Image intensifier transfer function high-precision detection method

Abstract

The invention belongs to the field of transfer function detection, and particularly relates to an image intensifier transfer function high-precision detection method. The method comprises the following steps: 1, connecting and fixing an image intensifier, a reference lead-out assembly and a measuring tool; 2, bonding the annular glass; 3, adjusting the parallelism of the anode of the image intensifier and the annular glass; 4, detecting coincidence precision delta T to be less than or equal to 20 ''by a theodolite; 5, connecting and adjusting the image intensifier and the multi-dimensional adjusting mechanism; 6, measuring the deviation delta d of the installation position of the image intensifier to be less than or equal to 0.005 mm; and 7, developing three coordinates to construct an over-focus curve, and completing transfer function detection of the image intensifier. According to the invention, the development three-coordinate measuring instrument and the multi-dimensional adjusting mechanism are adopted to realize the modular integration of the image intensifier transfer function detection system; and a multi-dimensional adjusting mechanism is adopted, so that the centering precision between the image intensifier and the detector is improved, the assembly error is reduced, and the measurement result is closer to a true value.

Description

Technical Field

[0001] The present invention relates to a method for detecting a transfer function of an image intensifier, and in particular to a method for detecting a transfer function of an image intensifier with high precision. Background Art

[0002] Image intensifiers are mainly used in the field of aerospace low-light level detection. Image intensifier transfer function detection is an important link to ensure the performance and quality of image intensifiers. Through scientific detection methods, the imaging quality of image intensifiers can be accurately evaluated, providing strong support for research and application in related fields.

[0003] The currently commonly used image intensifier transmission function detection method has the following shortcomings:

[0004] (1) The image intensifier transmission signal detection includes the central field of view and the edge field of view. The actual optical path required is composed of an integrating sphere, a target, a collimator, an optical lens and other equipment. The detection optical path is complex and the detection system module has a low integration level.

[0005] (2) In the image intensifier transmission signal detection optical path, the alignment accuracy between the image intensifier and the detector is insufficient, which introduces more measurement errors and reduces the authenticity of the transmission signal detection data;

[0006] (3) When testing the image intensifier transmission function, it is necessary to perform multiple trimming and polishing, which reduces the testing efficiency. In addition, multiple disassembly and assembly may easily cause damage to the anode surface of the image intensifier or the photosensitive surface of the detector.

[0007] (4) The interpretation of the image intensifier transmission function usually relies on the experience of the assembly personnel and cannot achieve more precise quantification;

[0008] (5) It is impossible to realize batch detection of image intensifier transmission functions within a limited time. Summary of the Invention

[0009] The purpose of the present invention is to solve the technical problems of the existing image intensifier transfer function detection method, such as complex detection optical path and low integration of detection system modules; low authenticity of transfer function detection data; low detection efficiency and easy damage to the image intensifier anode surface or detector photosensitive surface; inability to achieve fine quantification of image intensifier transfer function; and inability to achieve batch detection of image intensifier transfer function within a limited time, and to provide a high-precision detection method for image intensifier transfer function.

[0010] To achieve the above object, the technical solution adopted by the present invention is:

[0011] A high-precision detection method for an image intensifier transmission function is characterized in that it comprises the following steps:

[0012] S1. Connect the image intensifier, reference lead assembly and measurement fixture, and place the connected whole on the optical platform;

[0013] S2. Connecting an annular glass to the back of the reference lead-out assembly; the image intensifier, the reference lead-out assembly and the annular glass constitute an image intensifier assembly;

[0014] S3. Place a theodolite in front of the anode of the image intensifier and place the theodolite on a two-dimensional adjustable platform. Adjust the position of the theodolite via the two-dimensional adjustable platform so that the theodolite can simultaneously observe the reflected images of the anode and the annular glass.

[0015] S4. Adjust the overlap of the reflected images of the anode and the annular glass using the reflected image of the anode as a reference, and observe with a theodolite whether the overlap of the reflected images of the anode and the annular glass meets a set overlap condition; if so, execute step S5; if not, readjust the overlap of the reflected images of the anode and the annular glass until the set overlap condition is met;

[0016] S5. Placing the image intensifier assembly on the multi-dimensional adjustment mechanism, with the image intensifier anode facing the interior of the multi-dimensional adjustment mechanism; leveling the image intensifier assembly using the multi-dimensional adjustment mechanism, and measuring the installation position deviation of the image intensifier assembly using a three-dimensional coordinate measuring instrument to see whether it meets a set deviation condition; if so, executing step S6; if not, re-leveling the image intensifier assembly using the multi-dimensional adjustment mechanism until the set deviation condition is met;

[0017] S6. Place the detector inside the multi-dimensional adjustment mechanism and adjust it to be horizontal, and at the same time introduce its horizontal reference into the developing three-dimensional coordinate measuring instrument; use the multi-dimensional adjustment mechanism to air-couple the image intensifier anode and the detector, and adjust the relative position of the developing three-dimensional coordinate measuring instrument and the photocathode of the image intensifier so that the image of the target in the developing three-dimensional coordinate measuring instrument can be imaged by the detector, and the clarity meets the set clarity requirements, thereby determining the focal plane position of the detector; then use the developing three-dimensional coordinate measuring instrument to perform a focus sampling on the clarity of the target image at the focal plane position of the detector to obtain the focus sampling image information, construct an overfocus curve based on the focus sampling image information, and use the focus curve algorithm for machine vision interpretation, obtain the average value of the interpretation, and then realize the image intensifier transmission function detection.

[0018] Furthermore, S1 is specifically:

[0019] S1.1. Using the image intensifier anode as a reference, perform centering processing on the image intensifier and the reference lead-out assembly so that the parallelism of the image intensifier and the reference lead-out assembly meets the set parallelism condition;

[0020] S1.2. Connect the image intensifier anode to the reference lead assembly through the image intensifier flange;

[0021] S1.3. The measuring fixture includes a vertical plate and a bottom plate; the vertical plate and the bottom plate are arranged perpendicularly; the reference lead-out assembly is connected to the vertical plate, and then the bottom plate is placed on the optical platform.

[0022] Furthermore, the parallelism condition is: the parallelism is better than 0.015 mm.

[0023] Furthermore, in S2: the surface of the annular glass is evenly distributed along the circumference thereof with four differentiated cross lines; the surface of the annular glass is coated with a sector-shaped reflective film at each of the four differentiated cross lines; the sector-shaped reflective film is used for observing a reflected image of the annular glass by a theodolite; and the reflective surface of the sector-shaped reflective film of the annular glass is aligned with the direction of the anode of the image intensifier;

[0024] The reference lead-out component is provided with four light-through holes evenly distributed along the circumference, and the four light-through holes are provided in one-to-one correspondence with the four differentiation cross lines;

[0025] The side of the annular glass coated with the fan-shaped reflective film is bonded to the back of the reference lead-out component using hot melt adhesive.

[0026] Furthermore, in S5, any three differentiated cross lines on the annular glass surface are sampled by a developing three-dimensional coordinate measuring instrument to determine whether the parallelism difference Δd between any two of the three differentiated cross lines meets the set deviation condition, Δd∈(0, 0.005) mm; if all meet, execute step S6; if not, re-level the image intensifier assembly through a multi-dimensional adjustment mechanism until the set deviation condition is met.

[0027] Furthermore, in S6, the focus sampling image information is imported into Matlab software to construct an overfocus curve and a focus curve algorithm is used for machine vision interpretation.

[0028] Furthermore, in S4, the reflected image coincidence is defined as Δt, and the coincidence condition is set as: Δt∈(0, 20″).

[0029] The beneficial effects of the present invention are:

[0030] 1. The modular integration of the image intensifier transmission function detection system is realized by using a three-dimensional coordinate measuring instrument and a multi-dimensional adjustment mechanism;

[0031] 2. The multi-dimensional adjustment mechanism improves the centering accuracy between the image intensifier and the detector, reduces assembly errors, and makes the measurement results closer to the true value;

[0032] 3. The development three-dimensional coordinate measuring instrument is used to scan and determine the focal position of the image intensifier transmission letter, eliminating the risk of damage to the image intensifier caused by the traditional use of cutting pads;

[0033] 4. The focus curve is constructed by developing a three-coordinate measuring instrument, and rapid detection of image intensifier transfer function based on machine vision is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flow chart of an embodiment of the present invention;

[0035] Figure 2 Schematic diagram of reference conversion of an image intensifier anode in an embodiment of the present invention;

[0036] Figure 3 1 is a schematic structural diagram of an image intensifier assembly and a measuring tool in an embodiment of the present invention;

[0037] Figure 4 2 is a schematic structural diagram of an annular glass according to an embodiment of the present invention;

[0038] Figure 5 Schematic diagram of the connection between the image intensifier and the multi-dimensional adjustment mechanism in an embodiment of the present invention.

[0039] In the picture:

[0040] 1- Two-dimensional adjustable translation stage, 2- Theodolite, 3- Measuring fixture, 4- Optical platform, 5- Image intensifier assembly, 51- Anode, 52- Reference lead assembly, 53- Image intensifier flange, 54- Ring glass, 55- Differentiation crosshairs, 56- Fan-shaped reflective film, 6- Multi-dimensional adjustment mechanism. DETAILED DESCRIPTION

[0041] To further clarify the objectives, advantages, and features of the present invention, the following describes in further detail a high-precision detection method for image intensifier transmission signals, in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent through the following detailed description. It should be noted that the drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the objectives of the embodiments of the present invention. Furthermore, the structures shown in the drawings are often portions of actual structures.

[0042] See also Figure 1 The present embodiment provides a method for improving the detection accuracy of an image intensifier transmission function, which mainly includes the following steps:

[0043] S1. Connect and fasten the image intensifier, the reference lead-out assembly 52 and the measuring fixture 3 and place them on the optical platform 4.

[0044] For details, see Figure 2 and Figure 3, using the image intensifier anode 51 as a reference, complete the centering process of the image intensifier and the reference lead-out component 52; the centering process of the image intensifier and the reference lead-out component 52 should make the parallelism of the anode 51 and the reference lead-out component 52 better than 0.015mm.

[0045] The measuring fixture 3 is divided into a vertical plate and a base plate, which are used in combination and both have high vertical accuracy and plane accuracy.

[0046] The image intensifier is connected to the reference lead-out assembly 52 via the image intensifier flange 53 ; the reference lead-out assembly 52 is connected to the vertical plate, and then the bottom plate is placed on the optical platform 4 .

[0047] S2. The annular glass 54 is bonded to the back of the reference lead-out component 52.

[0048] See also Figure 4 The surface of the annular glass 54 is engraved with differentiated cross lines 55 and coated with a fan-shaped reflective film 56, and is evenly distributed on the surface of the annular glass 54 along the circumference; the differentiated cross lines 55 and the fan-shaped reflective film 56 of the annular glass 54 are kept in the same direction as the anode 51 of the image intensifier through the reference lead-out component 52; the reflective film surface of the annular glass 54 should be bonded to the back of the reference lead-out component 52 to reduce the influence of the glass optical path difference on the measurement accuracy.

[0049] The annular glass 54 on the back of the reference lead-out assembly 52 is bonded using hot melt adhesive, which has the advantage of facilitating the disassembly and assembly of the annular glass 54 without causing damage to the annular glass 54 .

[0050] The reference lead-out component 52 is provided with four light-through holes evenly distributed along the circumference. The four light-through holes are provided in one-to-one correspondence with the four differentiated cross lines 55 , thereby realizing combined use with the engraved surface of the annular glass 54 .

[0051] The image intensifier, the reference lead-out assembly 52 and the annular glass 54 together constitute the image intensifier assembly 5 .

[0052] S3, see Figure 2 Place theodolite 2 in front of the image intensifier's anode 51. Adjust theodolite 2 to infinity and use the autocollimation image as a reference for measurement. Place theodolite 2 on a two-dimensionally adjustable platform. Adjust the platform's position so that theodolite 2 can simultaneously observe the reflected image of the image intensifier's anode 51 and the annular glass 54.

[0053] S4. Based on the reflected image of the image intensifier anode 51, the coincidence of the reflected images of the image intensifier anode 51 and the annular glass 54 is adjusted. The coincidence of the reflected images of the image intensifier anode 51 and the annular glass 54 is observed through the theodolite 2 to see whether it meets the set coincidence condition. If so, step S5 is executed. If not, the coincidence of the reflected images of the image intensifier anode and the annular glass 54 is readjusted until the set coincidence condition is met.

[0054] Specifically, the precision of the overlap between the reflected image of the annular glass 54 and the reflected image of the image intensifier anode 51 is Δt; when Δt∈(0, 20″), the overlap precision requirement of the image intensifier anode 51 and the annular glass 54 is met, so that the two have a high degree of parallelism;

[0055] S5, see Figure 5 The image intensifier assembly 5 is placed on a multi-dimensional adjustment mechanism 6, an electrically controlled mechanical device capable of translation, rotation, tilt, and pitch with an accuracy of 0.1 μm. The image intensifier anode 51 is positioned facing the interior of the multi-dimensional adjustment mechanism 6. The image intensifier assembly 5 is leveled using the multi-dimensional adjustment mechanism 6. A three-dimensional coordinate measuring instrument is used to sample any three differentiated crosshairs 55 on the surface of the annular glass 54. A determination is made as to whether the parallelism difference Δd between any two of the three differentiated crosshairs 55 satisfies a set deviation condition, Δd∈(0, 0.005) mm. If so, the image intensifier assembly 5 is confirmed to be horizontal, and step S6 is executed. If not, the image intensifier assembly 5 is re-leveled using the multi-dimensional adjustment mechanism 6 until the set deviation condition is satisfied.

[0056] S6. Use the developing three-coordinate measuring instrument to complete the image intensifier transmission function detection.

[0057] The detector is placed inside the multi-dimensional adjustment mechanism 6 and adjusted to a horizontal level, while its reference is introduced into the development three-coordinate system. The image intensifier anode 51 is air-coupled to the detector placed on the optical platform 4 using the multi-dimensional adjustment mechanism 6. By adjusting the relative position of the development three-coordinate system and the photocathode of the image intensifier, the image of the target in the development three-coordinate measuring instrument can be imaged by the detector, and the clarity meets the set clarity requirements, thereby determining the focal plane position of the detector. The sampling step size is set, and the clarity of the target at the focal plane position is sampled. The image information sampled after the focus scan is imported into the Matlab software to construct the overfocus curve and the focus sampling algorithm is used for machine vision interpretation. The average value of the interpretation is obtained to achieve rapid detection of the image intensifier transfer function.

[0058] At the same time, according to the distribution of the area occupied by the image intensifier anode in the detector when the image intensifier is used, a developing three-coordinate measuring instrument can be used to achieve precise displacement and precision detection; according to the distribution of the channels occupied by the image intensifier anode 51 in the detector, the transfer function detection of different field of view ranges of the image intensifier can be achieved.

Claims

1. A high-precision detection method for image intensifier transmission function, characterized in that: The following steps are involved: S1, connecting the image intensifier, the reference lead assembly (52) and the measuring fixture (3), and placing the connected whole on the optical platform (4); S2, connecting an annular glass (54) to the back of the reference lead-out assembly (52); the image intensifier, the reference lead-out assembly (52) and the annular glass (54) constitute an image intensifier assembly (5); S3, placing a theodolite (2) at the front end of the anode (51) of the image intensifier, and placing the theodolite (2) on a two-dimensional adjustable platform, and adjusting the position of the theodolite (2) by using the two-dimensional adjustable platform so that the theodolite (2) can simultaneously observe the reflected images of the anode (51) and the annular glass (54); S4, taking the reflection image of the anode (51) as a reference, adjusting the reflection image coincidence of the anode (51) and the annular glass (54), and observing whether the reflection image coincidence of the anode (51) and the annular glass (54) meets the set coincidence condition through the theodolite (2); if so, executing step S5; if not, re-adjusting the reflection image coincidence of the anode (51) and the annular glass (54) until the set coincidence condition is met; S5, placing the image intensifier assembly (5) on the multi-dimensional adjustment mechanism (6), wherein the image intensifier anode (51) is arranged facing the interior of the multi-dimensional adjustment mechanism (6); leveling the image intensifier assembly (5) by the multi-dimensional adjustment mechanism (6), and measuring the installation position deviation of the image intensifier assembly (5) by a developing three-dimensional coordinate measuring instrument to determine whether it meets the set deviation condition; if so, executing step S6; if not, re-leveling the image intensifier assembly (5) by the multi-dimensional adjustment mechanism (6) until the set deviation condition is met; S6, placing the detector inside the multi-dimensional adjustment mechanism (6) and adjusting it to be horizontal, while introducing its horizontal reference into the development three-dimensional coordinate measuring machine; The image intensifier anode (51) is air-coupled with the detector using a multi-dimensional adjustment mechanism (6). The relative position of the developing three-dimensional coordinate measuring instrument and the photocathode of the image intensifier is adjusted so that the image of the target in the developing three-dimensional coordinate measuring instrument can be imaged by the detector and the clarity meets the set clarity requirement, thereby determining the focal plane position of the detector. The developing three-dimensional coordinate measuring instrument is then used to perform focus sampling on the clarity of the target image at the focal plane position of the detector to obtain focus sampling image information. An overfocus curve is constructed based on the focus sampling image information and a focus curve algorithm is used to perform machine vision interpretation. The average value of the interpretation is obtained, thereby realizing image intensifier transmission function detection.

2. The high-precision detection method for image intensifier transmission function according to claim 1, characterized in that: S1 is specifically: S1.

1. Using the image intensifier anode (51) as a reference, centering the image intensifier and the reference lead-out assembly (52) is performed so that the parallelism of the anode (51) and the reference lead-out assembly (52) meets a set parallelism condition; S1.

2. Connect the image intensifier to the reference lead assembly (52) via the image intensifier flange (53); S1.

3. The measuring fixture (3) includes a vertical plate and a bottom plate; the vertical plate and the bottom plate are arranged perpendicularly; the reference lead-out component (52) is connected to the vertical plate, and then the bottom plate is placed on the optical platform (4).

3. The high-precision detection method for image intensifier transmission function according to claim 2, characterized in that: The parallelism condition is: the parallelism is better than 0.015 mm.

4. A high-precision detection method for image intensifier transmission function according to any one of claims 1 to 3, characterized in that: In S2: The surface of the annular glass (54) is evenly distributed along the circumference with four differentiation cross lines (55); the surface of the annular glass (54) is plated with fan-shaped reflection films (56) at the four differentiation cross lines (55); the fan-shaped reflection films (56) are used for the theodolite (2) to observe the reflected image of the annular glass (54); the reflection surface of the fan-shaped reflection film (56) of the annular glass (54) is aligned with the direction of the anode (51) of the image intensifier; The reference lead-out component (52) is provided with four light-through holes evenly distributed along the circumference, and the four light-through holes are provided in one-to-one correspondence with the four differentiation cross lines (55); The side of the annular glass (54) coated with the fan-shaped reflective film (56) is bonded to the back of the reference lead-out component (52) using hot melt adhesive.

5. The high-precision detection method for image intensifier transmission function according to claim 4, characterized in that: In S5, any three differentiated cross lines (55) on the surface of the annular glass (54) are sampled by a developing three-dimensional coordinate measuring instrument to determine whether the parallelism difference Δd between any two of the three differentiated cross lines (55) all meet the set deviation condition, Δd∈(0, 0.005) mm; if all meet, step S6 is executed; if not, the image intensifier assembly (5) is re-leveled by a multi-dimensional adjustment mechanism (6) until the set deviation condition is met.

6. The high-precision detection method for image intensifier transmission function according to claim 1, characterized in that: In S6, the focus sampling image information is imported into Matlab software to construct the overfocus curve and the focus curve algorithm is used for machine vision interpretation.

7. A high-precision detection method for image intensifier transmission function according to claim 1 or 6, characterized in that: In S4, the reflected image coincidence is defined as Δt, and the coincidence condition is set as: Δt∈(0, 20″).

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