Ghost image analysis and elimination method for wide-field lobster eye telescope

Abstract

The invention discloses a ghost image analysis and elimination method for a wide-field lobster eye telescope. The method comprises the following steps: calculating a lower boundary value theta min of an incident light angle for generating a ghost image according to structural parameters of a wide-field lobster eye telescope; the maximum value of the total reflection angle of the incident light on the inner wall of the lens is calculated according to the energy of the incident light and the micropore inner wall substrate material, the film layer material and the film layer thickness of the lens of the optical lens, and the maximum value is the upper boundary value theta max of the incident light angle generating the ghost image; according to the upper boundary value theta < max > and the lower boundary value theta < min > of the incident light angle for generating the ghost image, the view field range for generating the ghost image is determined; a baffle is added in the wide-field lobster eye telescope to block a light path generating a ghost image and eliminate the ghost image of the wide-field lobster eye telescope. According to the method, the structural characteristics of a lobster eye optical system are considered, the incidence condition for generating the ghost image is analyzed, the baffle is designed to eliminate the ghost image, and the influence of the ghost image on the imaging quality and target positioning is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of space astronomical detection, and in particular to a method for analyzing and eliminating ghost images of a wide-field lobster-eye telescope. Background Art

[0002] The continuous advancement of space astronomical exploration technology has led to a higher demand for full-sky, high-sensitivity, and high temporal and spatial resolution X-ray observations. The LobsterEye telescope, with its unique wide-field imaging capabilities, has become one of the most promising optical system solutions for soft X-ray astronomical observations. The LobsterEye telescope utilizes the microchannel reflective structure of its optical lenses to focus incident X-rays, boasting a field of view covering tens of degrees. This telescope has broad application prospects in monitoring rapidly evolving celestial events and discovering unexpected celestial objects.

[0003] The optical lens of a wide-field-of-view Lobster Eye telescope typically consists of multiple sections, and the detection system is composed of multiple detectors, one for each section. Due to the structural complexity of the Lobster Eye optical system, light incident at specific angles during imaging can form multiple images on a single detector: a primary image and a ghost image. Ghost images can interfere with the true image of the target, reducing the signal-to-noise ratio, affecting target recognition accuracy, and in severe cases, even leading to misidentification or missed detections.

[0004] While the primary imaging characteristics of LobsterEye systems have been extensively studied, systematic analysis of ghost image generation mechanisms and their elimination methods remain incomplete. Consequently, there is a lack of a ghost image suppression solution that is both applicable to wide-field-of-view (FOV) designs and highly effective and feasible. Therefore, a ghost image analysis and elimination method suitable for wide-field-of-view LobsterEye telescopes is urgently needed to improve the overall imaging quality of the system, enhance target detection capabilities, and meet the requirements of high-precision space astronomical observation missions. Summary of the Invention

[0005] The technical problem solved by the present invention is to overcome the shortcomings of the existing technology and provide a method for analyzing and eliminating ghost images in a wide-field lobster-eye telescope. The method determines the light path that produces the ghost image by calculating the boundary value of the incident light angle that produces the ghost image, and then manufactures a baffle of corresponding length to block the light path and eliminate the ghost image.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for analyzing and eliminating ghost images in a wide-field lobster-eye telescope comprises the following steps:

[0008] Step 1: Calculate the lower boundary value θ of the incident light angle that produces ghost images based on the structural parameters of the wide-field lobster-eye telescope. min ;

[0009] Step 2: Calculate the maximum total internal reflection angle of the incident light on the inner wall of the lens according to the energy of the incident light, the base material, film layer material, and film layer thickness of the microporous inner wall of the optical lens of the optical lens, which is the upper boundary value θ of the incident light angle for ghost image generation max ;

[0010] Step 3: Determine the field of view range for ghost image generation according to the upper boundary value θ max and the lower boundary value θ min of the incident light angle for ghost image generation;

[0011] Step 4: Install a baffle in the wide-field lobster-eye telescope to block the light path for ghost image generation and eliminate the ghost image of the wide-field lobster-eye telescope;

[0012] The position of the baffle is at the central optical axis of the wide-field lobster-eye telescope, and the upper edge of the baffle is in contact with the optical lens.

[0013] As a further technical solution of the present invention: The structural parameters of the wide-field lobster-eye telescope include: the focal length f of the optical lens, the center distance O1O2 between adjacent partitions of the optical lens, and the edge distance D1D2 between adjacent detectors, where O1O2 > 0 and D1D2 > 0;

[0014] The lower boundary value θ min of the incident light angle for ghost image generation is:

[0015]

[0016] As a further technical solution of the present invention: The field of view range for ghost image generation means that on the premise of θ max ≥θ min , when the angle of the incident light is between the upper boundary value θ max and the lower boundary value θ min , a ghost image will be generated on the detector.

[0017] As a further technical solution of the present invention: The length of the baffle is y, and the thickness of the baffle is x; the length y of the baffle should be greater than or equal to the minimum length y min of the baffle to improve redundancy; the calculation method of the minimum length y min of the baffle is to first calculate the projection length l of the area of the optical lens participating in ghost image focusing in the direction perpendicular to the optical axis as:

[0018] l = sin(θ max -θ min ) * 2f,

[0019] Then calculate the minimum length y min of the baffle as:

[0020]

[0021] As a further technical solution of the present invention: the thickness x of the baffle needs to be calculated according to the incident light energy and the absorption coefficient of the baffle material for the incident light, and the absorption rate of the baffle for the incident light should be greater than 90%.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention proposes a method for analyzing and eliminating ghost images of a wide-field lobster-eye telescope, accurately analyzes the light path of the generated ghost images, and thus sets a baffle to eliminate the ghost images to avoid affecting the imaging quality and target positioning of the wide-field lobster-eye telescope;

[0024] (2) The present invention gives a method for designing the size of the baffle for eliminating ghost images, which will not cause other changes to the overall structure of the wide-field lobster-eye telescope, and has the advantages of simplicity and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic flow chart of the method for analyzing and eliminating ghost images of the wide-field lobster-eye telescope of the present invention;

[0026] Figure 2 is a schematic optical path diagram of the lower boundary value θ min of the incident light angle for generating ghost images of the present invention;

[0027] Figure 3 is a schematic optical path diagram of the upper boundary value θ max of the incident light angle for generating ghost images of the present invention;

[0028] Figure 4 is a view of the field of view range for generating ghost images of the present invention;

[0029] Figure 5 is a schematic diagram of the baffle for eliminating ghost images of the present invention;

[0030] Figure 6 is the relationship between the reflectivity of incident light with an energy of 1 keV on the inner wall of the lens and the angle of the present invention.

[0031] Description of the reference numerals:

[0032] 201 - Optical lens partition S1; 202 - Optical lens partition S2; 203 - Center of sphere O1 of optical lens partition S1 (abbreviation: center of sphere O1); 204 - Center of sphere O2 of optical lens partition S2 (abbreviation: center of sphere O2); 205 - Detector edge D1 corresponding to optical lens partition S1 (abbreviation: detector edge D1); 206 - Detector edge D2 corresponding to optical lens partition S2 (abbreviation: detector edge D2); 207 - Focal length f of the optical lens; 208 - Main image; 209 - Ghost image; 210 - Lower boundary value θ of the incident light angle min ;

[0033] 301 - Main image; 302 - Ghost image; 303 - Upper boundary value θ of the incident light angle max ;

[0034] 401 - Light path for generating ghost image;

[0035] 501 - Baffle. Detailed implementation manners

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Here, it should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0038] In addition, it should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non - exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0039] The present invention discloses a method for analyzing and eliminating ghost images of a wide - field lobster - eye telescope. As Figure 1 shown, the specific implementation manners of this method may include:

[0040] Step 1. Calculate the lower boundary value θ of the incident light angle for generating ghost images min ;

[0041] According to the structural parameters of the wide - field lobster - eye telescope, including the focal length f of the optical lens, the center - to - center distance O1O2 of adjacent partitions of the optical lens (O1O2 > 0), and the edge - to - edge distance D1D2 of adjacent detectors (D1D2 > 0), calculate the lower boundary value θ of the incident light angle for generating ghost images min The formula is:

[0042]

[0043] Step 2: Calculate the upper boundary value θ of the incident light angle that generates ghost images max ;

[0044] According to the energy of the incident light and the optical material parameters of the wide-field lobster-eye telescope (including the microporous inner wall base material, film layer material, and film layer thickness of the optical lens), use Fresnel's formula to calculate the maximum value of the total reflection angle of the incident light on the inner wall of the lens, which is the upper boundary value θ of the incident light angle that generates ghost images max .

[0045] Step 3: Determine the field of view range that generates ghost images based on the upper boundary value θ max and the lower boundary value θ min of the incident light angle that generates ghost images;

[0046] On the premise that θ max ≥θ min , when the angle of the incident light is between the upper boundary value θ max and the lower boundary value θ min , ghost images will be generated on the detector

[0047] Step 4: Add a baffle to eliminate ghost images;

[0048] To eliminate the ghost images of the wide-field lobster-eye telescope, add a baffle in the wide-field lobster-eye telescope to block the light path that generates ghost images and eliminate the ghost images of the wide-field lobster-eye telescope

[0049] The position of the baffle is at the central optical axis of the wide-field lobster-eye telescope. The upper edge of the baffle contacts the optical lens. The length of the baffle is y, the thickness of the baffle is x, and the width of the baffle is the same as the width of the optical lens

[0050] The length y of the baffle should be greater than or equal to the minimum length y min of the baffle to improve redundancy; the calculation method of the minimum length y min of the baffle is as follows: First, calculate the projection length l of the area of the optical lens participating in ghost image focusing in the direction perpendicular to the optical axis as:

[0051] l = sin(θ max -θ min ) * 2f;

[0052] Then calculate the minimum length y min of the baffle as:

[0053]

[0054] The thickness x of the baffle needs to be calculated according to the incident light energy and the absorption coefficient of the baffle for the incident light. The absorption rate of the baffle for the incident light should be greater than 90%.

[0055] The method for analyzing and eliminating ghost images of a wide-field lobster-eye telescope according to the present invention will be further described below in conjunction with specific embodiments:

[0056] Figure 2 For the lower boundary value θ of the incident light angle that generates ghost images in the present invention min is a schematic optical path diagram. The optical lens of the wide-field lobster-eye telescope contains two partitions, namely the optical lens partition S1 201 and the optical lens partition S2 202. The centers of the two partitions are the center of the sphere O1 203 and the center of the sphere O2 204 respectively. The distance O1O2 between the two centers of the spheres is 20 mm, and the distance D1D2 between the detector edges D1 205 and D2 206 of the two partitions is 22 mm. The focal length f of the optical lens is 400 mm. The lower boundary value θ of the incident light angle that generates ghost images min 210 is:

[0057]

[0058] When parallel light is incident on the wide-field lobster-eye telescope at the lower boundary value θ of the incident light angle min 210, most of the light is focused on the main image 208 after irradiating the optical lens partition S1 201, but a small part of the light is also focused on the detector corresponding to the optical lens partition S1 201 after irradiating the optical lens partition S2 202, generating a ghost image 209.

[0059] Figure 3 For the upper boundary value θ of the incident light angle that generates ghost images in the present invention max is a schematic optical path diagram. The microporous inner wall base material of the optical lens used in the wide-field lobster-eye telescope is SiO2, the film layer material is a metal Ir film, and the film layer thickness is 20 nm. The relationship between the reflectivity of incident light with an energy of 1 keV on the inner wall of the lens and the angle is as Figure 6 shown. When the grazing incident angle is 7.45°, the reflectivity is less than 1%, and this angle is considered the maximum value of the total reflection angle, that is, the upper boundary value θ of the incident light angle max 303 is 7.45°.

[0060] When parallel light is at the upper boundary value θ of the incident light angle maxWhen the incident light of 303 hits the wide - field lobster - eye telescope, most of the light is focused on the main image 301 after passing through the optical lens partition S1 201. However, a small part of the light hits the edge of the optical lens partition S2 202. Since the grazing - incidence angle is equal to the maximum value of the total - reflection angle, it is also reflected and then focused on the detector corresponding to the optical lens partition S1 201, generating a ghost image 302.

[0061] Figure 4 This is the field - of - view range diagram for generating ghost images of the present invention. When the incident - light angle is between 3.01° and 7.45°, the light hitting the optical lens partition S2 202 will be focused on the detector corresponding to the optical lens partition S1 201, generating a ghost image.

[0062] Figure 5 This is the schematic diagram of the baffle for eliminating ghost images of the present invention. The baffle 501 is located on the central optical axis of the wide - field lobster - eye telescope. The upper edge of the baffle is in contact with the optical lens. The length of the baffle is y, the thickness is x, and the width of the baffle is the same as the width of the optical lens. The material of the baffle 501 is aluminum (Al) with a thickness of 1 mm, and the absorption rate of the baffle 501 for 1 - keV incident light is 100%.

[0063] The projection length l of the light path 401 generating the ghost image in the direction perpendicular to the optical axis is:

[0064] l = sin(θ max - θ min ) * 2f = sin(7.45° - 3.01°) * 2 * 400 = 61.93 mm.

[0065] Therefore, the minimum length y of the baffle min is:

[0066]

[0067] In order to eliminate the influence of the ghost image on the wide - field lobster - eye telescope, the length y of the baffle 501 can be set to 350 mm, with a certain redundancy retained.

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for analyzing and eliminating ghost images of a wide-field lobster-eye telescope, characterized in that, The method includes the following steps: Step 1: Calculate the lower boundary value θ of the incident light angle that generates ghost images according to the structural parameters of the wide-field lobster-eye telescope min ; Step 2: Calculate the maximum value of the total reflection angle of the incident light on the inner wall of the lens, which is the upper boundary value θ of the incident light angle that generates ghost images, based on the energy of the incident light, the base material, film material, and film thickness of the microporous inner wall of the optical lens. max ; Step 3. Determine the field of view range where ghost images are generated according to the upper boundary value θ max and the lower boundary value θ min of the incident light angle that generates ghost images; Step 4: Install a baffle in the wide-field lobster-eye telescope to block the light path that generates ghost images and eliminate the ghost images of the wide-field lobster-eye telescope; The baffle is located on the central optical axis of the wide-field lobster-eye telescope, and the upper edge of the baffle contacts the optical lens.

2. The method for analyzing and eliminating ghost images of a wide-field lobster-eye telescope according to claim 1, characterized in that, The structural parameters of the wide-field lobster-eye telescope include: the focal length f of the optical lens, the center distance O1O2 between adjacent partitions of the optical lens, and the edge distance D1D2 between adjacent detectors, where O1O2 > 0 and D1D2 > 0; The lower boundary value θ of the incident light angle that generates ghost images min is as follows:

3. The method for analyzing and eliminating ghost images of a wide-field lobster-eye telescope according to claim 1, wherein The field of view range for generating ghost images refers to the case where, under the premise of θ max ≥θ min when the angle of the incident light is between the upper boundary value θ max and the lower boundary value θ min ghost images will be generated on the detector.

4. The method for analyzing and eliminating ghost images of a wide-field lobster-eye telescope according to claim 2, characterized in that, The length of the baffle is y, and the thickness of the baffle is x; the length y of the baffle should be greater than or equal to the minimum length y of the baffle min , to improve redundancy; the minimum length y of the baffle min The calculation method is as follows. First, calculate the projected length l of the area where the optical lens participates in ghost image focusing in the direction perpendicular to the optical axis as: l = sin(θ max - θ min ) * 2f, After that, calculate the minimum length y of the baffle min It is:

5. The method for analyzing and eliminating ghost images of a wide-field lobster-eye telescope according to claim 4, characterized in that, The thickness x of the baffle needs to be calculated according to the incident light energy and the absorption coefficient of the baffle material for the incident light, and the absorption rate of the baffle for the incident light should be greater than 90%.

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