Method for manufacturing hollow pentaprism and method for measuring internal angle error of hollow pentaprism

Abstract

The invention belongs to but not limited to the technical field of hollow pentaprisms, and discloses a hollow pentaprism manufacturing method and an internal angle error measurement method thereof, and the method comprises the steps: determining a 135-degree alignment relation between an autocollimator III and an autocollimator I by using an autocollimator I, an autocollimator II, a double-sided mirror I and a double-sided mirror II; a first autocollimator, a second autocollimator, a first single-sided mirror and a second single-sided mirror are used for manufacturing a hollow pentaprism and measuring the internal angle of the hollow pentaprism. According to the invention, a plurality of autocollimators and two single-sided mirrors can be used for quickly and accurately manufacturing a hollow pentaprism or performing internal angle error measurement on the manufactured hollow pentaprism.

Description

Technical Field

[0001] The present invention belongs to, but is not limited to, the technical field of hollow pentaprisms, and particularly relates to a method for manufacturing a hollow pentaprism and a method for measuring the internal angular error thereof. Background Art

[0002] A pentaprism is one of the beam angle fixers (90-degree deflectors). It has two uses: one is that regardless of the incident angle on the first surface, the outgoing light deflects the incident light by a certain angle (90 degrees); the other is that, different from a right-angle prism, the formed image has neither rotation nor specular reflection. Pentaprisms are commonly used in the viewfinders of cameras, image observation systems, or measuring instruments. A pentaprism cannot perform total internal reflection according to the critical angle principle. Therefore, generally, two reflecting surfaces of this prism are coated with aluminum film and painted with black paint, and the incident surface and the outgoing surface are coated with a single-layer MgF2 antireflection film.

[0003] The use of a hollow pentaprism can meet the requirements of occasions with a relatively large clear aperture, realizing that when the pentaprism deflects, the position change of the reflected light is very small, and the incident light and the outgoing light are parallel in the 90-degree vertical plane.

[0004] There are two requirements for the positional accuracy of the two reflecting surfaces of a hollow pentaprism: the two reflecting surfaces form an accurate 45-degree angle; the two reflecting surfaces are perpendicular to the same plane, and this requirement is often called the tower difference. There are two types of existing methods for manufacturing hollow pentaprisms. One type can only obtain the 90-degree rotation angle error of the hollow pentaprism and the non-parallelism of the outgoing light and the incident light in the vertical plane through the reading of an autocollimator, and cannot obtain the 45-degree angle error between the two reflecting surfaces of the hollow pentaprism and the "tower difference". Therefore, it is difficult to adjust the angle between the two reflecting mirrors according to the 90-degree error and the tower difference, and it is impossible to further reduce the 45-degree angle error and the tower difference to meet the requirements of high-precision measurement (error less than 100 nanoradians) using a hollow pentaprism. The other type is manufactured through a double-sided mirror and an autocollimator. This method can directly measure the 45-degree error and the tower difference of the hollow pentaprism, but this scheme requires that the working surface of the manufactured hollow pentaprism must be a double-sided mirror, has high requirements for the parallelism of the two mirror surfaces of the double-sided mirror, high cost, and a long manufacturing process and complex manufacturing technology. In addition, this scheme can only assemble the hollow pentaprism, and for a manufactured hollow pentaprism, the internal angular error cannot be directly measured, and other means are required for measuring the internal angular error of the hollow pentaprism.

[0005] In view of the above analysis, the technical problems that need to be urgently solved in the existing technology are:

[0006] The existing technology for manufacturing hollow pentaprisms has a long cycle, complex process, high cost, and cannot directly measure the internal angular error of hollow pentaprisms. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for manufacturing a hollow pentaprism and a method for measuring its internal angular error, aiming to solve the problems of the prior art in that the manufacturing period of a hollow pentaprism is long, the process is complex, the cost is high, and the internal angular error of the hollow pentaprism cannot be directly measured, thereby improving the convenience of manufacturing a high-precision hollow pentaprism.

[0008] The present invention is achieved by a method for manufacturing a hollow pentaprism, comprising the following steps:

[0009] S1, adjust the two autocollimators to a mutually perpendicular position and record the three-axis attitude angle μ of the two autocollimators. x , μ y , μ z ;

[0010] S2, the parallelism is θ AX|| and θ AY|| Place the double-sided mirror 1 at the intersection of the optical axes of the two autocollimators, and adjust the double-sided mirror 1 so that the two autocollimators can observe the other party's light spot at the center of the field of view. At this time, the double-sided mirror 1 and the two autocollimators form an angle of approximately 45 degrees;

[0011] S3, the parallelism is θ BX|| and θ BY|| Place the two-sided mirror at a perpendicular position to the optical axis of the second autocollimator and form an angle of approximately 45 degrees with the two-sided mirror. Adjust the two double-sided mirrors so that the yaw and pitch angle readings of the two autocollimators are close to 0.

[0012] S4, adjust the double-sided mirror 2 to make the deflection angle reading of the autocollimator 1 change continuously, and record the reading x after each change. A1 ,y A1 , according to y A1 / x A1 The fitting results show that the angle of the double-sided mirror rotates counterclockwise around its bottom axis.

[0013] S5, adjust the double-sided mirror 2 so that the yaw angle and pitch angle readings of the autocollimator 2 are close to 0, and record the reading of the autocollimator 1 at this time x B1 ,y B1 ;

[0014] S6, adjust the double-sided mirror to make the deflection angle reading of the autocollimator close to 0, and record the reading x at this time A2 ,y A2 ;

[0015] S7, according to μ x , μ y , μ z ,θ X|| ,θ Y|| 、x A2 ,y A2, ωa, x B1 , y B1 Obtain the attitude angle errors δa and ωa of the first double-sided mirror;

[0016] S8. After calibrating the attitude of the first double-sided mirror, place the third autocollimator in the direction perpendicular to the normal vector of the other side of the first double-sided mirror, and roughly adjust the third autocollimator so that its reading is close to 0;

[0017] S9. Adjust the first double-sided mirror to make the readings of the third autocollimator in the pitch direction change continuously, and record the readings x c1 , y c1 . According to y c1 / x c1 Fit to obtain the angle δcz by which the third autocollimator rotates counterclockwise around its own optical axis. After adjusting δcz to be close to 0, adjust the first double-sided mirror so that its attitude angles δb and ωb are close to 0;

[0018] S10. Through the reading x of the third autocollimator c2 , the parallelism θ of the first double-sided mirror AY|| , calculate the attitude angle δcy = -x of the third autocollimator around its own yaw direction through the attitude angle δa of the first double-sided mirror c2 +δa;

[0019] S11. Through the reading y of the third autocollimator c2 , the parallelism θ of the first double-sided mirror AX|| , calculate the attitude angle δcx = -y of the third autocollimator around its own yaw direction through the attitude angle ωa of the first double-sided mirror c2 -ωa, and adjust the third autocollimator so that its attitude angles δcx and δcy are close to 0;

[0020] S12. Remove the first double-sided mirror and the second double-sided mirror from the optical path, install the first plane mirror and the second plane mirror on the same flat plate perpendicular to the first autocollimator and the third autocollimator respectively, and adjust the two plane mirrors so that the readings of the two autocollimators are close to 0 to form a hollow pentaprism.

[0021] Furthermore, in S7, according to μ x , μ y , μ z , θ X|| , θ Y|| , x A2 , y A2 , ωa, x B1 , y B1 Obtain the attitude angle errors δa and ωa of the first double-sided mirror, including:

[0022] S71. According to the readings x of the second autocollimator B1 , y B1 , the three-axis attitude angles μ of the two autocollimators x , μ y , μz Parallelism θ of the two-sided mirror two BY|| , and find the attitude angle δ of the two-sided mirror two rotating counterclockwise around the Y-axis of the autocollimator one b = x B1 + μ y - θ BY|| ;

[0023] S72 Based on the reading x of the autocollimator one B1 , y B1 The attitude angles μ of the three axes of the two autocollimators z , the parallelism θ of the two-sided mirror BX|| , and find the attitude angle ω of the two-sided mirror rotating counterclockwise around the Z-axis of the autocollimator one b = -y B1 + μ z - θ BX|| ;

[0024] S73 Based on the readings x of the autocollimator one and the autocollimator two A2 , y A2 , x B1 , y B1 , the angle ωa of the two-sided mirror one rotating around the bottom axis, the attitude angles δb and ωb of the two-sided mirror two, find the attitude angle of the two-sided mirror one

[0025] Furthermore, when manufacturing the hollow pentaprism, adjust the two mirrors of the hollow pentaprism to adjust the 45° included angle error δβ and the tower difference ωβ of the hollow pentaprism to be close to 0 to complete the manufacturing.

[0026] Another object of the present invention is to provide a hollow pentaprism manufactured by a method for manufacturing a hollow pentaprism.

[0027] Another object of the present invention is to provide a method for measuring the internal angle error of a hollow pentaprism, including the following steps:

[0028] (1) Adjust the overall rotation of the hollow pentaprism around the pitch direction of the autocollimator one to make the reading of the autocollimator one change continuously, and record the reading x of the autocollimator one after each change a3 , y a3 . According to x a3 / y a3 Fit to obtain the attitude angle σz of the hollow pentaprism around the pitch direction of the autocollimator one, and adjust σz to be close to 0;

[0029] (2) Use the reading x of the autocollimator one a4 , the reading x of the autocollimator three c3 , and the attitude angle δcy of the autocollimator three to obtain the 45° included angle error δβ of the hollow pentaprism = x a4 + x c3 + δcy;

[0030] (3) Use the reading y of autocollimator 1 a4 and the reading y of autocollimator 3 c3 and the attitude angle δcx of autocollimator 3 to obtain the prism difference of the hollow pentaprism

[0031] When measuring the internal angle error of the hollow pentaprism, δβ and ωβ are the measurement results of the 45° angle error and the prism difference inside the hollow pentaprism.

[0032] Combining the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by the present invention are as follows:

[0033] First, the present invention can quickly and accurately manufacture a hollow pentaprism by using three autocollimators and two single-sided mirrors, and complete the measurement of the "prism difference" and the 45-degree included angle error of the already manufactured hollow pentaprism. The present invention has high measurement accuracy and can simultaneously realize the manufacture and internal angle measurement of the hollow pentaprism.

[0034] The present invention has significant cost-effectiveness. As the core detection device used in the solution, the autocollimator is widely used in the fields of optical industry, precision measurement and instrument calibration, with sufficient market supply and controllable procurement cost. With high-precision single-sided mirrors with moderate prices, the design of this solution can be completed without purchasing additional special detection equipment. It solves the problems of long production cycle, complex process and too high cost of manufacturing hollow pentaprisms in the prior art.

[0035] Second, as the creative auxiliary evidence of the claims of the present invention, it is also reflected in the following important aspects:

[0036] 1. The present invention provides a new solution for the manufacture of hollow pentaprisms. By jointly placing the system with three collimators and two plane mirrors, it can directly monitor and adjust the 45° included angle error and the "prism difference" of the two mirror surfaces of the hollow pentaprism. Compared with the traditional solution, the present invention reduces the operation steps, can directly measure and control the internal included angle of the hollow pentaprism, further reduces the error generated by excessive equipment assembly, and improves the measurement accuracy.

[0037] 2. The hollow pentaprism manufactured by the present invention can further improve the optical performance. By reducing the various errors of the hollow pentaprism, the angle measurement accuracy can be greatly improved. In the field of precision measurement, the calibration and detection capabilities of optical instruments are improved by one order of magnitude; secondly, through its stable hollow structure design, the optical drift caused by temperature changes can be reduced, and the long-term stability of the system in complex environments can be significantly improved.

[0038] 3. Compared with traditional solid prisms, its hollow design not only reduces weight, but also significantly improves thermal stability. Combined with customizable optical coating solutions, it can perfectly adapt to various wavelength requirements from ultraviolet to infrared, making it an irreplaceable key component in modern precision optical systems.

[0039] Third, in the optical system, the hollow pentaprism is widely used in high-precision optical measurement because of its stable reflection path and no need for coaxial adjustment. However, its internal 45° angle error and pyramid error (prism verticality error) directly affect the final measurement accuracy. The existing technology mainly estimates the internal angular error indirectly through static reflection path analysis, but lacks a systematic dynamic attitude compensation mechanism, and cannot effectively remove the interference of the pentaprism attitude angle on the measurement result, resulting in insufficient error measurement accuracy, cumbersome debugging process, and affecting measurement efficiency and consistency. Therefore, there is an urgent need for an angular error measurement method that is high in accuracy, easy to operate, and can correct the influence of the pentaprism attitude in real time.

[0040] The present invention provides a method for measuring the internal angular error of a hollow pentaprism. By introducing multiple autocollimators for collaborative measurement, and combining attitude angle analysis with error model fitting, the angle error and pyramidal error of the pentaprism body are accurately separated. The method comprises: (1) continuously scanning the attitude angle of the pentaprism rotating around the pitch axis using a pair of autocollimators, obtaining the attitude angle σz and zeroing and calibrating; (2) calculating the angle error δβ based on the horizontal readings and attitude angles of autocollimators one and three; (3) solving the pyramidal error ωβ based on the vertical readings and attitude angles of the two, combined with attitude correction. The above method significantly improves the resolution and repeatability of the angle error.

[0041] This method constructs a mathematical model based on the geometric relationship of the reflection path between the autocollimator and the pentaprism. First, the attitude angle σz is obtained by fitting xa3 / ya3, and this parameter is used to compensate for the pyramidal error calculation error; secondly, the angle error δβ=xa4+xc3+δcy, which combines the angular displacement of autocollimators one and three in the horizontal plane and the attitude angle difference, reflects the deviation between the two reflection surfaces inside the pentaprism; finally, the pyramidal error ωβ=yc3-√2 / 2·ya4-σz, integrates the influence of the pentaprism tilt angle σz on the path return in the vertical direction, and forms an accurate error representation. The model effectively decouples the originally coupled angular error and attitude change factors, ensuring that the measurement results reflect the error of the hollow pentaprism itself.

[0042] Compared with the existing static error measurement methods, the present invention introduces an attitude angle calibration mechanism, effectively stripping the interference of the placement attitude of the pentaprism on the measurement accuracy; at the same time, through the collaborative measurement of multiple autocollimators, the accuracy and stability of error estimation are improved. The sub-item modeling of angle error and tower difference and attitude correction in the mathematical model greatly improves the resolution of the measurement results and is applicable to the error diagnosis of precision optical components. This method has a simple structure, high operation efficiency, controllable measurement accuracy, and is significantly superior to the traditional measurement methods that rely on manual leveling and single-view estimation, and has broad application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic diagram of Principle 1 of the manufacturing method provided by an embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of Principle 2 of the manufacturing method provided by an embodiment of the present invention;

[0045] Figure 3 is a schematic diagram of Principle 3 of the manufacturing method provided by an embodiment of the present invention;

[0046] Figure 4 is a schematic diagram of Principle 4 of the manufacturing method provided by an embodiment of the present invention;

[0047] Figure 5 is a schematic diagram of the autocollimator light spot provided by an embodiment of the present invention;

[0048] Figure 6 is a schematic diagram of the σz fitting result provided by an embodiment of the present invention;

[0049] Figure 7 is a flowchart of the manufacturing method of the hollow pentaprism provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0051] Refer to Figure 1 , in the embodiment of the present invention, the autocollimator 1, the autocollimator 2, the double-sided mirror 3 and the double-sided mirror 4 are used to determine the 135° alignment relationship between the autocollimator 5 and the autocollimator 1.

[0052] Refer to Figure 2 , in the embodiment of the present invention, the autocollimator 1, the autocollimator 2, the single-sided mirror 6 and the single-sided mirror 7 are used for the manufacturing of the hollow pentaprism and the measurement of the internal angles of the hollow pentaprism.

[0053] The specific implementation steps of the method in the embodiment of the present invention are as follows:

[0054] 1) Refer to Figure 3 , place autocollimator 1 and autocollimator 2 in a relatively perpendicular position, and the optical axes of the two autocollimators are approximately in the same horizontal plane. The first double-sided mirror is placed at the intersection of the optical axes of the two autocollimators. The second double-sided mirror is located at the light outlet of autocollimator 2, perpendicular to the optical axis of autocollimator 2 and forming an angle of approximately 45 degrees with the first double-sided mirror. The central positions of the first double-sided mirror and the second double-sided mirror are at the same horizontal height as the optical axes of the two autocollimators.

[0055] 2) Adjust autocollimator 1 and autocollimator 2 to a relatively perpendicular position, with the optical axes parallel to the ground, and record the attitude angles of the three axes of the two autocollimators;

[0056] 3) Refer to Figure 4 , place the first double-sided mirror at the intersection of the optical axes of the two autocollimators, and adjust the first double-sided mirror so that both autocollimators can observe the other's light spot at the center position of the field of view;

[0057] 4) Place the second double-sided mirror in a position perpendicular to the optical axis of autocollimator 2, and adjust the first double-sided mirror and the second double-sided mirror so that the yaw angle and pitch angle readings of the two autocollimators are close to 0;

[0058] 5) Adjust the second double-sided mirror so that the yaw angle reading of autocollimator 1 changes continuously, record the readings after each change, and process the data to obtain the angle by which the first double-sided mirror rotates counterclockwise around its bottom axis;

[0059] 6) Adjust the second double-sided mirror so that the yaw angle and pitch angle readings of autocollimator 2 are close to 0, and record the readings of autocollimator 2 at this time;

[0060] 7) Adjust the first double-sided mirror so that the yaw angle reading of autocollimator 1 is close to 0, record the readings of autocollimator 1 at this time and calculate the attitude angles of the first double-sided mirror;

[0061] 8) Refer to Figure 2 , place autocollimator 3 at a position perpendicular to the other side of the first double-sided mirror, adjust the optical axis of autocollimator 3 to be parallel to the ground and perpendicular to the first double-sided mirror;

[0062] 9) Adjust the first double-sided mirror so that the yaw indication of autocollimator 3 changes continuously, and obtain the attitude angles of autocollimator 3 through data processing;

[0063] 10) Refer to Figure 1 , if manufacturing a hollow pentaprism, remove the first double-sided mirror and the second double-sided mirror from the optical path, install the first single-sided mirror and the second single-sided mirror, adjust the first single-sided mirror and the second single-sided mirror so that the readings of autocollimator 1 and autocollimator 3 are close to 0, obtain the internal angle of the hollow pentaprism through data processing, and adjust it so that the internal angle of the hollow pentaprism is close to 0 to complete the manufacturing of the hollow pentaprism;

[0064] 11) Refer toFigure 1 , if measuring the internal angle error of the hollow pentaprism, remove the first double-sided mirror and the second double-sided mirror from the optical path, install the first single-sided mirror and the second single-sided mirror, adjust the overall hollow pentaprism to make the readings of the two autocollimators close to 0, and perform data processing to obtain the internal angle error of the hollow pentaprism;

[0065] In summary, the method of the present invention can quickly and accurately fabricate a hollow pentaprism or measure the internal angle error of a fabricated hollow pentaprism by using multiple autocollimators and two single-sided mirrors.

[0066] The following is a detailed description of the method for fabricating a hollow pentaprism and the method for measuring its internal angle error:

[0067] As Figure 5 shown, an embodiment of the present invention provides a method for fabricating a hollow pentaprism, including the following steps:

[0068] S1. Adjust two autocollimators to perpendicular positions to each other, and record the three-axis attitude angles μ x , μ y , μ z ;

[0069] Measurement results: μx = 320.19 ± 26.6 μrad, μy = 22.6 ± 0.2 μrad, μz = 144.76 ± 29.85 μrad

[0070] S2. Place the first double-sided mirror with parallelism θ AX|| and θ AY|| at the intersection position of the optical axes of the two autocollimators, and adjust the first double-sided mirror so that both autocollimators can observe the other's light spot at the center position of the field of view. At this time, the first double-sided mirror forms an approximately 45-degree angle with both autocollimators;

[0071] S3. Place the second double-sided mirror with parallelism θ BX|| and θ BY|| at a position perpendicular to the optical axis of the second autocollimator and form an approximately 45-degree angle with the second double-sided mirror, and adjust the two double-sided mirrors so that the yaw angle and pitch angle readings of the two autocollimators are close to 0;

[0072] Parallelism of the double-sided mirror: θ X|| = -2.8 ± 0.2 μrad, θ Y|| = 3.8 ± 0.6 μrad

[0073] S4. Adjust the second double-sided mirror to continuously change the yaw angle reading of the first autocollimator, and record the readings x A1 , y A1 after each change. According to y A1 / x A1 fit to obtain the angle by which the first double-sided mirror rotates counterclockwise around its bottom axis

[0074] Fitting result: ω a = -275.13 ± 21.39 μrad

[0075] S5. Adjust the second double-sided mirror to make the yaw angle and pitch angle readings of the second autocollimator close to 0, and record the reading x of the first autocollimator at this time B1 , y B1 ;

[0076] S6. Adjust the first double-sided mirror to make the yaw angle reading of the first autocollimator close to 0, and record the readings x A2 , y A2 ;

[0077] S7. According to μ x , μ y , μ z , θ X|| , θ Y|| , x A2 , y A2 , ωa, x B1 , y B1 Obtain the attitude angle errors δa and ωa of the first double-sided mirror;

[0078] Measurement result: ω a = 100.03 ± 21.15 μrad, δa = 12.8 ± 1.72 μrad

[0079] S8. After calibrating the attitude of the first double-sided mirror, place the third autocollimator in the direction perpendicular to the normal vector of the other side of the first double-sided mirror, and roughly adjust the third autocollimator to make its reading close to 0;

[0080] S9. Adjust the first double-sided mirror to make the reading of the third autocollimator in the pitch direction change continuously, and record the readings x c1 , y c1 . According to y c1 / x c1 Fit to obtain the angle δcz by which the third autocollimator rotates counterclockwise around its own optical axis. After adjusting δcz to be close to 0, adjust the first double-sided mirror to make its attitude angles δb and ωb close to 0;

[0081] Fitting result: δcz = -30.76 ± 11.25 μrad

[0082] S10. Calculate the attitude angle δcy = -x c2 of the third autocollimator around its own yaw direction through the reading x of the third autocollimator, the parallelism θ AY|| of the first double-sided mirror, and the attitude angle δa of the first double-sided mirror; c2 + δa;

[0083] Measurement result: δcy = -0.16 ± 2.1 μrad

[0084] S11. The tri - indication y of the autocollimator c2 , the parallelism θ of the first double - mirror AX|| , and the attitude angle ωa of the first double - mirror are used to calculate the attitude angle δcx = -y c2 - ωa of the autocollimator around its own yaw direction. Adjust the autocollimator so that its attitude angle δcx is close to 0 as δcy;

[0085] Measurement result: δcx = -61.57 ± 21.39 μrad

[0086] S12. Remove the first double - mirror and the second double - mirror from the optical path. Install the first plane - mirror and the second plane - mirror on the same flat plate perpendicular to the first autocollimator and the third autocollimator respectively. Adjust the two plane - mirrors so that the indications of the two autocollimators are close to 0 to form a hollow pentaprism.

[0087] Furthermore, in S7, according to μ x , μ y , μ z , θ X|| , θ Y|| , x A2 , y A2 , ωa, x B1 , y B1 The attitude - angle errors δa and ωa of the first double - mirror are obtained, including:

[0088] S71. According to the readings x B1 , y B1 of the two autocollimators and the tri - axis attitude angles μ x , μ y , μ z and the parallelism θ of the second double - mirror BY|| , calculate the attitude angle δ b = x B1 +μ y - θ BY|| ;

[0089] Measurement result: δ b = 25.52 ± 1.36 μrad.

[0090] S72. According to the readings x B1 , y B1 of the first autocollimator, the tri - axis attitude angles μ z of the two autocollimators and the parallelism θ of the double - mirror BX|| , calculate the attitude angle ω b = -y B1 +μ z - θBX|| ;

[0091] Measurement result: ω b = 141.41 ± 29.86 μrad.

[0092] S73 According to the readings x A2 , y A2 , x B1 , y B1 , the angle ωa of the first double-sided mirror rotating around the bottom axis, the attitude angles δb and ωb of the second double-sided mirror, and calculate the attitude angle of the first double-sided mirror

[0093] Furthermore, when manufacturing the hollow pentaprism, adjust the two mirror surfaces of the hollow pentaprism to adjust the 45° included angle error δβ and the tower difference ωβ of the hollow pentaprism to be close to 0 to complete the manufacturing.

[0094] The embodiments of the present invention provide a hollow pentaprism manufactured by a method for manufacturing a hollow pentaprism.

[0095] The embodiments of the present invention provide a method for measuring the internal angle error of a hollow pentaprism, including the following steps:

[0096] (1) Adjust the overall rotation of the hollow pentaprism around the pitching direction of the first autocollimator to make the reading of the first autocollimator change continuously, and record the readings x a3 , y a3 . According to x a3 / y a3 Fit to obtain the attitude angle σz of the hollow pentaprism around the pitching direction of the first autocollimator, and adjust σz to be close to 0;

[0097] Fitting result: σz = -30.76 ± 11.26 μrad

[0098] (2) Use the reading x of the first autocollimator a4 , the reading x of the third autocollimator c3 , and the attitude angle δcy of the third autocollimator to obtain the 45° included angle error δβ of the hollow pentaprism = x a4 + x c3 + δcy;

[0099] Fitting result: δβ = 22.52 ± 2.7 μrad

[0100] (3) Use the reading y of the first autocollimator a4 , the reading y of the third autocollimator c3 , and the attitude angle δcx of the third autocollimator to obtain the tower difference of the hollow pentaprism

[0101] Fitting result: ωβ = -51.23 ± 11.39 μrad

[0102] When measuring the internal angular error of a hollow pentaprism, δβ and ωβ are the measurement results of the 45° angular error and tower error inside the hollow pentaprism.

[0103] I. The specific application fields or related products of the present invention.

[0104] A pentaprism has the property that the direction of the emitted light beam is always perpendicular to the direction of the incident light beam, making the pentaprism play a crucial role in optical instruments. By using pentaprisms, they can be widely used in surface shape measurement in large optical systems. For example, both the NASA Earth Observing System satellite and the Thorlabs quantum optical experimental platform adopt customized pentaprism components to meet the requirements of stable imaging and precise manipulation of the photon path in the space environment. In machine vision systems, they can be used for product defect detection, etc. Due to reasons such as mirror angular error and internal medium, the pentaprism cannot meet the usage accuracy. By designing and manufacturing a hollow pentaprism, the measurement accuracy can be further improved.

[0105] II. Evidence related to the technical effects obtained in the embodiments of the present invention.

[0106] As Figure 6 shown, the goal of the embodiments of the present invention is to measure the values of δβ and ωβ. Among them, δβ is obtained from the readings of the autocollimator three in the x c3 , y c3 and the autocollimator one in the x a4 , y a4 . ωβ is calculated from y c3 and y a4 . Among them, σz will form a coupling with the other four terms. It is necessary to first fit to obtain σz. After determining that σz is within 100 μrad, the coupling terms can be discarded. At this time, the values of δβ and ωβ can be measured using the instrument readings. Figure 6 is the fitting result of σz. -30.76 μrad indicates that σz is already extremely small. The quadratic and higher-order terms related to σz in the measurement formulas of δβ and ωβ can be ignored. At this time, the true values of δβ and ωβ can be measured using the instrument readings.

[0107] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be covered by the protection scope of the present invention.

Claims

1. A manufacturing method of a hollow pentaprism, characterized in that, A cross - optical - path system is constructed by using two autocollimators arranged perpendicular to each other and two double - sided mirrors. By adjusting the relative position and angle of the double - sided mirrors and combining the yaw - angle and pitch - angle readings of the autocollimators, the rotation angle of the double - sided mirror around the axis and the attitude error are inversely calculated by using the ratio - fitting method. A third autocollimator is introduced to further calibrate the normal deviation. Finally, by removing the double - sided mirrors and introducing plane mirrors, the spatial mapping conversion of the hollow pentaprism structure is realized. This method integrates key technical means such as attitude - angle tracking, spot - reading fitting, coordinate transformation, and angle inverse calculation, forming an optical alignment process for precisely constructing a hollow pentaprism.

2. The manufacturing method of the hollow pentaprism according to claim 1, characterized in that, It includes the following steps: S1. Adjust two autocollimators to a mutually perpendicular position and record the three-axis attitude angles μ x 、μ y 、μ z ; S2. Place a two-sided mirror with a parallelism of θ AX|| and θ AY|| at the intersection position of the optical axes of two autocollimators. Adjust the two-sided mirror 1 so that both autocollimators can observe the other's light spot at the center position of the field of view. At this time, the two-sided mirror 1 forms an angle of approximately 45 degrees with both autocollimators; S3. Place the double-sided mirror II with a parallelism of θ BX|| and θ BY|| at a position perpendicular to the optical axis of the autocollimator II and at an angle of approximately 45 degrees with respect to the double-sided mirror II. Adjust the two double-sided mirrors so that the yaw angle and pitch angle readings of the two autocollimators are close to 0; S4. Adjust the second double-sided mirror to continuously change the yaw angle reading of the first autocollimator, and record the readings x A1 , y A1 after each change. According to y A1 / x A1 , fit to obtain the angle 2ωa by which the first double-sided mirror rotates counterclockwise about its own bottom axis; S5. Adjust the second double-sided mirror to make the readings of the yaw angle and pitch angle of the second autocollimator close to 0, and record the reading x of the first autocollimator at this time B1 , y B1 ; S6. Adjust the first double-sided mirror to make the yaw angle reading of the first autocollimator close to 0, and record the readings x A2 , y A2 ; S7, according to μ x and μ y and μ z and θ X|| and θ Y|| and x A2 and y A2 and ωa, x B1 and y B1 obtain the attitude angle errors δa and ωa of the first double-sided mirror; S8. After calibrating the attitude of the first double - sided mirror, place the third autocollimator in the direction perpendicular to the normal vector of the other side of the first double - sided mirror, and roughly adjust the third autocollimator so that its reading is close to 0. S9. Adjust the first double-sided mirror so that the readings of the autocollimator three in the pitch direction change continuously, and record the readings x c1 , y c1 ; According to y c1 / x c1 Fit to obtain the angle δcz by which the autocollimator three rotates counterclockwise about its own optical axis. After adjusting δcz to be close to 0, adjust the first double-sided mirror so that its attitude angles δb and ωb are close to 0; S10. Calculate the attitude angle δcy = -x of the autocollimator three around its own yaw direction through the three readings x of the autocollimator c2 , the parallelism θ of the first double-sided mirror AY|| , and the attitude angle δa of the first double-sided mirror. c2 +δa; S11, obtaining the attitude angle δcx=-y of the autocollimator three around its own yaw direction through the three readings y of the autocollimator c2 , the parallelism θ of the first double-sided mirror AX|| , the attitude angle ωa of the first double-sided mirror, and calculating the attitude angle δcx=-y of the autocollimator three around its own yaw direction c2 -ωa, and adjusting the autocollimator three to make its attitude angle δcx close to δcy; S12. Remove the first double - sided mirror and the second double - sided mirror from the optical path, install the first plane mirror and the second plane mirror on the same flat plate perpendicular to the first autocollimator and the third autocollimator respectively, and adjust the two plane mirrors so that the readings of the two autocollimators are close to 0, thus forming a hollow pentaprism.

3. The manufacturing method of the hollow pentaprism according to claim 1, characterized in that, In the above S7, according to μ x , μ y , μ z , θ X|| , θ Y|| , x A2 , y A2 , ωa, x B1 , y B1 The attitude angle errors δa and ωa of the first double-sided mirror are obtained, including: S71, read the readings x B1 and y B1 of the three-axis attitude angles μ x , μ y , μ z of the two autocollimators and the parallelism θ BY|| of the second double-sided mirror, and calculate the attitude angle δ b at which the second double-sided mirror rotates counterclockwise around the Y-axis of the first autocollimator as follows: δ B1 = x y + μ BY|| - θ S72, according to the reading x of the autocollimator B1 , y B1 of the three-axis attitude angles μ of two autocollimators z , the parallelism θ of the double-sided mirror BX|| , find the attitude angle ω of the counterclockwise rotation of the double-sided mirror around the Z-axis of the first autocollimator b = -y B1 + μ z - θ BX|| ; S73, according to the readings x A2 , y A2 , x B1 , y B1 , the angle ωa of the first double-sided mirror rotating around the bottom axis, the attitude angles δb and ωb of the second double-sided mirror, and calculate the attitude angle of the first double-sided mirror 4. The manufacturing method of the hollow pentaprism according to claim 1, characterized in that, When manufacturing a hollow pentaprism, adjust the two mirror surfaces of the hollow pentaprism to adjust the 45° included - angle error δβ and the tower error ωβ of the hollow pentaprism to be close to 0, then the manufacturing can be completed.

5. A hollow pentaprism manufactured by the method for manufacturing a hollow pentaprism according to any one of claims 1 to 4.

6. A method for measuring the internal angular error of a hollow pentaprism as described in claim 5, characterized in that, It includes the following steps: (1) Adjust the overall rotation of the hollow pentaprism around the pitch direction of the autocollimator 1 so that the reading of the autocollimator 1 changes continuously. Record the reading x of the autocollimator 1 after each change. a3 , y a3 ; According to x a3 / y a3 Fit to obtain the attitude angle σz of the hollow pentaprism around the pitch direction of the autocollimator 1, and adjust σz to be close to 0; (2) Use the reading x of autocollimator 1 a4 , the reading x of autocollimator 3 c3 , and the attitude angle δcy of autocollimator 3 to obtain the 45° included angle error δβ of the hollow pentaprism, where δβ = x a4 + x c3 + δcy; (3) Use the reading y of autocollimator 1 a4 and the reading y of autocollimator 3 c3 and the attitude angle δcx of autocollimator 3 to obtain the pentaprism tower difference

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