CN113639677A - High-frequency-response two-dimensional photoelectric auto-collimation method and device based on wavefront correction - Google Patents
High-frequency-response two-dimensional photoelectric auto-collimation method and device based on wavefront correction Download PDFInfo
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Abstract
The invention belongs to the technical field of precision test and measurement, and provides a two-dimensional photoelectric auto-collimation method and device based on wavefront sensing and correction. The invention adds a wavefront measurement and correction link in the traditional autocollimator measurement method, realizes measurement and regulation of the aberration of an optical system of the autocollimator by using wavefront distortion information of a reference light path in a measuring instrument and compensating a distortion phase by driving a deformable mirror, improves the imaging quality and the light spot positioning precision of the optical system, and further improves the angle measurement precision of the autocollimator; the angle measurement and the correction process are carried out simultaneously, and the measurement speed of the autocollimator is improved. Meanwhile, the link is introduced, so that the autocollimator has the capability of resisting the interference of the external environment, and the resolution and the stability of the angle measurement of the autocollimator are further improved. The method makes the autocollimator have 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. The invention has the advantages of high frequency response, high resolution and high resolution under the same conditionThe method has the technical advantages of angle measurement of high precision and high stability, and has the capabilities of resisting environmental disturbance and compensating errors caused by disturbance.
Description
Technical Field
The invention belongs to the technical field of precision test and measurement, and particularly relates to a high-frequency-response 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 site is urgently needed. 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 measuring distance can reach several meters or even tens 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 rotating precision of a large scientific instrument, the linear precision of linear motion and the relative attitude and position between the instruments. In addition, the application scenarios are not limited to detection room and laboratory environments. Limited by the target to be measured, an autocollimator capable of performing real-time remote high-precision high-stability measurement in a manufacturing field, an assembly shop or even a field environment is required.
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 then 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 spots.
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 nanoradian-level angle measurement task 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 a measuring method and a measuring device of an autocollimator with a traditional structure, realize angle measurement with high frequency response, high precision, high resolution and high stability, and provides a high-frequency-response two-dimensional photoelectric autocollimation method and a device based on wavefront correction.
The invention relates to a high-frequency response two-dimensional photoelectric auto-collimation method based on wavefront correction, which comprises the following steps of:
a, collimating light emitted by two laser light sources with different wavelengths into parallel light through a convex lens, transmitting the parallel light through a first spectroscope in a common path, forming collimated light beams through a diaphragm, a spectroscope, a turning mirror and a collimating objective lens group, and emitting the collimated light beams;
b, splitting the emergent light beam by a first dichroic mirror 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 light beam and the reference light beam along the original emergent light path until the measuring light beam and the reference light beam are split by the second dichroic mirror after being reflected by the second dichroic mirror; wherein the transmitted beam is a measuring beam received by the image sensor; wherein, the reflected beam is a reference beam, and is converged into parallel light by the convex lens to be received by the wavefront sensor;
d, measuring the displacement information and the wavefront information of the incident reference beam spot by the wavefront sensor, and calculating to obtain the measurement error alpha introduced by factors such as beam drift, environmental disturbance and the like in the measurement process0And beta0；
Step e, when the plane reflector rotates along with the measured object to generate a yaw angle and a pitch angle, the image sensor 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 (2a) by using the measuring beam spot displacements x1 and y1, wherein (alpha-alpha)0) Generating a yaw angle for the compensated measured object; calculating beta according to y1 ═ f · tan (2 beta), wherein (beta-beta)0) And generating a pitch angle for the compensated measured object.
The invention relates to a high-frequency response two-dimensional photoelectric auto-collimation device based on wavefront correction, which comprises the following contents:
the device comprises a light source unit, a second spectroscope, an image sensor, a collimation objective lens group, a plane reflector, an aperture diaphragm, a first turning mirror, a second turning mirror, a first dichroic mirror, a reference reflector, a second dichroic mirror, a third convex lens and a wavefront sensor;
the device comprises a first light source, a second light source, a first dichroic mirror and a second dichroic mirror. Wherein the first light source and the second light source can emit light beams with two different wavelengths; the first dichroic mirror and the second dichroic mirror exhibit high transmittance for the first light source and high reflectance for the second light source;
the light source unit is composed of a first light source, a second light source, a first convex lens, a second convex lens and a first spectroscope. The first light source is positioned on a first convex lens focal plane, and the second light source is positioned on a second convex lens focal plane and is respectively arranged at two sides of the light splitting section of the first light splitter;
the light emitted by the first light source and the second light source is collimated into two beams of parallel light which are vertical to each other through the convex lenses corresponding to the first light source and the second light source, the two beams of parallel light are converged through the first beam splitter and then enter the aperture diaphragm, and the transmitted light beams are changed into parallel light beams after being transmitted by the second beam splitter, reflected by the first turning mirror, reflected by the second turning mirror and transmitted by the collimating objective lens group in sequence; the parallel light beams are split into transmission light beams and reflection light beams through a first dichroic mirror, the transmission light beams are measuring light beams and are vertically incident to a plane reflector; 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 mirror and then return along the original path, and are reflected by the second dichroic mirror, and then the reference light beam and the measuring light beam are separated through beam splitting of the second dichroic mirror; 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 incident wavefront sensor to collect imaging.
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; the first combined lens is formed by combining 2 or more convex lenses and concave lenses and has the same function of converging light beams with the convex lenses; the second combined lens is formed by combining 2 or more convex lenses and concave lenses and has the same light beam dispersing effect as the concave lenses; the focal length of the self-collimating lens is far larger than that of a single convex lens, so that the extreme angle resolution of the self-collimating lens is improved, and the self-collimating lens has smaller aberration and nonlinearity;
the third convex lens is positioned on the right side of the convergence focus of the reflected light beam of the second dichroic mirror, the focus is positioned on the focal plane of the third convex lens, the reference light beam is converged after being reflected by the second dichroic mirror, then is diverged and becomes a parallel light beam after being transmitted by the third convex lens, and is merged into the central position of the sensor before the incident wave.
Advantageous effects of the invention
According to the high-frequency-response two-dimensional photoelectric auto-collimation method based on wavefront correction, a wavefront measurement and correction link is added in a traditional auto-collimation instrument measurement method, wavefront distortion information of a reference light path in a measurement instrument compensates distortion phase through driving a deformable mirror, measurement and regulation of aberration of an optical system of the auto-collimation instrument are achieved, imaging quality and light spot positioning accuracy of the optical system are improved, and further angle measurement accuracy of the auto-collimation instrument is improved; the angle measurement and the correction process are carried out simultaneously, and the measurement speed of the autocollimator is improved. Meanwhile, the link is introduced, so that the autocollimator has the capability of resisting external environment interference, such as temperature change, micro vibration, air disturbance and the like, and the resolution and stability of angle measurement of the autocollimator are further improved; the method makes the traditional autocollimator have 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 high-frequency-response 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 volume of an optical path is reduced, and the extreme angle resolution of the system is improved to a nano radian order 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 transmitted by the small-hole diaphragm to be used 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) an independent light source is added in the device to serve as a reference light beam, angle drift and wavefront phase information of the light beam are measured and compensated while angle measurement is carried out, so that the measurement speed and frequency response of the device are improved, the imaging quality of light spots on an image sensor is improved, the positioning precision of the light spots is improved, and the measurement precision and stability of the auto-collimation device are further improved;
(5) the turning mirror folds the long-focus light path of the system twice, 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 measurement with high frequency response, high precision and high stability is realized while the angle limit resolution reaches the magnitude of nanoradian, and the device has the capacity 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 diagram of a collimating objective lens assembly formed by combining a first combined lens and a second combined lens according to the present invention;
FIG. 3 is a schematic structural diagram of a first embodiment of a high-frequency-response two-dimensional photoelectric 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 high-frequency-response two-dimensional photoelectric auto-collimation method and apparatus based on wavefront correction according to the present invention;
fig. 5 is a schematic structural diagram of a third embodiment of the high-frequency-response two-dimensional photoelectric auto-collimation method and device based on wavefront correction.
In the figure: the light source device comprises a light source unit 1, a first light source 1-1, a second light source 1-2, a first convex lens 1-3, a second convex lens 1-4, a first spectroscope 1-5, a second spectroscope 2, an image sensor 3, a collimating objective lens group 4, a first combined lens 4-1, a second combined lens 4-2, a plane mirror 5, a small-hole diaphragm 6, a first turning mirror 7, a second turning mirror 8, a first dichroic mirror 9, a reference mirror 10, a second dichroic mirror 11, a third convex lens 12, a wavefront sensor 13, a deformable mirror 14, a deformable mirror driver 15 and a spatial light modulator 16.
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 high-frequency-response two-dimensional photoelectric auto-collimation method and device based on wavefront correction.
The structural schematic diagram of the high-frequency-response two-dimensional photoelectric auto-collimation device based on wavefront correction in the embodiment is shown in fig. 3. The angle measuring device comprises a first light source 1-1, a second light source 1-2, a first convex lens 1-3, a second convex lens 1-4, a first spectroscope 1-5, a second spectroscope 2, an image sensor 3, a first combined lens 4-1, a second combined lens 4-2, a plane reflector 5, a small hole diaphragm 6, a first turning mirror 7, a second turning mirror 8, a first dichroic mirror 9, a reference reflector 10, a second dichroic mirror 11, a third convex lens 12 and a wavefront sensor 13;
the light beam emitted by the first light source 1-1 and the light beam emitted by the second light source 1-2 are combined after being collimated by the first spectroscope 1-5, the optical axes of the two light beams are superposed, the propagation directions of the two light beams are the same, and the combined light beams are incident to the pinhole diaphragm 6 in parallel; two beams of light emitted by the aperture diaphragm 6 are transmitted by the second beam splitter 2, reflected by the first turning mirror 7 and the second turning mirror 8 and vertically incident on the collimating objective lens group 4 to be collimated into parallel beams of light by taking the aperture diaphragm as an object plane.
The parallel light beam is split into a transmission light beam and a reflection light beam by a first dichroic mirror 9, and the light beam of a first light source 1-1 is transmitted and is used as a measuring light beam to vertically enter a plane reflector 5; the light beam of the second light source 1-2 is reflected and is used as a reference light beam which is vertically incident to the reference reflector 10; the two light beams return along the original path after being reflected by the reflecting mirror respectively, and are split by the second dichroic mirror 11 to separate the reference light beam from the measuring light beam after being reflected by the second dichroic mirror 2; 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 12 to become parallel light incident wavefront sensor 13 to collect imaging.
The first light source 1-1 is positioned on a focal plane of the first convex lens 1-3, and the second light source 1-2 is positioned on a focal plane of the second convex lens 1-4 and is respectively arranged at two sides of the light splitting section of the first light splitter 1-5;
the aperture diaphragm 6 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 4-1 and a second combined lens 4-2 to form a telephoto objective lens group; the first combined lens 4-1 is formed by combining 2 or more convex lenses and concave lenses and has the same light beam converging effect as the convex lenses; the second combined lens 4-2 is formed by combining 2 or more convex lenses and concave lenses and has the same light beam dispersing effect as the concave lenses; the focal length of the self-collimating lens is far larger than that of a single convex lens, so that the extreme angle resolution of the self-collimating lens is improved, and the self-collimating lens has smaller aberration and nonlinearity;
the third convex lens 12 is located on the right side of the convergence focus of the reflected light beam of the second dichroic mirror 11, the focus is located on the focal plane of the third convex lens 12, and the reference light beam is reflected by the second dichroic mirror 11, converged, diverged, transmitted by the third convex lens 12, changed into a parallel light beam, and merged into the central position of the wavefront sensor 13.
The first turning mirror 7 and the second turning mirror 8 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 angle changes of a yaw angle alpha and a pitch angle beta, the plane reflector 5 also generates angle changes of a yaw angle a and a 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 10 does not produce angle change along with the rotation of the measured object, and the reference beam incident to the reference reflector 10 returns in the original path after being reflected;
the returned measuring beam is reflected by the first beam splitter 2, transmitted by the second dichroic mirror 11, and enters the image sensor 3, and displacement of the light spot from the center of the sensor in the vertical and horizontal directions is x1 and y1, and the following relations are satisfied, where x1 is f · tan (2 α), y1 is f · tan (2 β), and f is an equivalent focal length of the collimating objective lens group 4.
The returned reference beam is reflected by the first beam splitter 2, reflected by the second dichroic mirror 11, converged, diverged and incident on the third convex lens 12 to become a parallel beam, and then the incident wavefront sensor 13 collects the beam wave of the reference beamPre-phase information; 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 the measurement error information α due to the above-mentioned factors0And beta0。
Error compensation is carried out on the yaw angle alpha and the pitch angle beta obtained by the calculation formula, and the compensated (alpha-alpha)0) And (beta-beta)0) And finally measuring the yaw angle and the pitch angle of the measured object.
The high-frequency-response 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;
b, lightening two laser light sources 1-1 and 1-2, adjusting the positions of the object to be measured and the plane reflector 5, and positioning the geometric center of a measuring beam spot image received by the image sensor 3 at the center of the sensor;
step c, the wavefront sensor 13 measures the displacement information and wavefront information of the incident reference beam light spot to obtain the measurement error alpha introduced by the factors of environmental disturbance, light source drift and the like in the measurement process of the device0And beta0；
D, 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;
e, calculating alpha according to x1 ═ f · tan (2 alpha) by using the spot displacements x1 and y1 of the measuring beams, wherein (alpha-alpha) is obtained0) Generating a yaw angle for the compensated measured object; calculating beta according to y1 ═ f · tan (2 beta), wherein (beta-beta)0) And generating a pitch angle for the compensated measured object.
In this embodiment, the convex lens 4 is replaced with a collimator objective lens group 4 composed of a first combined lens 4-1 and a second combined lens 4-2 as a collimator objective lens unit of the device to expand the focal length of the collimator objective lens, and the limiting angle resolution of the device is improved to a nano radian order under the same condition; the multi-lens combination enables the optical system to have smaller aberration and nonlinearity, improves the light spot imaging quality and is beneficial to improving the light spot positioning accuracy;
the laser light source 1 is replaced by the light transmitted by the small-hole diaphragm 6 to be used as a light source, so that the measurement instability caused by the self drift of the laser light source 1 is directly reduced;
an independent light source is added in the device to serve as a reference light beam and to be transmitted with a measuring light beam in a common light path, real-time monitoring and regulation of aberration of an optical system of the auto-collimation device are achieved through real-time measurement and correction of wavefront of the reference light beam, aberration of the optical system is reduced, imaging quality of light spots on an image sensor is improved, and measuring accuracy and stability of the auto-collimation device are improved. #
In addition, the first turning mirror 7 and the second turning mirror 8 are selected to fold the long-focus light path of the system twice, so that the size of the system device is reduced, the system device is more suitable for a field measurement environment, and the influence of air disturbance on a measurement result caused by overlarge size of the system device is avoided.
Detailed description of the invention
The embodiment is a high-frequency-response two-dimensional photoelectric auto-collimation method and device based on wavefront correction.
The structural schematic diagram of the high-frequency-response two-dimensional photoelectric auto-collimation device based on wavefront correction in this embodiment is shown in fig. 4. On the basis of the first embodiment, the present embodiment replaces the second turning mirror 8 with the deformable mirror 14 and the deformable mirror driver 15.
The high-frequency-response 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;
b, lightening two laser light sources 1-1 and 1-2, adjusting the positions of the object to be measured and the plane reflector 5, and positioning the geometric center of a measuring beam spot image received by the image sensor 3 at the center of the sensor;
step c, the wavefront sensor 13 measures the displacement information and wavefront information of the incident reference beam light spot to obtain the displacement information and wavefront information of the incident reference beam light spot in the measuring process of the deviceThe measurement error introduced by the factors of environmental disturbance, light source drift and the like is alpha0And beta0；
D, adjusting the surface shape of the deformable mirror 14 according to the reference beam wavefront information measured by the wavefront sensor 13 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 alpha according to x1, f · tan (2 alpha) by using the spot displacements x1 and y1 of the measuring beams, wherein the alpha is an angle of the measured object generating the yaw angle; β is calculated according to y1 ═ f · tan (2 β), where β is the angle at which the measured object produces a pitch angle.
The innovation points of the embodiment are as follows:
a deformable mirror 14 and a deformable mirror driver 15 are added as wavefront correction units, and the deformable mirror 14 is driven to correct wavefront according to wavefront phase information of the reference beam detected by the wavefront sensor 13, so that real-time measurement and regulation of the aberration of the optical system of the auto-collimation device are realized; meanwhile, the light beam phase distortion generated by environmental disturbance in the transmission process of light beams inside the instrument can be compensated, the imaging quality and stability of the image sensor 3 are improved, and the precision and stability of the angle measuring device with the nano radian magnitude are further improved.
Detailed description of the preferred embodiment
The embodiment is a high-frequency-response two-dimensional photoelectric auto-collimation method and device based on wavefront correction.
The structural schematic diagram of the high-frequency-response two-dimensional photoelectric auto-collimation device based on wavefront correction in this embodiment is shown in fig. 5. On the basis of the first specific embodiment, the spatial light modulator 16 is added between the first beam splitter 1-5 and the aperture stop 6, and the second turning mirror 8 is replaced by the deformable mirror 14 and the deformable mirror driver 15.
The high-frequency-response 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;
b, lightening two laser light sources 1-1 and 1-2, adjusting the positions of the object to be measured and the plane reflector 5, and positioning the geometric center of a measuring beam spot image received by the image sensor 3 at the center of the sensor;
step c, the wavefront sensor 13 measures the displacement information and wavefront information of the incident reference beam light spot to obtain the measurement error alpha introduced by the factors of environmental disturbance, light source drift and the like in the measurement process of the device0And beta0；
D, according to the reference beam wavefront information measured by the wavefront sensor 13, adjusting the attitude of the spatial light modulator 16 and the surface shape of the deformable mirror 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 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 of the measured object generating the yaw angle; β is calculated according to y1 ═ f · tan (2 β), where β is the angle at which the measured object produces a pitch angle.
The present embodiment places the reference mirror 11 on the side of the object to be measured; the reference beam and the measuring beam are transmitted on a common optical path and are disturbed by the same air, the wavefront phase information of the returned reference beam is measured in real time by using the wavefront sensor 13, the deformable mirror 14 and the spatial light modulator 16 are driven to correct wavefront distortion caused by light source beam angle drift and air disturbance, the light spot imaging quality of an optical system is improved, the light spot positioning precision and stability are improved, and the angle measurement precision, stability and air disturbance resistance of the auto-collimation device are improved under the long-distance measurement condition.
The above-mentioned embodiments are not intended to limit the present invention, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. The invention relates to a high-frequency response two-dimensional photoelectric auto-collimation method based on wavefront correction, which is characterized in that the influence of beam drift and beam wavefront distortion on spot positioning error is calculated by software, so that the measurement frequency response is improved, and the measurement method comprises the following steps:
a, fixing a plane reflector (5) on the surface of a measured object;
b, lightening two laser light sources (1-1 and 1-2), adjusting the positions of a measured object and a plane reflector (5), and positioning the geometric center of a measuring beam spot image received by an image sensor (3) at the center of the sensor;
step c, the wavefront sensor (13) 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 calculated to be alpha0And beta0；
D, 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 e, using the measuring beam spot displacements x1 and y1, calculating according to x1 ═ f · tan (2a) to obtain a, wherein (a-a)0) Generating a yaw angle for the compensated measured object; calculating beta according to y1 ═ f · tan (2 beta), wherein (beta-beta)0) And generating a pitch angle for the compensated measured object.
2. A high-frequency response two-dimensional photoelectric auto-collimation method based on wavefront correction as claimed in claim 1, wherein the beam drift and the beam wavefront distortion are compensated by a deformable mirror (14) to reduce the system aberration, and the measurement method comprises the following steps:
a, fixing a plane reflector (5) on the surface of a measured object;
b, lightening two laser light sources (1-1 and 1-2), adjusting the positions of a measured object and a plane reflector (5), and positioning the geometric center of a measuring beam spot image received by an image sensor (3) at the center of the sensor;
step c, the wavefront sensor (13) 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, wherein the measurement error is alpha0And beta0；
D, adjusting the surface shape of the deformable mirror (14) according to the reference beam wavefront information measured by the wavefront sensor (13) 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 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 high-frequency-response two-dimensional photoelectric auto-collimation method based on the wavefront correction as claimed in claim 2, wherein a link of compensating the light source drift of the spatial light modulator (16) is added, so as to improve the stability of the light source, and the measuring method comprises the following steps:
a, fixing a plane reflector (5) on the surface of a measured object;
b, lightening two laser light sources (1-1 and 1-2), adjusting the positions of a measured object and a plane reflector (5), and positioning the geometric center of a measuring beam spot image received by an image sensor (3) at the center of the sensor;
step c, the wavefront sensor (13) 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, wherein the measurement error is alpha0And beta0；
D, according to the reference beam wavefront information measured by the wavefront sensor (13), adjusting the posture of the spatial light modulator (16) and the surface shape of the deformable mirror (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 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.
4. The high-frequency-response two-dimensional photoelectric auto-collimation device based on the wavefront correction is characterized by comprising a light source unit (1), a second spectroscope (2), an image sensor (3), a collimation objective lens group (4), a plane mirror (5), an aperture diaphragm (6), a first turning mirror (7), a second turning mirror (8), a first dichroic mirror (9), a reference mirror (10), a second dichroic mirror (11), a third convex lens (12) and a wavefront sensor (13);
the light source unit (1) consists of a first light source (1-1), a second light source (1-2), a first convex lens (1-3), a second convex lens (1-4) and a first spectroscope (1-5);
the light beam emitted by the first light source (1-1) and the light beam emitted by the second light source (1-2) are collimated and then combined through the first spectroscope (1-5), the optical axes of the two light beams are superposed, the propagation directions of the two light beams are the same, and the combined light beams are incident to the aperture diaphragm (6) in parallel; two beams of light emitted by using the aperture diaphragm (6) as an object plane are transmitted by the second beam splitter (2), reflected by the first turning mirror (7) and the second turning mirror (8) and vertically incident on the collimating objective lens group (4) to be collimated into parallel beams;
the parallel light beams are split into a transmission light beam and a reflection light beam through a first dichroic mirror (9), and at the moment, the light beam of a first light source (1-1) is transmitted and is used as a measuring light beam to vertically enter a plane reflector (5); the light beam of the second light source (1-2) is reflected and is used as a reference light beam and vertically enters a reference reflector (10); the two light beams return along the original path after being reflected by the reflecting mirror respectively, and are split by the second dichroic mirror (11) to separate the reference light beam from the measuring light beam after being reflected by the second beam splitter (2); 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 (12) to be changed into parallel light to be incident to the wavefront sensor (13) to acquire images;
the first light source (1-1) is positioned on a focal plane of the first convex lens (1-3), and the second light source (1-2) is positioned on a focal plane of the second convex lens (1-4) and is respectively arranged at two sides of the light splitting section of the first beam splitter (1-5);
the aperture diaphragm (6) 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 (4-1) and a second combined lens (4-2) to form a telephoto objective lens group; the first combined lens (4-1) is formed by combining 2 or more convex lenses and concave lenses and has the same function of converging light beams with the convex lenses; the second combined lens (4-2) is formed by combining 2 or more convex lenses and concave lenses and has the same light beam dispersing effect as the concave lenses; the equivalent focal length of the collimation objective lens group (4) is far larger than that of a single lens;
the third convex lens (12) is positioned at the right side of the convergent focus of the reflected light beam of the second dichroic mirror (11), the focus is positioned at the focal plane of the third convex lens (12), the reference light beam is reflected by the second dichroic mirror (11), then converged, diverged and transmitted by the third convex lens (12) to become a parallel light beam, and is merged into the central position of the wavefront sensor (13);
the first turning mirror (7) and the second turning mirror (8) are arranged in parallel and have a fixed small angle with the main optical axis.
5. The high-frequency-response two-dimensional photoelectric auto-collimation device based on the wavefront correction as claimed in claim 2, wherein the second turning mirror (8) is replaced by a deformable mirror (14) and a deformable mirror driver (15);
the deformable mirror (14) is connected with a deformable mirror driver (15), and the deformable mirror driver (15) can control the surface shape of the reflecting surface of the deformable mirror (14); the deformable mirror (14) replaces the second turning mirror (8), and the position and the posture of the reflecting surface are not changed.
6. The high-frequency response two-dimensional photoelectric auto-collimation device based on the wave-front correction is characterized in that a spatial light modulator (16) is added between the first spectroscope (1-5) and the small aperture diaphragm (6), and the second turning mirror (8) is replaced by a deformable mirror (14) and a deformable mirror driver (15);
the spatial light modulator (16) is arranged between the first spectroscope (1-5) and the small-hole diaphragm (6), and light emitted by the first light source (1-1) and the second light source (1-2) is projected by the vertically arranged spatial light modulator (16) after being combined by the first spectroscope (1-5) and vertically incident on the small-hole diaphragm (6); the spatial light modulator (16) can adjust the direction of parallel light entering the aperture diaphragm (6);
the deformable mirror (14) is connected with a deformable mirror driver (15), and the deformable mirror driver (15) can control the surface shape of the reflecting surface of the deformable mirror (14); the deformable mirror (14) replaces the second turning mirror (8), and the position and the posture of the reflecting surface are not changed.
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