the reflected beam is a reference beam and is vertically incident on the reference mirror 11; the two light beams are respectively reflected by the reflecting mirrors and then return along the original path, and after being reflected by the first spectroscope 2, the reference light beam and the measuring light beam are separated by beam splitting of the second polarizing spectroscope 12; the measuring beam transmits and vertically enters the image sensor 3 to collect imaging, and the reference beam is reflected and transmitted by the third convex lens 13 to become parallel light to enter the wavefront sensor 14 to collect imaging.

The laser light source 1 is positioned at the focal plane of the second convex lens 6, and emergent light is parallel light;

the aperture diaphragm 7 is used as an object plane and is positioned at the equivalent focal plane of the collimating objective lens group 4;

the collimating objective lens group 4 consists of a first combined lens 42 and a second combined lens 43 to form a telephoto objective lens group, and the focal length of the telephoto objective lens group is far greater than that of the first convex lens 42, so that the limiting angle resolution of the autocollimator is improved;

the third convex lens 13 is positioned at the right side of the convergence focus of the reflected light beam of the second polarizing beam splitter 12, the focus is positioned at the focal plane of the third convex lens 13, and the reference light beam is converged after being reflected by the second polarizing beam splitter 12, then is diverged and is transmitted by the third convex lens 13 to become a parallel light beam and is merged into the central position of the wavefront sensor 14;

the first turning mirror 8 and the second turning mirror 9 are arranged in parallel and have a fixed small angle with the main optical axis.

The measurement principle is as follows:

when the measured object generates the angle changes of the yaw angle alpha and the pitch angle beta, the plane reflector 5 also generates the angle changes of the yaw angle alpha and the pitch angle beta. The measuring light beam incident on the plane reflector 5 generates deflection angles of 2 alpha and 2 beta between the light beam reflected by the plane reflector 5 and the original light beam because the plane reflector 5 rotates with the measured object to generate a yaw angle and a pitch angle; the reference reflector 11 does not change with the rotation of the object to be measured, and the reference beam incident on the reference reflector 11 is reflected and returns back.

The returned reference beam is reflected by the first beam splitter 2 and the second polarization beam splitter 12, converged, diverged and incident on the third convex lens 13 to become a parallel beam, and then is incident on the wavefront sensor 14; acquiring light beam wavefront phase information of a reference light beam, wherein the information reflects flat drift and angle drift information caused by factors such as external environment disturbance, light source light beam drift and the like in the transmission process of the reference light beam in the device; the measuring beam transmitted co-optically with the reference beam will also carry measurement error information a due to the above-mentioned factors₀And beta₀。

And driving the deformable mirror to generate a compensation phase according to the beam drift and wavefront distortion information measured by the wavefront sensor 14, so that the beam angle drift and the distortion phase of the autocollimator are compensated to 0. After compensation, the returned measuring beam is reflected by the first beam splitter 2, transmitted by the second polarization beam splitter 12 and enters the image sensor 3, and displacement of the light spot in the vertical and horizontal directions away from the center of the sensor is acquired as x1 and y1, and the following relations are satisfied, wherein x1 is f · tan (2 α), y1 is f · tan (2 β), and f is the equivalent focal length of the collimating objective lens group 4; and the yaw angle alpha and the pitch angle beta obtained by the formula are the yaw angle and the pitch angle of the measured object which are finally measured.

The low-aberration high-precision two-dimensional photoelectric auto-collimation method based on wavefront correction comprises the following steps of:

step a, fixing a plane reflector 5 on the surface of a measured object;

step b, lightening the laser light source 1, adjusting the positions of the measured object and the plane reflector 5, and enabling the geometric center of the measuring beam spot image received by the image sensor 3 to be positioned at the center position of the sensor;

step c, the wavefront sensor 14 measures the displacement information and wavefront information of the incident reference beam light spot, and the measurement error alpha caused by factors such as environmental disturbance and light source drift in the measurement process of the device is obtained₀And beta₀；

D, adjusting the surface shape of the deformable mirror 15 according to the reference beam wavefront information measured by the wavefront sensor 14 to enable the measurement error introduced by factors such as environmental disturbance and light source drift in the instrument to be 0;

step e, when the plane reflector 5 rotates along with the yaw angle and the pitch angle of the measured object, the image sensor 3 measures the displacement value of the light spot of the incident measuring light beam, wherein the distances of the light spot deviating from the center position of the image sensor are x1 and y1 respectively;

step f, calculating and obtaining alpha according to x1, namely f · tan (2 alpha) by using the spot displacement x1 and y1 of the measuring beam, wherein a is an angle for generating a yaw angle of the measured object; and calculating beta according to y1 ═ f · tan (2 beta), wherein beta is an angle of the measured object generating the pitch angle.

Detailed description of the invention

The embodiment is a two-dimensional photoelectric auto-collimation method and device with low aberration and high precision based on wavefront correction.

The structural schematic diagram of the low-aberration high-precision two-dimensional photoelectric auto-collimation device based on wavefront correction of the embodiment is shown in fig. 3.

On the basis of the device in the first embodiment, in this embodiment, the spatial light modulator 17 is added between the second convex lens 6 and the aperture stop 7, and the second turning mirror 9 is replaced by the deformable mirror 15 and the deformable mirror driver 16; the first polarizing beam splitter 10, the reference reflector 11 and the plane reflector 5 are arranged outside the angle measuring device and are positioned at one side of a measured object;

the low-aberration high-precision two-dimensional photoelectric auto-collimation method based on wavefront correction comprises the following steps of:

step a, fixing a plane reflector 5 on the surface of a measured object;

step b, lightening the laser light source 1, adjusting the positions of the measured object and the plane reflector 5, and enabling the geometric center of the measuring beam spot image received by the image sensor 3 to be positioned at the center position of the sensor;

step c, the wavefront sensor 14 measures the displacement information and wavefront information of the incident reference beam spot to obtain the angular drift information a of the laser light source 1 in the measuring process of the device₀And beta₀；

D, adjusting the spatial light modulator 17 to enable the angular drift information of the laser light source 1 to be 0 all the time;

e, adjusting the surface shape of the deformable mirror 15 at any time according to the wavefront information of the reference beam measured by the wavefront sensor 14 again, compensating the wavefront phase distortion of the measuring beam caused by long-distance air disturbance, enabling the wave aberration of the measuring beam to be 0, and improving the imaging quality and stability of the measuring beam on the image sensor 3;

step f, when the plane reflector 5 rotates along with the measured object to generate a yaw angle and a pitch angle, the image sensor 3 measures the displacement value of the light spot of the incident measuring light beam, wherein the distances of the light spot deviating from the center position of the image sensor are x1 and y1 respectively;

step g, calculating and obtaining a according to x1, namely f · tan (2a) by using the spot displacements x1 and y1 of the measuring beams, wherein a is an angle for generating a yaw angle of the measured object; and calculating beta according to y1 ═ f · tan (2 beta), wherein beta is an angle of the measured object generating the pitch angle.

In the embodiment, a deformable mirror 15, a deformable mirror driver 16 and a spatial light modulator 17 are added as a wavefront correction unit, and a reference reflecting mirror is placed on one side of a measured object; the spatial light modulator 17 can compensate the angular drift amount of the laser light source 1 in real time; the deformable mirror 15 and the deformable mirror driver 16 can measure and correct the distortion phase of the measuring beam affected by air disturbance under long-distance transmission, thereby greatly improving the imaging quality and stability of the light spot on the image sensor 3 and improving the stability of the auto-collimation device under the long-distance measuring condition.

The above description is a preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included within the scope of the present invention.