CN116428967A - Three-degree-of-freedom laser interferometry device and method for synchronous compensation - Google Patents
Three-degree-of-freedom laser interferometry device and method for synchronous compensation Download PDFInfo
- Publication number
- CN116428967A CN116428967A CN202310443961.9A CN202310443961A CN116428967A CN 116428967 A CN116428967 A CN 116428967A CN 202310443961 A CN202310443961 A CN 202310443961A CN 116428967 A CN116428967 A CN 116428967A
- Authority
- CN
- China
- Prior art keywords
- freedom
- degree
- sub
- unit
- longitudinal displacement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 58
- 230000001360 synchronised effect Effects 0.000 title claims abstract description 52
- 238000004556 laser interferometry Methods 0.000 title claims abstract description 49
- 238000005259 measurement Methods 0.000 claims abstract description 123
- 238000006073 displacement reaction Methods 0.000 claims abstract description 121
- 239000013307 optical fiber Substances 0.000 claims description 43
- 238000005305 interferometry Methods 0.000 claims description 10
- 238000004891 communication Methods 0.000 claims description 6
- 238000005516 engineering process Methods 0.000 description 16
- 230000003287 optical effect Effects 0.000 description 11
- 230000008569 process Effects 0.000 description 7
- 238000012937 correction Methods 0.000 description 6
- 238000001514 detection method Methods 0.000 description 6
- 238000000691 measurement method Methods 0.000 description 6
- 230000008878 coupling Effects 0.000 description 5
- 238000010168 coupling process Methods 0.000 description 5
- 238000005859 coupling reaction Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000011160 research Methods 0.000 description 4
- 230000033228 biological regulation Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000000737 periodic effect Effects 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000035559 beat frequency Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000009291 secondary effect Effects 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02015—Interferometers characterised by the beam path configuration
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Instruments For Measurement Of Length By Optical Means (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention discloses a synchronous compensation three-degree-of-freedom laser interferometry device and a method, wherein the device comprises: the device comprises a laser emitting unit, a laser beam splitting unit, an interference signal generating unit and a three-degree-of-freedom resolving unit which are sequentially arranged; the laser emission unit emits a laser beam to the laser beam splitting unit; the laser beam splitting unit splits a laser beam into reference light and measuring light with different frequencies; the interference signal generating unit generates an interference signal according to the reference light and the measuring light and outputs the interference signal to the three-degree-of-freedom resolving unit; the three-degree-of-freedom resolving unit obtains a deflection angle, a pitch angle and a longitudinal displacement measured value of the object to be measured according to the interference signals, and synchronously compensates the longitudinal displacement measured value according to the deflection angle and the pitch angle to obtain a longitudinal displacement actual value. The invention has simple and compact structure, adopts a single light beam to reduce the adjustment error, and can realize synchronous high-precision measurement of three degrees of freedom of longitudinal displacement, deflection angle and pitch angle of an object to be measured.
Description
Technical Field
The invention belongs to the technical field of precise measurement, and particularly relates to a three-degree-of-freedom laser interferometry device and method for synchronous compensation.
Background
Measurement is the basis of all scientific research and industrial production, and precision measurement refers to measurement performed with accuracy of millimeter or more. In precision engineering such as high-end equipment manufacturing and semiconductor industry, ultra-precision measurement and control of mesoscale is generally realized by means of a nano coordinate measuring machine, and along with development of the high-end equipment manufacturing and precision measurement field, the requirement on measurement precision in the ultra-precision coordinate measuring technology is higher and higher.
The laser interferometry technology is a measurement technology for sensing displacement information by taking laser wavelength as a scale and through frequency and phase changes of interference light spots, and has the advantages of high resolution, good traceability, quick response, large measurement range and the like. Along with the improvement of the measurement precision requirement, the laser interferometry mode is necessarily required to be changed from single-degree-of-freedom displacement measurement to three-degree-of-freedom synchronous measurement, so that the coordinate measurement precision is improved through decoupling of three-degree-of-freedom measurement results.
The existing three-degree-of-freedom laser interferometry technology commonly applies a parallel beam interferometry method, the resolution of the method can reach the sub-nanometer level, but the measurement precision is severely limited by the three-degree-of-freedom periodic nonlinear error, the extreme regulation and control requirement of the beam parallelism and the complexity of the device structure bring great challenges to engineering realization, and therefore, the existing three-degree-of-freedom laser interferometry device cannot meet the requirement of ultra-precise measurement yet.
Disclosure of Invention
The invention aims to provide a synchronous compensation three-degree-of-freedom laser interferometry device and a synchronous compensation three-degree-of-freedom laser interferometry method, which are used for solving the technical problems of complex structure, high adjustment difficulty and insufficient measurement precision in the existing three-degree-of-freedom laser interferometry device.
The aim of the invention can be achieved by the following technical scheme:
a synchronously compensated three degree of freedom laser interferometry apparatus comprising:
the device comprises a laser emission unit, a laser beam splitting unit, an interference signal generating unit and a three-degree-of-freedom resolving unit which are sequentially arranged, wherein the interference signal generating unit is in communication connection with the three-degree-of-freedom resolving unit;
wherein the laser emission unit emits a laser beam to the laser beam splitting unit;
the laser beam splitting unit splits the laser beam into reference light and measuring light with different frequencies;
the interference signal generating unit generates an interference signal according to the reference light and the measuring light and outputs the interference signal to the three-degree-of-freedom resolving unit;
and the three-degree-of-freedom resolving unit obtains a deflection angle, a pitch angle and a longitudinal displacement measured value of the object to be measured according to the interference signal, and synchronously compensates the longitudinal displacement measured value according to the deflection angle and the pitch angle to obtain a longitudinal displacement actual value of the object to be measured.
Optionally, the laser beam splitting unit includes:
the optical fiber beam splitter, the first sub-optical path and the second sub-optical path are arranged behind the optical fiber beam splitter in parallel;
the optical fiber beam splitter divides the laser beam into a first sub-beam and a second sub-beam, the first sub-beam enters the first sub-optical path, and the second sub-beam enters the second sub-optical path;
the first sub-optical path forms the reference light according to the first sub-beam and comprises a first acousto-optic frequency shifter, a first optical fiber and a first collimating mirror which are sequentially arranged;
the second sub-optical path forms the measuring light according to the second sub-beam and comprises a second optical frequency shifter, a second optical fiber and a second collimating mirror which are sequentially arranged.
Optionally, the interference signal generating unit includes:
the device comprises a beam splitting prism, a target reflector and a photoelectric detector, wherein the target reflector and the photoelectric detector are arranged behind the beam splitting prism, and the target reflector is a reflector preset on the object to be detected;
the target reflector reflects the measuring light to the beam splitting prism; the beam splitting prism transmits the reference light to the photoelectric detector and reflects the measuring light reflected by the target reflector to the photoelectric detector; the photoelectric detector generates interference signals according to the reference light and the measuring light, and outputs the interference signals to the three-degree-of-freedom resolving unit.
Optionally, the photodetector is a four-quadrant photodetector.
Optionally, the three-degree-of-freedom resolving unit performs synchronous compensation on the longitudinal displacement measured value according to the yaw angle and the pitch angle to obtain the actual longitudinal displacement value of the object to be measured, where the method includes:
the three-degree-of-freedom resolving unit performs cosine error synchronous compensation on the longitudinal displacement measured value according to the following steps of:
wherein alpha is x For the deflection angle alpha of the object to be measured y The pitch angle of the object to be measured is L, which is a longitudinal displacement measured value, and L' is a longitudinal displacement actual value.
The invention also provides a synchronous compensation three-degree-of-freedom laser interferometry method, which uses the synchronous compensation three-degree-of-freedom laser interferometry device to measure, and comprises the following steps:
transmitting the laser beam to a laser beam splitting unit by using a laser transmitting unit;
dividing the laser beam into reference light and measuring light with different frequencies by using a laser beam dividing unit;
generating an interference signal according to the reference light and the measuring light by using an interference signal generating unit and outputting the interference signal to a three-degree-of-freedom resolving unit;
and obtaining a deflection angle, a pitch angle and a longitudinal displacement measured value of the object to be measured according to the interference signals by using a three-degree-of-freedom resolving unit, and synchronously compensating the longitudinal displacement measured value according to the deflection angle and the pitch angle to obtain a longitudinal displacement actual value of the object to be measured.
Optionally, the laser beam splitting unit includes an optical fiber beam splitter, a first sub-optical path and a second sub-optical path, wherein the first sub-optical path and the second sub-optical path are arranged in parallel behind the optical fiber beam splitter, the first sub-optical path includes a first acousto-optic frequency shifter, a first optical fiber and a first collimating mirror, the second sub-optical path includes a second acousto-optic frequency shifter, a second optical fiber and a second collimating mirror, and the laser beam splitting unit is used for splitting the laser beam into reference light and measuring light with different frequencies, and the method includes:
dividing the laser beam into a first sub-beam and a second sub-beam by using the optical fiber beam splitter, wherein the first sub-beam enters the first sub-optical path, and the second sub-beam enters the second sub-optical path; the first sub-beam sequentially passes through the first acousto-optic frequency shifter, the first optical fiber and the first collimating mirror to form reference light, and the second sub-beam sequentially passes through the second acousto-optic frequency shifter, the second optical fiber and the second collimating mirror to form measuring light.
Optionally, the interference signal generating unit includes a beam splitter prism, a target mirror disposed behind the beam splitter prism, and a photodetector, the target mirror is a mirror preset on the object to be measured, and the generating unit generates an interference signal according to the reference light and the measurement light and outputs the interference signal to the three-degree-of-freedom resolving unit includes:
reflecting the measurement light to the beam splitting prism by using the target reflector;
transmitting the reference light to the photoelectric detector by using the beam splitting prism, and reflecting the measuring light reflected by the target reflector to the photoelectric detector;
and generating an interference signal according to the reference light and the measuring light by using the photoelectric detector, and outputting the interference signal to the three-degree-of-freedom resolving unit.
Optionally, the photodetector is a four-quadrant photodetector.
Optionally, the step of synchronously compensating the longitudinal displacement measured value by using a three-degree-of-freedom resolving unit according to the yaw angle and the pitch angle to obtain the actual longitudinal displacement value of the object to be measured includes:
and performing cosine error synchronous compensation on the longitudinal displacement measured value by using the three-degree-of-freedom resolving unit to obtain a longitudinal displacement actual value of the object to be measured:
wherein alpha is x For the deflection angle alpha of the object to be measured y The pitch angle of the object to be measured is L, which is a longitudinal displacement measured value, and L' is a longitudinal displacement actual value.
The invention provides a synchronous compensation three-degree-of-freedom laser interferometry device and a method, comprising the following steps: the device comprises a laser emission unit, a laser beam splitting unit, an interference signal generating unit and a three-degree-of-freedom resolving unit which are sequentially arranged, wherein the interference signal generating unit is in communication connection with the three-degree-of-freedom resolving unit; wherein the laser emission unit emits a laser beam to the laser beam splitting unit; the laser beam splitting unit splits the laser beam into reference light and measuring light with different frequencies; the interference signal generating unit generates an interference signal according to the reference light and the measuring light and outputs the interference signal to the three-degree-of-freedom resolving unit; and the three-degree-of-freedom resolving unit obtains a deflection angle, a pitch angle and a longitudinal displacement measured value of the object to be measured according to the interference signal, and synchronously compensates the longitudinal displacement measured value according to the deflection angle and the pitch angle to obtain a longitudinal displacement actual value of the object to be measured.
In view of this, the beneficial effects brought by the invention are:
the invention divides the single laser beam emitted by the laser emission unit into reference light and measuring light with different frequencies by the laser beam dividing unit, generates interference signals according to the reference light and the measuring light by the interference signal generating unit, obtains two-dimensional deflection angles (deflection angle and pitch angle) and longitudinal displacement measured values of an object to be measured according to the interference signals by the three-degree-of-freedom resolving unit, and compensates the cosine error coupled in the longitudinal displacement measured values in real time by utilizing the two-dimensional deflection angles, thereby realizing high-precision synchronous measurement of the longitudinal displacement, the deflection angle and the pitch angle. The invention has the advantages of simple and compact structure, reduced adjustment error by adopting a single beam, high measurement precision and the like, is suitable for synchronous high-precision measurement of three degrees of freedom of longitudinal displacement and pitching and swaying two-dimensional angles in the displacement direction, and can meet the requirement of ultra-precision measurement.
Drawings
FIG. 1 is a schematic diagram of the structure of the measuring device of the present invention;
FIG. 2 is a schematic illustration of a measurement process according to an embodiment of the invention;
FIG. 3 shows the longitudinal displacement and the two-dimensional deflection angle alpha in the embodiment of the invention x 、α y A schematic diagram;
FIG. 4 is a schematic diagram of differential wavefront sensing;
FIG. 5 is a schematic diagram of cosine error in an embodiment of the present invention;
FIG. 6 is a schematic flow chart of the measuring method of the present invention;
wherein,, the three-degree-of-freedom optical fiber three-dimensional resolution system comprises a frequency stabilization laser (1), an optical fiber beam splitter (2), a second acoustic frequency shifter (3), a second optical fiber (4), a second collimating mirror (5), a first acoustic frequency shifter (6), a first optical fiber (7), a first collimating mirror (8), a beam splitting prism (9), a target reflecting mirror (10), a photoelectric detector (11) and a three-degree-of-freedom resolution unit (12).
Detailed Description
The embodiment of the invention provides a synchronous compensation three-degree-of-freedom laser interferometry device and a synchronous compensation three-degree-of-freedom laser interferometry method, which are used for solving the technical problems of complex structure, high adjustment difficulty and insufficient measurement precision in the existing three-degree-of-freedom laser interferometry device.
In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The ultra-precise measurement and control of mesoscale is realized by means of a nano coordinate measuring machine, which is a great demand in precision engineering such as high-end equipment manufacturing and semiconductor industry, and the like, the front edge of the international research of nano measurement is promoted to atomic scale, measuring range above millimeter and three-dimensional measurement, the ultra-precise coordinate measuring technology is promoted to become one of strategic high points in the fields of high-end equipment manufacturing and precise measurement, and the three-degree-of-freedom displacement/angle synchronous measurement and the measurement precision break through the limit challenge of nano pointing to picometer level for the laser interferometry technology.
Compared with the traditional multi-beam three-degree-of-freedom laser interferometry method, the single-beam three-degree-of-freedom laser interferometry method has the advantages of simple system architecture, no need of extreme regulation and control of multi-beam parallelism and the like, and is expected to play an important role in the field of multi-degree-of-freedom ultra-precise synchronous measurement.
Along with the improvement of precision requirements, the laser interferometry mode is also necessarily required to be changed from single-degree-of-freedom displacement measurement to three-degree-of-freedom displacement/angle synchronous measurement, so that the coordinate measurement precision is improved through decoupling of three-degree-of-freedom measurement results. The three-dimensional movement of the displacement table is realized by superposition of linear movements with different dimensions, and the linear movements are inevitably accompanied by posture change and transverse displacement of the measured object due to unavoidable nonideal of the optical path and the guide rail, and the nonideal of the optical surface of the measured object directly or indirectly causes displacement and angle error of the measuring light beam, and causes a series of problems such as Abbe error, cosine error and the like. Therefore, even though the displacement accuracy of the single degree-of-freedom interferometry unit itself is already better than the nano level, the above secondary effect caused by the angle coupling will cause the actual coordinate measurement accuracy to be greatly restricted, and the decoupling and correction must be performed by the three degrees-of-freedom displacement/angle synchronous measurement.
At present, the three-degree-of-freedom laser interferometry technology cannot meet the requirement of ultra-precise measurement. The resolution of the commonly applied parallel beam interferometry method can reach the sub-nanometer level, but the three-degree-of-freedom periodic nonlinear error severely limits the measurement precision, and the extreme regulation and control requirement of the beam parallelism and the complexity of the device structure also bring great challenges to engineering realization. In contrast, the single-beam three-degree-of-freedom laser interferometry method has advantages and potential because of breaking through the limitation of multiple beams in principle, and is expected to play an important role in future three-degree-of-freedom measurement.
The three-degree-of-freedom laser interferometry method can be divided into two categories, namely multiple beams and single beam, according to the number of beams used. The former is called a parallel beam interferometry method, which is the most widely used three-degree-of-freedom laser interferometry method with highest precision at present; the latter can be divided into a single-beam heterodyne interference method and a single-beam homodyne interference method according to an interference mode, wherein the heterodyne method is called a differential wavefront interferometry method and is mainly oriented to space gravitational wave detection, and then the differential wavefront interferometry method is simplified and introduced into three-degree-of-freedom laser interferometry research; the homodyne method is called an improved Tasmann-Green interferometry method, which is used for multi-degree-of-freedom laser interferometry after being improved by the Tasmann-green interferometry method originally facing to optical element surface detection, and related research work is less at the starting stage at present. Although the parallel beam interferometry method has the advantages of high resolution, large measuring range, good traceability and the like, the method has limitations, and the method is limited to realize three-degree-of-freedom ultra-precise measurement at present, which is prominently reflected in the aspects of periodic nonlinear errors, beam parallelism and the like.
In addition, three-degree-of-freedom laser interferometry based on the parallel beam measurement method has several principle or application limitations:
(1) In the parallel beam measurement method, displacement measurement of three measurement optical axes is relatively independent and the beams are spaced apart by a certain distance. When the measurement distance is large, turbulence in the air will cause different degrees of disturbance to each measurement beam, which will directly be reflected in a relatively pronounced angle measurement instability.
(2) The displacement measurement on each beam is three sets of relatively independent measurement data, which require strict timing guarantees to give an effective measurement result.
(3) The angle of the reflecting mirror to be measured changes, so that the angle of the reflected light changes, and as the angle increases, the interference signal changes from a light spot with changed brightness to a stripe with alternate brightness, thereby rapidly reducing the contrast of the interference signal, and limiting the angle measurement range.
(4) The three-degree-of-freedom laser interference method is currently lacking in two-dimensional angle calibration in a true sense and a complete error model obtained by the method.
Another representative method that enables three degrees of freedom precision laser interferometry is differential wavefront measurement technology (Differential Wavefront Sensing, DWS), which is mainly oriented in the field of deep space gravitational wave detection. The core idea is to utilize a position sensitive device (usually a four-quadrant detector) to differentially detect phases of different areas (quadrants) in an interference signal, so as to calculate a wavefront angle between measuring light and reference light. This approach was originally proposed to address a series of problems caused by position and attitude errors of optical elements in gravitational wave detection. With the rise of space detection projects such as space gravitational wave detection and next generation gravitational field inversion, the technology is mainly used for solving the problems of inter-satellite baseline length measurement and angle coupling errors thereof in a large-range displacement measurement process.
In the actual measurement process, the target to be measured cannot do ideal single-axis movement, the movement process is often accompanied with gesture change and transverse displacement, and the measurement accuracy of the single-degree-of-freedom laser interferometer is greatly limited by the longitudinal displacement measurement error caused by the gesture change and the transverse displacement, so that the high-accuracy measurement of various micro components, complex surfaces, microelectronic devices and precise optical elements is simultaneously satisfied, the laser interferometry device is developed from single-degree-of-freedom displacement measurement to three-degree-of-freedom displacement-angle synchronous measurement, and the displacement measurement result is corrected by measuring the two-dimensional angle information of the target to be measured, so that the measurement accuracy is further improved. In order to compensate for measurement deviations, the rotation angle must be measured simultaneously, and single-beam measurements based on interference fringe analysis or differential sensing techniques use only one measuring beam to obtain both displacement and rotation angle. The DWS technology in the differential sensing technology is more suitable for large-range displacement measurement because a larger angle measurement range can be obtained.
The invention provides a three-degree-of-freedom laser interferometry device and a method for synchronous compensation, which have the limitations of various optical elements, complex system structure, large adjustment difficulty, adoption of multiple light beams, difficulty in further improving the precision of an optical path adjustment error and the like.
The invention aims to overcome the defects that the existing three-degree-of-freedom laser interferometry method is complex in structure, high in adjustment difficulty, difficult to further improve due to the fact that multiple light beams are adopted and limited by light path adjustment error precision, and the like, and is a high-precision three-degree-of-freedom measurement method based on cosine error synchronous compensation. The invention adopts differential wave front sensing technology to carry out displacement measurement, simultaneously obtains a two-dimensional deflection angle caused by the inclination of a measuring mirror (a target reflecting mirror) in the displacement measurement process, and utilizes the two-dimensional angle to carry out real-time compensation on the cosine error coupled in the longitudinal displacement measurement result, thereby realizing high-precision synchronous measurement of displacement, deflection angle and pitch angle.
Referring to fig. 1 and 2, the present invention provides an embodiment of a three-degree-of-freedom laser interferometry device with synchronous compensation, comprising:
the device comprises a laser emission unit, a laser beam splitting unit, an interference signal generating unit and a three-degree-of-freedom resolving unit which are sequentially arranged, wherein the interference signal generating unit is in communication connection with the three-degree-of-freedom resolving unit;
wherein the laser emission unit emits a laser beam to the laser beam splitting unit;
the laser beam splitting unit splits the laser beam into reference light and measuring light with different frequencies;
the interference signal generating unit generates an interference signal according to the reference light and the measuring light and outputs the interference signal to the three-degree-of-freedom resolving unit;
and the three-degree-of-freedom resolving unit obtains a deflection angle, a pitch angle and a longitudinal displacement measured value of the object to be measured according to the interference signal, and synchronously compensates the longitudinal displacement measured value according to the deflection angle and the pitch angle to obtain a longitudinal displacement actual value of the object to be measured.
In this embodiment, the laser emitting unit emits a laser beam to the laser beam splitting unit. Preferably, the laser emitting unit may be a frequency stabilized laser with an emitting frequency f 0 To the laser beam splitting unit.
Specifically, the laser beam splitting unit may include: the optical fiber beam splitter 2, and a first sub-optical path and a second sub-optical path which are arranged in parallel behind the optical fiber beam splitter 2; the optical fiber beam splitter 2 divides the laser beam into a first sub-beam and a second sub-beam, wherein the first sub-beam enters the first sub-optical path, and the second sub-beam enters the second sub-optical path.
In a preferred embodiment, the first sub-optical path is used for forming the reference light according to the first sub-optical beam, and the first sub-optical path may include a first acousto-optic frequency shifter 6, a first optical fiber 7 and a first collimating mirror 8 which are sequentially arranged; the second sub-optical path is used for forming measuring light according to the second sub-optical beam, and the second sub-optical path can comprise a second optical frequency shifter 3, a second optical fiber 4 and a second collimating mirror 5 which are sequentially arranged.
The first acousto-optic frequency shifter 6 and the second acousto-optic frequency shifter 3 are different in frequency shift amount. In one embodiment of the present invention, the frequency shift amount of the first acousto-optic frequency shifter 6 is f1, and the frequency shift amount of the second acousto-optic frequency shifter 3 is f 2 ，f 1 ≠f 2 。
Frequency f 0 The laser beam of (2) is divided into two sub-beams, namely a first sub-beam and a second sub-beam by the optical fiber beam splitter (2), wherein the first sub-beam enters the first sub-optical path to form reference light, and the second sub-beam enters the second sub-optical path to form measuring light. It should be noted that, the second sub-beam may enter the first sub-beam to form the reference light, and the first sub-beam enters the second sub-beam to form the measurement light.
In a preferred embodiment, the first sub-beam enters the first sub-optical path, and sequentially passes through the first acousto-optic frequency shifter 6 with the frequency shift amount f1, the first optical fiber 7 and the first collimating mirror 8 to form a beam with the frequency f 0 +f 1 Is a reference light of (a); the second sub-beam enters a second sub-light path and sequentially passes through a frequency shift quantity f 2 After the second acoustic frequency shifter 3, the second optical fiber 4 and the second collimator 5, a frequency f is formed 0 +f 2 Is a measuring light of (a).
In this embodiment, before measurement, the target mirror 10 is mounted on a target object to be measured (simply referred to as an object to be measured), the measurement light is reflected by the movable target mirror 10 and then forms an included angle (also referred to as a deflection angle) θ with the reference light, the two beams are combined to form a heterodyne interference signal, and the measurement light and the reference light are coherently mixed on the surface of the photodetector 11 (e.g., a four-quadrant photodetector) to form a frequency |f 1 -f 2 The beat signal (interference signal) of the i reads the output signal of the four-quadrant photodetector 11.
The differential wavefront sensing technology is adopted to carry out displacement measurement, meanwhile, a two-dimensional deflection angle caused by the inclination of a measuring mirror (a target reflecting mirror) in the displacement measurement process is obtained, and the two-dimensional angle is utilized to carry out real-time compensation on a cosine error coupled in a longitudinal displacement measurement result, so that high-precision synchronous measurement of displacement, deflection angle and pitch angle is realized.
It should be noted that, the target mirror 10 is preset on the object to be measured and moves together with the object to be measured, and therefore, the three-degree-of-freedom measurement value of the target mirror 10 may be equivalent to the three-degree-of-freedom measurement value of the object to be measured.
In this embodiment, referring to fig. 3 and 4, the three-degree-of-freedom resolving unit 12 obtains the interference signal output by the photodetector 11, and calculates according to the interference signal to obtain the yaw angle α of the object to be measured x Pitch angle alpha y And the longitudinal displacement measurement value L is used for obtaining a three-degree-of-freedom measurement value of the object to be measured, and the three-degree-of-freedom measurement value is shown as a formula (1); and then, synchronously compensating the longitudinal displacement measured value according to the deflection angle and the pitch angle to obtain the actual longitudinal displacement value of the object to be measured.
Wherein L is a longitudinal displacement measurement value, and the unit is m; alpha x The unit is rad and the deflection angle is the deflection angle; alpha y Is pitch angle, and the unit is rad; oc is proportional to phi A ,φ B ,φ C ,φ D The phase shift in rad for each quadrant detected in the four-quadrant photodetector 11; delta x For a predetermined yaw angle scaling factor, delta y Is a preset pitch angle scaling factor.
Delta is also described x 、δ y The two scale factors are obtained through calibration before experiments, the accuracy is determined by the measurement accuracy of the scale factors and the measurement accuracy of the phase, and the two scale factors belong to the technical content of differential wavefront sensing and are not described in detail herein.
Referring to fig. 3, the three-degree-of-freedom calculating unit 12 calculates a two-dimensional deflection angle α of the target mirror 10 according to the obtained two-dimensional deflection angle α x 、α y The offset angle θ between the measurement light and the reference light is calculated using equation (2):
referring to fig. 5, after the three-degree-of-freedom calculating unit 12 calculates the offset angle θ between the measurement light and the reference light, an actual value (actual distance) L' of the longitudinal displacement between the four-quadrant photodetector 11 and the target mirror 10 is further calculated according to the offset angle θ, as shown in equation (3):
of course, the formula (2) and the formula (3) may be combined to obtain the formula (4), and the three-degree-of-freedom calculating unit 12 may obtain the yaw angle α of the object to be measured x Pitch angle alpha y After the longitudinal displacement measured value L, performing cosine error correction on the longitudinal displacement measured value by utilizing the formula (4), and synchronously compensating the longitudinal displacement measured value to calculate the actual longitudinal displacement value L' of the object to be measured:
namely, the three-degree-of-freedom calculation unit 12 uses the obtained two-dimensional deflection angle α of the target mirror 10 with high accuracy x 、α y Cosine error correction is carried out on the longitudinal displacement measurement result L to obtain a high-precision two-dimensional deflection angle alpha of the target reflector 10 x 、α y And the measurement results of three degrees of freedom of the actual longitudinal displacement value L', thereby realizing ultra-precise synchronous measurement of the deflection angle, the pitch angle and the longitudinal displacement of the object to be measured (the target reflector 10).
It will be appreciated that the final result of the three degree of freedom calculation unit 12 is the actual values of yaw, pitch and longitudinal displacement of the object to be measured. The four-quadrant photoelectric detector in the embodiment adopts a differential wavefront sensing technology, can simultaneously measure the longitudinal displacement information and the two-dimensional angle deflection information of the target reflector, and carries out cosine error correction on a longitudinal displacement measurement result through the measured two-dimensional deflection angle of the target reflector, thereby further improving the measurement accuracy of longitudinal displacement and realizing three-degree-of-freedom synchronous ultra-precise measurement of an object to be measured.
According to the synchronous compensation three-degree-of-freedom laser interferometry device provided by the embodiment, a single laser beam emitted by a laser emission unit is divided into reference light and measuring light with different frequencies by a laser beam splitting unit, an interference signal is generated by an interference signal generating unit according to the reference light and the measuring light, a three-degree-of-freedom resolving unit obtains a two-dimensional deflection angle (deflection angle and pitch angle) and a longitudinal displacement measured value of an object to be measured according to the interference signal, and cosine errors coupled in the longitudinal displacement measured value are compensated in real time by the two-dimensional deflection angle, so that high-precision synchronous measurement of longitudinal displacement, deflection angle and pitch angle is realized. The invention has the advantages of simple and compact structure, reduced adjustment error by adopting a single beam, high measurement precision and the like, is suitable for synchronous high-precision measurement of three degrees of freedom of longitudinal displacement and pitching and swaying two-dimensional angles in the displacement direction, and can meet the requirement of ultra-precision measurement.
Referring to fig. 6, the present invention further provides an embodiment of a method for synchronously compensating three-degree-of-freedom laser interferometry, which uses the synchronously compensating three-degree-of-freedom laser interferometry device for measurement, including:
transmitting the laser beam to a laser beam splitting unit by using a laser transmitting unit;
dividing the laser beam into reference light and measuring light with different frequencies by using a laser beam dividing unit;
generating an interference signal according to the reference light and the measuring light by using an interference signal generating unit and outputting the interference signal to a three-degree-of-freedom resolving unit;
and obtaining a deflection angle, a pitch angle and a longitudinal displacement measured value of the object to be measured according to the interference signals by using a three-degree-of-freedom resolving unit, and synchronously compensating the longitudinal displacement measured value according to the deflection angle and the pitch angle to obtain a longitudinal displacement actual value of the object to be measured.
In this embodiment, the laser beam splitting unit includes an optical fiber beam splitter 2, and a first sub-optical path and a second sub-optical path that are disposed in parallel behind the optical fiber beam splitter 2, where the first sub-optical path includes a first acousto-optic frequency shifter 6, a first optical fiber 7, and a first collimating mirror 8 that are sequentially disposed, and the second sub-optical path includes a second acousto-optic frequency shifter 3, a second optical fiber 4, and a second collimating mirror 5 that are sequentially disposed, and the splitting the laser beam into reference light and measurement light with different frequencies by using the laser beam splitting unit includes:
dividing the laser beam into a first sub-beam and a second sub-beam by using the optical fiber beam splitter 2, wherein the first sub-beam enters a first sub-optical path, and the second sub-beam enters a second sub-optical path; the first sub-beam sequentially passes through the first acousto-optic frequency shifter 6, the first optical fiber 7 and the first collimating mirror 8 to form reference light, and the second sub-beam sequentially passes through the second acousto-optic frequency shifter 3, the second optical fiber 4 and the second collimating mirror 5 to form measuring light.
In one embodiment of the present invention, the interference signal generating unit includes a beam splitting prism 9, a target mirror 10 and a photodetector 11 disposed behind the beam splitting prism 9, the target mirror 10 being a mirror preset on an object to be measured, generating an interference signal from reference light and measurement light by the interference signal generating unit and outputting to the three-degree-of-freedom resolving unit includes:
reflecting the measurement light to the beam splitter prism 9 by the target mirror 10;
transmitting the reference light to the photodetector 11 by using the beam splitter prism 9, and reflecting the measurement light reflected by the target mirror 10 to the photodetector 11;
an interference signal is generated from the reference light and the measurement light by the photodetector 11, and is output to the three-degree-of-freedom resolving unit 12.
Preferably, the photodetector 11 in this embodiment is a four-quadrant photodetector.
In one embodiment of the present invention, the step of synchronously compensating the longitudinal displacement measurement value according to the yaw angle and the pitch angle by using the three-degree-of-freedom calculating unit 12 to obtain the actual longitudinal displacement value of the object to be measured includes:
the three-degree-of-freedom calculating unit 12 is utilized to carry out cosine error synchronous compensation on the longitudinal displacement measured value to obtain the actual longitudinal displacement value of the object to be measured according to the following steps:
wherein alpha is x For the deflection angle alpha of the object to be measured y The pitch angle of the object to be measured is L, which is a longitudinal displacement measured value, and L' is a longitudinal displacement actual value.
The invention provides a measurement method, which is a high-precision three-degree-of-freedom measurement method based on cosine error synchronous compensation, and the method comprises the following specific steps:
step one, the output frequency of the frequency stabilized laser is f 0 The laser beam is divided into two beams which respectively pass through different acousto-optic frequency shifters, and the output frequency after frequency shifting is f 0 +f 1 Is f 0 +f 2 Is a measuring light of (a).
Step two, the target reflector 10 is arranged on a target object to be detected, the target reflector 10 moves along with the target object, the measuring light has an included angle theta with the reference light after being reflected by the movable target reflector 10, the measuring light and the reference light are combined to form heterodyne interference signals, the measuring light and the reference light are coherently mixed on the surface of the four-quadrant photoelectric detector, and the frequency is |f 1 -f 2 And (3) reading the output signal of the four-quadrant photoelectric detector by using the beat frequency signal of the I.
Step three, the output signal of the four-quadrant photoelectric detector is resolved by utilizing a three-degree-of-freedom resolving unit to obtain the two-dimensional deflection angle alpha of the target reflector 10 x 、α y And a measurement of three degrees of freedom of the longitudinal displacement L;
according to the obtained two-dimensional deflection angle alpha of the target reflecting mirror 10 x 、α y Calculating a deflection angle theta between the measuring light and the reference light;
further, according to the deflection angle theta of the measuring light and the reference light, the actual distance L' between the four-quadrant photoelectric detector and the target reflector 10 is calculated;
i.e. using the resulting two-dimensional deflection angle alpha of the target mirror 10 with high accuracy x 、α y Cosine error correction is carried out on the longitudinal displacement measurement result L to obtain a high-precision two-dimensional deflection angle alpha of the target reflector 10 x 、α y And the longitudinal displacement L' to realize the deflection of the target reflector 10Ultra-precise synchronous measurement of angle, pitch angle and displacement.
The invention aims to overcome the defects that the existing three-degree-of-freedom laser interferometry method is complex in structure, high in adjustment difficulty, difficult to further improve due to the fact that multiple light beams are adopted and limited by light path adjustment error precision, and the like, and is a high-precision three-degree-of-freedom measurement method based on cosine error synchronous compensation. The method adopts a differential wavefront sensing technology to carry out displacement measurement, simultaneously obtains a two-dimensional deflection angle caused by the inclination of a measuring mirror (a target reflecting mirror) in the displacement measurement process, and utilizes the two-dimensional angle to carry out real-time compensation on a cosine error coupled in a longitudinal displacement measurement result, thereby realizing high-precision synchronous measurement of displacement, deflection angle and pitch angle.
The invention has the following characteristics and beneficial effects:
the differential wavefront sensing technology is adopted to measure the longitudinal displacement information and the two-dimensional angle deflection information of the target reflector simultaneously, and meanwhile, the measured two-dimensional deflection angle of the target reflector is used for carrying out cosine error correction on a longitudinal displacement measurement result, so that the displacement measurement precision is further improved, three-degree-of-freedom synchronous precise measurement is realized, and the three-degree-of-freedom synchronous precise measurement device has the advantages of simple and compact structure, adjustment error reduction by adopting a single beam, high measurement precision and the like. The invention is suitable for synchronous high-precision measurement of three degrees of freedom in total of longitudinal displacement and pitching and swaying two-dimensional angles in the displacement direction.
It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.
In the embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A synchronously compensated three degree of freedom laser interferometry device comprising:
the device comprises a laser emission unit, a laser beam splitting unit, an interference signal generating unit and a three-degree-of-freedom resolving unit which are sequentially arranged, wherein the interference signal generating unit is in communication connection with the three-degree-of-freedom resolving unit;
wherein the laser emission unit emits a laser beam to the laser beam splitting unit;
the laser beam splitting unit splits the laser beam into reference light and measuring light with different frequencies;
the interference signal generating unit generates an interference signal according to the reference light and the measuring light and outputs the interference signal to the three-degree-of-freedom resolving unit;
and the three-degree-of-freedom resolving unit obtains a deflection angle, a pitch angle and a longitudinal displacement measured value of the object to be measured according to the interference signal, and synchronously compensates the longitudinal displacement measured value according to the deflection angle and the pitch angle to obtain a longitudinal displacement actual value of the object to be measured.
2. The synchronous compensated three degree of freedom laser interferometry device of claim 1 wherein the laser beam splitting unit comprises:
the optical fiber beam splitter, the first sub-optical path and the second sub-optical path are arranged behind the optical fiber beam splitter in parallel;
the optical fiber beam splitter divides the laser beam into a first sub-beam and a second sub-beam, the first sub-beam enters the first sub-optical path, and the second sub-beam enters the second sub-optical path;
the first sub-optical path forms the reference light according to the first sub-beam and comprises a first acousto-optic frequency shifter, a first optical fiber and a first collimating mirror which are sequentially arranged;
the second sub-optical path forms the measuring light according to the second sub-beam, and comprises a second acousto-optic frequency shifter, a second optical fiber and a second collimating mirror which are sequentially arranged, wherein the frequency shift amounts of the first acousto-optic frequency shifter and the second acousto-optic frequency shifter are different.
3. The synchronous compensated three degree of freedom laser interferometry device of claim 1 wherein the interferometry signal generating unit comprises:
the device comprises a beam splitting prism, a target reflector and a photoelectric detector, wherein the target reflector and the photoelectric detector are arranged behind the beam splitting prism, and the target reflector is a reflector preset on the object to be detected;
the target reflector reflects the measuring light to the beam splitting prism; the beam splitting prism transmits the reference light to the photoelectric detector and reflects the measuring light reflected by the target reflector to the photoelectric detector; the photoelectric detector generates interference signals according to the reference light and the measuring light, and outputs the interference signals to the three-degree-of-freedom resolving unit.
4. The synchronous compensated three degree of freedom laser interferometry device of claim 3 wherein the photodetector is a four quadrant photodetector.
5. The synchronous-compensated three-degree-of-freedom laser interferometry device of claim 1, wherein the synchronous compensation of the longitudinal displacement measurement value by the three-degree-of-freedom resolving unit according to the yaw angle and the pitch angle to obtain the actual longitudinal displacement value of the object to be measured comprises:
the three-degree-of-freedom resolving unit performs cosine error synchronous compensation on the longitudinal displacement measured value according to the following steps of:
wherein alpha is x For the deflection angle alpha of the object to be measured y The pitch angle of the object to be measured is L, which is a longitudinal displacement measured value, and L' is a longitudinal displacement actual value.
6. A synchronous compensated three degree of freedom laser interferometry method using the synchronous compensated three degree of freedom laser interferometry apparatus of any of claims 1-5, comprising:
transmitting the laser beam to a laser beam splitting unit by using a laser transmitting unit;
dividing the laser beam into reference light and measuring light with different frequencies by using a laser beam dividing unit;
generating an interference signal according to the reference light and the measuring light by using an interference signal generating unit and outputting the interference signal to a three-degree-of-freedom resolving unit;
and obtaining a deflection angle, a pitch angle and a longitudinal displacement measured value of the object to be measured according to the interference signals by using a three-degree-of-freedom resolving unit, and synchronously compensating the longitudinal displacement measured value according to the deflection angle and the pitch angle to obtain a longitudinal displacement actual value of the object to be measured.
7. The synchronous compensated three degree of freedom laser interferometry method of claim 6 wherein the laser beam splitting unit comprises an optical fiber beam splitter, a first sub-optical path and a second sub-optical path disposed in parallel behind the optical fiber beam splitter, the first sub-optical path comprising a first acousto-optic frequency shifter, a first optical fiber and a first collimating mirror disposed in sequence, the second sub-optical path comprising a second acousto-optic frequency shifter, a second optical fiber and a second collimating mirror disposed in sequence, the splitting the laser beam into reference light and measuring light of different frequencies with the laser beam splitting unit comprising:
dividing the laser beam into a first sub-beam and a second sub-beam by using the optical fiber beam splitter, wherein the first sub-beam enters the first sub-optical path, and the second sub-beam enters the second sub-optical path; the first sub-beam sequentially passes through the first acousto-optic frequency shifter, the first optical fiber and the first collimating mirror to form reference light, and the second sub-beam sequentially passes through the second acousto-optic frequency shifter, the second optical fiber and the second collimating mirror to form measuring light.
8. The synchronous-compensated three-degree-of-freedom laser interferometry method of claim 6, wherein the interference signal generating unit includes a beam splitting prism, a target mirror disposed behind the beam splitting prism, the target mirror being a mirror preset on the object to be measured, and the generating an interference signal from the reference light and the measurement light by the interference signal generating unit and outputting to a three-degree-of-freedom resolving unit includes:
reflecting the measurement light to the beam splitting prism by using the target reflector;
transmitting the reference light to the photoelectric detector by using the beam splitting prism, and reflecting the measuring light reflected by the target reflector to the photoelectric detector;
and generating an interference signal according to the reference light and the measuring light by using the photoelectric detector, and outputting the interference signal to the three-degree-of-freedom resolving unit.
9. The synchronous compensated three degree of freedom laser interferometry method of claim 8 wherein the photodetector is a four quadrant photodetector.
10. The synchronous-compensated three-degree-of-freedom laser interferometry method of claim 6, wherein performing synchronous compensation on the longitudinal displacement measurement value according to the yaw angle and the pitch angle by using a three-degree-of-freedom resolving unit to obtain an actual longitudinal displacement value of the object to be measured comprises:
and performing cosine error synchronous compensation on the longitudinal displacement measured value by using the three-degree-of-freedom resolving unit to obtain a longitudinal displacement actual value of the object to be measured:
wherein alpha is x For the deflection angle alpha of the object to be measured y The pitch angle of the object to be measured is L, which is a longitudinal displacement measured value, and L' is a longitudinal displacement actual value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310443961.9A CN116428967A (en) | 2023-04-21 | 2023-04-21 | Three-degree-of-freedom laser interferometry device and method for synchronous compensation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310443961.9A CN116428967A (en) | 2023-04-21 | 2023-04-21 | Three-degree-of-freedom laser interferometry device and method for synchronous compensation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116428967A true CN116428967A (en) | 2023-07-14 |
Family
ID=87094250
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310443961.9A Pending CN116428967A (en) | 2023-04-21 | 2023-04-21 | Three-degree-of-freedom laser interferometry device and method for synchronous compensation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116428967A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117375708A (en) * | 2023-09-27 | 2024-01-09 | 威海激光通信先进技术研究院 | Optical fiber coupling-based spatial two-dimensional deflection angle measurement and communication integrated implementation method |
-
2023
- 2023-04-21 CN CN202310443961.9A patent/CN116428967A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117375708A (en) * | 2023-09-27 | 2024-01-09 | 威海激光通信先进技术研究院 | Optical fiber coupling-based spatial two-dimensional deflection angle measurement and communication integrated implementation method |
| CN117375708B (en) * | 2023-09-27 | 2024-03-19 | 威海激光通信先进技术研究院 | Optical fiber coupling-based spatial two-dimensional deflection angle measurement and communication integrated implementation method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Gao et al. | Measurement technologies for precision positioning | |
| Badami et al. | Displacement measuring interferometry | |
| CN107228638B (en) | The method and apparatus that five degree of freedom error based on beam drift compensation measures simultaneously | |
| CN108168465A (en) | A kind of light path laser heterodyne interferometry roll angle high precision measuring device and method altogether | |
| US20140160489A1 (en) | Four-axis four-subdividing interferometer | |
| CN207180619U (en) | Three-dimensional small angle error simultaneous measuring apparatus based on beam drift compensation | |
| CN109470176B (en) | High-precision three-dimensional angle measuring method and device based on double gratings | |
| CN106918349A (en) | Star sensor is in-orbit to be mounted opposite error calibration system and calibration compensation method | |
| CN113701640B (en) | Three-axis grating ruler | |
| CN102384716A (en) | Fixed wavelength absolute distance interferometer | |
| Lee et al. | Uncertainty investigation of grating interferometry in six degree-of-freedom motion error measurements | |
| TW201809612A (en) | Grating measurement apparatus | |
| CN116428967A (en) | Three-degree-of-freedom laser interferometry device and method for synchronous compensation | |
| Fan et al. | Techniques of multi-degree-of-freedom measurement on the linear motion errors of precision machines | |
| CN116428966A (en) | Three-degree-of-freedom laser interferometry device | |
| Quan et al. | A new method for evaluation of the pitch deviation of a linear scale grating by an optical angle sensor | |
| Wiseman et al. | Three-dimensional interferometric stage encoder using a single access port | |
| US20220260452A1 (en) | Plane grating calibration system | |
| CN113687521A (en) | Low-aberration high-precision two-dimensional photoelectric auto-collimation method and device based on wavefront correction | |
| CN211072866U (en) | Take receiving and dispatching split type five degree of freedom measuring device of light path drift compensation | |
| Ren et al. | A three-dimensional small angle measurement system based on autocollimation method | |
| Budzyn et al. | Laser interferometer based instrument for 3D dynamic measurements of CNC machines geometry | |
| CN110487172A (en) | Multi-beam laser feedback interferometer | |
| Tan et al. | Design of a laser autocollimator-based optical sensor with a rangefinder for error correction of precision slide guideways | |
| CN116819551A (en) | Device for measuring transverse displacement of object based on differential wavefront |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |