A precise calibration device and method for a folded-axis mirror assembly

Abstract

The present invention relates to the field of optical alignment technology, and specifically to a device and method for precisely calibrating a folding mirror assembly. The device comprises: a light source, a first beam splitter prism, a dispersion objective lens, and a folding mirror assembly to be measured, which are located on the same optical axis and arranged sequentially from top to bottom, and are optically connected in sequence, with the dispersion objective lens receiving the transmitted light from the first beam splitter prism; the light source uses polychromatic light; the first beam splitter prism, a second beam splitter prism, and a spectrometer are optically connected in sequence, with the second beam splitter prism receiving the reflected light from the first beam splitter prism; and a detector is optically connected to the second beam splitter prism to receive the reflected light from the second beam splitter prism. The device employs a spectrometer to calculate the surface position of a lens by analyzing the wavelength and intensity of the reflected light, thereby achieving greater reliability and accuracy. Polychromatic light is used as a detection light source to achieve high-precision measurement of the air gap between two lenses.

Description

Technical Field

[0001] The present invention relates to the technical field of optical assembly and adjustment, and in particular to a precise calibration device and a calibration method for a folded-axis mirror assembly. Background Art

[0002] In precision optical lenses, 45-degree folding axis reflectors are widely used in various optical systems to change the direction of the optical path, optimize the optical path layout, or achieve specific optical functions. The tilt or eccentricity of the reflector will cause increased aberrations in the optical system; the deviation of the reflector may also cause the misalignment of the optical path, making it impossible for light to accurately reach the intended optical element or detector. This will not only affect the imaging quality of the optical system, but may also cause the loss of light energy and reduce the optical quality of the system. To this end, a variety of methods have been proposed in the prior art:

[0003] The optical autocollimation method uses optical measuring instruments such as an autocollimator to adjust the angle of the reflector based on the principles of optical reflection and imaging. This method requires high-precision equipment such as an autocollimator and requires a high level of operator skill. The operation process is relatively complex and requires multiple adjustments and measurements to achieve the required accuracy.

[0004] The interferometer-assisted adjustment method uses an interferometer to detect mirror installation errors. By observing changes in interference fringes, the mirror's flatness, angle, and other parameters are determined to be in compliance with requirements, allowing adjustments to be made accordingly. This method has strict environmental requirements, requiring stable temperature, humidity, and cleanliness conditions; otherwise, measurement accuracy will be affected. Furthermore, its operation is complex, requiring specialized technicians for operation and data analysis, and the adjustment process is lengthy.

[0005] The theodolite adjustment method aligns the theodolite with the reflector, measures the reflector's azimuth and pitch angles, and compares them with the design requirements. Based on the measurement results, the reflector's installation position and posture are adjusted to ensure that the reflector's optical axis coincides with the design optical axis. This method requires complex calculations and judgments based on the theodolite's measurement data when adjusting the reflector. The operation process is relatively cumbersome, especially when high-precision adjustments are required. Repeated measurements and adjustments may be necessary. It is also easily affected by the environment and has high requirements for the testing environment.

[0006] Based on this, those skilled in the art urgently need to provide a new folding mirror assembly technology to overcome the technical problems existing in the above-mentioned prior art. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the defects existing in the above-mentioned prior art, thereby providing a precise calibration device and calibration method for a folded axis mirror assembly.

[0008] A device for precisely calibrating a folding mirror assembly includes: a dispersion objective lens, a first beam splitter prism, a second beam splitter prism, a spectrometer, a detector, and a light source;

[0009] The light source, the first beam splitter prism, the dispersive objective lens and the folding mirror group to be measured are located on the same optical axis and arranged in sequence from top to bottom and are optically connected in sequence, and the dispersive objective lens receives the transmitted light of the first beam splitter prism; the light source uses polychromatic light;

[0010] The first beam splitter prism, the second beam splitter prism and the spectrometer are optically connected in sequence, and the second beam splitter prism receives the reflected light from the first beam splitter prism;

[0011] The detector is connected to the optical path of the second beam splitter prism and receives the reflected light from the second beam splitter prism.

[0012] Preferably, it also includes a supporting base and a connecting frame;

[0013] The supporting base is composed of a base, a horizontal adjustment platform, a first supporting column, a second supporting column, a first guide rail and a second guide rail;

[0014] The two ends of the base are fixedly connected to the first support column and the second support column respectively; the horizontal adjustment platform for placing the folding axis mirror to be measured is installed on the top surface of the base;

[0015] The first guide rail and the second guide rail are respectively fixed at the same height to the first support column away from the base end and the second support column away from the base end;

[0016] The dispersion objective lens, the first beam splitter prism, the second beam splitter prism, the spectrometer, the detector and the light source are installed on the connecting frame, and the left and right sides of the connecting frame are respectively slidably connected with the first guide rail and the second guide rail.

[0017] Preferably, the structure of the dispersion objective lens is a biconvex structure.

[0018] A method for precisely calibrating a folding axis mirror assembly is implemented using a device for precisely calibrating a folding axis mirror assembly and specifically comprises the following steps:

[0019] S1. Preparation: Mount the lens assembly to be tested on a horizontal adjustment stage and adjust the stage angle so that the optical axis of the first lens in the lens assembly to be tested coincides with the optical axis M1 of the dispersion objective lens.

[0020] S2. Adjust the height of the connecting frame, obtain the position of the lower surface center image of the first lens and the second lens, and further calculate the angular deviation of the plane mirror;

[0021] S3 adjusts the height of the connecting frame, obtains the lower surface position of the first lens and the second lens, and further calculates the air gap between the first lens and the second lens;

[0022] S4. Repeat steps S2 to S3 and adjust the angle and orientation of the plane reflector accordingly until the actual requirements are met.

[0023] Preferably, adjusting the height of the connecting frame, obtaining the positions of the spherical center images of the lower surfaces of the first lens and the second lens, and further calculating the angular deviation of the plane reflector specifically include:

[0024] S201. Move the connecting frame on the first guide rail and the second guide rail until the detector captures the spherical center image of the lower surface of the first lens, and record the position of the light spot on the detector at this time as (X1, Y1);

[0025] S202. Move the connecting frame on the first guide rail and the second guide rail until the detector captures the spherical center image of the lower surface of the second lens again, and record the position of the light spot on the detector at this time as (X2, Y2);

[0026] S203. Calculate the difference between (X1, Y1) and (X2, Y2) as the angular deviation of the plane mirror.

[0027] Preferably, adjusting the height of the connecting frame, obtaining the lower surface positions of the first lens and the second lens, and further calculating the air gap between the first lens and the second lens specifically include:

[0028] S301. Move the connecting frame on the first guide rail and the second guide rail until the detector captures the spherical top image of the lower surface of the first lens, and further calculate the position of the lower surface of the first lens according to the spectrometer analysis results, recorded as Z1;

[0029] S302. The connecting frame is moved on the first and second guide rails until the detector captures the spherical top image of the lower surface of the second lens again, and the position of the lower surface of the second lens is further calculated based on the spectrometer analysis results, recorded as Z2;

[0030] S303. Calculate the difference between Z1 and Z2 as the air space between the first lens and the second lens.

[0031] Preferably, the spectrometer analysis result is specifically: the spectrometer performs light intensity analysis on the light returned by the second lens to obtain the wavelength of light with the highest reflected light intensity.

[0032] The technical solution of the present invention has the following advantages:

[0033] The present invention uses polychromatic light as the detection light source. Polychromatic light has a wider spectrum and can provide more wavelength information than monochromatic light. It can form a one-to-one correspondence between wavelength and focus position, and can achieve high-precision measurement of the air gap between the two lenses.

[0034] The polychromatic light source used in the present invention can effectively reduce the influence of ambient light and stray light on the detection results during the actual measurement process, thereby improving the anti-interference ability and stability of the measurement.

[0035] The present invention adopts a non-contact measurement method, which does not require contact with the surface of the lens being measured, thus avoiding scratches on the lens surface.

[0036] The present invention uses a spectrometer to calculate the surface position of the lens by analyzing the wavelength and intensity of the reflected light. Compared with using an altimeter to determine the surface height by human eye, it is more accurate and reliable.

[0037] For some optical lenses with complex structures, it is difficult to measure the air gap between the lenses on both sides of the reflector using an altimeter. This design uses the method of analyzing the reflected light intensity to indirectly calculate the air gap between the lenses, which has wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 This is a schematic diagram of the principle of a method for precisely calibrating a folded-axis mirror assembly;

[0040] Figure 2 This is a structural diagram of a precise calibration device for a folded-axis mirror assembly;

[0041] Figure 3 Schematic diagram of the structure of the folding mirror group to be tested;

[0042] Figure 4 This is the spectrometer analysis diagram when the detector captures the spherical top image of the lower surface of the first lens;

[0043] Figure 5 Schematic diagram of the light spot position on the detector;

[0044] Figure 6 Schematic diagram of the dome image of the first lens of the present invention.

[0045] Description of reference numerals:

[0046] 1-connecting frame, 2-dispersive objective lens, 3-first beam splitter prism, 4-second beam splitter prism, 5-spectrometer, 6-detector, 7-light source, 8-horizontal adjustment stage, 91-first guide rail, 92-second guide rail, 101-first support column, 102-second support column, 11-base, 12-plane reflector, 13-first lens, 14-second lens, 15-lens barrel to be measured. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0050] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0051] Example 1

[0052] This embodiment discloses a device for precisely calibrating a folding mirror assembly, comprising: a dispersion objective lens 2, a first beam splitter prism 3, a second beam splitter prism 4, a spectrometer 5, a detector 6, and a light source 7;

[0053] The light source 7, the first beam splitter prism 3, the dispersive objective lens 2, and the folding mirror group to be measured are located on the same optical axis and arranged in sequence from top to bottom. The dispersive objective lens 2 receives the transmitted light from the first beam splitter prism 3. The light source 7 uses polychromatic light and is a point light source 7.

[0054] The first beam splitter prism 3, the second beam splitter prism 4 and the spectrometer 5 are optically connected in sequence, and the second beam splitter prism 4 receives the reflected light from the first beam splitter prism 3;

[0055] The detector 6 is optically connected to the second beam splitter prism 4 and receives the reflected light from the second beam splitter prism 4 .

[0056] like Figure 2 In addition, in this embodiment, a device for precisely calibrating a folded-axis mirror assembly further includes a supporting base and a connecting frame 1;

[0057] The support base is composed of a base 11, a horizontal adjustment platform 8, a first support column 101, a second support column 102, a first guide rail 91 and a second guide rail 92;

[0058] The two ends of the base 11 are fixedly connected to the first support column 101 and the second support column 102 respectively; the horizontal adjustment platform 8 for placing the folding mirror to be tested is installed on the top surface of the base 11;

[0059] The first guide rail 91 and the second guide rail 92 are fixed at the same height to the end of the first support column 101 away from the base 11 and the end of the second support column 101 away from the base 11 respectively;

[0060] The dispersive objective lens 2, the first beam splitter prism 3, the second beam splitter prism 4, the spectrometer 5, the detector 6 and the light source 7 are mounted on the connecting frame 1. The left and right sides of the connecting frame 1 are slidably connected to the first guide rail 91 and the second guide rail 92 respectively.

[0061] The structure of the dispersion objective lens 2 is a biconvex structure.

[0062] Example 2

[0063] This embodiment further discloses a method for precisely calibrating a folding mirror assembly based on the embodiment 1, which is implemented by using a precise calibration device for a folding mirror assembly according to the embodiment 1.

[0064] It should be noted that this embodiment is applicable to the mirror assembly to be measured consisting of a 45-degree folding axis reflector; Figure 3 In this embodiment, the folding mirror assembly to be measured is composed of a first lens 13, a plane reflector 12, a second lens 14 and a lens barrel to be measured 15;

[0065] In the lens barrel 15 to be measured, the first lens 13, the plane reflector 12 and the second lens 14 are optically connected in sequence; and the plane reflector 12 is a 45-degree folding axis reflector.

[0066] A method for precisely calibrating a folded-axis mirror assembly comprises the following steps:

[0067] S1. Preparation: Install the lens assembly to be tested on the horizontal adjustment stage 8 and adjust the angle of the horizontal adjustment stage 8 so that the optical axis of the first lens 13 in the lens assembly to be tested coincides with the optical axis M1 of the dispersive objective lens 2. At this time, the polychromatic light emitted by the light source 7 passes through the first beam splitter prism 3, the dispersive objective lens 2, and the first lens 13, and then passes through the plane mirror 12 and is deflected 90°. It converges to the surface of the second lens 14 and then returns along the original path. On the way back, it is deflected by the first beam splitter prism 3 and then split into two beams by the second beam splitter prism 4. The two beams are respectively converged to the spectrometer 5 and the detector 6. Figure 1 As shown;

[0068] S2 adjusts the height of the connecting frame 1, obtains the lower surface center image position of the first lens 13 and the second lens 14, and further calculates the angular deviation of the plane mirror 12;

[0069] S3 adjusts the height of the connecting frame 1, obtains the lower surface position of the first lens 13 and the second lens 14, and further calculates the air gap between the first lens 13 and the second lens 14;

[0070] S4. Repeat steps S2 to S3 and adjust the angle and orientation of the plane reflector 12 accordingly until the actual requirements are met.

[0071] Wherein, step S2 specifically includes:

[0072] S201. Move the connecting frame 1 on the first guide rail 91 and the second guide rail 92 until the detector 6 captures the spherical center image of the lower surface of the first lens 13 and records the position of the light spot on the detector 6 as (X1, Y1).

[0073] S202. Move the connecting frame 1 on the first guide rail 91 and the second guide rail 92 until the detector 6 captures the spherical center image of the lower surface of the second lens 14 again, and records the position of the light spot on the detector 6 at this time as (X2, Y2). Figure 5 As shown;

[0074] S203 . Calculate the difference between (X1, Y1) and (X2, Y2) as the angular deviation of the plane reflector 12 .

[0075] Since it is difficult to measure the air gap between the lenses on both sides of a traditional 45-degree reflector using an altimeter for some optical lenses with complex structures, this embodiment indirectly calculates the air gap between the lenses by analyzing the reflected light intensity, which has wide applicability: Step S3 specifically includes:

[0076] S301. Move the connecting frame 1 on the first guide rail 91 and the second guide rail 92 until the detector 6 captures the spherical top image of the lower surface of the first lens 13, and further calculates the position of the lower surface of the first lens 13 based on the analysis results of the spectrometer 5, which is recorded as Z1. Specifically: since the connecting frame 1 is moved on the first guide rail 91 and the second guide rail 92, all components on the connecting frame 1 move up and down, and the components originally located on the optical axis M1 remain on the optical axis M1, but the height changes. Among them, the polychromatic light emitted by the light source 7 forms a series of continuous measurement points on the optical axis M1 after passing through the dispersive objective lens 2. When the light hits the lens surface, only light of a specific wavelength will converge on the object surface. At this time, the light intensity of the light of this wavelength is the strongest, and the light of other wavelengths will be in a defocused state, for example Figure 6 The figure shows the dome image on the first lens 13. The spectrometer 5 is further used to analyze the intensity of the reflected light of different wavelengths to obtain the wavelength of the light with the highest reflected light intensity, as shown in FIG. Figure 4 , calculate the position of the lower surface of the first lens 13, and record the position as Z1;

[0077] S302. Similarly, the connecting frame 1 is moved on the first guide rail 91 and the second guide rail 92 until the detector 6 captures the spherical top image of the lower surface of the second lens 14 again, and the position of the lower surface of the second lens 14 is further calculated based on the analysis results of the spectrometer 5, recorded as Z2;

[0078] S303. Calculate the difference between Z1 and Z2 as the air gap between first lens 13 and second lens 14. It should be noted that step S3 utilizes spectrometer 5 to analyze the wavelength and intensity of reflected light to calculate the surface position of the lens. This method is more accurate and reliable than using an altimeter to determine the surface height using human observation.

[0079] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A precise calibration device for a folding axis mirror assembly, characterized in that: include: A dispersion objective lens (2), a first beam splitter prism (3), a second beam splitter prism (4), a spectrometer (5), a detector (6), and a light source (7); A light source (7), a first beam splitter prism (3), a dispersion objective lens (2), and a folding axis lens group to be measured, which are located on the same optical axis and arranged in sequence from top to bottom, are optically connected in sequence, and the dispersion objective lens (2) receives the transmitted light of the first beam splitter prism (3); the light source (7) uses polychromatic light; The first beam splitter prism (3), the second beam splitter prism (4), and the spectrometer (5) are optically connected in sequence, and the second beam splitter prism (4) receives the reflected light from the first beam splitter prism (3); The detector (6) is connected to the optical path of the second beam splitter prism (4) and receives the reflected light from the second beam splitter prism (4).

2. The device for precisely calibrating a folded-axis mirror assembly according to claim 1, wherein: Also includes a support base and a connecting frame (1); The supporting base is composed of a base (11), a horizontal adjustment platform (8), a first supporting column (101), a second supporting column (102), a first guide rail (91) and a second guide rail (92); The two ends of the base (11) are fixedly connected to the first support column (101) and the second support column (102) respectively; a horizontal adjustment platform (8) for placing the folding axis mirror to be measured is installed on the top surface of the base (11); The first guide rail (91) and the second guide rail (92) are fixed at the same height to the end of the first support column (101) away from the base (11) and the end of the second support column (102) away from the base (11); The dispersion objective lens (2), the first beam splitter prism (3), the second beam splitter prism (4), the spectrometer (5), the detector (6) and the light source (7) are mounted on the connecting frame (1). The left and right sides of the connecting frame (1) are respectively slidably connected to the first guide rail (91) and the second guide rail (92).

3. The precise calibration device for a folded-axis mirror assembly according to claim 2, characterized in that: The structure of the dispersion objective lens (2) is a biconvex structure.

4. A method for precise calibration of a folded axis mirror assembly, characterized in that: The application of the folded-axis mirror assembly precision calibration device described in claim 3 specifically includes the following steps: S1. Preparation: Install the lens group to be tested on the horizontal adjustment table (8) and adjust the angle of the horizontal adjustment table (8) so that the optical axis of the first lens (13) in the lens group to be tested coincides with the optical axis M1 of the dispersion objective lens (2); S2. Adjust the height of the connecting frame (1), obtain the position of the spherical center image of the lower surface of the first lens (13) and the second lens (14), and further calculate the angular deviation of the plane reflector (12); S3. Adjust the height of the connecting frame (1), obtain the lower surface positions of the first lens (13) and the second lens (14), and further calculate the air gap between the first lens (13) and the second lens (14); S4. Repeat steps S2 to S3, and adjust the angle and orientation of the plane reflector (12) accordingly until the actual requirements are met.

5. The method for precise calibration of a folded-axis mirror assembly according to claim 4, wherein: Adjusting the height of the connecting frame (1), obtaining the positions of the spherical center images of the lower surfaces of the first lens (13) and the second lens (14), and further calculating the angular deviation of the plane reflector (12), specifically including: S201. Move the connecting frame (1) on the first guide rail (91) and the second guide rail (92) until the detector (6) captures the spherical center image of the lower surface of the first lens (13), and records the position of the light spot on the detector (6) as (X1, Y1); S202. Move the connecting frame (1) on the first guide rail (91) and the second guide rail (92) until the detector (6) captures the spherical center image of the lower surface of the second lens (14) again, and record the position of the light spot on the detector (6) as (X2, Y2); S203. Calculate the difference between (X1, Y1) and (X2, Y2) as the angular deviation of the plane reflector (12).

6. The method for precise calibration of a folded-axis mirror assembly according to claim 4, wherein: Adjusting the height of the connecting frame (1), obtaining the lower surface positions of the first lens (13) and the second lens (14), and further calculating the air gap between the first lens (13) and the second lens (14), specifically including: S301. Move the connecting frame (1) on the first guide rail (91) and the second guide rail (92) until the detector (6) captures the spherical top image of the lower surface of the first lens (13), and further calculate the position of the lower surface of the first lens (13) based on the analysis result of the spectrometer (5), which is recorded as Z1; S302. Move the connecting frame (1) on the first guide rail (91) and the second guide rail (92) until the detector (6) captures the spherical top image of the lower surface of the second lens (14) again, and further calculate the position of the lower surface of the second lens (14) based on the analysis result of the spectrometer (5), which is recorded as Z2; S303. Calculate the difference between Z1 and Z2 as the air space between the first lens (13) and the second lens (14).

7. The method for precise calibration of a folded-axis mirror assembly according to claim 6, wherein: The analysis result of the spectrometer (5) is specifically as follows: the spectrometer (5) performs light intensity analysis on the light returned by the second lens (14) to obtain the wavelength of the light with the highest reflected light intensity.

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