A laser interferometer calibration device and calibration method

Abstract

The application provides a laser interferometer calibration device and a calibration method, and belongs to the field of laser calibration. Two fixed seats are arranged at two ends of a platform. A first interferometer and a second interferometer are arranged between the two fixed seats. A double-angle prism is arranged on the platform and reciprocally moves between the first interferometer and the second interferometer. The double-angle prism is symmetrically provided with two identical angle prisms on two end faces facing the first interferometer and the second interferometer. The two laser interferometers are simultaneously calibrated by comparing the distances between the first interferometer, the second interferometer and the double-angle prism. The two interferometers are independently arranged and correspond to the laser interferometers, so that the two laser interferometers do not need to share the same optical path when being calibrated, and the two laser interferometers can be simultaneously and independently calibrated. Meanwhile, the reciprocating movement of the double-angle prism makes the measurement changes of the two interferometers present opposite trends, and the common error source can be effectively eliminated through differential calculation.

Description

Technical Field

[0001] This invention relates to the field of laser calibration technology, and in particular to a laser interferometer calibration device and calibration method. Background Technology

[0002] Laser interferometers are universal length measurement instruments that use the laser wavelength as a known length and employ the Michelson interferometer system to measure displacement. As a core technology for micro- and nano-scale linear displacement detection, laser interferometry has been deeply integrated into high-end fields such as precision machining, semiconductor manufacturing equipment, and defense technology. Its measurement accuracy is directly related to equipment performance, making instrument calibration a crucial step in quality assurance. Precise optical alignment of the laser transmitter and receiver is required before measurement. This process relies on the operator's experience and repeated adjustments, and is particularly prone to introducing systematic error sources such as beam deflection and interference fringe misalignment under complex operating conditions.

[0003] Currently, laser interferometers of different specifications cannot be calibrated using the same set of measurement standards, resulting in very low calibration efficiency. Moreover, there are small errors between laser interferometers of the same specifications, which can affect the accuracy of laser measurements. Therefore, how to effectively eliminate the impact of errors is an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the present invention proposes a laser interferometer calibration device and calibration method to solve the problem of how to improve calibration efficiency and eliminate equipment errors as much as possible.

[0005] The technical solution of this invention is implemented as follows: This invention provides a laser interferometer calibration device, including a platform; two fixed seats, respectively disposed at both ends of the platform; a first interferometer and a second interferometer, respectively disposed at both ends of the platform and both located between the two fixed seats; a double-sided corner prism, disposed on the platform and reciprocating between the first interferometer and the second interferometer; wherein, the fixed seats are used to load the laser interferometer to be calibrated; identical corner prisms are symmetrically disposed on the two end faces of the double-sided corner prism facing the first interferometer and the second interferometer, and the two laser interferometers are calibrated simultaneously by comparing the distances between the first interferometer and the second interferometer and the double-sided corner prism respectively.

[0006] In some embodiments, the first interference mirror and the second interference mirror are coaxially arranged with the bifaceted prism, and the two first interference mirrors and the second interference mirror are coaxially aligned with the bifaceted prism.

[0007] In some embodiments, a slide rail is further included, which is disposed on the platform and located between the first interference mirror and the second interference mirror; wherein a bi-faceted prism is disposed on the slide rail and the bi-faceted prism reciprocates along the slide rail.

[0008] In some embodiments, a scale is provided on the platform, with the midpoint of the scale aligned with the exact center of the first interferometer and the second interferometer.

[0009] In some embodiments, the two mounting bases may each be equipped with laser interferometers of different specifications.

[0010] In some embodiments, the mounting base and the laser interferometer are detachably connected via a snap-fit ​​or locking structure.

[0011] On the other hand, the present invention also provides a laser interferometer calibration method, using the aforementioned laser interferometer calibration device, comprising the following steps: Step 1, moving the dihedral prism to its initial position; Step 2, moving the dihedral prism toward the direction of the first or second interferometer, and recording the distance between the dihedral prism and the first and second interferometers, as well as recording the readings of the two laser interferometers at this time; Step 3, moving the dihedral prism again toward the direction of the first or second interferometer, and recording the distance between the dihedral prism and the first and second interferometers, as well as recording the readings of the two laser interferometers at this time; Step 4, comparing the two sets of data from the two laser interferometers and the corresponding distances between the dihedral prism and the interferometers, respectively, to complete the calibration of the two laser interferometers.

[0012] In some embodiments, the initial position of the bifaceted prism is the exact center between the first and second interferometers.

[0013] In some embodiments, when two laser interferometers are of the same specification and both need to be calibrated, in step three, the bifacial prism is first moved back to its initial position, and then the bifacial prism is moved the same distance in the opposite direction to step two; in step four, the two distances between the bifacial prism and the first interferometer are recorded as L1 and L3, and the two distances between the bifacial prism and the second interferometer are recorded as L2 and L4. The error between the two laser interferometers is calculated as α = ||L1-L3|-|L2-L4||. After calibrating one laser interferometer, the other laser interferometer is calibrated in combination with the error.

[0014] In some embodiments, when one laser interferometer specification has been calibrated and another laser interferometer specification is to be calibrated, in step four, the two distances between the bifacial prism and the first interferometer are recorded as L1 and L3, and the two distances between the bifacial prism and the second interferometer are recorded as L2 and L4. The error between the two laser interferometers is calculated as α = ||L1-L3|-|L2-L4||. The calibrated laser interferometer is then combined with the error to calibrate the laser interferometer to be calibrated.

[0015] The laser interferometer calibration device and method of the present invention have the following advantages over the prior art: (1) The present invention sets up two interferometers independently and corresponds to laser interferometers respectively, so that the two laser interferometers do not need to share the same optical path when calibrating. The two laser interferometers can be calibrated simultaneously and independently, which greatly improves the calibration efficiency. At the same time, the reciprocating movement of the double-sided corner prism makes the measurement changes of the two interferometers show opposite trends. The common error source can be effectively eliminated through differential calculation, which improves the stability of calibration and comparison results.

[0016] (2) By symmetrically setting the first and second interferometers at both ends of the platform and arranging them coaxially with the double-sided corner prism, the measurement optical axes of the two laser interferometers are highly coincident with the motion axis of the double-sided corner prism. From the structural principle, this invention effectively suppresses Abbe error and improves the accuracy and consistency of calibration results. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a side view of the laser interferometer calibration device of the present invention; Figure 2 This is a side view of another state of the laser interferometer calibration device of the present invention.

[0019] In the diagram: 1. Platform; 2. Fixture; 3. First interferometer; 4. Second interferometer; 5. Double-sided corner prism; 6. Laser interferometer; 7. Slide rail. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0025] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Additionally, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0026] like Figure 1 As shown, combined with Figure 2 The present invention provides a laser interferometer calibration device, comprising a platform 1, a fixed base 2, a first interferometer 3, a second interferometer 4, and a double-sided corner prism 5.

[0027] Platform 1 serves as the overall installation reference. It can be made of rigid plastic, metal, or ceramic to ensure the relative position of each component is stable during the calibration process and to avoid additional errors caused by deformation or vibration of platform 1.

[0028] Two mounting bases 2 are respectively set at both ends of the platform 1; both mounting bases 2 are used to mount the laser interferometers 6 to be calibrated. The two laser interferometers 6 are under the same geometric reference and environmental conditions, providing consistent external conditions for subsequent comparison and calibration.

[0029] The first interferometer 3 and the second interferometer 4 are respectively set at both ends of the platform 1 and are both located between the two fixed seats 2.

[0030] A double-sided corner prism 5 is mounted on platform 1 and reciprocates between the first interferometer 3 and the second interferometer 4. Identical corner prisms are symmetrically arranged on the two end faces of the double-sided corner prism 5 facing the first and second interferometers 3 and 4, respectively. The two laser interferometers 6 are simultaneously calibrated by comparing the distances between the first and second interferometers 3 and 4 and the double-sided corner prism 5. This arrangement allows each laser interferometer 6 to form an independent but complete interferometric measurement system with its corresponding interferometer through its own interference optical path, without sharing optical paths or optical components with another laser interferometer 6, thus avoiding optical path coupling and mutual interference.

[0031] During the calibration process, since identical corner prism structures are symmetrically arranged on the two opposite end faces of the bifacial prism 5, its geometric changes relative to the first interferometer 3 and the second interferometer 4 remain symmetrical and consistent during movement. When the bifacial prism 5 moves along the platform 1, the distance between it and the two interferometers 3 changes simultaneously. By recording the measurement readings of the two laser interferometers 6 respectively, and combining the changes in the geometric distance between the bifacial prism 5 and the interferometers, a differential measurement relationship based on the same moving target can be constructed. This allows the two laser interferometers 6 to obtain measurement data under the same motion event, which not only significantly improves calibration efficiency and enables simultaneous calibration of the two laser interferometers 6, but also, based on the distance difference on both sides of the bifacial prism 5 and the difference between the two distance differences during the two movements, can quickly and significantly reflect the error between the two laser interferometers 6.

[0032] exist Figure 1 In one embodiment shown, the first interferometer 3 and the second interferometer 4 are coaxially arranged with the bifacial prism 5. The two first interferometers 3 and the second interferometer 4 are coaxially aligned with the bifacial prism 5, ensuring that the measurement reference axis is consistent with the motion reference axis of the bifacial prism 5, effectively avoiding the Abbe error problem. Even if the bifacial prism 5 experiences slight attitude changes during movement, the impact of these changes on the interferometric measurement results on both sides is highly consistent, thus being canceled out in subsequent comparison calculations and improving calibration accuracy.

[0033] exist Figure 1In one embodiment shown, a slide rail 7 is also included. The slide rail 7 is disposed on the platform 1 and located between the first interferometer 3 and the second interferometer 4. A bifaceted prism 5 is disposed on the slide rail 7, and a slot is provided at the bottom of the bifaceted prism 5 to hold the slide rail 7 in place. The bifaceted prism 5 reciprocates along the slide rail 7. The slide rail 7 ensures that the bifaceted prism 5 maintains stable linear movement during measurement.

[0034] exist Figure 1 In one embodiment shown, a scale is provided on platform 1, with the midpoint of the scale aligned with the exact center of the first interferometer 3 and the second interferometer 4. The scale provides a visual reference for the movement distance of the bifacial prism 5 and facilitates the preset initial position of the bifacial prism 5. Simultaneously, when the bifacial prism 5 needs to be moved symmetrically or in the opposite direction, it can serve as a displacement reference for manual or automatic control, thereby improving the consistency and operability of the calibration process.

[0035] exist Figure 1 In one embodiment shown, the two mounting bases 2 can respectively mount laser interferometers 6 of different specifications, making the device applicable to laser interferometers 6 of different models, different ranges or different manufacturers, thus expanding the practicality and versatility of the device.

[0036] exist Figure 1 In one embodiment shown, the mounting base 2 and the laser interferometer 6 are detachably connected by a snap-fit ​​or locking structure, which allows for the quick installation or replacement of laser interferometers 6 of different specifications without changing the reference of the platform 1.

[0037] like Figure 1 As shown, combined with Figure 2 The present invention provides a laser interferometer calibration method, employing the laser interferometer calibration apparatus of any of the above embodiments, comprising the following steps: Step 1: Move the double-sided prism 5 to its initial position.

[0038] Step 2: Move the bifacial prism 5 toward either the first interferometer 3 or the second interferometer 4, and record the distance between the bifacial prism 5 and the first interferometer 3 and the second interferometer 4, as well as the readings of the two laser interferometers 6 at this time.

[0039] Step 3: Move the double-sided corner prism 5 again toward the first interferometer 3 or the second interferometer 4, and record the distance between the double-sided corner prism 5 and the first interferometer 3 and the second interferometer 4, as well as the readings of the two laser interferometers 6 at this time.

[0040] Step four: Compare the two sets of data from the two laser interferometers 6 and the corresponding distance between the double-sided corner prism 5 and the interferometer mirror to complete the calibration of the two laser interferometers 6.

[0041] This embodiment establishes a correspondence between the interferometer readings and the actual displacement by moving the double-sided corner prism 5 to multiple positions and simultaneously collecting geometric spacing data and interferometer reading data. Furthermore, by comparing and analyzing multiple measurement data, it avoids random errors caused by single-point measurements, making the calibration results more stable and reliable.

[0042] exist Figure 1 In one embodiment shown, the initial position of the bifacial prism 5 is exactly between the first interference mirror 3 and the second interference mirror 4, giving the device a clear symmetrical reference.

[0043] exist Figure 2 In one embodiment shown, when two laser interferometers 6 are of the same specification and both need to be calibrated, in step three, the dihedral prism 5 is first moved back to its initial position, and then the dihedral prism 5 is moved the same distance in the opposite direction to step two. In step four, the two distances between the dihedral prism 5 and the first interferometer 3 are recorded as L1 and L3, and the two distances between the dihedral prism 5 and the second interferometer 4 are recorded as L2 and L4. The error between the two laser interferometers 6 is calculated as α = ||L1-L3|-|L2-L4||. After calibrating one laser interferometer 6, the other laser interferometer 6 is calibrated based on the error. This embodiment can directly obtain the measurement difference between the two laser interferometers 6 by calculating the symmetrical displacement of the dihedral prism 5 and the error parameter α. Moreover, this method can complete the mutual calibration between the two instruments without the need for an external high-precision reference.

[0044] exist Figure 2 In one embodiment shown, when one laser interferometer 6 is calibrated and the other is to be calibrated, in step four, the distances between the bifacial prism 5 and the first interferometer 3 are recorded as L1 and L3, and the distances between the bifacial prism 5 and the second interferometer 4 are recorded as L2 and L4. The error between the two laser interferometers 6 is calculated as α = ||L1-L3|-|L2-L4||. The calibrated laser interferometer 6 is then used in conjunction with the error to calibrate the laser interferometer 6 to be calibrated. In this embodiment, the calibrated laser interferometer 6 is used as a reference instrument, and its accuracy is transferred to the laser interferometer 6 to be calibrated through differential measurement, thus achieving traceability of the measurement results.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A laser interferometer calibration device, characterized in that, include: Platform (1); Two fixed seats (2) are respectively set at both ends of the platform (1); The first interference mirror (3) and the second interference mirror (4) are respectively set at both ends of the platform (1) and are both located between the two fixed seats (2); A bifaceted prism (5) is mounted on the platform (1) and moves back and forth between the first interference mirror (3) and the second interference mirror (4); The fixed base (2) is used to mount the laser interferometer (6) to be calibrated. The double-sided corner prism (5) has identical corner prisms symmetrically arranged on the two end faces of the first interferometer (3) and the second interferometer (4). The two laser interferometers (6) are simultaneously calibrated by comparing the distances between the first interferometer (3) and the second interferometer (4) and the double-sided corner prism (5).

2. The laser interferometer calibration device according to claim 1, characterized in that: The first interference mirror (3) and the second interference mirror (4) are coaxially arranged with the bi-faceted prism (5), and the two first interference mirrors (3) and the second interference mirror (4) are coaxially aligned with the bi-faceted prism (5).

3. The laser interferometer calibration device according to claim 1, characterized in that, Also includes: A slide rail (7) is provided on the platform (1) and located between the first interference mirror (3) and the second interference mirror (4); The slide rail (7) is provided with a double-sided corner prism (5), which moves back and forth along the slide rail (7).

4. The laser interferometer calibration device according to claim 3, characterized in that: A scale is provided on the platform (1), and the midpoint of the scale is aligned with the center of the first interference mirror (3) and the second interference mirror (4).

5. The laser interferometer calibration device according to claim 1, characterized in that: The two mounting bases (2) can each be equipped with laser interferometers (6) of different specifications.

6. The laser interferometer calibration device according to claim 5, characterized in that: The mounting base (2) and the laser interferometer (6) are detachably connected via a snap-fit ​​structure or a locking structure.

7. A laser interferometer calibration method, characterized in that: The laser interferometer calibration apparatus according to any one of claims 1 to 6 includes the following steps: Step 1: Move the bifacial prism (5) to its initial position; Step 2: Move the bifacial prism (5) toward the first interferometer (3) or the second interferometer (4), and record the distance between the bifacial prism (5) and the first interferometer (3) and the second interferometer (4), as well as the readings of the two laser interferometers (6) at this time; Step 3: Move the bifacial prism (5) again toward the first interferometer (3) or the second interferometer (4), and record the distance between the bifacial prism (5) and the first interferometer (3) and the second interferometer (4), and record the readings of the two laser interferometers (6) at this time; Step four: Compare the two sets of data from the two laser interferometers (6) and the corresponding distance between the double-sided corner prism (5) and the interferometer mirror to complete the calibration of the two laser interferometers (6).

8. The laser interferometer calibration method according to claim 7, characterized in that: The initial position of the double-sided prism (5) is the exact center between the first interference mirror (3) and the second interference mirror (4).

9. A laser interferometer calibration method according to claim 7, characterized in that: When the two laser interferometers (6) are of the same specification and both need to be calibrated, In step three, the bifacial prism (5) is first moved back to its initial position, and then the bifacial prism (5) is moved the same distance in the opposite direction to step two. In step four, the distances between the double-sided corner prism (5) and the first interferometer (3) are recorded as L1 and L3, and the distances between the double-sided corner prism (5) and the second interferometer (4) are recorded as L2 and L4. The error between the two laser interferometers (6) is calculated. α = ||L1-L3|-|L2-L4||, After calibrating one of the laser interferometers (6), the other laser interferometer (6) is calibrated in conjunction with the error.

10. A laser interferometer calibration method according to claim 7, characterized in that: When one of the laser interferometers (6) is calibrated and another laser interferometer (6) is to be calibrated, In step four, the distances between the double-sided corner prism (5) and the first interferometer (3) are recorded as L1 and L3, and the distances between the double-sided corner prism (5) and the second interferometer (4) are recorded as L2 and L4. The error between the two laser interferometers (6) is calculated. α = ||L1-L3|-|L2-L4||, The calibrated laser interferometer (6) is used to calibrate the laser interferometer (6) to be calibrated, taking into account the error.

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