CN103499286A - Reset compensation type two-optical-axis linear displacement laser interferometer calibration method and device - Google Patents

Abstract

The calibration method and device of the return-compensated dual optical axis displacement laser interferometer belong to the technical field of laser measurement. The measurement beam is placed parallel to the middle of two parallel standard measurement beams; the vertical distance between the standard measurement beam and the calibrated laser interferometer measurement beam is very small, and the average refractive index of the air of the two standard measurement beams is close to the calibrated laser interferometer measurement beam The air refractive index value; the two beam position detectors can respectively measure the derivative displacement of the two standard measurement beams relative to the target mirror in any two-dimensional direction perpendicular to the standard measurement beam plane; the micro-motion device is based on the two beam position detectors The average value of the derived displacement is measured, and real-time return compensation is performed on the derived displacement of the target mirror, so that the incident position of the measuring beam on the reflective surface of the target mirror does not change.

Description

Calibration method and device for return-compensated dual-optical axis displacement laser interferometer

technical field

The invention belongs to the technical field of laser measurement, and mainly relates to a laser interferometer calibration method and device.

Background technique

Laser interferometry linear displacement technology is a standard measurement technology with high precision. It is widely used in precision and ultra-precision machining, microelectronics equipment, nanotechnology industrial equipment and national defense equipment. In order to ensure the accuracy of laser interferometer measurement of linear displacement , requires a scientific and effective linear displacement laser interferometer calibration method and device. The general idea of calibrating a linear displacement laser interferometer is to use a linear displacement laser interferometer with a higher level of precision for calibration. When the accuracy of the two is similar, it is called comparison. In the actual calibration work, most of the linear displacement laser interferometers have considerable precision, so the calibration of the linear displacement laser interferometer is realized by comparison. At present, the general calibration methods of linear displacement laser interferometers include parallel, face-to-face and common optical path (Liao Qing, Zhu Xiaoping, Wang Weichen, Du Hua. Research on the calibration method of laser interferometer length measurement accuracy. Modern measurement and laboratory management, 2005, 1:6-7).

Figure 1 is a schematic diagram of the parallel laser interferometer calibration device. The standard measuring mirror and the calibrated measuring mirror are installed on the same movable platform. When the moving platform moves, the optical path of the two sets of laser interferometer measuring beams increases and decreases simultaneously. Small. Since the two sets of laser interferometers are placed in parallel, the two paths of light are similarly affected by the environment, and the refractive index of air has little influence on the two paths of light. Bay error is large.

Figure 2 is a schematic diagram of the face-to-face laser interferometer calibration device. The standard measuring mirror and the calibrated measuring mirror are installed on the moving platform face to face. The advantage is that the measuring beam axes of the two sets of laser interferometers can be adjusted to almost the same measuring axis. The Abbe error of the latter is very small, and the disadvantage is that the near end of one interferometer is the far end of the other, the optical paths of the two are not equal, and the interference of the environment is different. Inconsistent impact.

In 2011, the National Institute of Metrology established the first 80-meter long-length laser interferometer measurement device in China (Leng Yuguo, Tao Lei, Xu Jian. Analysis of the accuracy and influencing factors of the dual-frequency laser interferometer system based on the 80-meter measurement device. Metrology and Testing Technology, 2011, 38(9): 47-49), the standard device used is to place three Agilent5530 long-distance dual-frequency laser interferometers in parallel to form a three-way laser interferometer, and the calibrated laser interferometer The instrument is placed between them for calibration and calibration. This scheme is a derivative of the parallel calibration method, and since three-way light is used for simultaneous measurement, it can compensate for the Abbe error during measurement. However, since three lasers are placed in parallel Therefore, the spatial position of the three-way standard measurement light is relatively far away, and the distance between the measurement light of the calibrated laser interferometer and each standard measurement light is also relatively long. All measurement light paths are affected by the environment differently, and the air refractive index has inconsistent effects on all measurement light paths. , resulting in inaccurate calibration measurements.

Figure 3 is a schematic diagram of the structure of the common optical path laser interferometer calibration device. The difference between the common optical path type and the parallel laser interferometer calibration device is that the two lasers and the receiver are bent at 90 degrees, and the two sets of laser interferometers share the same interference mirror group. and measuring mirrors. Since the two sets of laser interferometers share one interferometer group and measuring mirror, it is impossible to determine whether the shared interferometer group and measuring mirror belong to the standard laser interferometer part or the calibrated standard laser interferometer part. Therefore, it is not exactly two sets The calibration of the laser interferometer is calibrated.

In 1985, Dr-Ing H.-H.Schussler made full use of the spatial distribution (Dr-Ing H.-H.Schussler. Comparison and calibration of laser interferometer systems. Measurement, 1985, 3(4): 175-184), and multi Common optical path calibration of the linear displacement laser interferometer. Since only the number of common optical path laser interferometers is increased, this method also has the disadvantages of the common optical path laser interferometer calibration device mentioned above.

Contents of the invention

In view of the relatively large Abbe error, serious air refractive index inconsistency and inaccurate calibration of two sets of laser interferometers in the existing linear displacement laser interferometer calibration device, the present invention proposes and develops a return compensation formula Calibration method and device for a dual optical axis displacement laser interferometer, the invention makes the vertical distance between the standard measurement beam and the calibrated laser interferometer measurement beam very small, thereby reducing the Abbe error and the influence of air refractive index inconsistency, and In the accurate sense, two sets of laser interferometers are calibrated.

The object of the present invention is achieved through the following technical solutions:

A method for calibrating a return compensation type dual optical axis displacement laser interferometer, the method steps are as follows:

(1) The output light of the standard laser interferometer laser passes through the biaxial hollow laser interferometer group to form two parallel standard measurement beams. The two standard measurement beams are incident on the plane mirror with a middle hole. Each standard measurement beam has a After part of the light with plane mirror displacement information is reflected back to the biaxial hollow laser interferometer group, according to the two interference signals obtained from the biaxial hollow laser interferometer group and corresponding to the two standard measuring beams respectively, it can be obtained that there is a center hole The two displacement values of the plane mirror moving along the direction of the standard measuring beam, and the remaining part of each standard measuring beam is transmitted to the two beam position detectors through the plane mirror with a middle hole;

(2) The output light of the calibrated laser interferometer laser passes through the calibrated laser interferometer interferometer group to form the calibrated laser interferometer measurement beam, and the calibrated laser interferometer measurement beam passes through the middle through hole of the biaxial hollow laser interferometer group , parallel and coplanar with the two standard measuring beams, the measuring beam of the calibrated laser interferometer is incident on the mirror of the calibrated laser interferometer, after being reflected back to the interferometer group of the calibrated laser interferometer, according to the calibrated laser interferometer The interference signal obtained in the laser interferometer group can be used to obtain the displacement value of the calibrated laser interferometer mirror moving along the direction of the standard measuring beam;

(3) During the reciprocating movement of the moving table along the direction of the standard measuring beam, there is a derivative displacement in any two-dimensional direction perpendicular to the plane of the standard measuring beam. The target mirror mounted on the moving table is perpendicular to the plane of the standard measuring beam There is a free displacement relative to the telescopic stage in any two-dimensional direction, and the two beam position detectors respectively measure the derivative displacement of the standard measurement beam relative to the target mirror in any two-dimensional direction perpendicular to the standard measurement beam plane. A beam position detector measures the average value of the derived displacement, and performs real-time return compensation for the derived displacement of the target mirror to ensure that the incident position of the measuring beam on the reflective surface of the target mirror does not change;

(4) During the reciprocating movement of the moving table along the direction of the standard measuring beam, the two measured displacement values of the standard laser interferometer and the measured displacement values of the calibrated laser interferometer are sampled synchronously at a uniform or non-uniform sampling rate, and each sampling is obtained After taking the average value of the two measured displacements of the standard laser interferometer and taking the difference with the measured displacement value of the calibrated laser interferometer obtained by simultaneous sampling, several sampling measurement error values are obtained.

A return compensation type dual-optical axis displacement laser interferometer calibration device, including a standard laser interferometer laser and two receivers arranged at a position that can receive the interference signal of the standard laser interferometer, the wires connect the two receivers to the standard laser interferometer respectively The connection of the signal processing system of the laser interferometer; on the output optical path of the standard laser interferometer laser, there is a double-axis hollow standard laser interferometer group with a middle through hole that allows the measured beam of the calibrated laser interferometer to pass through; the double-axis hollow standard laser interferometer One side of the mirror group is equipped with a guide rail, and the moving table is mounted on the guide rail. A plane mirror with a middle hole is installed on the moving table through a micro-movement device, and a calibrated laser interferometer reflector is installed in the middle hole of the plane mirror. The mirror and the plane mirror with the middle hole constitute the target reflector whose incident surface is coplanar and the relative position is fixed; the two beam position detectors are arranged behind the transmission area of the plane mirror with the middle hole, and are respectively located on two parallel standard measurement beam transmission light paths ; The calibrated laser interferometer interferometer group and the calibrated laser interferometer laser are arranged on the other side of the biaxial hollow standard laser interferometer group, and the calibrated laser interferometer interferometer group is located on the output optical path of the calibrated laser interferometer laser The receiver of the calibrated laser interferometer is arranged at a position capable of receiving the interference signal of the calibrated laser interferometer, and the wire connects the receiver of the calibrated laser interferometer with the signal processing system of the calibrated laser interferometer.

The present invention has following characteristics and good effect:

(1) Compared with the parallel laser interferometer calibration device, since the measured beam of the calibrated laser interferometer passes through the middle through hole of the biaxial hollow laser interferometer group, the distance between the measured optical axis of the calibrated laser interferometer and the parallel standard optical axis The vertical distance of the two laser interferometers is shorter, and the optical paths of the two are closer, so the Abbe error is very small when the two sets of laser interferometers are calibrated.

(2) Compared with the face-to-face laser interferometer calibration device, in the plane perpendicular to the two standard measuring beams, in the line segment area formed by the projection points of the two standard measuring beams on the plane, the two standard measuring beams and the measured There is little difference in the degree of interference of the measuring beam of the calibrated laser interferometer by the environment, and the average value of the air refractive index of the two standard measuring beams is close to the value of the air refractive index of the calibrated laser interferometer measuring beam.

(3) Compared with the common optical path laser interferometer calibration device, there is no shared interferometer group and measuring mirror, and the ownership of the standard laser interferometer components and the calibrated standard laser interferometer components is clear. It is accurate to calibrate two sets of laser interferometers .

(4) The two beam position detectors can respectively measure the derivative displacement of the two standard measuring beams relative to the target reflector in any two-dimensional direction perpendicular to the standard measuring beam plane, and the micro-motion device can measure the derived displacement according to the two beam position detectors. The average value of the displacement, real-time return compensation for the derived displacement of the target mirror, so that the incident position of the measuring beam on the reflective surface of the target mirror does not change, and ensures that different morphology features on the reflective surface of the target mirror will not be introduced during calibration The measurement error caused by the value.

Description of drawings

Figure 1 is a schematic diagram of the parallel laser interferometer calibration device

Figure 2 is a schematic diagram of the face-to-face laser interferometer calibration device

Figure 3 is a schematic diagram of the calibration device of the common optical path laser interferometer

Figure 4 is a schematic diagram of the structure of the calibration device for the return-compensated dual-optical axis displacement laser interferometer

Figure 5 is a schematic diagram of spot position distribution on the incident surface of the target mirror composed of a plane mirror with an intermediate hole and a calibrated laser interferometer mirror

In the figure: 1 standard laser interferometer laser, 2 biaxial hollow standard laser interferometer group, 3, 4 two parallel standard measuring beams, 5 plane mirror with middle hole, 6, 7 standard laser interferometer receiver, 8 standard signal Processing system, 9 calibrated laser interferometer laser, 10 calibrated laser interferometer interferometer group, 11 calibrated laser interferometer measurement beam, 12 middle through hole, 13 calibrated laser interferometer mirror, 14 calibrated laser interferometer Receiver, 15 calibrated laser interferometer signal processing system, 16 micro-movement device, 17 motion table, 18 guide rail, 19, 20 two beam position detectors, 21, 22 two parallel standard measuring beam spot positions, 23 calibrated Laser interferometer beam spot position.

Detailed ways

The specific embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

A return compensation type dual-optical axis displacement laser interferometer calibration device, including a standard laser interferometer laser 1 and two receivers 6, 7 arranged at positions that can receive the interference signal of the standard laser interferometer, the wire connects the two receivers The devices 6 and 7 are respectively connected to the signal processing system 8 of the standard laser interferometer; the output optical path of the standard laser interferometer laser 1 is equipped with an intermediate through hole 12, which allows the calibrated laser interferometer measurement beam 11 to pass through the biaxial hollow standard Laser interference mirror group 2; one side of the two-axis hollow standard laser interference mirror group 2 is equipped with a guide rail 18, and the moving table 17 is fitted on the guide rail 18, and the plane mirror 5 with a middle hole is installed on the moving table 17 through a micro-motion device 16. A calibrated laser interferometer reflector 13 is installed in the middle hole of the plane mirror 5, and the calibrated laser interferometer reflector 13 and the plane mirror 5 with the middle hole form a target reflector whose incident plane is coplanar and whose relative position is fixed; two beam position detectors 19 and 20 are arranged behind the transmission area of the plane mirror 5 with a middle hole, and are respectively located on the transmission light paths of the two parallel standard measurement beams 3 and 4; the calibrated laser interferometer is arranged on the other side of the biaxial hollow standard laser interferometer group 2 Interference mirror group 10 and calibrated laser interferometer laser 9, said calibrated laser interferometer interference mirror group 10 is located on the output optical path of calibrated laser interferometer laser 9; calibrated laser interferometer receiver 14 is configured to receive and calibrate At the position of the interference signal of the laser interferometer, the wire connects the receiver 14 of the laser interferometer to be calibrated with the signal processing system 15 of the laser interferometer to be calibrated.

The two parallel standard measuring beams 3, 4 and the calibrated laser interferometer measuring beam 11 are both perpendicular to the incident surface of the target mirror.

The middle through hole 12 of the biaxial hollow standard laser interference mirror group 2 includes any shape, and the number is one or more than one.

Each of the parallel standard measuring beams 3 and 4 and the calibrated laser interferometer measuring beam 11 are reflected once or more by the plane mirror 5 with a middle hole and the calibrated laser interferometer mirror 13 respectively.

The laser interferometer reflector 13 to be calibrated includes a plane mirror, a corner cube prism, and a rectangular prism.

A method for calibrating a return compensation type dual optical axis displacement laser interferometer, the method steps are as follows:

(1) The output light of the standard laser interferometer laser 1 passes through the biaxial hollow laser interferometer group 2 to form two parallel standard measurement beams 3, 4, and the two standard measurement beams 3, 4 are incident on the plane mirror 5 with a middle hole Above, part of the light with the displacement information of the plane mirror 5 in each standard measurement beam is reflected back to the biaxial hollow laser interferometer group 2, according to the two standard measurement beams 3 obtained from the biaxial hollow laser interferometer group 2 , 4 corresponding to the two interference signals respectively, the two displacement values of the plane mirror 5 with the middle hole moving along the direction of the standard measuring beam 3, 4 can be obtained, and the remaining part of each standard measuring beam is transmitted through the plane mirror 5 with the middle hole onto the two beam position detectors 19, 20;

(2) The output light of the calibrated laser interferometer laser 9 passes through the calibrated laser interferometer interferometer group 10 to form the calibrated laser interferometer measurement beam 11, and the calibrated laser interferometer measurement beam 11 passes through the biaxial hollow laser interferometer group The middle through hole 12 of 10 is parallel and coplanar with the two standard measuring beams 3 and 4. The calibrated laser interferometer measuring beam 11 is incident on the calibrated laser interferometer reflector 13 and is reflected back to the calibrated laser interferometer. After the interference mirror group 10, according to the interference signal obtained from the calibrated laser interferometer interferometer group 10, the displacement value of the calibrated laser interferometer mirror 13 moving along the direction of the standard measuring beam 3, 4 can be obtained;

(3) During the reciprocating motion of the moving table 17 along the directions of the standard measuring beams 3 and 4, there is a derivative displacement in any two-dimensional direction perpendicular to the plane of the standard measuring beams 3 and 4, and the target reflection mounted on the moving table 17 The mirror has a free displacement relative to the telescopic table 17 in any two-dimensional direction perpendicular to the standard measuring beam 3, 4 plane, and the two beam position detectors 19, 20 respectively measure the standard measuring beam 3, 4 relative to the target reflector at the vertical Deriving the displacement in any two-dimensional direction within the plane of the standard measuring beam 3, 4, the micro-motion device 16 measures the average value of the deriving displacement according to the two beam position detectors 19, 20, and performs real-time return compensation for the deriving displacement of the target mirror, Ensure that the incident position of the measuring beam on the reflective surface of the target mirror does not change;

(4) During the reciprocating movement of the moving table 17 along the directions of the standard measuring beam 3 and 4, the two measured displacement values of the standard laser interferometer and the measured displacement values of the calibrated laser interferometer are sampled synchronously at a uniform or non-uniform sampling rate, and the The two measured displacements of the standard laser interferometer obtained by each sampling are averaged and then compared with the measured displacement values of the calibrated laser interferometer obtained by simultaneous sampling to obtain several sampling measurement error values.

The spot positions 21 and 22 of the standard measuring beams are respectively the positions where the two parallel standard measuring beams 3 and 4 are incident on the plane mirror 5 with a middle hole, and the spot position 23 of the beam of the calibrated laser interferometer is the incident position of the measuring beam 11 of the calibrated laser interferometer. The position of the calibrated laser interferometer reflector 13 can be seen from the position distribution of the calibrated laser interferometer beam spot position 23 at the middle position of the standard measurement beam spot positions 21, 22, that is, two parallel standard measurement beams 3, 4 Clamp the measuring beam 11 of the laser interferometer to be calibrated in the middle position.

Claims (6)

1. A method for calibrating a return compensation type dual optical axis displacement laser interferometer, characterized in that the steps of the method are as follows: (1) The output light of the standard laser interferometer laser passes through the biaxial hollow laser interferometer group to form two parallel standard measurement beams. The two standard measurement beams are incident on the plane mirror with a middle hole. Each standard measurement beam has a After part of the light with plane mirror displacement information is reflected back to the biaxial hollow laser interferometer group, according to the two interference signals obtained from the biaxial hollow laser interferometer group and corresponding to the two standard measuring beams respectively, it can be obtained that there is a center hole The two displacement values of the plane mirror moving along the direction of the standard measuring beam, and the remaining part of each standard measuring beam is transmitted to the two beam position detectors through the plane mirror with a middle hole; (2) The output light of the calibrated laser interferometer laser passes through the calibrated laser interferometer interferometer group to form the calibrated laser interferometer measurement beam, and the calibrated laser interferometer measurement beam passes through the middle through hole of the biaxial hollow laser interferometer group , parallel and coplanar with the two standard measuring beams, the measuring beam of the calibrated laser interferometer is incident on the mirror of the calibrated laser interferometer, after being reflected back to the interferometer group of the calibrated laser interferometer, according to the calibrated laser interferometer The interference signal obtained in the laser interferometer group can be used to obtain the displacement value of the calibrated laser interferometer mirror moving along the direction of the standard measuring beam; (3) During the reciprocating movement of the moving table along the direction of the standard measuring beam, there is a derivative displacement in any two-dimensional direction perpendicular to the plane of the standard measuring beam. The target mirror mounted on the moving table is perpendicular to the plane of the standard measuring beam There is a free displacement relative to the telescopic stage in any two-dimensional direction, and the two beam position detectors respectively measure the derivative displacement of the standard measurement beam relative to the target mirror in any two-dimensional direction perpendicular to the standard measurement beam plane. A beam position detector measures the average value of the derived displacement, and performs real-time return compensation for the derived displacement of the target mirror to ensure that the incident position of the measuring beam on the reflective surface of the target mirror does not change; (4) During the reciprocating movement of the moving table along the direction of the standard measuring beam, the two measured displacement values of the standard laser interferometer and the measured displacement values of the calibrated laser interferometer are sampled synchronously at a uniform or non-uniform sampling rate, and each sampling is obtained After taking the average value of the two measured displacements of the standard laser interferometer and taking the difference with the measured displacement value of the calibrated laser interferometer obtained by simultaneous sampling, several sampling measurement error values are obtained. 2. A return-compensated dual-optical axis displacement laser interferometer calibration device, including a standard laser interferometer laser (1) and two receivers (6, 7) arranged at positions that can receive interference signals from the standard laser interferometer , the two receivers (6, 7) are respectively connected to the standard laser interferometer signal processing system (8) by wires; it is characterized in that an intermediate through hole (12) is arranged on the output optical path of the standard laser interferometer laser (1) A biaxial hollow standard laser interferometer group (2) that allows the calibrated laser interferometer measurement beam (11) to pass through; one side of the biaxial hollow standard laser interferometer group (2) is equipped with a guide rail (18), and a moving table (17 ) is assembled on the guide rail (18), and the plane mirror (5) with the middle hole is installed on the moving platform (17) through the micro-movement device (16), and the calibrated laser interferometer reflector is installed in the middle hole of the plane mirror (5) (13), calibrated laser interferometer reflector (13) and the plane mirror (5) that has middle hole form the target reflector that incident surface is coplanar and relative position is fixed; Two beam position detectors (19,20) are arranged in The plane mirror (5) with a middle hole is behind the transmission area, and is respectively located on the two parallel standard measurement beams (3, 4) transmission light paths; on the other side of the biaxial hollow standard laser interferometer group (2), the calibrated laser interference An instrument interferometer group (10) and a calibrated laser interferometer laser (9), the calibrated laser interferometer interferometer group (10) is located on the output optical path of the calibrated laser interferometer laser (9); the calibrated laser interferometer The receiver (14) is arranged at a position capable of receiving the interference signal of the calibrated laser interferometer, and the wire connects the receiver (14) of the calibrated laser interferometer with the signal processing system (15) of the calibrated laser interferometer. 3. The return compensation type dual optical axis displacement laser interferometer calibration device according to claim 2, characterized in that the two parallel standard measurement beams (3, 4) and the calibrated laser interferometer measurement beam (11 ) are perpendicular to the incident surface of the target mirror. 4. The return compensation type dual optical axis displacement laser interferometer calibration device according to claim 2, characterized in that the middle through hole (12) of the biaxial hollow standard laser interferometer group (2) includes any shape , the number is one or more. 5. The return compensation type dual-optical axis displacement laser interferometer calibration device according to claim 2, characterized in that each of the parallel standard measurement beams (3, 4) and the calibrated laser interferometer measurement beam (11 ) are respectively reflected one or more times by the flat mirror (5) with the middle hole and the mirror (13) of the calibrated laser interferometer. 6. The return-compensated dual optical axis displacement laser interferometer calibration device according to claim 2, characterized in that the laser interferometer reflector (13) to be calibrated includes a plane mirror, a corner cube prism, and a right-angle prism.

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