Optical view field expansion and dynamic distortion compensation method for light field display

Abstract

The invention discloses an optical view field expansion and dynamic distortion compensation method for light field display, and particularly relates to the technical field of light field display, and the method comprises the steps: determining a configuration scheme through building a collaborative structure parameter model of a microlens array and a free-form surface optical element; then, the focal length distribution of the micro-lens array and the curvature distribution of the free-form surface optical element are adjusted, so that the expansion of an optical view field is realized; acquiring light information in an expanded view field range by using a wavefront sensor, and establishing an optical distortion mathematical model; calculating wavefront error distribution based on an optical error inversion algorithm and generating a compensation control signal; and adjusting response parameters of the optical element according to the compensation control signal, correcting the light wavefront, feeding back the corrected light field information to update wavefront error distribution, and iteratively generating a new compensation control signal. According to the invention, a light field display field angle can be effectively expanded, distortion after field expansion is reduced, and good application compatibility is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of light field display technology, and more particularly, to an optical field of view expansion and dynamic distortion compensation method for light field display. BACKGROUND

[0002] Light field display technology provides a display effect with three-dimensional spatial sense for users by restoring the direction and intensity information of light rays, and is a key supporting technology in the fields of virtual reality, naked-eye 3D, etc. At present, in order to improve the immersion experience of users, the light field display system needs to expand the field of view as much as possible, while ensuring the uniformity of the edge field of view light rays to match the human visual characteristics.

[0003] However, the existing light field display system has obvious deficiencies in field of view expansion and distortion control: first, when a microlens array is used alone for field of view expansion, the light ray direction sampling is incomplete due to the sampling condition limitation, and the edge field of view is prone to vignetting effect, the light ray collection efficiency is greatly deviated, and it is difficult to meet the large field of view display requirement; second, when a freeform optical element is used for field of view angle deflection, the asymmetric surface shape is easy to introduce wavefront aberration and geometric distortion, and the existing technology mostly uses static correction scheme, which cannot cope with the dynamic distortion caused by environmental factors (such as temperature drift) and mechanical vibration during system operation, seriously affecting the display clarity; third, the coordinated design of microlens array and freeform element lacks a unified parameter modeling method, and the element spacing and optical parameter matching is unreasonable, which easily leads to disorder of light ray propagation path, further reducing the display effect after field of view expansion.

[0004] The above problems make it difficult for the existing light field display system to balance large field of view and low distortion, limiting its application in high requirement scenarios, and therefore an integrated method for efficient field of view expansion and accurate dynamic distortion compensation is urgently needed. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present application provide an optical field of view expansion and dynamic distortion compensation method for light field display, which solves the problems of limited field of view angle, significant distortion after field of view expansion and lack of dynamic compensation ability of the existing light field display system in the above background technology through the following scheme.

[0006] To achieve the above purpose, the present application provides the following technical scheme: an optical field of view expansion and dynamic distortion compensation method for light field display, comprising: S1: According to the target field of view angle requirement of the light field display system, a synergistic structure parameter model of a microlens array and a free-form optical element is established, the microlens array is used to realize spatial division of light rays, the free-form optical element is used to realize field of view angle deflection of the light rays, the arrangement spacing and the optical parameter matching relationship between the two are determined according to light ray transmission modeling, and an optical element configuration scheme is formed; S2: According to the optical element configuration scheme, the microlens array and the free-form optical element are arranged in the imaging channel of the light field display system, the spatial distribution of the light ray incidence angle and the exit angle is changed by adjusting the focal length distribution of the microlens array and the curvature distribution of the free-form optical element, the coverage expansion of the light ray propagation path is realized, and the expansion process of the optical field of view is completed; S3: After the expansion of the optical field of view is completed, the wavefront sensor is used to collect light ray information in the expanded field of view range, wavefront aberration parameters and geometric distortion parameters are obtained, and an optical distortion mathematical model is established based on the parameters; S4: The parameter solving unit of the controller inputs the optical distortion mathematical model into the solving process, calculates the wavefront error distribution according to the optical error inversion algorithm, and generates a compensation control signal of the optical element according to the calculation result; S5: According to the compensation control signal, the response parameters of the optical element are adjusted by the signal output unit of the controller, the wavefront of the light rays in the expanded field of view range is corrected, and the corrected light field information is fed back to the parameter solving unit to update the wavefront error distribution, a new compensation control signal is generated by iteration, and the dynamic closed-loop compensation of the optical distortion is realized.

[0007] Technical effects and advantages of the present application: 1: The present application can effectively expand the field of view angle of the light field display system through the synergistic regulation and control of the microlens array and the free-form optical element, and the light ray distribution in the expanded field of view range is uniform, which can fully meet the demand of virtual reality, naked eye 3D and other scenes for large field of view display, and significantly improve the immersion experience of users; 2: The present application can accurately calculate the wavefront error distribution by high-precision acquisition of light ray information by the wavefront sensor, combination of the optical distortion mathematical model and the optical error inversion algorithm, and real-time adjustment of the optical element parameters through dynamic closed-loop compensation, effectively reduce the wavefront aberration and geometric distortion after the field of view expansion, and ensure the clarity of the light field imaging; 3: The present application adopts a dynamic closed-loop compensation mechanism, which can respond to dynamic distortion caused by environmental factors and mechanical vibration in system operation in real time, and the controller integrates iterative optimization strategy and hardware protection mechanism, which can not only ensure the stability of the compensation signal, but also avoid overload damage of the optical element, and ensure long-term stable operation of the system; 4. The collaborative structural parameter model and arrangement of the microlens array and freeform surface optical element in this invention are in line with existing optical processing and assembly processes. It can be integrated and applied without major modifications to the existing light field display system, and is compatible with mainstream light field display devices, making it flexible and diverse in application scenarios. Attached Figure Description

[0008] Fig. 1 This is a schematic diagram of the overall method flow of the present invention; Fig. 2 This is a schematic diagram of the optical field of view expansion process of the present invention; Fig. 3 This is a schematic diagram of the dynamic distortion compensation process of the present invention. Detailed Implementation

[0009] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0010] As attached Figs. 1 to 3 The method for optical field of view expansion and dynamic distortion compensation for light field display includes: S1: Based on the target field of view requirements of the light field display system, a collaborative structural parameter model of microlens array and freeform surface optical element is established. The microlens array is used to realize the spatial segmentation of light rays, and the freeform surface optical element is used to realize the field of view deflection of light rays. The arrangement spacing and optical parameter matching relationship between the two are determined based on the light transmission modeling to form an optical element configuration scheme. S2: According to the optical element configuration scheme, the microlens array and freeform optical element are arranged in the imaging channel of the light field display system. By adjusting the focal length distribution of the microlens array and the curvature distribution of the freeform optical element, the spatial distribution of the incident angle and the exit angle of the light is changed, thereby realizing the coverage expansion of the light propagation path and completing the process of expanding the optical field of view. S3: After the optical field of view is expanded, the wavefront sensor is used to collect light information within the expanded field of view, obtain wavefront aberration parameters and geometric distortion parameters, and establish an optical distortion mathematical model based on the parameters. S4: The optical distortion mathematical model is input into the solution process through the parameter calculation unit of the controller, the wavefront error distribution is calculated according to the optical error inversion algorithm, and the compensation control signal of the optical element is generated according to the calculation result. S5: adjusting the response parameter of the optical element according to the compensation control signal through the signal output unit of the controller, correcting the wavefront of the light in the extended field of view range, and feeding back the corrected light field information to the parameter solving unit to update the wavefront error distribution, iteratively generating a new compensation control signal, and realizing dynamic closed-loop compensation of optical distortion.

[0011] It needs to be specifically pointed out that according to the target field of view angle requirement of the light field display system, the cooperative structure parameter model of the microlens array and the free-form optical element is established, the microlens array is used to realize the spatial division of light, and the free-form optical element is used to realize the field of view angle deflection of light. The arrangement distance and the optical parameter matching relationship between them are determined according to the light transmission modeling, which is used to form the optical element configuration scheme.

[0012] It needs to be further pointed out that the determination method of the target field of view angle requirement specifically includes: determining the field of view angle index through the application scene of the light field display system (such as virtual reality headgear, naked eye 3D display), for example, the virtual reality device usually requires that the horizontal field of view angle is greater than or equal to 110 degrees, and the vertical field of view angle is greater than or equal to 90 degrees, and the light uniformity threshold of the edge field of view is set according to the human eye vision characteristics (such as energy attenuation is less than or equal to 30%).

[0013] It needs to be further pointed out that the specific mechanism of the microlens array for realizing the spatial division of light is that the incident light field is divided into a plurality of sub-beams according to the microlens unit, each microlens corresponds to a directional light sampling point, and the array density needs to meet the Nyquist sampling theorem, that is, the angular sampling interval θ sam (unit: rad) needs to meet: , wherein E is the number of pixels in a single direction (such as horizontal or vertical), for example, when the horizontal direction is 1920 pixels, θ≤0.05°.

[0014] It needs to be further pointed out that the principle of the free-form optical element for realizing the field of view angle deflection of light is that the light is refracted and deflected through the asymmetric surface shape, and the surface shape design needs to meet Snell's law: , wherein n1 is the refractive index of air (the value is 1.0); n2 is the refractive index of the free-form element material (such as fused quartz n2=1.458); θ in is the incident angle of light (unit: rad, the included angle between light and normal line); θ out is the refraction angle of light (unit: rad, the included angle between the refracted light and the normal line); through the optimization of the surface shape, the deflection angle of the edge field of view light reaches the target value (such as ±55°).

[0015] It needs to be specifically pointed out that the implementation of the light transmission modeling includes: constructing an optical system model containing a light source, a microlens array, a free-form surface element and an image plane, and simulating the propagation path of more than 10 5 above light rays, wherein the light source model is set as a Lambertian light source, the light emitting surface size is matched with the microlens array (such as 10mm×10mm), and the wavelength range covers the visible light band of 480nm~650nm.

[0016] It needs to be further pointed out that the calculation method of the arrangement distance d (unit: mm) of the microlens array and the free-form surface element is: based on Gaussian optical approximation, the distance d needs to meet: , wherein f m,avg is the average focal length of the microlens (unit: mm, such as 2.3mm); Δf surf is the adjustment amount (unit: mm, usually 0.1~0.3mm) for compensating the free-form surface aberration; through iterative optimization, the incident height h (unit: mm) of the edge field light on the free-form surface surface meets h≤0.9×R (R is the effective radius of the free-form surface, typical value is 5, unit: mm), and the typical optimized distance d=2.5mm (when f m,avg =2.3mm, Δf surf =0.2mm).

[0017] It needs to be further pointed out that the focal length distribution optimization method of the microlens array is: the standard focal length f m,0 (unit: mm, such as 1.8mm) is set for the central field microlens, and the focal length of the edge microlens is distributed according to the following formula: , wherein: x, y are two-dimensional coordinates (unit: mm, the origin is the center of the array) of the microlens unit in the array; r m,arr is the effective radius (unit: mm, such as 12mm) of the microlens array; α is the focal length correction coefficient (dimensionless, value 0.1~0.15), which is used to compensate the vignetting effect of the edge field; through the distribution, the light collection efficiency deviation of each microlens unit is ≤15% (efficiency=actual collected light energy / theoretical maximum energy).

[0018] It needs to be further pointed out that the curvature distribution modeling process of the free-form surface optical element is: the Zernike polynomial expansion surface equation is used to describe the height z (unit: mm) of the curved surface along the optical axis direction: , wherein: ρ is the normalized radial coordinate (ρ=s / R, s is the actual radial distance, unit: mm); Φ is the azimuth angle (unit: rad, value range 0~2π); Z n,surf (ρ,Φ) is the Zernike polynomial describing the height of the free-form surface; a n,surfZernike coefficients of the freeform surface shape (unit: mm, adjusted according to the polynomial order); M is the polynomial order (usually 8-12 orders are taken to balance the precision and complexity); the coefficients a n,surf The exit angle error of the light rays after passing through the freeform surface is less than or equal to 0.3°, and the first five coefficients a 0,surf = 0.5 mm, a 1,surf = 0, a 2,surf = -0.2 mm, a 3,surf = 0, a 4,surf = 0.1 mm.

[0019] It needs to be specifically pointed out that the verification method of the optical element configuration scheme is to set a field of view detection grid at the image plane, count the energy distribution of the light rays in each direction, require that the light energy ratio in the target field of view angle range is greater than or equal to 92%, and the light angle deviation of adjacent microlens units is less than or equal to 0.1°, and the light divergence angle of the edge field of view is verified to be less than or equal to 0.5° by RayFan analysis of ZEMAX software.

[0020] It needs to be further pointed out that the output content of the collaborative structure parameter model includes: the focal length distribution function f(x, y) of the microlens array, the freeform surface shape coefficient list {a n,surf}, the element spacing d = 2.5 ± 0.05 mm, the coaxiality tolerance of the optical axis is less than or equal to 3 μm, and the material selection (the microlens adopts PMMA, and the freeform surface adopts fused quartz), which ensures that the model parameters meet the processing technology feasibility (such as the minimum line width of the microlens array is less than or equal to 50 μm, the freeform surface shape precision PV is less than or equal to λ / 10, and λ = 550 nm).

[0021] It needs to be specifically pointed out that according to the optical element configuration scheme, the microlens array and the freeform optical element are installed into the imaging channel of the light field display system, and the focal length and curvature distribution of the two are adjusted to realize the coverage and expansion of the light propagation path, and the expansion process of the optical field of view is completed.

[0022] It needs to be further pointed out that the mechanical arrangement of the imaging channel needs to meet the high-precision assembly requirements: the microlens array is fixed by a quartz glass support with low expansion coefficient, the flatness tolerance of the support is controlled within 5 μm, and a three-point support structure is adopted to avoid stress deformation; the freeform optical element is installed through a six-axis precision adjustment frame, which has a translation accuracy of 1 μm and a rotation accuracy of 0.001°, so that the coaxiality deviation of the element optical axis and the main optical axis of the imaging channel is not more than 30 μrad (corresponding to a edge light ray offset of less than or equal to 0.1 mm).

[0023] It needs to be further explained that the focal length distribution adjustment of the microlens array adopts an electrowetting driving technology: the initial focal length of the central field of view microlens is set to 1.8 mm, and the focal length of the edge microlens is increased by 1.1-1.15 times of the central value (for example, the edge focal length is adjusted to 1.98-2.07 mm), and the driving voltage and the focal length change are in a linear relationship (after calibration, the focal length changes by 0.1 mm for every 5 V change in voltage), and the gradient distribution adjustment of the array focal length is realized through line-by-line scanning voltage loading.

[0024] It needs to be further explained that the curvature distribution optimization of the free-form optical element is based on the principle of piezoelectric deformation mirror: the surface shape of the free-form surface is dynamically modulated through the first 7 orders of Zernike polynomials, and the curvature parameters of the edge region are adjusted (the typical adjustment range is 0.3-0.7 mm -1 ), so that the deflection angle of the edge field of view light is increased by 5°-10° compared with the initial design value; the corresponding relationship between the curvature and the light deflection angle follows Snell's law, and the influence coefficient of the surface curvature change on the exit angle is pre-calibrated through optical simulation (for example, the edge light deflection angle increases by 1.5° for every 0.1 mm -1 increase in curvature).

[0025] It needs to be further explained that the extension of the light propagation path is realized through coordinated adjustment: the microlens array first divides the incident light into angles (the angle sampling interval of a single microlens unit is ≤0.05°), and the free-form surface element then performs secondary deflection on the light, so that the overall field of view angle is expanded to 1.05-1.1 times of the target value (for example, when the target horizontal field of view angle is 110°, the actual expansion is 115.5°-121°).

[0026] It needs to be further explained that the iterative optimization process of the field of view expansion includes a quantitative convergence condition: the focal length adjustment step is set to 0.02 mm, the curvature adjustment step is set to 0.01 mm -1 , and the light information is collected through the wavefront sensor after each adjustment; when the field of view angle change amount of two consecutive adjustments is ≤0.5%, and the angle deviation of the edge field of view light is ≤0.3°, it is determined that the optimization process converges, and the parameter adjustment is stopped.

[0027] It needs to be specifically explained that after the optical field of view expansion is completed, the light information in the expanded field of view range is collected using the wavefront sensor, the wavefront aberration parameters and the geometric distortion parameters are obtained, and an optical distortion mathematical model is established based on the parameters.

[0028] It needs to be further explained that the wavefront sensor is usually a Hartmann-Shack sensor, and the number of sub-apertures of the microlens array of the sensor needs to meet the sampling theorem: the number of sub-apertures N, the expanded field of view angle θ FOV , and the angular sampling resolution δθ satisfy , where θ FOVin radian (e.g. a horizontal field of view of ±55° corresponds to θ FOV =1.92 rad), δθ is usually taken as 0.5° (i.e. 8.727 x 10 -3 rad), and the sub-aperture array is taken as 220 x 220 in size; during acquisition, the field of view is divided into several sub-aperture regions according to the preset sampling density, for example, divided into 5 concentric annular zones in polar coordinates, with 12 sub-apertures uniformly distributed in each annular zone, so that the sampling point density ratio of the central region (normalized radial coordinate ρ≤0.3) to the edge region (ρ≥0.8) is 4:1, in order to capture the high-order aberrations of the edge field of view.

[0029] It should be further explained that the wavefront aberration parameters are acquired by measuring the centroid displacement (Δx i , Δy i ) of the light rays in each sub-aperture, from which the wavefront slopes S x,i =Δx i / f WS , S y,i =Δy i / f WS are calculated, where f WS is the focal length of the wavefront sensor microlens (e.g. 10 mm); the wavefront aberration is decomposed based on a set of orthogonal Zernike polynomial basis functions , where N z is usually taken as 36 to cover up to 6th order aberrations, a n,wav is the Zernike coefficient of the wavefront aberration (unit: μm), and Z n,wav (ρ, φ) is the Zernike polynomial describing the wavefront phase, ρ is the normalized radial coordinate, and φ is the azimuth angle; the coefficients are solved by the least squares method, and the objective function is , where K is the total number of sampling points (e.g. 500), and W meas,i is the measured wavefront value.

[0030] It should be further explained that the geometric distortion parameters are acquired by imaging a calibration plate: a calibration plate with a grid spacing of 1 mm is placed in the object space, and the imaging coordinates corresponding to the ideal coordinates (x j , y j ) are determined by geometric relationships; a radial and tangential distortion model is used to construct the mapping relationship: the radial distortion expression is x d =x(1+k1r 2 +k2r 4 +k3r 6 ), y d =y(1+k1r 2 +k2r 4 +k3r 6 ), where , (unit: mm), k1, k2, k3 are radial distortion coefficients (typical values k1≈-10 -3 , k2≈10 -6 ), k1 unit: mm -2 , k2 unit: mm -4 , k3 unit: mm -6 ; tangential distortion expression is x t =x+2p1xy+p2(r 2 +2x 2 ), y t =y+p1(r 2 +2y 2 )+2p2xy, wherein p1, p2 are tangential distortion coefficients (typical values≈10 -5 ), p1, p2 unit: mm -1 ; distortion coefficients are solved by minimizing , wherein L is the number of characteristic points (such as 100).

[0031] It should be further explained that the optical distortion mathematical model couples the wavefront aberration and the geometric distortion into , wherein D is the distortion matrix, W is the wavefront phase distortion term, and G is the geometric coordinate offset term; a parameter equation group is constructed based on the wavefront sampling data set , wherein A is a system matrix (element ), b is a measured wavefront vector, λ is a regularization parameter (10 -4 ~10 -2 ), and C is a smoothing constraint matrix; Tikhonov regularization is used for solving, and the convergence condition is the iteration residual .

[0032] It should be further explained that the model verification needs to meet: the root mean square error (RMS) of the wavefront is ≤0.05λ (λ=550nm), and the geometric distortion RMS is ≤0.5 pixels; the final output parameters include: the wavefront base coefficient set {a n,wav}, the geometric distortion coefficient set {k1, k2, k3, p1, p2}, and the distortion mapping function describing the transformation from the ideal coordinates to the observed coordinates .

[0033] It should be specifically explained that the optical distortion mathematical model is substituted into the solving process by the parameter solving unit of the controller, the wavefront error distribution is calculated by means of the optical error inversion algorithm, and the compensation control signal of the optical element is generated accordingly; in this process, the parameter solving unit is usually built with high-performance AI chips, and parallel computing modules are integrated to ensure the operation efficiency, and the input data includes the wavefront base coefficient set (the wavefront base coefficient set is the first 36 Zernike polynomial coefficients), the wavefront sampling data set, and the geometric distortion mapping relationship.

[0034] It needs to be further explained that in the optical error inversion link, the wavefront error is expanded by Zernike polynomial as: Where ΔΦ is the wavefront phase error (unit: rad), c n is the error coefficient, usually N=36 to balance the precision and computational load; to solve the error coefficient c, the algorithm adopts an optimization strategy with Tikhonov regularization: , where W is the wavefront sampling data matrix (unit: rad), Z is the Zernike basis function matrix, λ is the regularization parameter (typical value 10 -4 ), L is the second-order difference regularization matrix, which is used to impose a smoothing constraint to suppress noise interference; the calculated wavefront error needs to be quantified by peak-to-valley (PV) and root mean square (RMS) values, and when PV>λ / 4 (137.5nm when λ=550nm) or RMS>λ / 20 (27.5nm), the compensation control signal generation is triggered.

[0035] It needs to be further explained that the generation of the compensation control signal is based on the mapping relationship established by the system calibration: , where u is the control signal vector (microlens drive: V; freeform drive: μm), K is the calibration matrix (microlens scenario: V / rad, used to match the voltage and wavefront error dimension; freeform scenario: μm / rad, used to match the displacement and wavefront error dimension), u0 is the initial bias, which is consistent with u; to achieve dynamic optimization, the signal adopts an iterative update strategy: , where α is the iteration step (value 0.1~0.3), H is a low-pass filter matrix (such as a 3x3 Gaussian kernel), and the iteration is terminated or reaches the upper limit of 20 times.

[0036] It needs to be specifically explained that through the signal output unit of the controller, the response parameters of the optical element are adjusted according to the compensation control signal, the light wavefront in the extended field of view is corrected, and the corrected light field information is fed back to the parameter solving unit to update the wavefront error distribution, a new compensation control signal is generated by iteration, and the dynamic closed-loop compensation of optical distortion is realized.

[0037] It needs to be further explained that the compensation control signal corresponds to the adjustable physical parameters of the optical element: the microlens array adjusts the focal length through electrically controlled zoom technology, the control signal is the driving voltage, and the focal length distribution of each microlens unit can be changed in real time; the freeform optical element adjusts the curvature through a piezoelectric ceramic driving mechanism, the control signal is the displacement, and the surface shape of the curved surface can be accurately adjusted; both control signals are generated by the controller and act on the microlens and the freeform surface to change the spatial distribution of the light incidence angle and the exit angle.

[0038] It needs to be further explained that the compensation control signal adopts an iterative updating strategy, a correction amount is calculated based on the difference between the current wavefront error distribution and the historical compensation signal, and high-frequency noise is removed through a preset filtering rule to ensure signal stability;For example, first calculate the deviation of the current wavefront error from the ideal state, then determine the increment of the control signal this time combined with the historical adjustment data, and output to the driving unit after filtering, to realize continuous adjustment of the response parameters of the optical element.

[0039] It needs to be further explained that in the wavefront correction process, the driving execution unit converts the compensation control signal into actual driving signals (such as voltage, current), transmits it to the electric control unit of the microlens array and the piezoelectric ceramic driver of the free-form surface, and the adjustment period is synchronized with the sampling frequency of the wavefront sensor (such as 5ms);After correction, the wavefront sensor collects new light field information at a frequency of 200Hz, obtains the wavefront phase distribution and geometric distortion coordinate pair, and feeds back to the parameter solving unit to update the wavefront error distribution, forming a closed-loop process of "error calculation-signal generation-element adjustment-feedback correction".

[0040] It needs to be further explained that the iteration termination condition is based on a preset accuracy threshold: when the root mean square value of the wavefront error of the last 5 iterations is less than 1 / 20 of the reference wavelength (550nm), or the geometric distortion residual (deviation of observed coordinates from ideal coordinates) is less than 5 microns, terminate the current closed-loop period, otherwise continue iteration.

[0041] It needs to be further explained that in hardware implementation, the microlens drive adopts a high-resolution digital-to-analog converter (16 bits), and the voltage output accuracy is ±0.1% of the full scale;The free-form surface drive adopts a nanometer-precision piezoelectric ceramic displacement stage (resolution 0.1μm), and a capacitive displacement sensor (accuracy ±0.2μm) is used to feedback the displacement in real time;It also needs to set hardware protection threshold (such as driving voltage not more than ±15V, displacement not more than 90% of the stroke), to avoid damage of the element overload, and to ensure long-term stable operation.

[0042] Secondly: in the drawings of the disclosed embodiments, only the structures related to the disclosed embodiments are involved, other structures can be referred to the usual design, and in the case of no conflict, the same embodiment and different embodiments of the present application can be combined with each other; Finally: the above only describes the preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for optical field-of-view expansion and dynamic distortion compensation for light field display, characterized in that, The method comprises the following steps: S1: According to the target field of view angle requirement of the light field display system, a cooperative structure parameter model of the microlens array and the free-form optical element is established, the microlens array is used to realize the spatial division of light rays, and the free-form optical element is used to realize the field of view angle deflection of light rays, the arrangement spacing and the optical parameter matching relationship between the two are determined according to the light ray transmission modeling, and the optical element configuration scheme is formed; S2: According to the optical element configuration scheme, the microlens array and the free-form optical element are arranged in the imaging channel of the light field display system, the spatial distribution of the light ray incidence angle and the exit angle is changed by adjusting the focal length distribution of the microlens array and the curvature distribution of the free-form optical element, the coverage expansion of the light ray propagation path is realized, and the optical field of view expansion process is completed; S3: After the expansion of the optical field of view is completed, the wavefront sensor is used to collect the light ray information in the expanded field of view range, the wavefront aberration parameters and the geometric distortion parameters are obtained, and an optical distortion mathematical model is established based on the parameters; S4: The parameter solving unit of the controller inputs the optical distortion mathematical model into the solving process, calculates the wavefront error distribution according to the optical error inversion algorithm, and generates a compensation control signal of the optical element according to the calculation result; S5: The signal output unit of the controller adjusts the response parameters of the optical element according to the compensation control signal, corrects the wavefront of the light rays in the expanded field of view range, and feeds back the corrected light field information to the parameter solving unit to update the wavefront error distribution, iteratively generates a new compensation control signal, and realizes the dynamic closed-loop compensation of the optical distortion. 2.The method for optical view field extension and dynamic distortion compensation for light field display according to claim 1, characterized in that: When collecting the light ray information, the wavefront sensor divides the expanded field of view into sub-aperture regions according to a preset sampling density, obtains wavefront sampling data sets of the central region and the edge region, and inputs the wavefront sampling data sets as basic data for establishing the optical distortion mathematical model. 3.The method for optical view field extension and dynamic distortion compensation for light field display according to claim 1, characterized in that: When establishing the optical distortion mathematical model, the wavefront aberration parameters are decomposed according to an orthogonal basis function set to obtain a wavefront basis coefficient set, and the wavefront basis coefficient set is used to represent the phase deviation distribution characteristics of each spatial position in the light ray propagation process. 4.The method for optical view field extension and dynamic distortion compensation for light field display according to claim 1, characterized in that: The optical distortion mathematical model establishes a parameter equation set based on the wavefront basis coefficient set and the wavefront sampling data set, and limits the solving range through smoothing constraints and stability constraints, and the parameter equation set is used to identify and solve the parameters of the optical distortion model.

5. The method for optical view field extension and dynamic distortion compensation for light field display according to claim 1, characterized in that: Before the optical distortion mathematical model is established and solved, a corresponding relationship between the wavefront basis coefficient set and the response parameters of the optical element is established, and the corresponding relationship is used to convert the inversion distortion coefficients into optical element control quantities.

6. The method of claim 1, wherein: The generation of the compensation control signal adopts an iterative updating strategy, calculates a correction amount based on the difference between the current wavefront error distribution and the historical compensation signal, and updates the compensation control signal according to a preset step size and filtering rule.

7. The method of claim 1, wherein: In the process of establishing the optical distortion mathematical model, a set of geometric distortion mapping relationships is generated simultaneously, which is composed of ideal image point coordinates and observed image point coordinates, and which cooperates with wavefront aberration correction in the correction process to guide optical element adjustment and perform inverse correction of observed coordinates to ideal coordinates. 8.The method for optical view field extension and dynamic distortion compensation for light field display according to claim 1, wherein: The optical element includes a microlens array and a free-form optical element, and the controller includes a parameter solving unit, a compensation signal generating unit, and a driving execution unit. The parameter solving unit is used to perform wavefront error distribution calculation based on the optical distortion mathematical model, the compensation signal generating unit is used to form optical element response parameters, and the driving execution unit is used to drive the optical element to complete wavefront correction and geometric coordinate transformation according to the compensation control signal.

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