A light splitting prism light collimating device for multi-directional optical axis detection alignment

Abstract

The application discloses a light collimating device for multi-directional light axis detection and alignment. The light collimating device divides a laser beam into an angle of 90 degrees through a light splitting prism, one light beam returns along the original path after passing through a parallel flat glass, and a part of the laser beam returns along the original path, and the light splitting prism divides the laser beam into an angle of 90 degrees again, so that the detection of the light axes in three directions is realized. The patent solves the problem of the detection and alignment of the light axes in three directions, and can also be used for the detection and alignment of any two directions, so that real-time high-precision monitoring of a measured plane is realized.

Description

Technical Field

[0001] This invention relates to a beam splitter optical alignment device for multi-directional optical axis detection and alignment, which is particularly suitable for registration and real-time detection of the optical axis of an optical system with the optical axis of a standard plane mirror at 90 degrees or 180 degrees. Background Technology

[0002] The optical axis of an optical system is one of its key technical indicators. Changes in the optical axis directly affect the system's detection capability. With increasing demands from various optical instruments and equipment, the requirements for the accuracy and stability of optical axis registration during optical calibration are becoming increasingly stringent, placing higher demands on the calibration and performance testing of optical systems. In optical system assembly and adjustment, a large-aperture standard plane mirror is often used as a reference for the optical axis, calibrating the optical axis of the optical system parallel to the normal of the standard plane mirror. In optical loads using a oscillating mirror as a pointing mirror, the position of the 45-degree pointing mirror needs to be accurately calibrated, requiring the optical axis of the optical system to be perpendicular to the normal of the standard plane mirror beforehand.

[0003] This invention proposes a beam splitter prism optical alignment device for multi-directional optical axis detection and alignment. Based on the beam splitter function of the beam splitter prism, a laser beam is split into two laser beams with a 90-degree angle. One of the beams returns after passing through a parallel plate and is split into two laser beams with a 90-degree angle again, forming three laser beams with an angle difference of 90 degrees for auxiliary installation of the optical axis of the optical system. This can effectively align the parallelism or perpendicularity of the optical axis of the optical system with a standard plane mirror and achieve real-time detection. Summary of the Invention

[0004] The purpose of this invention is to provide a beam splitter prism optical alignment device for multi-directional optical axis detection and alignment, used for aligning the parallelism or perpendicularity of the optical axis of an optical system with a standard plane mirror. The device of this invention is shown in the attached diagram. Figure 1 As shown, the central position is the device of the present invention, which consists of the following parts:

[0005] The optical calibration device is located between the planes being measured. Except for the electronic autocollimator 5, the upper, lower, left, and right sides are all reflective surfaces being measured. The electronic autocollimator 5 emits collimated laser beams onto the b and c surfaces of the beam splitter 1. A portion of the laser beam that is incident on the c surface and then passes through the parallel plate 2 returns along the original path and passes through the beam splitter prism again to the d surface, where the laser beam is split into three laser beams with an angle difference of 90 degrees, forming three laser beams with an angle difference of 90 degrees.

[0006] During the assembly and adjustment process, this optical calibration device performs registration and real-time detection of the normals of the standard plane mirror, which consists of the following steps:

[0007] 1. Self-test of the device of the present invention.

[0008] Align the electronic autocollimator 5 with surface a of the beam splitter and return it to the electronic autocollimator 5 via the same path. After the light is transmitted to surface e of the parallel plate 2, return it to the electronic autocollimator 5 again via the same path. Check if the crosshairs of the two return paths overlap. If they overlap, the equipment is in good working order and subsequent tests can be performed.

[0009] 2. Align the optical axis of the reference plane mirror with the normal of the reference plane mirror.

[0010] Turn on the electronic autocollimator 5 and adjust it so that the crosshair X1 returned by this patented device and the crosshair X2 returned by the reference plane mirror appear simultaneously in the field of view of the electronic autocollimator 5. Fine-tune the optical alignment device of this beam splitter prism until they coincide. At this time, check the positions of the crosshairs X3 and X4 returned by the other two reference plane mirrors, and adjust the angles of the two reference plane mirrors so that their returned crosshairs X3 and X4 coincide with the first two crosshairs X1 and X2. When all three crosshairs are completely coincident, the fine alignment of the reference optical axis of the telescope optical system with the normal of the reference plane mirror is completed.

[0011] 3. Real-time detection of the parallelism and perpendicularity between the reference optical axis of the reference plane mirror and the normal of the reference plane mirror.

[0012] This patented device is relatively small in size and, positioned between the telescope's optical system and the reference plane mirror, does not interfere with optical calibration testing. Therefore, it can monitor the parallelism between the system's optical axis and the normal to the standard plane mirror in real time. When the orientation of the reference plane mirror and the other two reference plane mirrors remains unchanged, the crosshair X2 returned by the reference plane mirror and the crosshairs X3 and X4 returned by the other two reference plane mirrors still coincide in the vertical direction and are symmetrical in the horizontal direction relative to the reference crosshair X1 of this beam splitter prism optical calibration device. This allows for monitoring of the parallelism between the reference plane mirror's optical axis and the normal to the reference plane mirror. When the orientation of the reference plane mirror and the reference plane mirrors changes, the crosshair X2 returned by the reference plane mirror separates from the crosshairs X3 and X4 returned by the reference plane mirrors in the vertical direction and is asymmetrical in the horizontal direction relative to the reference crosshair X1 of this beam splitter prism optical calibration device. The deviation between these two crosshairs can be directly calculated on the electronic autocollimator 5, achieving the goal of real-time monitoring of the parallelism and perpendicularity between the reference plane mirror's optical axis and the normal to the reference plane mirror.

[0013] The main features of this invention are as follows:

[0014] 1) The structure is simple and compact, and easy to assemble.

[0015] 2) It can perform the alignment and perpendicularity of the optical axis of the optical system with the normal of the standard plane mirror used for testing, and can also meet the alignment and testing of the optical axis of the optical system with the normal of the standard plane mirror used for testing at a specified angle. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the device of the present invention used for optical calibration.

[0017] Figure 2 This is a schematic diagram of the optical calibration steps of the device of the present invention. Detailed Implementation

[0018] The following is in conjunction with the appendix Figure 1 The embodiments of the method of the present invention are described in detail.

[0019] The main components used in this invention are described below:

[0020] 1) Beam splitter 1: The beam splitter cube of ThorLab, model BS013, is used. The beam splitting ratio is 50:50, the wavelength range is 400-700nm, and the aperture is 25.4mm.

[0021] 2) Parallel plate 2: Custom-made, side length 60mm, 90-degree angle difference and tower difference are both better than 3 seconds, the RMS of each surface is better than λ / 15@632.8nm, the front surface near the beam splitter is coated with a 50% transmittance and 50% reflectance film, the rear surface is coated with an anti-reflection film, the wavelength range is 400-700nm, material K9.

[0022] 3) Reference mirror 3: Custom-made, with 90-degree angular difference and tower difference both better than 3 seconds, 10*10*10mm, RMS of each facet better than λ / 15@632.8nm, five-sided silver coating, material K9.

[0023] 4) Mounting base 4: Custom-made for fixing the equipment and allowing for rotation and pitch operations.

[0024] 5) Electronic autocollimator 5: The TriAngle autocollimator from TRIOPTICS, model TA 300-57, has a light aperture of 30mm, a resolution of 0.02 seconds, a repeatability of ±0.05 seconds, and an accuracy of ±0.4 seconds.

[0025] The specific steps for calibrating this patented device are as follows:

[0026] 1) Fix the parallel plate 2. Using the electronic autocollimator 5, align the reference mirror 3 and the parallel plate 2. Adjust the electronic autocollimator 5 until the return crosshairs are centered. Fix the parallel plate 2, as shown in the attached diagram. Figure 2 As shown in step 1.

[0027] 2) Add beam splitter 1 based on step 1. Align the reference mirror 3 and beam splitter 1 using the electronic autocollimator 5, as shown in the attached diagram. Figure 2 As shown in step 2, two crosshairs can be seen in the image returned by the electronic autocollimator. Adjust the angle of the beam splitter 1 so that the two crosshairs completely overlap, and then fix the beam splitter 1.

Claims

1. A beam splitter prism optical alignment device for multi-directional optical axis detection and alignment, comprising a beam splitter prism (1), a parallel plate (2), a reference mirror (3), a mounting base plate (4), and an electronic autocollimator (5), characterized in that: The optical calibration device is located between the first, second, and third reflective mirrors under test; the beam splitter (1) is installed near the center of the mounting base (4); the parallel plate (2) is set and fixed on the mounting base (4) adjacent to the beam splitter (1), and the side closest to the beam splitter (1) must maintain a distance from the c-plane of the beam splitter (1) to ensure that the laser emitted from the c-plane of the beam splitter (1) can reach the parallel plate (2). The beam reflected from the e-plane of the beam splitter (1) can return to the c-plane of the beam splitter (1) via the same path. The reference mirror (3) is also fixed on the mounting base (4), and its position must correspond to that of the beam splitter (1) and the parallel plate (2). If the electronic autocollimator (5) is aimed at the e-plane of the reference mirror (3) and the parallel plate (2) and emits a laser, the beam reflected from the e-plane of the reference mirror (3) and the parallel plate (2) can return to the electronic autocollimator (5) via the same path. At the same time, if the electronic autocollimator (5) is aimed at the d-plane of the reference mirror (3) and the beam splitter (1) and emits a laser, The laser beam incident from the d-plane of the beam splitter (1) is reflected by the beam splitter (1) and exits from the c-plane of the beam splitter (1), and is incident on the e-plane of the parallel plate (2). After being reflected by the e-plane, it returns along the original incident path, and then passes through the c-plane and d-plane of the beam splitter (1) in sequence, and finally returns to the electronic autocollimator (5). The beam splitter (1) and the parallel plate (2) can reflect the laser beam back to the electronic autocollimator (5) along the original path at the same time as the reference mirror (3). The electronic autocollimator (5) is installed on the edge side of the mounting base plate (4), and its output optical axis needs to be aligned with the a-plane and c-plane of the beam splitter (1) to ensure that the collimated laser beam can be emitted to the beam splitter (1) and at the same time, the laser beam reflected back by the three measured reflector surfaces can be received. The a-face is the incident surface of the beam splitter (1), used to receive the parallel laser directly emitted by the electronic autocollimator (5); the b-face is the reflected light exit surface of the beam splitter (1), which receives the laser reflected by the beam splitter (1) and directs it toward the first test mirror surface; the c-face is the transmitted light exit surface of the beam splitter (1), which receives the laser transmitted by the beam splitter (1) and directs it toward the e-face of the parallel plate (2). Part of the laser incident on the e-face is reflected back to the beam splitter (1) by the e-face, and the other part passes through the parallel plate (2) and is directed toward the second test mirror surface; the d-face is the secondary reflected light exit surface of the beam splitter (1), which receives the laser reflected back to the beam splitter (1) by the e-face of the parallel plate (2) and is directed toward the third test mirror surface. The electronic autocollimator (5) emits collimated laser beams onto surface a of the beam splitter (1). The three beams received by the beam splitter (1) on surfaces b, c, and d form a 90-degree angle. The three laser beams reflected back by the three tested mirrors return to the electronic autocollimator (5) along their original paths. Due to the different paths, the intensity of the three returning laser beams is different. The crosshairs formed by the three returning laser beams and the crosshairs of the optical calibration device itself coincide, thus completing the alignment and detection of the optical axes of the three-directional optical system.

2. The beam splitter prism optical alignment device for multi-directional optical axis detection and alignment according to claim 1, characterized in that: The parallel plate (2) is made of quartz material, with a parallelism of better than 3 seconds between the front and rear surfaces, a transmission wavefront RMS value better than λ / 15, λ = 632.8 nm, a 50% transmission and 50% reflection film on the front surface near the beam splitter, and an anti-reflection film on the rear surface.

3. The beam splitter prism optical alignment device for multi-directional optical axis detection and alignment according to claim 1, characterized in that: The beam splitter (1) has a beam splitting ratio of 5:5 for the wavelength used, and the RMS value of the surface shape deviation of each light-transmitting surface is better than λ / 10, where λ = 632.8 nm.

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