CN104848782A - Contrast type anti-interference micro-cascading ladder angle reflector laser interferometer as well as calibration method and measurement method - Google Patents

Abstract

The invention relates to the field of precision testing technology and instruments, in particular to a laser interferometer of a contrasting anti-interference micro-motion cascaded angle reflector, a calibration method and a measurement method, and a comparative anti-interference micro-motion cascaded angle mirror The laser interferometer includes a laser source, a micro-moving step angle reflector group, an interferometric photodetector group, a moving angle reflector and a beam splitter group, and also includes a reflection measurement photodetector group, and the reflection measurement photodetector group The group includes z photodetectors for reflection measurement, and the second laser beam group is also formed with a reflected laser beam group after being shot to the beam splitter group by the moving angle reflector, and each of the reflected laser beam groups The laser beams are respectively irradiated to one of the reflection measurement photodetectors. The laser interferometer of the present application determines the interference state of the laser interference beam according to the intensity of the reflected laser beam group, so as to achieve the purpose of anti-environmental interference.

Description

A comparative anti-interference micro-movement cascade step-angle mirror laser interferometer, calibration method and measurement method

technical field

The invention relates to the field of precision testing technology and instruments, in particular to a comparative anti-interference micro-movement cascade step-angle mirror laser interferometer, a calibration method and a measurement method.

Background technique

The emergence of lasers has enabled the rapid development of ancient interferometric technology. Lasers have the characteristics of high brightness, good directionality, monochromaticity and good coherence. Laser interferometry technology has been relatively mature. Laser interferometry system is widely used: measurement of precision length and angle, such as detection of linear scale, grating, gauge block, and precision screw; positioning detection system in precision instruments, such as control and correction of precision machinery; special purpose for large-scale integrated circuits Positioning detection systems in equipment and testing instruments; measurement of tiny dimensions, etc. At present, Michelson interferometers or similar optical path structures are used in most laser interferometric length measurement systems, for example, single-frequency laser interferometers commonly used at present.

The single-frequency laser interferometer is the beam emitted from the laser, which is divided into two paths by the beam splitter after beam expansion and collimation, and reflected from the fixed mirror and the movable mirror respectively to meet on the beam splitter to generate interference fringes. When the movable mirror moves, the light intensity change of the interference fringe is converted into an electric pulse signal by the photoelectric conversion element and electronic circuit in the receiver, and after being shaped and amplified, it is input to the reversible counter to calculate the total pulse number N, and then the electronic The computer calculates the displacement L of the movable mirror according to the calculation formula L=N×λ/2, where λ is the laser wavelength.

In actual use, the inventor of the present application found that the above-mentioned measurement structure and measurement method still have deficiencies:

The current single-frequency laser interferometer still has the problem of being seriously affected by the environment. When the movable mirror of the laser interferometer moves, the light intensity changes of the interference fringes are converted into electrical pulse signals by the photoelectric conversion elements and electronic circuits in the receiver. When it is the strongest constructive interference, the signal exceeds the trigger level of the counter and is recorded. If the environment changes, such as air turbulence, increased impurities in the air, machine tool oil mist, and the impact of cutting chips during processing on the laser beam, making The intensity of the laser beam decreases. At this time, even the strongest constructive interference occurs, and the intensity may be lower than the trigger level of the counter and not be counted.

Therefore, based on the above shortcomings, there is an urgent need for a laser interferometer that can resist environmental interference and improve measurement accuracy.

Contents of the invention

The object of the present invention is to provide a laser interferometer capable of resisting environmental interference to solve the deficiency of the existing laser interferometer in its ability to resist environmental interference.

In order to realize the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

A comparative anti-interference laser interferometer with cascaded micro-movement step-angle mirrors, including a laser source, a micro-movement step-angle mirror group, an interferometric photodetector group, a moving corner mirror, a spectroscopic mirror group and a micro-motion platform , the micro-movement step-angle reflector group includes m fine-motion step-angle reflectors and m-1 fixed-angle reflectors, m>2, and the m micro-movement step-angle reflectors are arranged on the micro-movement on the platform;

The laser source emits z laser beams to the beam splitter group, where z is a positive integer greater than or equal to 2, and the interferometric photodetector group includes z interferometric photodetectors, each interferometric photoelectric detector The detector corresponds to a laser beam;

Each laser beam is divided into a first laser beam group and a second laser beam group after passing through the beam splitter group, and the first laser beam group shoots to the micro-movement step-angle reflector group, passes through the micro-movement step angle After being reflected by the reflector group, it shoots to the beam splitter group again, and then shoots to the interferometric photodetector group after passing through the beam splitter group, and the second laser beam group shoots to the moving angle reflector, passes through After being reflected by the moving angle reflector, it shoots to the beam splitter group again, and after passing through the beam splitter group, it interferes with the first laser beam group that is directed to the interferometric photodetector group to form an interference laser beam. Beam group, each interference beam of the interference laser beam group is directed to the respective corresponding interferometric photodetectors;

The set of micro-movable step-angle reflectors includes two finely-movable step-angle reflectors and one fixed-angle reflector, each of which has two reflective step surfaces at right angles, and each of the reflective steps The surface includes z step-shaped reflective planes. When the first laser beam group enters the micro-movable step-angle reflector group, it first hits a reflective step surface of one of the micro-movable step-angle reflectors. The first laser beam The z laser beams of the beam group correspond to the z reflective planes of the reflective step surface one by one. The fixed-angle reflector is reflected by the fixed-angle reflector and then shoots to another micro-movable step-angle reflector, and then shoots to the beam splitter group after being reflected by the micro-movable step-angle reflector;

The comparative anti-interference micro-movement cascaded angle mirror laser interferometer also includes a reflection measurement photodetector group, and the reflection measurement photodetector group includes z reflection measurement photodetectors, and the second laser After the beam group is irradiated to the spectroscope group by the moving angle reflector, a reflected laser beam group is also formed, and each laser beam of the reflected laser beam group is respectively directed to one of the reflective measurement photodetectors.

As a further preferred solution, the beam splitter group includes a first beam splitter and a second beam splitter, the z laser beam emitted by the laser source first hits the first beam splitter, and is reflected by the first beam splitter to form a first beam splitter. The laser beam group is transmitted through the first beam splitter to form the second laser beam group, and the first laser beam group shoots to the micro-movable stepped angle reflector group, and then shoots to the first beam splitter again after being reflected, and then transmits After passing through the first beam splitter, the second laser beam group shoots to the moving angle mirror, is reflected by the moving angle mirror and then shoots to the second beam splitter, and is transmitted through the second beam splitter Then shoot to the first beam splitter, and interfere with the first laser beam group transmitted from the first beam splitter, form an interference laser beam group and shoot to the interferometric photodetector group, by the The second laser beam group emitted to the second beam splitter by the moving corner reflector is also reflected by the second beam splitter to form the reflected laser beam group.

In the laser interferometer of the present application, since the reflection measurement photodetector group can measure the intensity of the laser beam group reflected by the moving angle mirror, the interference state of the laser interference beam can be determined according to the intensity of the reflected laser beam group, so as to achieve the purpose of anti-environmental interference.

As a further preferred solution, the laser beam between any two of the laser source, micro-step angle reflector group, interferometric photodetector group, spectroscopic mirror group, and reflection measurement photodetector group is arranged in a closed space within without contact with the external environment. In the present application, the laser beam between any two of these components, the laser source, the micro-stepped angle reflector group, the interferometric photodetector group, the beam splitter group and the reflection measurement photodetector group, is arranged in a closed space, so that During the measurement process, the laser beams between the above components will not be affected by environmental factors, thereby ensuring the measurement accuracy of the laser interferometer of the present application.

As a further preferred solution, the laser beam between the beam splitter group and the moving corner mirror is exposed to ambient air. In actual use, the moving angle reflector is set on the measured object and moves with the measured object, so in this application, the laser beam between the beam splitter group and the moving angle reflector is exposed to the ambient air, first This makes the structure of the laser interferometer of the present application simple, and at the same time facilitates the arrangement of the laser interferometer of the present application.

The application also discloses a calibration method for the above-mentioned laser interferometer structure,

A method for calibrating laser interferometers with contrastive anti-jamming micro-movement cascaded angle mirrors, comprising the following steps:

Step 1. Position adjustment: adjust the positions of the laser source, the micro-movement step angle mirror group, the beam splitter group, the interferometric photodetector group, the reflection measurement photodetector group, the moving corner mirror and the micro-motion platform;

Step 2, adjust the optical path: start the laser source, and further accurately adjust the micro-movement stepped angle reflector group, the beam splitter group, the interferometric photodetector group, the reflection measurement photodetector group, the moving angle reflector and the micro-movement platform Position, so that the optical path of the laser interferometer meets the design requirements;

Step 3, generate the strongest interference database: select an interferometric photodetector in the interferometric photodetector group as the calibration interferometric photodetector, select a reflection measurement photodetector in the reflection measurement photodetector group as the calibration reflection Measuring photodetectors, the calibrated interferometric photodetectors correspond to the same laser beams emitted by the calibrated reflection measurement photodetectors and the laser source, and control the movement of the micro-motion platform in a clean air environment, Fix the micro-motion platform when the interference beam directed at the calibration interferometric photodetector is the strongest constructive interference, record the readings of the calibration reflectance measurement photodetector and the calibration interferometric photodetector readings at this time, and change the air environment Change the readings of the calibrated reflectance measurement photodetectors, and simultaneously record the readings of several calibrated reflectance measurement photodetectors and the corresponding calibration interferometric photodetector readings to obtain the strongest interference database.

As a further preferred solution, the third step is repeated, each time selecting a different calibrated reflectance measurement photodetector and calibrated interferometric photodetector, to obtain z strongest interference databases. Since step three is repeated, the z strongest interference databases are obtained, and the directly increased number of databases is more conducive to the matching query of data in the detection process, and realizes the multi-wavelength laser source, the micro-moving step angle reflector group and the z most The mutual cooperation between the strong interference database improves the measurement accuracy of the laser interferometer.

The laser interferometer structure and calibration method of the present application, when the strongest constructive interference, change the measurement environment, record the readings of the calibration reflectance measurement photodetector and the calibration interferometric photodetector readings to form the strongest interference database, in the actual measurement process , if there is an interferometric photodetector group that cannot normally detect the strongest constructive interference due to environmental factors, the readings of the calibrated reflectance photodetector and the calibrated interferometric photodetector readings can be compared with those in the strongest interference database The data are compared, if there is matching data, then this position is the strongest constructive interference, so that the laser interferometer of the present application can achieve the ability to resist environmental interference.

As a further preferred solution, it also includes step 4, generating the weakest interference database: controlling the movement of the micro-motion platform in a clean air environment, when the interference beam directed at the calibration interferometric photodetector is the weakest phase When eliminating interference, fix the micro-movement platform, record the readings of the calibration reflectance measurement photoelectric detector and the calibration interferometric photodetector readings at this time, change the air environment to change the readings of the calibration reflection measurement photoelectric detector, and record several calibration reflections at the same time Measure the photodetector readings and the corresponding calibration interferometric photodetector readings to obtain the weakest interference database.

As a further preferred solution, the fourth step is repeated, each time a different calibrated reflectance measurement photodetector and calibrated interferometric photodetector are selected to obtain z weakest interference databases.

As a further preferred solution, it also includes step five, generating a 1/n wavelength interference database, where n is a positive integer greater than or equal to 2, and controlling the movement of the micro-motion platform in a clean air environment, when shooting towards the calibration When the interference beam of the interferometric photodetector is the strongest constructive interference, continue to move the distance of 1/2mn wavelength, record the readings of the calibrated reflectance photodetector and the calibrated interferometric photodetector at this time, and then change the air environment to use The readings of the calibrated reflectance measurement photodetectors change, and simultaneously record several readings of the calibrated reflectance measurement photodetectors and the corresponding calibration interferometric photodetector readings to obtain a 1/n wavelength interference database.

When two laser beams interfere, the optical path difference between the adjacent strongest constructive interference and the weakest destructive interference is half a wavelength. In the calibration method of this application, for the strongest constructive interference, the weakest Both destructive interference and 1/n wavelength interference have been calibrated, that is to say, when the laser interferometer of the present application is used for actual measurement, the photodetector readings of the calibration reflection measurement and the calibration interferometric photodetector readings can be compared with the most Compare the data in the strong interference database, the weakest interference database, and the 1/n wavelength interference database, and determine whether the position is the strongest constructive interference, the weakest destructive interference or 1/n wavelength interference according to the matching of the data. This makes the laser interferometer of the present application not only resistant to environmental interference, but also improves measurement accuracy.

As a further preferred solution, the fifth step is repeated, each time a different calibrated reflectance measurement photodetector and calibrated interferometric photodetector are selected to obtain z 1/n wavelength interference databases.

The invention also discloses a measurement method using the above-mentioned interferometer and calibration method,

A measurement method using a comparative anti-interference micro-movement cascaded step-angle mirror laser interferometer and a calibration method:

In the actual measurement environment, it is assumed that the signal reading measured by the calibration reflection measurement photodetector is x, the signal reading obtained by the calibration interferometric photodetector measurement is y, and the x value and the y value are in the strongest interference database , the weakest interference database, and the 1/n wavelength interference database for comparison. When the x value and y value match a certain set of values in the strongest interference database, this position is considered to be the strongest constructive interference position. When The x value and y value match a set of values in the weakest interference database, and this position is considered as the weakest destructive interference position. When the x value and y value match a set of values in the 1/n wavelength interference database match, it is considered that this position is the 1/n wavelength interference position.

In the measurement method of the present application, the interference condition of the current interference beam is determined through the x value and the y value, so as to realize the ability of resisting environmental interference and improve the measurement accuracy at the same time.

As a further preferred solution, the matching threshold △ of the y value is set, and the value corresponding to the calibration interferometric photodetector in the strongest interference database, the weakest interference database, and the 1/n wavelength interference database is set to y', according to the value of x to The strongest interference database, the weakest interference database, and the 1/n wavelength interference database carry out the query of y', if there is y' so that |y-y'|<△, and then distinguish the database where y' is located, if y' is in the strongest In the interference database, this position is considered to be the strongest constructive interference position, if y' is in the weakest interference database, then this position is considered to be the weakest destructive interference position, if y' is in the 1/n wavelength interference database, It is considered that this position is the 1/n wavelength interference position.

As a further preferred solution, set the value corresponding to the calibration reflectance measurement photodetector in the strongest interference database, the weakest interference database, and the 1/n wavelength interference database as x', and in the actual measurement, select the one closest to the actual measured value x x' is used as a matching value, and y' is queried according to the value of x' to the strongest interference database, the weakest interference database, and the 1/n wavelength interference database. If y' exists so that |y-y'|<△, then distinguish y The database where 'is located, if y' is in the strongest interference database, then this position is considered as the strongest constructive interference position, if y' is in the weakest interference database, then this position is considered as the weakest destructive interference position, if If y' is in the 1/n wavelength interference database, this position is considered to be the 1/n wavelength interference position.

As a further preferred solution, the size of the matching threshold Δ ensures that when performing data query, y' is a unique value when |y-y'|<Δ is satisfied. When the matching threshold △ is large, a set of x values and y values may match two or more sets of x' and y' values, which brings inconvenience to the measurement, so the threshold △ should be matched first, so that during the measurement A set of x and y values matches at most a set of x' and y' values for easy measurement.

As a further preferred solution, the size of the matching threshold △ is set according to the accuracy requirements of the actual measurement. When a high-precision measurement value is required, a smaller matching threshold is used. When a high-precision measurement value is not required, a higher matching threshold is used. Large matching threshold.

As a further preferred solution, set Δ=5%.

In the measurement method of the present application, by setting the matching threshold △, the size of the matching threshold △ is set according to the needs of the actual measurement accuracy, so as to facilitate the matching selection of data during the measurement process and reduce the difficulty of measurement.

Compared with prior art, the beneficial effect of the present invention:

The comparative anti-interference laser interferometer with micro-movement cascaded angle mirrors of this application first improves the measurement accuracy of the laser interferometer by setting multiple beams, micro-movement stepped angle mirror groups and corner mirrors, and at the same time measures the photoelectricity by setting reflection Detector, after the laser interferometry environment changes, the laser intensity reflected by the moving angle mirror can be measured. The laser interference state is no longer directly determined by the signal size of the interferometry photodetector group, but by the reflection measurement photodetector It is determined jointly with the interferometric photodetector group, so as to realize the anti-interference ability of the laser interferometer.

Beneficial effects of other embodiments of the present application:

The laser interferometer of the present application can not only determine the position of the strongest constructive interference, but also can determine the position of the weakest destructive interference and the 1/n wavelength interference position, so that the laser interferometer of the present application can not only resist environmental interference, Moreover, the measurement accuracy is improved; moreover, the mutual cooperation among the measurement method, the calibration method, the multi-beam laser source, and the micro-moving step-angle reflector group of the present application further improves the measurement accuracy of the laser interferometer of the present application.

Description of drawings:

Fig. 1 is the optical path schematic diagram of laser interferometer structure of the present invention;

Fig. 2 is a structural schematic diagram when the moving corner reflector moves,

Marked in the figure:

1-laser source, 2-micro step angle mirror group, 3-moving angle mirror group, 4-interferometric photodetector group, 5-beam splitter group, 6-reflection measurement photodetector group, 7-first Laser beam group, 8-second laser beam group, 9-reflected laser beam group, 10-micro-motion platform, 21-micro-movement stepped angle reflector, 22-fixed angle reflector, 41-interferometric photodetector, 41a - calibration interferometric photodetector, 51 - first beam splitter, 52 - second beam splitter, 61 - reflection measurement photodetector, 61a - calibration reflection measurement photodetector.

Detailed ways

The present invention will be further described in detail below in conjunction with test examples and specific embodiments. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

Embodiment 1, as shown in the figure, a contrastive anti-interference micro-motion cascaded step-angle mirror laser interferometer includes a laser source 1, a micro-motion step-angle mirror group 2, an interferometric photodetector group 4, The moving corner mirror 3, the beam splitter group 5 and the micro-motion platform 10, the micro-moving stepped corner mirror group 2 includes two micro-moving stepped corner mirrors 21 and a fixed corner mirror 22, and the two micro-movable stepped corner mirrors 21 The moving step angle reflector 21 is arranged on the micro-moving platform 10;

The laser source 1 emits z laser beams to the beam splitter group 5, wherein z is a positive integer greater than or equal to 2, and the interferometric photodetector group 4 includes z interferometric photodetectors, each The interferometric photodetector 41 corresponds to a laser beam;

Each laser beam is divided into a first laser beam group 7 and a second laser beam group 8 after the beam splitter group 5, and the first laser beam group 7 shoots to the micro-moving stepped angle reflector group 2, and passes through the After the reflection of the micro-moving stepped angle mirror group 2, it shoots to the beam splitter group 5 again, and then shoots to the interferometric photodetector group 4 after passing through the beam splitter group 5, and the second laser beam group 8 Shot toward the moving corner reflector 3, after being reflected by the moving corner reflector 3, shoot to the beam splitter group 5 again, after passing through the beam splitter group 5, corresponding to the photoelectric detector for the interferometric measurement The first laser beam group 7 of the device group 4 interferes to form an interfering laser beam group, and each interfering beam of the interfering laser beam group is directed to the respective corresponding interferometric photodetectors 41;

The micro-movable step-angle reflector group 2 includes two fine-motion step-angle reflectors 21 and a fixed-angle reflector 22, each finely-movable step-angle reflector 21 has two reflecting step surfaces at right angles, each The reflective step surface includes z stepped reflective planes. When the first laser beam group 7 enters the micro-movable step-angle reflector group 2, it first hits a reflection of one of the micro-movable step-angle reflectors 21. On the step surface, the z laser beams of the first laser beam group correspond to the z reflection planes of the reflective step surface one by one, and are reflected by the reflective step surface and then hit another reflective step surface of the micro-movable step angle reflector , shoot to described fixed-angle reflector 22 again after being reflected, shoot to another micro-motion stepped-angle reflector 21 again after being reflected by fixed-angle reflector 22, after being reflected by this micro-movable stepped-angle reflector 21, shoot again To the beam splitter group 5;

The comparative anti-jamming micro-movement cascade step angle mirror laser interferometer also includes a reflection measurement photodetector group 6, and the reflection measurement photodetector group 6 includes z reflection measurement photodetectors 61, the The second laser beam group 8 also forms a reflected laser beam group 9 after being shot to the beam splitter group 5 by the moving angle reflector 3, and each laser beam of the reflected laser beam group 9 shoots to one of the laser beam groups respectively. Reflection measurement photodetector 61 .

As a further preferred solution, the beam splitter group 5 includes a first beam splitter 51 and a second beam splitter 52, the z laser beam emitted by the laser source 1 first hits the first beam splitter 51, and passes through the first beam splitter. The mirror 51 reflects to form the first laser beam group 7, which is transmitted through the first beam splitter 51 to form the second laser beam group 8, and the first laser beam group 7 shoots to the micro-moving step angle reflector group 2, and then shoots again after being reflected. to the first beam splitter 51, and then transmitted through the first beam splitter 51, the second laser beam group 8 is directed to the moving angle reflector 3, and then projected after being reflected by the moving angle reflector 3 To the second beam splitter 52, after being transmitted by the second beam splitter 52, it is transmitted to the first beam splitter 51, and interferes with the first laser beam group 7 transmitted from the first beam splitter 51 , after forming an interference laser beam group, shoot to the interferometric photodetector group 4, and the second laser beam group 8 that is sent to the second beam splitter 52 by the moving angle reflector 3 is also captured by the first Two beam splitters 52 reflect to form the reflected laser beam group 9 .

The laser interferometer of the present application can measure the intensity of the reflected laser beam group 9 by the reflective measurement photodetector group 6, and determine the interference state of the laser interference beam according to the intensity of the reflected laser beam group 9, so as to realize anti-environmental purpose of interference.

As a further preferred solution, the laser light between any two of the laser source 1, the micro-step angle mirror group 2, the interferometric photodetector group 4, the spectroscopic mirror group 5, and the reflection measurement photodetector group 6 The beam is arranged in an enclosed space without contact with the external ambient space. In the present application, the laser beam between any two of these components of the laser source 1, the micro-step angle mirror group 2, the interferometric photodetector group 4, the spectroscopic mirror group 5 and the reflection measurement photodetector group 6 is set at In the enclosed space, the laser beams between the above-mentioned components will not be affected by environmental factors during the measurement process, thereby ensuring the measurement accuracy of the laser interferometer of the present application.

As a further preferred solution, the laser beam between the beam splitter group 5 and the moving corner mirror 3 is exposed to ambient air. In actual use, the moving angle reflector 3 is arranged on the measured object and moves with the measured object, so in this application, the laser beam between the beam splitter group 5 and the moving angle reflecting mirror 3 is exposed to the ambient air Among them, first of all, it makes the structure of the laser interferometer of the present application simple, and at the same time facilitates the arrangement of the laser interferometer of the present application.

Embodiment 2, as shown in the figure, a method for calibrating laser interferometers with contrastive anti-interference micro-movement cascaded angle mirrors, including the following steps:

Step 1. Position adjustment: Adjust the laser source 1, the micro-movement step angle mirror group 2, the beam splitter group 5, the interferometric photodetector group 4, the reflection measurement photodetector group 6, the moving corner mirror 3 and the micro-motion the location of platform 10;

Step 2. Adjusting the optical path: start the laser source 1, and further precisely adjust the micro-movement stepped angle mirror group 2, the beam splitter mirror group 5, the interferometric photodetector group 4, the reflection measurement photodetector group 6, and the moving angle mirror 3 and the position of the micro-movement platform, so that the optical path of the laser interferometer meets the design requirements;

Step 3, generate the strongest interference database: select an interferometric photodetector 41 in the interferometric photodetector group 4 as the calibration interferometric photodetector 41a, select a reflection measurement photodetector in the reflection measurement photodetector group 6 The device 61 is used as a calibration reflectance measurement photodetector 61a, and the calibration interferometric photodetector 41a corresponds to the same laser beam emitted by the laser source 1 as the calibration reflection measurement photodetector 41a. Next control the movement of the micro-motion platform 10, fix the micro-motion platform 10 when the interference beam directed at the calibration interferometric photodetector 41a is the strongest constructive interference, and record the calibration reflectance measurement photodetector 61a at this time Reading and calibration interferometric photodetector 41a readings, changing the air environment to change the readings of the calibration reflectance measurement photodetector 61a, and simultaneously record the readings of several calibration reflection measurement photodetectors 61a and the corresponding calibration interferometric photodetector 41a readings , to get the strongest interference database.

As a further preferred solution, the third step is repeated, each time a different calibrated reflectance measurement photodetector 61a and calibrated interferometric photodetector 41a are selected to obtain z strongest interference databases.

The laser interferometer structure and calibration method of the present application, when the strongest constructive interference occurs, the measurement environment is changed, and the readings of the calibration reflectance measurement photodetector 41a and the calibration interferometric photodetector 41a readings are recorded to form the strongest interference database. In the process, if the interferometric photodetector group 4 cannot normally detect the strongest constructive interference due to environmental factors, the readings of the calibrated reflectance photodetector 61a and the calibrated interferometric photodetector 41a readings can be compared with the maximum The data in the strong interference database are compared, if there is matching data, then this position is the strongest constructive interference, so that the laser interferometer of the present application can achieve the ability to resist environmental interference.

As a further preferred solution, it also includes step 4, generating the weakest interference database: controlling the movement of the micro-motion platform 10 in an environment with clean air, when the interference beam directed at the calibration interferometric photodetector 41a is the weakest Fix the micro-movement platform 10 during weak destructive interference, record the readings of the calibration reflection measurement photodetector 61a and the calibration interference measurement photodetector 41a at this time, and change the air environment to change the readings of the calibration reflection measurement photodetector 61a, Simultaneously record the readings of several calibrated reflectance measurement photodetectors 61a and the corresponding calibrated interferometric photodetector 41a readings to obtain the weakest interference database.

As a further preferred solution, the fourth step is repeated, each time a different calibrated reflectance measurement photodetector 61a and calibrated interferometric photodetector 41a are selected to obtain z weakest interference databases.

As a further preferred solution, it also includes step 5, generating a 1/n wavelength interference database, n is a positive integer greater than or equal to 2, and controlling the movement of the micro-motion platform 10 in a clean air environment, when shooting at the When the interference light beam of the calibration interferometric photodetector 41a is the strongest constructive interference, continue to move the distance of 1/2mn wavelength, record the readings 61a of the calibration reflectance measurement photodetector and the readings of the calibration interferometric photodetector 41a at this time, and then Change the air environment to change the readings of the calibrated reflectance measurement photodetector 61a, and record several readings of the calibrated reflectance measurement photodetector 61a and the corresponding calibration interferometric photodetector 41a readings to obtain a 1/n wavelength interference database.

When two laser beams interfere, the optical path difference between the adjacent strongest constructive interference and the weakest destructive interference is half a wavelength. In the calibration method of this application, for the strongest constructive interference, the weakest Both destructive interference and 1/n wavelength interference have been calibrated, that is to say, when the laser interferometer of the present application is used for actual measurement, the readings of the photodetector 61a for calibration reflection measurement and the readings of photodetector 41a for calibration interferometric measurement can be used Compare with the data in the strongest interference database, the weakest interference database, and the 1/n wavelength interference database, and determine whether the position is the strongest constructive interference, the weakest destructive interference or 1/n wavelength interference according to the matching of the data . This makes the laser interferometer of the present application not only resistant to environmental interference, but also improves measurement accuracy.

As a further preferred solution, the fifth step is repeated, each time a different calibrated reflectance measurement photodetector 61a and calibrated interferometric photodetector 41a are selected to obtain z 1/n wavelength interference databases.

Embodiment 3, as shown in the figure, a measurement method using a contrastive anti-interference micro-motion cascaded step angle mirror laser interferometer and a calibration method:

In the actual measurement environment, it is assumed that the signal reading measured by the calibration reflectance measurement photodetector 61a is x, the signal reading obtained by the calibration interferometric photodetector 41a is y, and the x value and the y value are at the strongest Comparisons are made in the interference database, the weakest interference database, and the 1/n wavelength interference database. When the x value and y value match a certain set of values in the strongest interference database, this position is considered to be the strongest constructive interference position , when the x value and y value match a set of values in the weakest interference database, this position is considered as the weakest destructive interference position, when the x value and y value match a certain set of values in the 1/n wavelength interference database If the group values match, the position is considered to be the 1/n wavelength interference position.

In the measurement method of the present application, the interference condition of the current interference beam is determined through the x value and the y value, so as to realize the ability of resisting environmental interference and improve the measurement accuracy at the same time.

As a further preferred solution, the matching threshold △ of the y value is set, and the value corresponding to the calibration interferometric photodetector in the strongest interference database, the weakest interference database, and the 1/n wavelength interference database is set to y', according to the value of x to The strongest interference database, the weakest interference database, and the 1/n wavelength interference database carry out the query of y', if there is y' so that |y-y'|<△, and then distinguish the database where y' is located, if y' is in the strongest In the interference database, this position is considered to be the strongest constructive interference position, if y' is in the weakest interference database, then this position is considered to be the weakest destructive interference position, if y' is in the 1/n wavelength interference database, It is considered that this position is the 1/n wavelength interference position.

As a further preferred solution, set the value corresponding to the calibration reflectance measurement photodetector 61a in the strongest interference database, the weakest interference database, and the 1/n wavelength interference database as x', and in the actual measurement, select the closest to the actual measured value x x' is used as the matching value, and y' is queried on the strongest interference database, the weakest interference database, and the 1/n wavelength interference database according to the x' value, and if there is y' such that |y-y'|<△, then distinguish The database where y' is located, if y' is in the strongest interference database, this position is considered as the strongest constructive interference position, if y' is in the weakest interference database, this position is considered as the weakest destructive interference position, If y' is in the 1/n wavelength interference database, the position is considered to be the 1/n wavelength interference position.

As a further preferred solution, the size of the matching threshold Δ ensures that when performing data query, y' is a unique value when |y-y'|<Δ is satisfied. When the matching threshold △ is large, a set of x values and y values may match two or more sets of x' and y' values, which brings inconvenience to the measurement, so the threshold △ should be matched first, so that during the measurement A set of x and y values matches at most a set of x' and y' values for easy measurement.

As a further preferred solution, the size of the matching threshold △ is set according to the accuracy requirements of the actual measurement. When a high-precision measurement value is required, a smaller matching threshold is used. When a high-precision measurement value is not required, a higher matching threshold is used. Large matching threshold.

As a further preferred solution, set Δ=5%.

In the measurement method of the present application, by setting the matching threshold △, the size of the matching threshold △ is set according to the needs of the actual measurement accuracy, so as to facilitate the matching selection of data during the measurement process and reduce the difficulty of measurement.

The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the specification has described the present invention in detail with reference to the above-mentioned embodiments, the present invention is not limited to the above-mentioned specific implementation methods, so Any modification or equivalent replacement of the present invention; and all technical solutions and improvements that do not deviate from the spirit and scope of the invention shall be covered by the claims of the present invention.

Claims (10)

1. A comparative anti-interference laser interferometer with micro-movement cascaded angle mirrors, including a laser source, a micro-motion stepped angle mirror group, an interferometric photodetector group, a moving angle mirror, a beam splitter group and a micro The moving platform, the set of micro-movable step-angle reflectors includes m micro-movable step-angle reflectors and m-1 fixed-angle reflectors, m>2, and the m micro-movable step-angle reflectors are arranged on the on the micro-motion platform; The laser source emits z laser beams to the beam splitter group, where z is a positive integer greater than or equal to 2, and the interferometric photodetector group includes z interferometric photodetectors, each interferometric photoelectric detector The detector corresponds to a laser beam, and each laser beam is divided into a first laser beam group and a second laser beam group after passing through the beam splitter group, and the first laser beam group shoots to the micro-movement step angle reflection The mirror group, after being reflected by the micro-moving stepped angle mirror group, shoots to the beam splitter group again, and then shoots to the interferometric photodetector group after passing through the beam splitter group, and the second laser beam group shoot to the moving angle reflector, and then shoot to the beam splitter group after being reflected by the moving angle mirror, and after passing through the beam splitter group, corresponding to the first beam that is directed to the interferometric photodetector group A laser beam group interferes to form an interfering laser beam group, and each interference beam of the interfering laser beam group is respectively directed to the respective corresponding interferometric photodetectors; It is characterized in that the comparative anti-interference micro-movement cascade step-angle mirror laser interferometer also includes a reflection measurement photodetector group, and the reflection measurement photodetector group includes z reflection measurement photodetectors, so The second laser beam group also forms a reflected laser beam group after being shot to the beam splitter group by the moving angle reflector, and each laser beam of the reflected laser beam group shoots to one of the reflective measurement photoelectric detectors respectively. device. 2. The contrasting anti-interference micro-motion cascade step angle mirror laser interferometer according to claim 1, wherein the beam splitter group includes a first beam splitter and a second beam splitter, and the laser source The emitted z laser beam first hits the first beam splitter, is reflected by the first beam splitter to form the first laser beam group, and is transmitted through the first beam splitter to form the second laser beam group, and the first laser beam group is directed to the micro The moving stepped angle reflector group, after being reflected, shoots to the first beam splitter again, and then transmits through the first beam splitter, and the second laser beam group shoots to the moving angle reflector, passes through the After being reflected by the moving angle reflector, it is directed to the second beam splitter, and after being transmitted by the second beam splitter, it is directed to the first beam splitter, and is combined with the first laser beam transmitted from the first beam splitter Interference occurs, the interfering laser beam group is formed and then directed to the interferometric photodetector group, and the second laser beam group directed to the second beam splitter by the moving angle reflector is also captured by the second beam splitter Mirror reflection forms the set of reflected laser beams. 3. A calibration method for the contrastive anti-interference micro-movement cascaded angle mirror laser interferometer described in any one of claims 1 and 2, characterized in that it comprises the following steps: Step 1. Position adjustment: adjust the positions of the laser source, the micro-movement step angle mirror group, the beam splitter group, the interferometric photodetector group, the reflection measurement photodetector group, the moving corner mirror and the micro-motion platform; Step 2, adjust the optical path: start the laser source, and further accurately adjust the micro-movement stepped angle reflector group, the beam splitter group, the interferometric photodetector group, the reflection measurement photodetector group, the moving angle reflector and the micro-movement platform Position, so that the optical path of the laser interferometer meets the design requirements; Step 3, generate the strongest interference database: select an interferometric photodetector in the interferometric photodetector group as the calibration interferometric photodetector, select a reflection measurement photodetector in the reflection measurement photodetector group as the calibration reflection Measuring photodetectors, the calibrated interferometric photodetectors correspond to the same laser beams emitted by the calibrated reflection measurement photodetectors and the laser source, and control the movement of the micro-motion platform in a clean air environment, Fix the micro-motion platform when the interference beam directed at the calibration interferometric photodetector is the strongest constructive interference, record the readings of the calibration reflectance measurement photodetector and the calibration interferometric photodetector readings at this time, and change the air environment Change the readings of the calibrated reflectance measurement photodetectors, and simultaneously record the readings of several calibrated reflectance measurement photodetectors and the corresponding calibration interferometric photodetector readings to obtain the strongest interference database. 4. The calibration method according to claim 3, further comprising step 4, generating the weakest interference database: controlling the movement of the micro-motion platform in an air-clean environment, when shooting at the calibration interferometric Fix the micro-motion platform when the interference beam of the photodetector is the weakest destructive interference, record the readings of the photodetector for calibration reflection measurement and the readings of the photodetector for calibration interferometric measurement at this time, and change the air environment to make the photoelectric detection of calibration reflection measurement The readings of the detector readings are changed, and the readings of several calibrated reflection measurement photodetectors and the corresponding calibration interferometric photodetector readings are recorded at the same time to obtain the weakest interference database. 5. The calibration method according to claim 4, further comprising step 5, generating a 1/n wavelength interference database, n being a positive integer greater than or equal to 2, controlling the micro The moving platform moves, and when the interference beam directed at the calibration interferometric photodetector is the strongest constructive interference, continue to move the distance of 1/2mn wavelength, and record the readings of the calibration reflection measurement photodetector and the calibration interferometry at this time Read the photodetector, then change the air environment to change the reading of the calibrated reflection measurement photodetector, and record several readings of the calibrated reflectance measurement photodetector and the corresponding calibration interferometric photodetector readings to obtain 1/n wavelength interfere with the database. 6. A method of measuring using the comparative anti-interference micro-motion cascaded step-angle mirror laser interferometer described in any one of claim 1 or 2 and the calibration method described in claim 5, wherein In the actual measurement environment, it is assumed that the signal reading measured by the calibration reflection measurement photodetector is x, the signal reading obtained by the calibration interferometric photodetector measurement is y, and the x value and the y value are stored in the strongest interference database, The weakest interference database and the 1/n wavelength interference database are compared. When the x value and y value match a certain set of values in the strongest interference database, this position is considered to be the strongest constructive interference position. When x value and y value match a set of values in the weakest interference database, then this position is considered as the position of the weakest destructive interference, when the x value and y value match a set of values in the 1/n wavelength interference database match, the position is considered to be the 1/n wavelength interference position. 7. measuring method as claimed in claim 6, it is characterized in that, the matching threshold △ of setting y value, set in the strongest interference database, the weakest interference database, 1/n wavelength interference database, demarcate interferometric photodetector correspondence The value of is y', according to the value of x, the query of y' is performed on the strongest interference database, the weakest interference database, and the 1/n wavelength interference database. If there is y' so that |y-y'|<△, then distinguish y' If y' is in the strongest interference database, this position is considered as the strongest constructive interference position, if y' is in the weakest interference database, this position is considered as the weakest destructive interference position, if y 'In the 1/n wavelength interference database, this position is considered to be the 1/n wavelength interference position. 8. measuring method as claimed in claim 7, it is characterized in that, set the numerical value corresponding to the reflection measurement photodetector in the strongest interference database, the weakest interference database, the 1/n wavelength interference database to be x ', in actual measurement In , select x' which is closest to the actual measured value x as the matching value, and query y' from the strongest interference database, the weakest interference database, and the 1/n wavelength interference database according to the x' value. If there is y', |y -y'|<△, and then distinguish the database where y' is located, if y' is in the strongest interference database, this position is considered as the strongest constructive interference position, if y' is in the weakest interference database, then this position is considered The position is the weakest destructive interference position, if y' is in the 1/n wavelength interference database, this position is considered as the 1/n wavelength interference position. 9. The measurement method according to claim 7 or 8, characterized in that, the size of the matching threshold △ ensures that when performing data query, when |y-y'|<△ is satisfied, y' is a unique value. 10. The measurement method according to claim 9, characterized in that, the size of the matching threshold △ is set according to the accuracy requirements of actual measurement, when a high-precision measurement value is required, a smaller matching threshold is used, and when Larger matching thresholds are used when high-precision measurements are not required.