A superlens phase design method for correcting field asymmetric chromatic aberration of a multi-aperture system and a multi-aperture system based on a superlens

Abstract

The application belongs to the technical field of optical instruments, and discloses a superlens phase design method for correcting field asymmetric chromatic aberration of a multi-aperture system and a multi-aperture system based on a superlens. 020 111 , and are parameters of an original multi-aperture system without the superlens, and are parameters of the superlens; and dispersion phase compensation is performed on the diffraction phase of the superlens to obtain a final phase of the superlens. The method realizes correction of field asymmetric chromatic aberration of the multi-aperture system based on the superlens. The superlens is used, and the superlens is simple to assemble, the system structure is simple and compact, the machining precision of the superlens is high, and through design of the phase of the superlens, effective correction of field asymmetric chromatic aberration in the multi-aperture system can be realized.​

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field related to optical instruments, and more particularly, to a superlens phase design method for correcting field asymmetric chromatic aberration of a multi-aperture system and a multi-aperture system based on a superlens. BACKGROUND

[0002] In the current data-driven era, the demand for multi-dimensional information beyond the perception ability of the human eye is increasing. Multi-aperture optical systems obtain different dimensions of information through multiple optical channels composed of sub-lenses with different apertures, and have shown great potential in commercial applications and academic research. However, the asymmetric characteristics of multi-aperture systems introduce field asymmetric monochromatic aberration and lateral chromatic aberration, which severely limits the development of large-aperture, long-focal-length multi-aperture systems.

[0003] There are some methods for chromatic aberration correction. Using a reflective system with a free-form surface, this method can effectively correct aberration and does not need to consider chromatic aberration, but the system is large in size and complex in assembly, which is not suitable for application scenarios that require miniaturization and simplification. Using a refractive system, combining lenses of different shapes and materials, this method effectively corrects chromatic aberration and monochromatic aberration, but often leads to complex and bulky optical system structure, thereby limiting its practical application in optical systems. Using diffractive optical elements (DOEs), this method provides a more compact solution, but adding diffractive optical elements to multi-aperture systems has low machining precision and poor efficiency, and the chromatic aberration correction effect in multi-aperture systems is not ideal. As an array of subwavelength structures, metalenses exhibit excellent ability in manipulating light fields. Compared with traditional DOEs, metalenses have higher precision and efficiency, but they are difficult to solve the problem of field asymmetric chromatic aberration introduced by the asymmetric characteristics of multi-aperture systems.

[0004] Therefore, the present application proposes a multi-aperture system asymmetric chromatic aberration correction method, which effectively corrects the field asymmetric chromatic aberration in the multi-aperture system in a simple way. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a superlens phase design method for correcting field asymmetric chromatic aberration of a multi-aperture system and a multi-aperture system based on a superlens, which aims to effectively correct the field asymmetric chromatic aberration in the multi-aperture system in a simple way.

[0006] To achieve the above purpose, the present application provides a superlens phase design method for correcting field asymmetric chromatic aberration of a multi-aperture system, which includes:

[0007] According to the relationship and Calculating expansion coefficients in diffraction phase expansion expression of superlens and obtaining a diffraction phase of the superlens; wherein λ is a wavelength, W 020 , W 111 , and are parameters of an original multi-aperture system without the superlens, W 020 and W 111 are wave aberrations of defocus and wavefront tilt in the system, and respectively represent amounts of stop decentration and stop shift, an image height vector and a normalized pupil vector in the system, and are parameters of the superlens, and are wave aberrations of defocus and wavefront tilt provided by the superlens to correct, and are amounts of stop decentration and stop shift provided by the superlens, is a partial derivative with respect to the wavelength λ, is a partial derivative with respect to the wavelength λ;

[0008] performing dispersion phase compensation on the diffraction phase of the superlens to obtain a final phase of the superlens for correcting field asymmetrical chromatic aberration of the multi-aperture system.

[0009] Optionally, the diffraction phase expansion expression of the superlens is:

[0010]

[0011]

[0012] wherein, is a diffraction phase of the superlens, j>2 is an order of expansion, is a j-th order expansion term, ξ j (λ) is a coefficient of the j-th order expansion term, represents a j-th order diffraction phase expansion expression.

[0013] Optionally, the calculation formula for performing dispersion phase compensation on the diffraction phase of the superlens is:

[0014]

[0015] wherein, is a diffraction phase of the superlens, Δφ meta (λ) is a phase dispersion transferred by a cylindrical microstructure in the superlens at the wavelength λ, ​is the final phase of the superlens at wavelength λ.

[0016] Optionally, one superlens is installed in each aperture channel, and the phase distribution of the superlens in any aperture channel is calculated first, and then the phase distribution of the superlens in other aperture channels is determined through the plane symmetry of the multi-aperture system.

[0017] Optionally, the parameter is determined by constructing and fitting the relationship of the field-asymmetric aberration of the original multi-aperture system affected by the diaphragm eccentricity and displacement.

[0018] Optionally, the relationship of the field-asymmetric aberration of the multi-aperture system affected by the diaphragm eccentricity and displacement is:

[0019]

[0020] wherein, is the wave aberration coefficient of the original multi-aperture system is the partial derivative of wavelength λ, and the piston is an aberration coefficient independent of the pupil coordinate.

[0021] The application also provides a multi-aperture system based on a superlens, wherein the multi-aperture system is installed with a superlens for realizing field-asymmetric aberration correction, and the phase of the superlens satisfies the phase designed by the method according to any one of the above.

[0022] The application also provides an electronic device comprising a memory and a processor, wherein the memory stores a computer program, and wherein the processor implements the steps of the method according to any one of the above when executing the computer program.

[0023] The application also provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and wherein the computer program is executed by a processor to implement the steps of the method according to any one of the above.

[0024] The application also provides a computer program product comprising a computer program or instructions, wherein the computer program or instructions are executed by a processor to implement the steps of the method according to any one of the above.

[0025] Overall, compared with the prior art, the above technical solutions conceived by the application mainly have the following beneficial effects:

[0026] The present application realizes efficient correction of field asymmetric chromatic aberration of a multi-aperture system, so that the imaging quality of the system is significantly improved.

[0027] The present application significantly simplifies the structural design of the multi-aperture system, while ensuring high-precision assembly of the system.

[0028] Further, by constructing a theoretical model of the influence of the off-centering and displacement of the diaphragm on the field asymmetric chromatic aberration of the multi-aperture system, the parameters of the off-focus dispersion term and the lateral dispersion term required by the superlens for chromatic aberration correction of the multi-aperture system can be accurately obtained.

[0029] Further, by determining the phase distribution of the superlens of other aperture channels through the planar symmetry of the multi-aperture system, the design efficiency of the phase distribution of the superlens of other aperture channels can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic diagram of the axial movement and lateral off-centering of the diaphragm in the multi-aperture system leading to lateral chromatic aberration;

[0031] Figure 2 is a step flow chart of the superlens phase design method for correcting the field asymmetric chromatic aberration of the multi-aperture system in an embodiment of the present application;

[0032] Figure 3 is a schematic diagram of the theoretical model of the asymmetric chromatic aberration of the multi-aperture system;

[0033] Figure 4 is a schematic diagram of the structure of the multi-aperture quantum dot camera in an embodiment of the present application, wherein (a) is a three-dimensional structure schematic diagram of the multi-aperture quantum dot camera, and (b) is an elevation view of the multi-aperture quantum dot camera;

[0034] Figure 5(a) is an MTF curve for camera channel 2;

[0035] Figure 5(b) is a point spread diagram for camera channel 2. DETAILED DESCRIPTION

[0036] 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 embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0037] As shown in Figure 1, in a multi-aperture system, the axial movement and lateral eccentricity of the stop can cause lateral chromatic aberration. As shown in Figure 2, when the stop is located at the center of the thin lens, the chief rays of different wavelengths all pass through the center of the lens without deflection, so no lateral chromatic aberration is generated; as shown in Figure 3, when the stop is moved along the optical axis, the chief rays of different wavelengths are incident on the lens at different angles and positions, and after refraction, they pass through the center of the stop and converge at different heights on the image plane, generating lateral chromatic aberration; as shown in Figure 4, when the stop is further eccentric, this chromatic aberration becomes more pronounced. Figure 1 Figure 1 To achieve effective correction of field asymmetrical chromatic aberration in a multi-aperture system in a simple way, the present application proposes the following solutions. Figure 1 Figure 1 Embodiment 1

[0038] The present application is based on the correction of field asymmetrical chromatic aberration in a multi-aperture system using a superlens. The superlens is simple to assemble, the system structure is simple and compact, and the machining precision of the superlens is high. The present application can also achieve effective correction of field asymmetrical chromatic aberration in a multi-aperture system by designing the phase of the superlens. As shown in Figure 5, the present application is an embodiment of a method for designing the phase of a superlens for correcting field asymmetrical chromatic aberration in a multi-aperture system. The steps of the method are described in detail below.

[0039] Specifically, the superlens diffraction phase can be expanded to obtain the superlens diffraction phase expansion expression, as shown below.

[0040] Step S1: According to the relationship Figure 2 and

[0041] Step S2: Calculate the expansion coefficients in the superlens diffraction phase expansion expression and Step S3: Obtain the diffraction phase of the superlens. Specifically, the superlens diffraction phase can be expanded to obtain the superlens diffraction phase expansion expression, as shown below.

[0042] Specifically, the superlens diffraction phase can be expanded to obtain the superlens diffraction phase expansion expression, as shown below.​​​

[0043]

[0044] represents the image height vector, represents the normalized pupil vector, and the two parameters are system parameters of the multi-aperture system;

[0045] Φ diff is the diffraction phase of the superlens to be solved for chromatic aberration correction of the multi-aperture system;

[0046] is the wave aberration of the defocus required to be provided by the superlens, is the partial derivative with respect to the wavelength λ, reflecting the defocus dispersion term parameter required to be provided by the superlens; is the wave aberration of the wavefront tilt required to be provided by the superlens, is the partial derivative with respect to the wavelength λ, reflecting the lateral dispersion term parameter required to be provided by the superlens; is the diffraction stop shift amount provided by the superlens, which is determined by the installation position of the superlens, and the installation position of the superlens determines the provided diffraction stop shift amount; is the second-order expansion in the expansion expression, is the first-order expansion in the expansion expression, and the parameter are parameters to be solved for;

[0047] is the high-order expansion, j>2 represents the expansion order, and ξ j (ω) is the coefficient of the j-order expansion term, ω is the optical wave frequency, represents the j-order phase expansion expression. In specific operations, the high-order expansion or its value is determined by fitting.

[0048] Based on the above superlens diffraction phase expansion expression, the values of and need to be determined, and then the diffraction phase Φ diff of the superlens is calculated, and the final phase of the superlens is determined through phase compensation, so that the superlens can realize the non-symmetrical chromatic aberration correction of the multi-aperture system.

[0049] Therefore, the key of the technical solution is how to calculate the defocus dispersion term parameter required to be provided by the superlens and the lateral dispersion term parameter required to be provided by the superlens. The phase of the superlens is designed to have the function of correcting the non-symmetrical chromatic aberration of the multi-aperture system.

[0050] Analysis of the diffraction chromatic aberration of the superlens and the inherent chromatic aberration of the optical system By making the two opposite in sign and equal in magnitude, the following specific calculation relationship can be derived:

[0051]

[0052] In the formula, W 020 W 111 , and For the parameters of the original multi-aperture system without the superlens installed, W 020 and W 111 These are the defocused wavefront aberration and the wavefront tilted wavefront aberration in the system, respectively. and These represent the aperture eccentricity, aperture shift, image height vector, and normalized pupil vector in the system, respectively. The aperture shift is... y is the height of the principal ray, and y is the height of the rim ray.

[0053] This relationship allows for the rapid calculation of the defocus dispersion parameters required by the superlens. And the lateral dispersion parameters required by the superlens Substituting the diffraction phase expansion expression of the superlens, the diffraction phase of the superlens is obtained. Experiments show that the superlens designed by this method can effectively correct the field asymmetric chromatic aberration in a multi-aperture system.

[0054] In a specific embodiment, in order to obtain the defocused wavefront aberration W in the original multi-aperture system 020 Wavefront tilt and wavefront aberration W 111 By constructing a theoretical model of the field asymmetric chromatic aberration in a multi-aperture system affected by aperture eccentricity and displacement, the nodal characteristics of chromatic aberration can be determined, and the defocused wave aberration W in the multi-aperture system can be determined by fitting the model. 020 Wavefront tilt and wavefront aberration W 111 .

[0055] Specifically, the theoretical model is as follows:

[0056]

[0057] In the formula, Waveform coefficients of the original multi-aperture system The partial derivative with respect to wavelength λ, pistons is an aberration coefficient independent of pupil coordinates, which can usually be ignored in aberration analysis.

[0058] like Figure 3As shown in the schematic diagram of the theoretical model of the asymmetric chromatic aberration of the multi-aperture system, (a) is a schematic diagram of the lateral chromatic aberration distribution of the full field of view of the system when the diaphragm is eccentric, and (b) is a wavelength-dependent beam footprint caused by diaphragm offset and eccentricity, wherein the dashed circle represents the influence of diaphragm offset, the solid circle represents the influence of eccentricity, and different gray levels represent different wavelengths. Through the model, the relationship between the diaphragm position and the lateral chromatic aberration can be quantitatively analyzed.

[0059] Step S2: Dispersive phase compensation is performed on the diffraction phase of the superlens to obtain the final phase of the superlens for realizing field asymmetric chromatic aberration correction of the multi-aperture system.

[0060] Specifically, after obtaining the diffraction phase of the superlens, the final phase of the superlens is calculated by a dispersive phase compensation algorithm, and the specific calculation formula is:

[0061]

[0062] In the formula, φ is the diffraction phase of the superlens, Δφ meta (λ) is the phase dispersion transmitted by the columnar microstructure in the superlens at the wavelength λ, is the final phase of the superlens at the wavelength λ.

[0063] Since the multi-aperture system usually has multiple light waves of different wavelengths, the light wave types can cover the visible light waveband to the long-wave infrared, and the wavelength range can cover 0.39 μm to 14 μm, which can meet the requirements of high-end optical systems for imaging quality. In order to correct the asymmetric chromatic aberration at different wavelengths, different phase designs are required for the superlens at different wavelengths. In specific operations, the above steps can be performed for each wavelength to determine the phase of the superlens at that wavelength. As found through analysis, the diffraction phase of the superlens calculated at different wavelengths is the same, so a wavelength can be selected as a reference wavelength, and after the diffraction phase of the superlens is calculated, the dispersive phase compensation algorithm is performed based on the diffraction phase for other wavelengths, so that the phase of the superlens at each wavelength can be quickly obtained. Specifically, the central wavelength can generally be selected as the reference wavelength.

[0064] Since the multi-aperture system has multiple aperture channels, each aperture channel corresponds to the installation of an ultra-lens, and the phase of the ultra-lens used in each aperture channel is different, therefore, the phase distribution of the ultra-lens in each aperture channel needs to be calculated respectively. Specifically, the above method can be repeated for each aperture channel to obtain the phase distribution of the ultra-lens in each aperture channel. In this embodiment, the phase distribution of the ultra-lens under any aperture channel is calculated first, and then the phase distribution of the ultra-lens of other aperture channels is determined through the plane symmetry of the multi-aperture system. The strategy utilizes the plane symmetry of the system, and through the design of the basic phase distribution and the mirror transformation, the phase distribution of the ultra-lens of all channels can be determined efficiently.

[0065] Embodiment 2

[0066] The application also provides a multi-aperture system based on an ultra-lens, wherein the multi-aperture system is provided with an ultra-lens for realizing field asymmetric chromatic aberration correction, and the phase of the ultra-lens satisfies the phase designed in Embodiment 1. The ultra-lens is specifically installed between a spherical array and a detector window sheet.

[0067] Embodiment 3

[0068] The application also relates to an electronic device, which comprises a memory and a processor, the memory stores a computer program, and the processor realizes the steps of Embodiment 1 when executing the computer program.

[0069] The electronic device can be a desktop computer, a notebook computer, a palm computer, a cloud server and the like. The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The memory can be used to store computer programs and / or modules, and the processor realizes various functions of the electronic device by running or executing the computer programs and / or modules stored in the memory, and calling data stored in the memory.

[0070] Embodiment 4

[0071] The application also relates to a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the method provided in Embodiment 1.

[0072] In particular, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one magnetic disk storage device, a flash memory device, or other volatile solid-state memory device.

[0073] Embodiment 5

[0074] The embodiment of the present application provides a computer program product or computer program, which comprises computer instructions stored in a computer readable storage medium. A processor of a computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions, so that the computer device executes steps of the method in the above embodiment 1 of the present application.

[0075] The effect of the present application is verified through specific experiments below.

[0076] The experiment designs a multi-aperture quantum dot camera working in a 2.5um-4um wave band range based on a quantum dot detector, adopts a hybrid optical system of a super lens and a traditional refractive lens, and corrects field asymmetric chromatic aberration of the multi-aperture system through the super lens.

[0077] Figure 4 Fig. 1 is a structural schematic diagram of a multi-aperture quantum dot camera, wherein (a) is a three-dimensional structural schematic diagram of the multi-aperture quantum dot camera, and (b) is an elevation view of the multi-aperture quantum dot camera. The camera comprises a plurality of parallel optical channels, each channel comprising even aspheric lenses, refractive lenses, super lenses and quantum dot detectors, specifically comprising aspheric lens 1, aspheric lens 2, aspheric lens 3, aspheric lens 4, aspheric lens 5, aspheric lens 6, spherical array 7, spherical array 8, super lens 9, super lens 10, detector window sheet 11, cold light diaphragm 12 and image surface 13.

[0078] The camera uses three aspheric refractive lenses, one spherical array lens and one nine-channel super lens array design. The specific performance parameters of the camera are shown in Table 1, the structural parameters of the camera are shown in Table 2, the aspheric lens parameters in the multi-aperture camera are shown in Table 3, the spherical array parameters in the multi-aperture camera are shown in Table 4, the super lens phase coefficient table and eccentricity in the multi-aperture camera are shown in Table 5. Only the parameters of three channels are provided in Table 4 and Table 5, and the parameters of other channels can be determined by plane symmetry.

[0079] Table 1: Performance parameters of the multi-aperture camera

[0080]

[0081] Table II: Structural parameters of the multi-aperture camera

[0082]

[0083]

[0084] Table III: Aspherical lens parameters in the multi-aperture camera

[0085] Conic coefficient 4th order coefficient 6th order coefficient 8th order coefficient Asphere 1 -8.352 1.238E-005 -3.328E-009 -5.507E-012 Asphere 2 5.641 2.306E-005 -2.187E-008 5.086E-012 Asphere 3 -6.087 9.965E-005 -1.327E-007 1.097E-010 Asphere 4 -1.238 -1.1503E-005 7.876E-007 -2.989E-009 Asphere 5 -3.246 -7.913E-005 1.226E-006 -3.906E-009 Asphere 6 -9.491 -4.696E-005 1.237E-006 -4.234E-009

[0086] Table IV: Spherical array parameters and decentration in the multi-aperture camera

[0087]

[0088] Table V: Superlens phase coefficient table and decentration in the multi-aperture camera

[0089]

[0090] Figure 5(a) 、 5(b) The MTF curve and the spot diagram of the camera channel 2 are shown in FIGS. 9 and 10, respectively, which verifies that the system has good imaging quality and effectively solves the problem of field asymmetric chromatic aberration in the multi-aperture system.

[0091] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure. It should be noted that the “in an embodiment of the present disclosure”, “for example”, “for instance” and the like are intended to illustrate the present disclosure, but not to limit the present disclosure.

[0092] The above-described embodiments only express several embodiments of the present disclosure, which are described in detail and specifically, but should not be construed as limiting the scope of the patent application. It should be noted that for those skilled in the art, without departing from the concept of the present disclosure, a number of modifications and improvements can be made, which are within the scope of the present disclosure.

Claims

1. A method for designing the phase of a superlens to correct field asymmetry chromatic aberration in a multi-aperture system, characterized in that, include: According to the relation and Calculate the expansion coefficients in the expression for phase expansion of superlens diffraction. and The diffraction phase of the superlens is obtained; where, For wavelength, , , , , and The parameters are for the original multi-aperture system without the superlens installed. and These are the defocused wavefront aberration and the wavefront tilted wavefront aberration in the system, respectively. , , and These represent the aperture eccentricity, aperture shift, image height vector, and normalized pupil vector in the system, respectively. , , and These are the parameters of the superlens. and The superlens is used to correct the defocused wavefront aberration and the wavefront tilted wavefront aberration required for correction. and The aperture offset and aperture shift provided for the superlens for For wavelength The partial derivatives, For wavelength The partial derivatives; Dispersion phase compensation is performed on the diffraction phase of the superlens to obtain the final phase for the superlens to achieve field asymmetric chromatic aberration correction of the multi-aperture system. The expression for the phase expansion of the superlens diffraction is as follows: ； In the formula, This represents the diffraction phase of the superlens. j >2 indicates the order of the expansion. for j Order expansion term, for j The coefficients of the expansion terms of order, represent j The expression for the phase expansion of the diffraction order.

2. The superlens phase design method for correcting field asymmetric chromatic aberration in multi-aperture systems as described in claim 1, characterized in that, The formula for calculating the dispersive phase compensation of the diffraction phase of the superlens is as follows: In the formula, This represents the diffraction phase of the superlens. For columnar microstructures in superlenses at wavelength Downward propagation of phase dispersion, For the wavelength of the superlens The final phase below.

3. The superlens phase design method for correcting field asymmetric chromatic aberration in multi-aperture systems as described in claim 1, characterized in that, Each aperture channel corresponds to a superlens. After calculating the phase distribution of the superlens in any aperture channel, the phase distribution of the superlens in other aperture channels is determined by the planar symmetry of the multi-aperture system.

4. The superlens phase design method for correcting field asymmetric chromatic aberration in multi-aperture systems as described in claim 1, characterized in that, parameter , The relationship between the field asymmetric chromatic aberration of the original multi-aperture system and the influence of aperture eccentricity and displacement was determined by constructing and fitting the equation.

5. The superlens phase design method for correcting field asymmetric chromatic aberration in multi-aperture systems as described in claim 4, characterized in that, The relationship between the field asymmetric chromatic aberration of the multi-aperture system and the influence of aperture eccentricity and displacement is as follows: In the formula, Waveform coefficients of the original multi-aperture system For wavelength The partial derivatives, These are aberration coefficients that are independent of pupil coordinates.

6. A multi-aperture system based on a superlens, characterized in that, The multi-aperture system is equipped with a superlens for achieving field asymmetric chromatic aberration correction, the phase of which satisfies the phase designed by the method according to any one of claims 1 to 5.

7. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 5.

9. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method as described in any one of claims 1 to 5.

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