Channel spectrum test system based on point detector and test method thereof

Abstract

The invention belongs to the field of spectrum testing, and particularly relates to a channel spectrum testing system and method based on a point detector, and the method comprises the steps: S1, enabling a light source to emit composite light to a splicing primary mirror; s2, the compound light is reflected by each sub-mirror of the spliced primary mirror and then enters an interferometer for interference to form interference light; s3, interference light is subjected to dispersion of a dispersion prism and compression shaping of a cylindrical lens in sequence to form linear light spots, and the linear light spots are received by a point detector array; and S4, performing fitting and phase calculation on the dispersion interference fringes to realize confocal adjustment of the spliced primary mirror. The method does not need to calibrate dispersion interference fringes, greatly reduces the cost and complexity of the system, and improves the reliability of the system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical measurement and detection, and particularly relates to a channel spectrum testing system based on a point detector and a testing method thereof. BACKGROUND

[0002] Traditional large-aperture space telescopes using a single mirror have great difficulties in mirror processing, detection, and transportation and launching of the entire mirror body, and therefore, a spliced primary mirror structure has become an important trend in the development of new-generation large-aperture space telescopes. However, the co-phasal errors between the sub-mirrors of the spliced primary mirror need to be strictly corrected, and in order to achieve diffraction-limited imaging resolution, the co-phasal errors between the sub-mirrors of the spliced primary mirror need to be less than 1 / 40 wavelength.

[0003] The dispersive interference fringe sensing technology is one of the commonly used methods for co-phasal error detection. It uses a light source and a dispersive element to realize wide-spectrum interference, thereby improving the detection range of the translation errors between the sub-mirrors. Compared with Hartmann sensors, four-pyramid sensors, and Zernike contrast sensors, the dispersive interference fringe sensing technology is not affected by the 2π ambiguity, and does not require strict pupil alignment or focal point alignment, and therefore has a good application prospect. The dispersive interference fringe sensing technology needs a specific dispersive interference fringe processing method to extract the co-phasal error information from the dispersive interference fringes. However, the current dispersive interference fringe processing methods generally rely on calibration, including wavelength calibration, light source spectrum calibration, and detector pose calibration. For a spliced space telescope, these complex calibration processes will greatly increase the cost and complexity of the system and reduce the reliability. SUMMARY

[0004] Therefore, the present application aims to provide a channel spectrum testing system based on a point detector and a testing method thereof, so as to solve the technical problem that the current dispersive interference fringe processing methods are difficult to be applied to a spliced space telescope.

[0005] To achieve the above-mentioned object, the technical scheme of the present application is as follows: A channel spectrum testing system based on a point detector, comprising a light source, a spliced primary mirror, and an interferometer; wherein, The light source is used for emitting composite light; The spliced primary mirror is used for receiving and reflecting the composite light emitted by the light source, and the spliced primary mirror is spliced by at least two sub-mirrors, and the composite light reflected by the adjacent two sub-mirrors enters the interferometer to form interference light; The interferometer comprises a dispersive prism, a cylindrical lens, and a point detector array; wherein, The dispersive prism is used for dispersing the interference light to form dispersed light; The cylindrical lens is used for compressing the dispersed light into a line light spot; The point detector array is used for receiving a line light spot and fitting and phase resolving of the dispersive interference fringes, so that the confocal adjustment of the mosaic primary mirror is realized.

[0006] Further, a microlens array is arranged between the cylindrical lens and the point detector array, and the line light spot is converged to the point detector array through the microlens array.

[0007] Further, a spiral phase plate is arranged in the outgoing direction of the light source, and is used for modulating the composite light into vortex light.

[0008] Further, the channel spectrum test system further comprises the same number of actuators as the sub-mirrors, and each sub-mirror is adjusted through the corresponding actuator.

[0009] A channel spectrum test method based on a point detector is realized by using the channel spectrum test system based on the point detector, and comprises the following steps: S1: The light source emits composite light to the mosaic primary mirror; S2: The composite light is reflected by each sub-mirror of the mosaic primary mirror and then enters the interferometer to form interference light; S3: The interference light is dispersed by the dispersive prism and compressed and shaped by the cylindrical lens into a line light spot and is received by the point detector array; S4: The dispersive interference fringes are fitted and phase-resolved, so that the confocal adjustment of the mosaic primary mirror is realized.

[0010] Further, the light intensity values on the point array detector array are extracted, the extracted light intensity values are fitted by using a spline function selection to realize the minimum order of fitting, the light intensity values are fitted by using a sinusoidal curve, and extreme points are extracted, the phase of the dispersive interference fringes is solved according to the extreme points, and the confocal adjustment of the mosaic primary mirror is realized.

[0011] Further, the light intensity values on a single sub-mirror are fitted first, and then the light intensity values at the joint of two sub-mirrors are fitted.

[0012] Further, when the test system is provided with a microlens array, the average light intensity is obtained through the microlens array, and the light intensity values are fitted based on the average light intensity.

[0013] Further, a beam splitter is arranged between the cylindrical lens and the point detector array, the point detector array is arranged on one outgoing surface of the beam splitter, a camera is arranged on the other outgoing surface of the beam splitter, the line light spot is split by the beam splitter, part of the line light spot enters the camera, and the other part enters the point detector array, the dispersive interference fringes collected by the camera are converted into concentric fringes with a preset sparsity, and then the sinusoidal curve fitting is performed on the point detector array.

[0014] Compared with the prior art, the present application does not need to calibrate the dispersive interference fringes, greatly reduces the system cost and complexity, and improves the system reliability. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application, illustrate preferred embodiments of the application, and assist in explaining the application. In the drawings: Figure 1 Structure diagram of the point detector based channel spectral test system according to the embodiments of the present application; Figure 2 Flow chart of the point detector based channel spectral test method according to the embodiments of the present application; Figure 3 Interference diagram of the dispersed interference fringes according to the embodiments of the present application; Figure 4 Fitting result diagram of the dispersed interference fringes according to the embodiments of the present application; Figure 5 Fitting diagram of the light intensity value on a single sub-mirror according to the embodiments of the present application; Figure 6 Fitting diagram of the light intensity value at the splicing position of two sub-mirrors according to the embodiments of the present application; Figure 7 Pre-step diagram of the point detector based channel spectral test method according to the embodiments of the present application.

[0016] Legend: Splicing primary mirror 1, dispersive prism 2, cylindrical lens 3, dispersed interference fringes 4, composite light 5, beam splitter 6, camera 7, point detector array 8. DETAILED DESCRIPTION

[0017] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and do not constitute limitation of the present application.

[0018] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0019] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0020] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "assembly", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0021] The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0022] As Figure 1 shown, the channel spectrum test system based on point detector provided by the embodiment of the present application includes a light source, a spliced main mirror 1 and an interferometer, the light source is used to emit composite light 5; the spliced main mirror 1 is used to receive and reflect the composite light 5 emitted by the light source, the spliced main mirror 1 is spliced by at least two sub-mirrors, the composite light 5 reflected by the adjacent two sub-mirrors enters the interferometer to interfere and form interference light; the interferometer includes a dispersion prism 2, a cylindrical lens 3 and a point detector array, the dispersion prism 2 is used to disperse the interference light to form dispersed light; the cylindrical lens 3 is used to compress the dispersed light into a line light spot; the point detector array is used to receive the line light spot and fit and phase solve the dispersed interference fringes 4, to realize the confocal adjustment of the spliced main mirror 1.

[0023] The light intensity values on the point array detector array are extracted, the spline function is used to fit the extracted light intensity values and extract extreme points, the phase of the dispersed interference fringes 4 is solved according to the extreme points, and the confocal adjustment of the spliced main mirror 1 is realized.

[0024] A microlens array is placed between the cylindrical lens 3 and the point detector array. The line light spot is converged to the point detector array through the microlens array. The average light intensity is obtained after the line light spot passes through the microlens array, and the light intensity value is fitted based on the average light intensity.

[0025] A spiral phase plate is set in the emission direction of the light source to modulate the composite light into vortex light. The vortex light has symmetry, which is used to improve the measurement accuracy.

[0026] The channel spectral testing system also includes actuators of the same number as the sub-mirrors. Each sub-mirror is adjusted by a corresponding actuator, that is, the confocal adjustment of the stitching primary mirror 1 is achieved by the actuators.

[0027] like Figure 2 As shown, this invention also provides a channel spectral testing method based on a point detector, implemented using the aforementioned channel spectral testing system based on a point detector, comprising the following steps: S1: The light source emits composite light to the splicing main mirror.

[0028] S2: The composite light is reflected by the sub-mirrors of the splicing main mirror and then enters the interferometer to form interference light.

[0029] S3: The interference light is dispersed by the dispersive prism and compressed and shaped into a line spot by the cylindrical lens and then received by the point detector array.

[0030] S4: Fit and phase-calculate the dispersive interference fringe 4 to achieve confocal adjustment of the splicing primary mirror.

[0031] The light intensity values ​​on the dot matrix detector array are extracted, and a sine curve is fitted to the extracted light intensity values ​​by gradually reducing the order of the spline function. In this way, the minimum order to achieve the fitting is found, and then the fitted sine curve is obtained according to the minimum order. The extreme points are extracted from the sine curve, and the phase of the dispersive interference fringes is solved according to the extreme points to realize the confocal adjustment of the stitching primary mirror.

[0032] like Figure 5 and Figure 6 As shown, when fitting the light intensity value, the light intensity value on a single sub-mirror is fitted first, and then the light intensity value at the junction of the two sub-mirrors is fitted.

[0033] like Figure 7 As shown, a beam splitter 6 is set between the cylindrical lens 3 and the point detector array. The point detector array 8 is set on one exit surface of the beam splitter 6, and a camera 7 is set on the other exit surface of the beam splitter 6. After the line light spot is split by the beam splitter 6, part of it enters the camera 7 and the other part enters the point detector array 8. The dispersive interference fringes collected by the camera 7 are adjusted into concentric fringes with a preset sparsity, and then a sine curve is fitted to the point detector array 8.

[0034] To achieve automated adjustment of the actuator, the light intensity value is used as input and the adjustment amount of the actuator on the sub-mirror is used as output. The neural network is trained to obtain the sub-mirror adjustment model. When the light intensity value is obtained, it is input into the trained sub-mirror adjustment model to calculate the corresponding adjustment amount of the sub-mirror and output to the actuator to adjust the sub-mirror.

[0035] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0036] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A channel spectral testing system based on a point detector, characterized in that, Includes a light source, a mosaic primary mirror, and an interferometer; among which, The light source is used to emit composite light; The splicing primary mirror is used to receive and reflect the composite light emitted by the light source. The splicing primary mirror is composed of at least two sub-mirrors. The composite light reflected by two adjacent sub-mirrors enters the interferometer to interfere and form interference light. The interferometer comprises a dispersive prism, cylindrical lenses, and a point detector array; among which, Dispersive prisms are used to disperse interfering light, forming dispersed light; Cylindrical lenses are used to compress dispersed light into linear light spots; The point detector array is used to receive line light spots and fit and calculate the phase of the dispersive interference fringes to achieve confocal adjustment of the splicing primary mirror.

2. The channel spectral testing system based on a point detector according to claim 1, characterized in that, A microlens array is placed between the cylindrical lens and the point detector array, and the line light spot is converged to the point detector array through the microlens array.

3. The channel spectral testing system based on a point detector according to claim 1, characterized in that, A spiral phase plate is provided in the emission direction of the light source to modulate the composite light into vortex light.

4. The channel spectral testing system based on a point detector according to claim 1, characterized in that, It also includes actuators equal to the number of sub-scopes, with each sub-scope being adjusted via a corresponding actuator.

5. A channel spectral testing method based on a point detector, implemented using the channel spectral testing system based on a point detector as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1: The light source emits composite light towards the splicing main mirror; S2: The composite light is reflected by each of the sub-mirrors of the splicing main mirror and then enters the interferometer to form interference light; S3: The interference light is dispersed by the dispersive prism and compressed and shaped into a line spot by the cylindrical lens and then received by the point detector array. S4: Fit and calculate the phase of the dispersive interference fringes to achieve confocal adjustment of the splicing primary mirror.

6. The channel spectral testing method based on a point detector according to claim 5, characterized in that, The light intensity values ​​on the dot matrix detector array are extracted. A spline function is used to select the minimum order of fitting to fit the extracted light intensity values ​​as a sine curve and extract the extreme points. The phase of the dispersive interference fringes is solved based on the extreme points to achieve confocal adjustment of the splicing primary mirror.

7. The channel spectral testing method based on a point detector according to claim 6, characterized in that, First, the light intensity value on a single sub-mirror is fitted, and then the light intensity value at the junction of two sub-mirrors is fitted.

8. The channel spectral testing method based on a point detector according to claim 6 or 7, characterized in that, When the testing system is equipped with a microlens array, the average light intensity is obtained through the microlens array, and the light intensity value is fitted based on the average light intensity.

9. The channel spectral testing method based on a point detector according to claim 6, characterized in that, A beam splitter is placed between the cylindrical lens and the point detector array. The point detector array is set on one exit surface of the beam splitter, and a camera is set on the other exit surface of the beam splitter. After the line light spot is split by the beam splitter, part of it enters the camera and the other part enters the point detector array. The dispersive interference fringes collected by the camera are adjusted into concentric fringes with a preset sparsity, and then a sine curve is fitted to the point detector array.

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