An optimization method of a free-form surface prism and a free-form surface prism

Abstract

The embodiment of the application provides an optimization method and a free-form surface prism, and relates to the technical field of optical systems.Based on obtaining three groups of surface data, a first direction, a second direction and a third direction, an initial prism is established.Then, related parameters of the initial prism are obtained, variable quadratic constants and aspherical coefficient corrections are introduced, and a surface is optimized to obtain a first optimized prism with an expanded field of view in the second direction.Then, related parameters of the first optimized prism are obtained, variable asymmetric coefficient corrections are introduced, and the surface is optimized again to obtain a second optimized prism with an expanded field of view in the first direction.Based on the above, by adjusting the related parameters of the prisms in each stage at a suitable optimization stage, the optimization efficiency of the prisms in each stage is improved, so that the initial surface data is optimized into a good free-form surface prism, thereby achieving the purposes of reducing the difficulty of obtaining the free-form surface prism and saving time.

Description

Technical Field

[0001] This invention relates to the field of optical system technology, and more specifically, to an optimization method for a freeform prism and the freeform prism itself. Background Technology

[0002] To obtain freeform prisms with good performance and a large field of view, the partial differential equation method can be used, which is a method of solving a set of partial differential equations to design the freeform surface.

[0003] However, this method requires a high level of mathematical expertise and is rarely used. Summary of the Invention

[0004] This invention provides an optimization method for freeform prisms and a freeform prism, which can reduce the difficulty of obtaining freeform prisms and save time.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides an optimization method for a freeform prism, comprising:

[0007] Acquire three sets of surface data, a first direction, a second direction, and a third direction. Each set of surface data includes geometric parameters and a first adjustment parameter. The first direction, the second direction, and the third direction are mutually perpendicular.

[0008] Based on the three sets of surface data, an initial prism is established; the three sets of surface data correspond one-to-one with the three initial optical surfaces of the initial prism.

[0009] Acquire reference data for the initial prism, reference data between the initial prism and the image plane, reference data between the initial prism and the object plane, and optical path data of the beam within the initial prism;

[0010] Based on the reference data of the initial prism, the reference data between the initial prism and the image plane, the reference data between the initial prism and the object plane, and the optical path data of the beam in the initial prism, and by introducing a quadratic constant and an aspherical coefficient, the surface shape of the initial prism is optimized to obtain a first optimized prism, so as to increase the field of view of the beam passing through the first optimized prism in the second direction.

[0011] Acquire reference data for the first optimized prism, reference data between the first optimized prism and the image plane, reference data between the first optimized prism and the object plane, and reference data of the beam within the first optimized prism;

[0012] Based on the reference data of the first optimized prism, the reference data between the first optimized prism and the image plane, the reference data between the first optimized prism and the object plane, and the reference data of the beam within the first optimized prism, an asymmetry coefficient is introduced to optimize the surface shape of the first optimized prism, thereby obtaining a second optimized prism to increase the field of view of the beam passing through the second optimized prism in the first direction.

[0013] In an optional implementation, the specific steps for obtaining reference data of the initial prism, reference data between the initial prism and the image plane, reference data between the initial prism and the object plane, and optical path data of the beam within the initial prism include:

[0014] Obtain the spacing between any two initial optical surfaces, the spacing between the initial optical surface closest to the image surface and the image surface, and the second adjustment parameters of the three initial optical surfaces.

[0015] In an optional implementation, after obtaining the spacing between any two initial optical surfaces, the spacing between the initial optical surface closest to the image plane and the image plane, and the second adjustment parameters of the three initial optical surfaces, the method further includes:

[0016] Based on the distance between any two initial optical surfaces, the distance between the initial optical surface closest to the image plane and the image plane, and the second adjustment parameters of the three initial optical surfaces, and by introducing a quadratic constant and an aspherical coefficient, the surface shape of the initial prism is optimized to obtain a reference prism; the reference prism includes a first reference optical surface, a second reference optical surface, and a third reference optical surface from the object plane to the image plane;

[0017] Acquire the first edge ray and the second edge ray; the first edge ray and the second edge ray are two edge rays along the second direction in the reference prism and within the field of view;

[0018] The refraction point of the first edge ray with the first reference optical surface is determined as the first reference point; the reflection point of the first edge ray with the second reference optical surface is determined as the second reference point; the total internal reflection point of the first edge ray with the first reference optical surface is determined as the third reference point; and the refraction point of the first edge ray with the third reference optical surface is determined as the fourth reference point. The refraction point of the second edge ray with the first reference optical surface is determined as the fifth reference point; the reflection point of the second edge ray with the second reference optical surface is determined as the sixth reference point; the total internal reflection point of the second edge ray with the first reference optical surface is determined as the seventh reference point; and the refraction point of the second edge ray with the third reference optical surface is determined as the eighth reference point.

[0019] The difference between the fourth reference point and the third reference point in the second direction is defined as greater than 0.4 mm, and the difference between the fourth reference point and the third reference point in the third direction is defined as 0.4 mm to 3 mm.

[0020] In an optional implementation, the method further includes:

[0021] The difference between the seventh reference point and the fifth reference point in the second direction is set to be greater than 0 mm, and the difference between the sixth reference point and the fifth reference point in the third direction is set to be between 0.5 mm and 3 mm.

[0022] In an optional implementation, the method further includes:

[0023] The difference between the second reference point and the eighth reference point in the third direction is defined as 0.2 mm to 3 mm.

[0024] In an optional implementation, the method further includes:

[0025] The minimum distance between the reference prism and the object plane in the third direction is determined to be greater than 18 mm.

[0026] In an optional implementation, the method further includes:

[0027] The refraction angle of any ray on the first reference optical surface is determined to be greater than 42.2°.

[0028] In an optional implementation, the geometric parameters include the radius, the distance between any two initial optical surfaces, and the radius of curvature, and the first adjustment parameters include a first tilt parameter in a first direction and a first eccentricity parameter in a second direction.

[0029] In an optional implementation, after introducing an asymmetry coefficient based on reference data of the first optimized prism, reference data between the first optimized prism and the image plane, reference data between the first optimized prism and the object plane, and reference data of the beam between the first optimized prisms, to optimize the surface shape of the first optimized prism and obtain a second optimized prism, thereby increasing the field of view of the beam passing through the second optimized prism in the first direction, the method further includes:

[0030] Acquire reference data for the second optimized prism, reference data between the second optimized prism and the image plane, reference data between the second optimized prism and the object plane, and reference data for the beam within the second optimized prism;

[0031] The reference data of the second optimized prism, the reference data between the second optimized prism and the image plane, the reference data between the second optimized prism and the object plane, and the reference data of the beam within the second optimized prism are used to perform surface transformation and introduce polynomial coefficients using a least squares fitting algorithm to obtain a polynomial curved surface prism.

[0032] Secondly, the present invention provides a freeform prism, which is manufactured using an optimized method for a freeform prism as described in any of the foregoing embodiments.

[0033] The beneficial effects of the embodiments of the present invention include:

[0034] This invention provides an optimization method for a freeform prism and a freeform prism itself. Based on acquiring three sets of surface shape data, a first direction, a second direction, and a third direction, an initial prism is established. Then, relevant parameters of the initial prism are acquired, and a quadratic constant and aspherical coefficient correction are introduced to optimize the surface shape, resulting in a first optimized prism with an extended field of view in the second direction. Next, relevant parameters of the first optimized prism are acquired, and asymmetric coefficient correction is introduced to further optimize the surface shape, resulting in a second optimized prism with an extended field of view in the first direction. Based on the above, by adjusting the relevant parameters of the prism at appropriate optimization stages, the optimization efficiency of each stage of the prism is improved, and the dependence on the initial prism is reduced. This allows for the optimization of a good freeform prism based on different initial surface shape data, thereby reducing the difficulty of acquiring freeform prisms and saving time. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A schematic flowchart illustrating an optimization method for a freeform prism provided in an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of a reference prism provided for an embodiment of the present invention;

[0038] Figure 3 This is a schematic flowchart of a specific step S210 provided in an embodiment of the present invention;

[0039] Figure 4 A schematic diagram of the second optimized prism provided in an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of a rectangular sampling area provided in an embodiment of the present invention;

[0041] Figure 6 Another flowchart illustrating the optimization method for a freeform prism provided in an embodiment of the present invention;

[0042] Figure 7 A schematic diagram of the third optimized prism provided in an embodiment of the present invention.

[0043] Icons: 100 - Reference prism; 30 - Object plane; 50 - Image plane; 110 - First reference optical plane; 120 - Second reference optical plane; 130 - Third reference optical plane; 210 - First marginal ray; 230 - Second marginal ray; 310 - First reference point; 320 - Second reference point; 330 - Third reference point; 340 - Fourth reference point; 350 - Fifth reference point; 360 - Sixth reference point; 370 - Seventh reference point; 380 - Eighth reference point; 400 - Second optimization prism; 500 - Polynomial curved surface prism; 71 - First direction; 73 - Second direction; 75 - Third direction. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0046] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0047] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0048] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0049] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0050] Please see Figure 1 , Figure 1A schematic flowchart of an optimization method for a freeform prism provided in an embodiment of the present invention is shown. Furthermore, this optimization method for a freeform prism can fabricate a freeform prism. The following section focuses on... Figure 1 The process shown is explained in detail. The optimization method for this freeform prism can specifically include the following steps:

[0051] Step S110: Obtain three sets of surface data, a first direction 71, a second direction 73, and a third direction 75. Each set of surface data includes geometric parameters and a first adjustment parameter; the first direction 71, the second direction 73, and the third direction 75 are perpendicular to each other.

[0052] In some implementations, please refer to Figure 2 The second direction 73 refers to the vertical direction, which is the y direction in the diagram; the third direction 75 refers to the horizontal direction, which is the z direction in the diagram; and the first direction 71 refers to the direction perpendicular to the yoz plane formed by the second direction 73 and the third direction 75, which is the x direction in the diagram.

[0053] Step S130: Based on the three sets of surface data, establish the initial prism; the three sets of surface data correspond one-to-one with the three initial optical surfaces of the initial prism.

[0054] In some implementations, a coordinate system is established based on the aforementioned directions, and an initial prism composed of three initial optical surfaces is obtained based on three sets of surface data. It should be noted that the initial optical surfaces are spherical structures at this time.

[0055] In some implementations, the initial prism has yoz-plane symmetry. Furthermore, the symmetry of the prism remains unchanged during subsequent optimization processes.

[0056] Step S210: Obtain the reference data of the initial prism, the reference data between the initial prism and the image plane 50, the reference data between the initial prism and the object plane 30, and the optical path data of the beam within the initial prism.

[0057] In some implementations, a reverse optical path design method is used, that is, the position of the human eye during actual use is determined as follows: Figure 2 The light beam is incident from the object plane 30, passes through the prism, and is focused onto the image plane 50, i.e., the microdisplay plane. The optical path data of the beam in the initial prism can refer to the optical path data of the edge rays in the beam within the initial prism, as detailed below. Figure 2 As indicated by the arrow.

[0058] Step S230: Based on the reference data of the initial prism, the reference data between the initial prism and the image plane 50, the reference data between the initial prism and the object plane 30, and the optical path data of the beam in the initial prism, and by introducing a quadratic constant and an aspherical coefficient, the surface shape of the initial prism is optimized to obtain a first optimized prism, so as to increase the field of view of the beam passing through the first optimized prism in the second direction 73.

[0059] In some embodiments, the data related to the initial prism is input into the optical design software, along with the quadratic constant and aspherical coefficient, to ensure that all light rays converge while converting the spherical optical surface of the initial prism into an aspherical optical surface. Based on this, a first optimized prism is obtained, which can increase the field of view of the light beam passing through it in the second direction 73 (i.e., the y-direction).

[0060] In some implementations, to avoid information loss and facilitate subsequent optimization and transformation, the specific order of the aspherical coefficients is between the fourth and tenth orders.

[0061] In some embodiments, after the above optimization stage, the field of view of the beam passing through the first optimization prism in the second direction 73 can be extended to 26°.

[0062] Step S310: Obtain reference data for the first optimized prism, reference data between the first optimized prism and the image plane 50, reference data between the first optimized prism and the object plane 30, and reference data for the light beam within the first optimized prism.

[0063] Step S330: Based on the reference data of the first optimized prism, the reference data between the first optimized prism and the image plane 50, the reference data between the first optimized prism and the object plane 30, and the reference data of the beam within the first optimized prism, an asymmetry coefficient is introduced to optimize the surface shape of the first optimized prism, thereby obtaining a second optimized prism 400 to increase the field of view of the beam passing through the second optimized prism 400 in the first direction 71.

[0064] In some embodiments, the data related to the first optimized prism is input into optical design software, and the aspherical optical surface of the first optimized prism is transformed into a deformable aspherical optical surface using the surface conversion tool built into the optical design software. Then, an asymmetry coefficient is input to further optimize and correct the prism surface shape, thereby obtaining the second optimized prism 400. Furthermore, this second optimized prism 400 can increase the field of view of the light beam passing through it in the first direction 71 (i.e., the x-direction).

[0065] In some implementations, the asymmetric coefficients are specifically asymmetric coefficients of order 10 or less.

[0066] In some embodiments, after undergoing the above-mentioned optimization stage based on the first optimized prism, the field of view of the beam of the second optimized prism 400 in the first direction 71 can be extended to 44°, and the diagonal field of view angle can be extended to 51°.

[0067] It is understood that the optimization method provided by this invention, through a progressive optimization strategy, gradually adjusts the relevant parameters of the prism at appropriate optimization stages, increasing the adjustability of the relevant parameters and significantly reducing the designer's dependence on the initial prism. Designers can directly obtain deformable aspherical structures that meet parameter requirements by optimizing data at each stage, thus avoiding wasting time searching for suitable initial prisms.

[0068] Based on this, the optimization method for freeform prisms provided in this embodiment of the invention establishes an initial prism by acquiring three sets of surface shape data, a first direction 71, a second direction 73, and a third direction 75. Then, relevant parameters of the initial prism are acquired, and a quadratic constant and aspherical coefficient correction are introduced to optimize the surface shape to obtain a first optimized prism with an extended field of view in the second direction 73. Next, relevant parameters of the first optimized prism are acquired, and asymmetric coefficient correction is introduced to further optimize the surface shape to obtain a second optimized prism 400 with an extended field of view in the first direction 71. Based on the above, by adjusting the relevant parameters of the prisms at appropriate optimization stages, the optimization efficiency of each stage of the prism is improved, and the dependence on the initial prism is reduced. This allows for the optimization of a good freeform prism based on different initial surface shape data, thereby reducing the difficulty of acquiring freeform prisms and saving time.

[0069] In some implementations, the acquisition of geometric parameters and the first adjustment parameter in step S110 specifically refers to the following: the geometric parameters include the radius, the distance between any two initial optical surfaces, and the radius of curvature; the first adjustment parameter includes the first tilt parameter in the first direction 71 and the first eccentricity parameter in the second direction 73.

[0070] It should be noted that the shape and size of the initial optical surface are determined by the radius in the geometric parameters, and the thickness of the initial prism is determined by the distance between any two initial optical surfaces. The position of the initial optical surface is then determined by adjusting the tilt parameter in the first direction 71 and the eccentricity parameter in the second direction 73, thus setting the initial optical surface as a planar structure. Different initial optical surfaces are designed by taking values ​​that vary according to actual needs. Next, the planar initial optical surface is transformed into a spherical structure by adding a radius of curvature, facilitating surface shape adjustment and transformation in subsequent optimization stages. During this process, the tilt parameter in the first direction 71 and the eccentricity parameter in the second direction 73 are gradually fine-tuned until the beam is focused, thus determining the first tilt parameter in the first direction 71 and the first eccentricity parameter in the second direction 73, thereby establishing the initial prism based on the off-axis and eccentricity system. Here, the radius is a non-zero value, and the radius of curvature is a non-infinite value. It can be understood that the eccentricity or tilt parameters in other directions can be set to 0.

[0071] In some implementations, please refer to Figure 3 The specific steps of step S210 include:

[0072] Step S211: Obtain the spacing between any two initial optical surfaces, the spacing between the initial optical surface near the image surface 50 and the image surface 50, and the second adjustment parameters of the three initial optical surfaces.

[0073] It should be noted that the spacing mentioned above specifically refers to the distance between the center of the initial optical surface and the center of the image plane 50. The second adjustment parameter specifically refers to the second tilt parameter in the first direction 71 and the second eccentricity parameter in the second direction 73. Furthermore, the second adjustment parameter is a parameter based on a change in the first adjustment parameter, and its purpose is to correct the increased parallax during the field of view expansion. In addition, it should be noted that at this time, the surface shape of the initial prism maintains a spherical structure.

[0074] At this point, inputting the data related to the initial prism into the optical design software, along with the quadratic constant and aspherical coefficient, can also ensure that the spherical optical surface of the initial prism is transformed into an aspherical optical surface.

[0075] In some embodiments, to prevent light from escaping from the prism during the expansion of the second direction 73 field of view, further fine-tuning can be performed based on the above steps. Therefore, the specific steps of step S210 further include:

[0076] Step S212: Based on the distance between any two initial optical surfaces, the distance between the initial optical surface near the image surface 50 and the image surface 50, and the second adjustment parameters of the three initial optical surfaces, and by introducing a quadratic constant and an aspherical coefficient, the surface shape of the initial prism is optimized to obtain a reference prism 100; the reference prism 100 includes a first reference optical surface 110, a second reference optical surface 120, and a third reference optical surface 130 from the object surface 30 to the image surface 50.

[0077] Understandably, by utilizing the reversibility of light, the first reference optical surface 110, the second reference optical surface 120, and the third reference optical surface 130 of the reference prism 100 are determined from the object plane 30 to the image plane 50. Specifically, the light beam passing through the reference prism 100 exits from the object plane 30, with the incident surface being the first reference optical surface 110; it is refracted through the first reference optical surface 110 to another reference optical surface, which is the second reference optical surface 120; it is reflected through the second reference optical surface 120 back to the first reference optical surface 110; it is then totally internally reflected through the first reference optical surface 110 to yet another reference optical surface, which is the third reference optical surface 130; and finally, it is refracted through the third reference optical surface 130 to the image plane 50.

[0078] It is also understandable that the second reference optical surface 120 is a reflective surface, which allows some external light to enter the prism, thereby improving the user experience.

[0079] Step S213: Obtain the first edge ray 210 and the second edge ray 230; the first edge ray 210 and the second edge ray 230 are two edge rays along the second direction 73 in the reference prism 100 and within the field of view.

[0080] Specifically, the first edge ray 210 is the edge ray of the positive half field of view in the second direction 73 (with the vertical upward direction as the positive direction), and the second edge ray 230 is the edge ray of the negative half field of view in the second direction 73. The first edge ray 210 and the second edge ray 230 are the farthest apart in the second direction 73.

[0081] Step S214: The refraction point of the first edge ray 210 and the first reference optical surface 110 is determined as the first reference point 310; the reflection point of the first edge ray 210 and the second reference optical surface 120 is determined as the second reference point 320; the total internal reflection point of the first edge ray 210 and the first reference optical surface 110 is determined as the third reference point 330; the refraction point of the first edge ray 210 and the third reference optical surface 130 is determined as the fourth reference point 340; the refraction point of the second edge ray 230 and the first reference optical surface 110 is determined as the fifth reference point 350; the reflection point of the second edge ray 230 and the second reference optical surface 120 is determined as the sixth reference point 360; the total internal reflection point of the second edge ray 230 and the first reference optical surface 110 is determined as the seventh reference point 370; and the refraction point of the second edge ray 230 and the third reference optical surface 130 is determined as the eighth reference point 380.

[0082] In detail, the reference values ​​from the first reference point 310 to the eighth reference point 380 are as follows: Figure 2 As shown.

[0083] Step S221: The difference between the fourth reference point 340 and the third reference point 330 in the second direction 73 is determined to be greater than 0.4 mm, and the difference between the fourth reference point 340 and the third reference point 330 in the third direction 75 is determined to be between 0.4 mm and 3 mm.

[0084] Based on the above steps, the first reference optical surface 110 and the third reference optical surface 130 are finely adjusted and constrained to prevent the light beam from escaping from the connection between the first reference optical surface 110 and the third reference optical surface 130, thus affecting the imaging quality.

[0085] Step S222: The difference between the seventh reference point 370 and the fifth reference point 350 in the second direction 73 is determined to be greater than 0 mm, and the difference between the sixth reference point 360 and the fifth reference point 350 in the third direction 75 is determined to be between 0.5 mm and 3 mm.

[0086] Based on the above steps, the first reference optical surface 110 and the second reference optical surface 120 are finely adjusted and constrained to prevent the light beam from escaping from the connection between the first reference optical surface 110 and the second reference optical surface 120, which would affect the imaging quality.

[0087] Step S223: Determine the range of the difference between the second reference point 320 and the eighth reference point 380 in the third direction 75 as 0.2mm to 3mm.

[0088] Based on the above steps, the second reference optical surface 120 and the third reference optical surface 130 are finely adjusted and constrained to prevent the light beam from escaping from the connection between the second reference optical surface 120 and the third reference optical surface 130, thus affecting the imaging quality.

[0089] Step S224: Determine the shortest distance between the reference prism 100 and the object plane 30 in the third direction 75 as greater than 18 mm.

[0090] It is understandable that the minimum distance between the first reference optical surface 110 and the object surface 30 in the third direction 75 is determined to be greater than 18mm to meet the human eye gap.

[0091] Step S225: Determine the refraction angle of any ray on the first reference optical surface 110 to be greater than 42.2°.

[0092] Specifically, the refraction angle of the first edge ray 210 at the first reference optical surface 110 is determined to be greater than 42.2° to satisfy the total internal reflection condition of the first reference optical surface 110.

[0093] It should be noted that steps S221, S222, and S223 are all constraints and optimizations applied to the reference prism 100 to prevent light escape; step S224 is a constraint and optimization of the reference prism 100 based on the condition of total internal reflection; and step S225 is a constraint and optimization of the reference prism 100 based on the condition of satisfying the human eye gap. The above five steps can be adjusted, merged, or reduced in order according to actual needs to achieve fine-tuning of the reference prism 100 to obtain the second optimized prism 400. It can be understood that the reference prism 100 is a transitional prism in the process of optimizing the first optimized prism to the second optimized prism 400. The reference prism 100 is as follows... Figure 2 As shown, the second optimized prism 400 is as follows Figure 4 As shown.

[0094] It is understandable that, in order to facilitate the expansion of the field of view in the first direction 71, the reference data of the first optimized prism obtained in step S310 refers to the distance between any two first optimized optical surfaces of the first optimized prism and the third adjustment parameter of each first optimized optical surface; while the reference data between the first optimized prism and the image plane 50 or the object plane 30 mainly refers to the shortest distance between the first optimized optical surface and the object plane 30 or the image plane 50, specifically the distance between the first optimized optical surface closest to the image plane 50 and the image plane 50, and the distance between the first optimized optical surface closest to the object plane 30 and the object plane 30; the optical path data of the beam in the first optimized prism can refer to the optical path data of the edge rays in the beam in the first optimized prism.

[0095] Among them, the third adjustment parameter refers to the third tilt parameter in the first direction 71 and the third eccentricity parameter in the second direction 73.

[0096] In some embodiments, the following steps are included after step S330: a rectangular sampling area is drawn in the plane formed by the first direction 71 and the second direction 73, and within a preset field of view using a rectangular sampling method; the distance between the projection point of each ray in the beam on the rectangular sampling area and the center of the rectangular sampling area is obtained, and the weighting factor of each ray in the beam is obtained; the weighting factor is determined to be inversely proportional to the distance.

[0097] Since aberrations increase non-linearly as the field of view increases, priority is given to sampling light rays that are far from the center of the projection point and the rectangular sampling area to increase their weighting factor (weight), ensuring that the light rays at the edge of the image are clear without excessive distortion or distortion, thereby ensuring image quality.

[0098] It should also be noted that when the prism has yoz-plane symmetry, such as Figure 5 As shown, sampling can be performed on half of the rectangular sampling area to simplify the sampling process. Therefore, in the first direction 71, only three fields of view—0°, 11°, and 22°—were uniformly sampled. In the second direction 73, five fields of view—-13°, -6.5°, 0°, 6.5°, and 13°—were uniformly sampled. It should be noted that uniform sampling can smooth the prism surface.

[0099] Furthermore, throughout the uniform sampling process, a progressive optimization strategy is employed to gradually increase the number of samples in the beam. Specifically, in the first direction 71, the 0° field of view is optimized first, then expanded to a 6.5° field of view, and finally to a 13° field of view; in the second direction 73, the 0° field of view is optimized first, then expanded to an 11° field of view, and finally to a 22° field of view. It should be noted that the negative half-field of view sampling in the first direction 71 or the second direction 73 is similar to that described above, and will not be repeated here.

[0100] In other embodiments, such as Figure 6 As shown, the following steps are included after step S330:

[0101] Step S410: Obtain reference data for the second optimized prism 400, reference data between the second optimized prism 400 and the image plane 50, reference data between the second optimized prism 400 and the object plane 30, and reference data for the light beam within the second optimized prism 400.

[0102] Step S430: The reference data of the second optimized prism 400, the reference data between the second optimized prism 400 and the image plane 50, the reference data between the second optimized prism 400 and the object plane 30, and the reference data of the beam within the second optimized prism 400 are converted into a surface shape and polynomial coefficients are introduced to obtain a polynomial curved surface prism 500.

[0103] Understandably, the deformable aspherical surface is transformed into a polynomial surface using a least-squares fitting algorithm. Specifically, the polynomial surface is an XY polynomial surface, thus introducing polynomial coefficients as new variable parameters. Subsequently, by adding or adjusting the polynomial coefficients, the system performance is further optimized by utilizing the greater degrees of freedom of the polynomial surface, thereby further improving the prism's imaging quality. Among these, the polynomial surface prism 500, for example... Figure 7 As shown.

[0104] In summary, the freeform prism optimization method and freeform prism provided in this embodiment of the invention establish an initial prism based on three sets of surface shape data, a first direction 71, a second direction 73, and a third direction 75. Then, relevant parameters of the initial prism are obtained, and a quadratic constant and aspherical coefficient correction are introduced to optimize the surface shape to obtain a first optimized prism with an expanded field of view in the second direction 73. Next, relevant parameters of the first optimized prism are obtained, and asymmetric coefficient correction is introduced to further optimize the surface shape to obtain a second optimized prism 400 with an expanded field of view in the first direction 71. Based on the above, by adjusting the relevant parameters of the prism at appropriate optimization stages, the optimization efficiency of each stage of the prism is improved, and the dependence on the initial prism is reduced. This allows for the optimization of a good freeform prism based on different initial surface shape data, thereby reducing the difficulty of obtaining freeform prisms and saving time.

[0105] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An optimization method for a freeform prism, characterized in that, include: Acquire three sets of surface data, a first direction (71), a second direction (73), and a third direction (75). Each set of surface data includes geometric parameters and a first adjustment parameter. The first direction (71), the second direction (73), and the third direction (75) are perpendicular to each other. Based on the three sets of surface data, an initial prism is established; the three sets of surface data correspond one-to-one with the three initial optical surfaces of the initial prism. Acquire reference data for the initial prism, reference data between the initial prism and the image plane (50), reference data between the initial prism and the object plane (30), and optical path data of the beam within the initial prism; Based on the reference data of the initial prism, the reference data between the initial prism and the image plane (50), the reference data between the initial prism and the object plane (30), and the optical path data of the beam in the initial prism, and by introducing a quadratic constant and an aspherical coefficient, the surface shape of the initial prism is optimized to obtain a first optimized prism, so as to increase the field of view of the beam passing through the first optimized prism in the second direction (73); Acquire reference data for the first optimized prism, reference data between the first optimized prism and the image plane (50), reference data between the first optimized prism and the object plane (30), and reference data of the beam within the first optimized prism; Based on the reference data of the first optimized prism, the reference data between the first optimized prism and the image plane (50), the reference data between the first optimized prism and the object plane (30), and the reference data of the beam within the first optimized prism, an asymmetry coefficient is introduced to optimize the surface shape of the first optimized prism, thereby obtaining a second optimized prism (400) to increase the field of view of the beam passing through the second optimized prism (400) in the first direction (71).

2. The optimization method for a freeform prism according to claim 1, characterized in that, The specific steps for obtaining the reference data of the initial prism, the reference data between the initial prism and the image plane (50), the reference data between the initial prism and the object plane (30), and the optical path data of the beam within the initial prism include: The spacing between any two initial optical surfaces, the spacing between the initial optical surface near the image surface (50) and the image surface (50), and the second adjustment parameters of the three initial optical surfaces are obtained.

3. The optimization method for a freeform prism according to claim 2, characterized in that, After obtaining the spacing between any two initial optical surfaces, the spacing between the initial optical surface near the image surface (50) and the image surface (50), and the second adjustment parameters of the three initial optical surfaces, the method further includes: Based on the spacing between any two initial optical surfaces, the spacing between the initial optical surface near the image surface (50) and the image surface (50), and the second adjustment parameters of the three initial optical surfaces, and by introducing the quadratic constant and the aspherical coefficient, the surface shape of the initial prism is optimized to obtain a reference prism (100); the reference prism (100) includes a first reference optical surface (110), a second reference optical surface (120), and a third reference optical surface (130) from the object surface (30) to the image surface (50); Acquire a first edge ray (210) and a second edge ray (230); the first edge ray (210) and the second edge ray (230) are two edge rays along the second direction (73) in the reference prism (100) and within the field of view. The refraction point of the first edge ray (210) and the first reference optical surface (110) is determined as the first reference point (310), the reflection point of the first edge ray (210) and the second reference optical surface (120) is determined as the second reference point (320), the total internal reflection point of the first edge ray (210) and the first reference optical surface (110) is determined as the third reference point (330), and the refraction point of the first edge ray (210) and the third reference optical surface (130) is determined as the fourth reference point (340). The refraction point of the second edge ray (230) with the first reference optical surface (110) is determined as the fifth reference point (350), the reflection point of the second edge ray (230) with the second reference optical surface (120) is determined as the sixth reference point (360), the total internal reflection point of the second edge ray (230) with the first reference optical surface (110) is determined as the seventh reference point (370), and the refraction point of the second edge ray (230) with the third reference optical surface (130) is determined as the eighth reference point (380). The difference between the fourth reference point (340) and the third reference point (330) in the second direction (73) is determined to be greater than 0.4 mm, and the difference between the fourth reference point (340) and the third reference point (330) in the third direction (75) is determined to be from 0.4 mm to 3 mm.

4. The optimization method for the freeform prism according to claim 3, characterized in that, The method further includes: The difference between the seventh reference point (370) and the fifth reference point (350) in the second direction (73) is determined to be greater than 0 mm, and the difference between the sixth reference point (360) and the fifth reference point (350) in the third direction (75) is determined to be 0.5 mm to 3 mm.

5. The optimization method for the freeform prism according to claim 3, characterized in that, The method further includes: The difference between the second reference point (320) and the eighth reference point (380) in the third direction (75) is determined to be between 0.2 mm and 3 mm.

6. The optimization method for a freeform prism according to claim 3, characterized in that, The method further includes: The shortest distance between the reference prism (100) and the object plane (30) in the third direction (75) is determined to be greater than 18 mm.

7. The optimization method for a freeform prism according to claim 3, characterized in that, The method further includes: The refraction angle of any ray on the first reference optical surface (110) is determined to be greater than 42.2°.

8. The optimization method for a freeform prism according to claim 1, characterized in that, The geometric parameters include the radius, the distance between any two initial optical surfaces, and the radius of curvature. The first adjustment parameter includes a first tilt parameter in a first direction (71) and a first eccentricity parameter in a second direction (73).

9. The optimization method for a freeform prism according to any one of claims 1-8, characterized in that, After introducing an asymmetry coefficient based on the reference data of the first optimized prism, the reference data between the first optimized prism and the image plane (50), the reference data between the first optimized prism and the object plane (30), and the reference data of the beam between the first optimized prisms, to optimize the surface shape of the first optimized prism and obtain a second optimized prism (400) to increase the field of view of the beam passing through the second optimized prism (400) in the first direction (71), the method further includes: Acquire reference data for the second optimized prism (400), reference data between the second optimized prism (400) and the image plane (50), reference data between the second optimized prism (400) and the object plane (30), and reference data of the beam within the second optimized prism (400); The reference data of the second optimized prism (400), the reference data between the second optimized prism (400) and the image plane (50), the reference data between the second optimized prism (400) and the object plane (30), and the reference data of the beam within the second optimized prism (400) are used to perform surface transformation and introduce polynomial coefficients to obtain a polynomial curved surface prism (500).

10. A freeform prism, characterized in that, It is manufactured using the optimized method for freeform prisms as described in any one of claims 1-9.

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