Edge enhancement imaging system and method of manufacture

Abstract

The application relates to an edge enhancement imaging system, which comprises a point light source, an object-side polarization filter unit arranged on the light-emitting side of the point light source and used for modulating light into specific polarized light to irradiate on a sample, an imaging unit arranged on the light-emitting side of the object-side polarization filter unit and used for propagating an input light field to an imaging surface, a spatial variable polarization modulation element arranged on the conjugate surface of the point light source relative to the imaging unit and used for spatial variable polarization modulation to obtain a modulated light field, an image-side polarization filter unit arranged between the spatial variable polarization modulation element and the imaging surface and used for screening the modulated light field to obtain a specific polarization direction light field, and the specific polarization direction light field forms an edge enhancement imaging light field on the imaging surface. The application also relates to a preparation method of the edge enhancement imaging system. The beneficial effect is that the imaging effect of arbitrary direction or full direction edge enhancement is realized, the common microscope imaging system can be compatible, the phase modulation is realized through polarization state transformation, and the sensitivity to wavelength is reduced.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to an edge-enhancing imaging system and its fabrication method. Background Technology

[0002] The feature information of an object is mostly concentrated at its edges. Determining the edge location and extracting information has important applications in image recognition, autonomous driving, and optical information processing. The object edge corresponds to the region with a large amplitude or phase gradient in its optical field mathematical expression. Spatial filtering techniques are usually used in optical 4f systems to filter out low-order Fourier components and enhance high-order Fourier components to achieve edge processing. However, this intensity-based filtering system often affects the overall imaging intensity, resulting in insufficient efficiency.

[0003] Currently, spiral phase-contrast imaging is a boundary detection method that can achieve boundary enhancement in any direction without changing the overall light intensity. It is based on the traditional 4f system and obtains edge enhancement effect on the imaging plane by placing a spiral phase filter on the confocal Fourier surface. However, this method has obvious drawbacks: the optical path of the 4f system is complex, requiring multiple lenses for coordinated filtering, and it has strict requirements for the light source, making it incompatible with common microscope imaging systems; at the same time, the traditional spiral phase filter relies on the thickness difference of the filter changing with the angle to introduce spiral phase, which is highly wavelength sensitive and only effective for specific wavelengths. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide an edge enhancement imaging system and preparation method that does not rely on the traditional 4f system. The spatial polarization modulation element is placed on the conjugate surface of the point light source relative to the imaging unit, and a polarization filter element is placed in front of the imaging unit to achieve edge enhancement imaging effect in any direction or all directions. It is compatible with common microscope imaging systems. Phase modulation is achieved through polarization state transformation, which reduces the sensitivity to wavelength.

[0005] To address the aforementioned technical problems, the present invention provides an edge enhancement imaging system, comprising,

[0006] A point light source is used to emit light.

[0007] An object-side polarization filter unit is located on the light-emitting side of the point light source to modulate the light into specific polarized light and irradiate the sample to form an input light field;

[0008] An imaging unit is located on the light-emitting side of the object-side polarization filter unit and is used to propagate the input light field to the imaging surface.

[0009] A spatial polarization modulation element is disposed on the conjugate surface of the point light source relative to the imaging unit, and is used to perform spatial polarization modulation on the input light field to obtain a modulated light field;

[0010] The image polarization filtering unit is disposed between the spatial polarization modulation element and the imaging surface, and is used to filter the modulated light field to obtain a light field with a specific polarization direction. The light field with the specific polarization direction forms an edge-enhanced imaging light field on the imaging surface.

[0011] In one feasible implementation, the imaging unit includes a lens or objective lens or an optical imaging device based on the principle of conjugate imaging.

[0012] In one feasible implementation, the object-side polarization filter unit includes a linear polarizer that modulates the light into linearly polarized light.

[0013] Alternatively, the light can be modulated into a circularly polarized waveplate.

[0014] In one feasible implementation, the image-side polarization filtering unit includes the linear polarizer for filtering the light field to the specific polarization direction for edge enhancement in all directions or a specific direction.

[0015] In one feasible implementation, when the object-side polarization filter unit is the linear polarizer, the image-side polarization filter unit performs edge enhancement in a specific direction.

[0016] When the object-side polarization filter unit is the waveplate, the image-side polarization filter unit performs omnidirectional edge enhancement.

[0017] In one feasible implementation, the spatially variable polarization modulation element is a polarization spiral waveplate, the intrinsic polarization state of which varies linearly with the angle, and the Jones matrix of the polarization spiral waveplate varying with space is: ,

[0018] ;

[0019] in, This represents the distance from a point on the polarization spiral waveplate to the central axis;

[0020] This indicates the circumferential position of a point on the polarization spiral waveplate with respect to the central axis.

[0021] In one feasible implementation, the conjugate condition between the plane containing the point light source and the plane containing the spatially variable polarization modulation element is expressed by the following expression.

[0022] ;

[0023] in, This represents the distance from the point light source to the image-side principal plane in the imaging unit;

[0024] This represents the distance from the image-side principal plane of the imaging unit to the spatially variable polarization modulation element;

[0025] This indicates the focal length of the imaging unit.

[0026] In one feasible implementation, the conjugate condition between the imaging plane and the object plane containing the sample is expressed by the following expression.

[0027] ；

[0028] in, This represents the distance from the object plane to the image-side principal plane in the imaging unit;

[0029] This represents the distance from the image-side principal plane to the imaging surface in the imaging unit;

[0030] This indicates the focal length of the imaging unit.

[0031] In one feasible implementation, the expression for the edge-enhanced imaging light field is:

[0032] ;

[0033] in, This represents the edge-enhanced imaging light field;

[0034] The radial coordinate of the imaging surface corresponds to the radius of its spatial position;

[0035] The azimuth angle of the imaging plane corresponds to the circumferential angle of the spatial position;

[0036] This represents the distance from the image-side principal plane to the imaging surface in the imaging unit;

[0037] This represents the distance from the image-side principal plane of the imaging unit to the spatially variable polarization modulation element;

[0038] This indicates a second phase that does not affect the imaging results;

[0039] This represents the input light field;

[0040] Represents the polarization point spread function;

[0041] This indicates the angle between the polarization direction of the input light and the x-axis;

[0042] The Jones matrix represents the spatial variation of the polarization spiral waveplate;

[0043] This represents the Jones vector of the input light.

[0044] In one feasible implementation, a light intensity capturing unit is also included for capturing the edge-enhanced imaging light field filtered by the spatial polarization modulation element. The light intensity capturing unit includes a charge-coupled device sensor or a complementary metal-oxide-semiconductor sensor.

[0045] Accordingly, the present invention also provides a method for fabricating an edge-enhancing imaging system, comprising,

[0046] Provide a point light source for emitting light;

[0047] A surface polarization filter unit is provided and placed on the light-emitting side of the point light source to modulate the light into specific polarized light and irradiate the sample to form an input light field;

[0048] An imaging unit is provided and disposed on the light-emitting side of the object-side polarization filter unit to propagate the input light field to the imaging surface;

[0049] A spatial polarization modulation element is provided and disposed on the conjugate surface of the point light source relative to the imaging unit, for spatial polarization modulation of the input light field to obtain a modulated light field;

[0050] A side-polarization filtering unit is provided and disposed between the spatial polarization modulation element and the imaging surface to filter the modulated light field to obtain a light field with a specific polarization direction. The light field with the specific polarization direction forms an edge-enhanced imaging light field on the imaging surface.

[0051] Implementing this invention has the following beneficial effects:

[0052] By placing the spatially variable polarization modulation element on the conjugate surface of the point light source relative to the imaging unit, and placing a polarization filter element in front of the imaging unit, it is possible to achieve imaging effects with edge enhancement in any direction or all directions. It does not rely on the traditional 4f system and is compatible with common microscope imaging systems. Phase modulation is achieved through polarization state transformation, reducing sensitivity to wavelength.

[0053] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0054] Figure 1This is a schematic diagram of the edge enhancement imaging system of the present invention;

[0055] Figure 2 This is a schematic diagram of the spatial polarization modulation element of the present invention;

[0056] Figure 3 This is a schematic diagram of the input object of the present invention;

[0057] Figure 4 This is a schematic diagram of the point spread function of the object-side input circularly polarized and image-side unpolarized filtering system of the present invention.

[0058] Figure 5 This is a schematic diagram of the imaging result when the object-side input is circularly polarized and the image-side is unpolarized filtering system of the present invention.

[0059] Figure 6 This is a schematic diagram of the point spread function of the present invention when the object input is linearly polarized in the x-direction and the image-side is unpolarized filter system.

[0060] Figure 7 This is a schematic diagram of the imaging result when the object-side input of the present invention is linearly polarized in the x-direction and the image-side has no polarization filtering system.

[0061] Figure 8 This is a step diagram of the preparation method of the edge enhancement imaging system of the present invention. Detailed Implementation

[0062] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0063] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0065] This invention provides an edge enhancement imaging system, with reference to Figure 1 ,include,

[0066] Point light source 110, used to emit light;

[0067] The object-side polarization filter unit 120 is located on the light-emitting side of the point light source 110, which modulates the light into specific polarized light and irradiates the sample to form an input light field;

[0068] Imaging unit 130 is located on the light-emitting side of object-side polarization filter unit 120 and is used to propagate the input light field to imaging surface 160.

[0069] Spatial polarization modulation element 140 is disposed on the conjugate surface of point light source 110 relative to imaging unit 130, and is used to spatially polarize the input light field to obtain the modulated light field.

[0070] The image polarization filter unit 150 is located between the spatial polarization modulation element 140 and the imaging surface 160. It is used to filter the modulated light field to obtain a light field with a specific polarization direction. The light field with the specific polarization direction forms an edge-enhanced imaging light field on the imaging surface 160.

[0071] Specifically, this invention provides an edge-enhancing imaging system that can be directly integrated into a microscope system without altering the microscope structure. Edge enhancement imaging in a specific direction is achieved by applying a spatially variable polarization modulation element 140 in the optical path. Using a superstructure waveplate whose polarization eigenstates change linearly with angle, placed on the conjugate plane of the point light source 110 with respect to the transmission imaging unit 130, edge enhancement can be achieved in the final image when the object, the object-side principal plane, and the imaging distance from the image-side principal plane satisfy a Gaussian imaging relationship, without affecting the light intensity.

[0072] In one feasible implementation, the imaging unit 130 includes a lens or objective lens or an optical imaging device based on the principle of conjugate imaging.

[0073] Specifically, the imaging unit 130 includes a single lens or objective lens or any optical imaging device based on the conjugate imaging principle. Optical imaging devices based on the conjugate imaging principle (such as telecentric lenses or imaging lens groups) can be adapted to different types of optical systems, thus broadening the application scenarios of edge enhancement technology.

[0074] In one feasible implementation, the object-side polarization filter unit 120 includes a linear polarizer that modulates light into linearly polarized light.

[0075] Or a waveplate that modulates light into circularly polarized light;

[0076] The image polarization filter unit 150 includes a linear polarizer for filtering light fields to a specific polarization direction for edge enhancement in all directions or a specific direction;

[0077] When the object-side polarization filter unit 120 is a linear polarizer, the image-side polarization filter unit 150 performs edge enhancement in a specific direction.

[0078] When the object-side polarization filter unit 120 is a waveplate, the image-side polarization filter unit 150 performs omnidirectional edge enhancement.

[0079] Specifically, when circularly polarized light is input, the light intensity is concentrated at the edge of the object; when linearly polarized light is input, it only enhances the boundary in a specific direction.

[0080] In one feasible implementation, the spatially variable polarization modulation element 140 is a polarization spiral waveplate, the intrinsic polarization state of which changes linearly with the angle, as referenced. Figure 2 The Jones matrix of the polarization spiral waveplate varies with space as follows: ,

[0081] ;

[0082] in, This represents the distance from a point on the polarizing spiral plate to the central axis.

[0083] It indicates the circumferential position of a point on a polarizing spiral waveplate with respect to the central axis.

[0084] In one feasible implementation, the conjugate condition between the plane containing the point light source 110 and the plane containing the spatially polarized modulation element 140 is expressed by the following expression.

[0085] ;

[0086] in, This represents the distance from point light source 110 to the image-side principal plane in imaging unit 130;

[0087] This represents the distance from the image-side principal plane in the imaging unit 130 to the spatial polarization modulation element 140;

[0088] This indicates the focal length of imaging unit 130.

[0089] In one feasible implementation, the conjugate condition between the imaging plane 160 and the object plane 170 containing the sample is expressed by the following expression.

[0090] ；

[0091] in, This represents the distance from the object plane 170 to the image-side principal plane in the imaging unit 130;

[0092] This represents the distance from the image-side principal plane in the imaging unit 130 to the imaging plane 160;

[0093] This indicates the focal length of imaging unit 130.

[0094] In a feasible implementation, when the above conjugate condition relationship is satisfied, the expression for the final output edge-enhanced imaging light field is:

[0095] ;

[0096] in, Indicates the edge-enhanced imaging light field;

[0097] This represents the radial coordinate of the imaging plane 160°, corresponding to the radius of the spatial position.

[0098] This represents the azimuth angle of the imaging plane at 160 degrees, corresponding to the circumferential angle of the spatial position.

[0099] This represents the distance from the image-side principal plane in the imaging unit 130 to the imaging plane 160;

[0100] This represents the distance from the image-side principal plane in the imaging unit 130 to the spatial polarization modulation element 140;

[0101] This indicates a second phase that does not affect the imaging results;

[0102] Indicates the input light field;

[0103] Represents the polarization point spread function;

[0104] This indicates the angle between the polarization direction of the input light and the x-axis;

[0105] The Jones matrix representing the spatial variation of a polarizing spiral waveplate;

[0106] This represents the Jones vector of the input light.

[0107] In one feasible implementation, a light intensity capturing unit is also included for capturing the edge-enhanced imaging light field filtered by the spatially variable polarization modulation element 140. The light intensity capturing unit includes a charge-coupled device sensor (CCD) or a complementary metal-oxide-semiconductor sensor (CMOS).

[0108] Specifically, charge-coupled devices (CCDs) can capture photons with an efficiency of over 90%, and can capture even weaker edge-enhancing light fields in low-light environments (such as fluorescence imaging and biological sample observation), avoiding the loss of edge information due to insufficient light intensity. For example, in this embodiment, circularly polarized input does not result in light intensity loss, but the reflected light from the sample may be weak. The high sensitivity of the CCD ensures that the edge light intensity distribution is clearly recorded.

[0109] CCDs typically have lower noise levels than CMOS, making them suitable for scenarios with high signal-to-noise ratio requirements (such as medical microscopy). They can reduce noise interference with edge positioning and ensure the accuracy of edge enhancement effects.

[0110] Complementary metal-oxide-semiconductor (CMOS) sensors can simultaneously handle both high-intensity and low-intensity light regions, avoiding contrast distortion between bright edges and dark backgrounds in edge-enhanced light fields. For example, when there are significant differences in light intensity at the sample edges, CMOS can effectively preserve edge details in each region. CMOS sensors consume far less power than CCDs, making them suitable for portable devices (such as field inspection microscopes), and they can integrate signal processing circuitry, simplifying system design and reducing hardware costs.

[0111] In one embodiment, a point light source 110 is placed at infinity for the experiment. The point light source 110 emits 532nm spherical waves that illuminate the sample, which is shaped like the English letter N. Figure 3 As shown. Since point light source 110 is located at infinity, according to the Jones matrix described above, Equal to f, a polarizing spiral waveplate is placed in this plane. The distance between the sample and the object-side principal plane of the imaging system is... for The focal length of the imaging system is Therefore, according to the conjugate condition formula, the distance from the imaging plane to the image-side principal plane of the imaging system is... for Therefore, its magnification is approximately 1.11 times.

[0112] First, we calculate the case where the object-side spiral polarization filter system has circularly polarized incident light, in which case L is... Based on the expression for the final output imaging surface light field, the point spread function expression is now:

[0113] ;

[0114] in, The first-order Bessel function is represented. It can be seen that, except for the polarization Jones vector at the very front, the point spread function expression is the same as that of ordinary spiral phase-contrast imaging, both possessing a spiral phase function. Therefore, the final imaging effect is the same as that of ordinary spiral phase-contrast imaging based on a spiral phase plate. The final result is as follows... Figure 4 , Figure 5 As shown, the light intensity is mainly concentrated at the edge of the object, and the boundary in any direction is highlighted.

[0115] When the object-space polarization filter system is Directional polarizer, i.e., the Jones vector of the input light In the expression It is 0.

[0116] ;

[0117] In the object-space polarization system, applying Because of the directional linear polarizer, according to the above formula, the intensity of the point spread function will differ from the previous symmetrical form, exhibiting an asymmetrical distribution. After convolution with the input light field, enhancement of the boundary in a specific direction can be achieved. The final imaging result is as follows... Figure 6 , Figure 7 As shown, it is consistent with the theory, only The boundaries of one direction are enhanced, while the boundaries of another direction change are not highlighted.

[0118] Accordingly, the present invention also provides a method for fabricating an edge enhancement imaging system, referring to... Figure 8 ,include,

[0119] Step S100: Provide a point light source 110 for emitting light;

[0120] Step S200: Provide an object-side polarization filter unit 120, place it on the light-emitting side of the point light source 110, and modulate the light into specific polarized light to irradiate the sample to form an input light field;

[0121] Step S300: Provide an imaging unit 130 and place it on the light-emitting side of the object-side polarization filter unit 120 to propagate the input light field to the imaging surface 160.

[0122] Step S400: A spatial polarization modulation element 140 is provided and disposed on the conjugate surface of the point light source 110 relative to the imaging unit 130, for spatial polarization modulation of the input light field to obtain the modulated light field.

[0123] In step S500, an image-side polarization filtering unit 150 is provided and disposed between the spatial polarization modulation element 140 and the imaging surface 160. It is used to filter the modulated light field to obtain a light field with a specific polarization direction. The light field with the specific polarization direction forms an edge-enhanced imaging light field on the imaging surface 160.

[0124] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0125] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An edge-enhanced imaging system, characterized by, Comprising, a point light source for emitting light rays; an object-side polarization filter unit arranged on the light emitting side of the point light source, for modulating the light rays into specific polarized light to irradiate on a sample, forming an input light field; an imaging unit arranged on the light emitting side of the object-side polarization filter unit, for propagating the input light field to an imaging plane; a spatially variable polarization modulation element arranged on the conjugate plane of the point light source relative to the imaging unit, for spatially variable polarization modulation of the input light field, obtaining a modulated light field; an image-side polarization filter unit arranged between the spatially variable polarization modulation element and the imaging plane, for screening the modulated light field to obtain a specific polarization direction light field, which forms an edge-enhanced imaging light field on the imaging plane.

2. The edge-enhanced imaging system of claim 1, wherein, The imaging unit comprises an optical imaging device based on the principle of conjugate imaging.

3. The edge-enhanced imaging system of claim 2, wherein, The optical imaging device comprises an objective lens.

4. The edge-enhanced imaging system of claim 2, wherein, The optical imaging device comprises a lens.

5. The edge-enhanced imaging system of claim 1, wherein, The object-side polarization filter unit comprises a linear polarizer for modulating the light rays into linearly polarized light, or a wave plate for modulating the light rays into circularly polarized light.

6. The edge-enhanced imaging system of claim 5, wherein, The image-side polarization filter unit comprises the linear polarizer, for screening the specific polarization direction light field to perform edge enhancement in all directions or specific directions.

7. The edge-enhanced imaging system of claim 5, wherein, When the object-side polarization filter unit is the linear polarizer, the image-side polarization filter unit performs specific direction edge enhancement; When the object-side polarization filter unit is the wave plate, the image-side polarization filter unit performs edge enhancement in all directions.

8. The edge-enhanced imaging system of claim 1, wherein, The spatially varying polarization modulation element is a polarization spiral waveplate whose eigenpolarization states vary linearly with angle, and whose spatially varying Jones matrix is , ； wherein denotes the distance of a point on the polarizing spiral wave plate to the center axis; denotes the circumferential position of a point on the polarization spiral wave plate with respect to the central axis.

9. The edge-enhanced imaging system of claim 1, wherein, The conjugate condition between the plane where the point light source is located and the plane where the spatially variable polarization modulation element is located is represented by the following expression, ； wherein represents the distance of the point light source to the image-side principal plane in the imaging unit; denotes the distance of the image-side principal plane in the imaging unit to the spatially varying polarization-modulating element; denotes the focal length of the imaging unit.

10. The edge-enhanced imaging system of claim 1, wherein, The conjugate condition between the imaging plane and the object plane where the sample is located is represented by the following expression, ； wherein denotes the distance of the object plane to the image-side principal plane in the imaging unit; denotes the distance of the image-side principal plane in the imaging unit to the imaging surface; denotes the focal length of the imaging unit.

11. The edge-enhanced imaging system of claim 8, wherein, The expression of the edge-enhanced imaging light field is ； wherein, represents the edge-enhanced imaging light field; a radial coordinate of the imaging surface, corresponding to a radius of the spatial position; azimuth angle of the imaging surface, corresponding to the circumferential angle of the spatial position; denotes the distance of the image-side principal plane in the imaging unit to the imaging surface; denotes the distance of the image-side principal plane in the imaging unit to the spatially varying polarization-modulating element; represents a secondary phase that does not affect the imaging result; representing the input light field; denotes the point spread function of polarization; denotes the angle between the input light polarization direction and the x-axis; a Jones matrix representing a spatial variation of the polarization spiral wave plate; J represents the Jones vector of the input light.

12. The edge-enhanced imaging system of claim 1, wherein, Further comprising a light intensity capturing unit for capturing the edge-enhanced imaging light field filtered by the spatially variable polarization modulation element, the light intensity capturing unit comprising a charge coupled device sensor or a complementary metal oxide semiconductor sensor.

13. A method of making an edge-enhanced imaging system, the method comprising: Comprising, providing a point light source for emitting light rays; providing an object-side polarization filter unit arranged on the light emitting side of the point light source, for modulating the light rays into specific polarized light to irradiate on a sample, forming an input light field; providing an imaging unit arranged on the light emitting side of the object-side polarization filter unit, for propagating the input light field to an imaging plane; providing a spatially variable polarization modulation element arranged on the conjugate plane of the point light source relative to the imaging unit, for spatially variable polarization modulation of the input light field, obtaining a modulated light field; providing an image-side polarization filter unit arranged between the spatially variable polarization modulation element and the imaging plane, for screening the modulated light field to obtain a specific polarization direction light field, which forms an edge-enhanced imaging light field on the imaging plane.

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