CN116257896A

CN116257896A - Design method, system, terminal and storage medium of uniform illumination light source

Info

Publication number: CN116257896A
Application number: CN202111510208.4A
Authority: CN
Inventors: 叶新; 田杰文; 方伟
Original assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Current assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Priority date: 2021-12-10
Filing date: 2021-12-10
Publication date: 2023-06-13

Abstract

According to the design method, the system, the terminal and the storage medium of the uniform illumination light source, the mathematical model of the free-form surface is constructed so as to acquire the geometric relation between the free-form surface and the light source, the mathematical model is subjected to discrete processing, the mathematical model after the discrete processing is solved, the surface shape of the free-form surface is obtained according to the solved mathematical model, the uniform illumination light source is obtained according to the surface shape of the free-form surface, large-area uniform collimation illumination of the small-opening integrating sphere light source can be realized, and the detector response errors caused by non-uniformity of incident light, incident angles and positions are reduced.

Description

Design method, system, terminal and storage medium of uniform illumination light source

Technical Field

The application belongs to the technical field of optical design, and particularly relates to a design method, a system, a terminal and a storage medium of a uniform illumination light source.

Background

The on-board calibration of the space remote sensing instrument is to observe the reference light source simultaneously by using the transmission radiometer and the space remote sensing instrument, and the uniformity of the reference light source directly influences the calibration precision because the fields of view of the transmission radiometer and the space remote sensing instrument cannot be completely matched. The calibration transmission chain used at present generally uses sunlight to irradiate the diffuse reflection plate to generate lambertian light as a reference light source, but the diffuse reflection plate directly exposed to the space environment can cause great attenuation. The calibration mode of the built-in lamp mainly comprises two modes of a lamp, a diffuse reflection plate and an integrating sphere. The calibration mode of the lamp and the diffuse reflection plate is to irradiate the diffuse reflection plate with known dichroic reflectivity by using a standard illumination lamp to generate a large-area calibration source with uniform radiance to realize calibration. The integrating sphere has better lambertian than the diffuse reflecting plate, so that the scaling mode of 'lamp + integrating sphere' is also presented. The lamp + integrating sphere approach has better calibration performance than the lamp + diffuser plate approach. However, in the "lamp+diffuse reflector" system, both the intensity and stability of the light vary with the angle of view of the incident light. The response errors of the detector caused by the non-uniformity of the incident light, the incident angle and the incident position are easily introduced. In the system of the lamp and the integrating sphere, if a large-area uniform light spot is wanted, the opening of the integrating sphere is good according to the uniform light characteristic of the integrating sphere, and the volume and the weight of the integrating sphere are increased, so that the on-satellite calibration is not facilitated.

The Chinese patent 200910046129.5 proposes a design method of a point light source light distribution lens, which is characterized in that a partial differential equation satisfied by a free-form surface is constructed according to a light propagation law, then a mapping relation between a light source and target illumination is determined according to an energy topological relation, and the mapping relation is realized by solving the partial differential equation to construct the free-form surface. However, the mapping relation constructed by the man-made method is difficult to meet the smooth and continuous requirements of the free-form surface, namely integrality, and only discontinuous free-form surfaces can be obtained.

Disclosure of Invention

In view of this, it is necessary to provide a method for designing a uniform illumination light source that can achieve uniform illumination characteristics of a small F-number and a large area and that can improve the utilization efficiency of the light source, aiming at the defects existing in the prior art.

In order to solve the problems, the following technical scheme is adopted in the application:

the application provides a design method of a uniform illumination light source, which comprises the following steps:

constructing a mathematical model of the free-form surface to obtain the geometric relationship between the free-form surface and the light source;

performing discrete processing on the mathematical model;

solving the mathematical model after discrete processing;

obtaining the surface shape of the free curved surface according to the solved mathematical model;

and obtaining a uniform illumination light source according to the surface shape of the free curved surface.

In some of these embodiments, in the step of constructing a mathematical model of the free-form surface to obtain the geometric relationship of the free-form surface to the light source, the mathematical model of the free-form surface is as follows:

wherein: ρ _uu Representing the second order bias of ρ in the u-direction, ρ _vv Representing the second order bias of ρ in the v direction, ρ _uv Representing the mixed bias of p in the u, v direction.

In some of these embodiments, the step of performing discrete processing on the mathematical model specifically includes the steps of:

the mathematical model is discretized using chebyshev grids.

In some of these embodiments, in the step of solving the discrete processed mathematical model, the method specifically includes the steps of:

solving the mathematical model by adopting a 9-point difference method, wherein:

points inside the grid are defined as interpolation points in the process of solving the mathematical model by using a 9-point difference method, and the interpolation points are represented by the following formula:

points outside the grid are defined as boundary points in the process of solving the mathematical model by using a 9-point difference method, and the boundary points are expressed by the following formula:

z _x representing the derivative of z in the x-direction, z _y Representing the derivative of z in the y-direction, z _xx Representing the second derivative of z in the x-direction, z _yy Representing the second derivative of z in the y-direction, z _xy Indicating the mixed bias of z in the x, y directions.

In some embodiments, in the step of obtaining the surface shape of the free-form surface according to the solved mathematical model, the method specifically includes the following steps:

and carrying the interpolation value points and the boundary points into the B spline curve by the ug software to obtain the surface shape of the free-form surface.

In addition, the application also provides a design system of the uniform illumination light source, which comprises:

the model construction unit is used for constructing a mathematical model of the free-form surface so as to acquire the geometric relationship between the free-form surface and the light source;

the discrete processing unit is used for performing discrete processing on the mathematical model;

the computing unit is used for solving the mathematical model after the discrete processing;

the curved surface model construction unit is used for obtaining the surface model of the free curved surface according to the solved mathematical model;

and the light source unit is used for obtaining a uniform illumination light source according to the surface shape of the free curved surface.

In addition, the application also provides a terminal, which comprises: the terminal includes a processor, a memory coupled to the processor, wherein,

the memory stores program instructions for implementing the design method of the uniform illumination source;

the processor is configured to execute the program instructions stored by the memory to control the design of a uniform illumination source.

Furthermore, the application provides a storage medium storing program instructions executable by a processor, the program instructions being configured to perform the method for designing a uniform illumination source.

The application adopts the technical scheme that the following effects are achieved:

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the embodiments of the present application or the description of the prior art will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a flowchart of steps of a method for designing a uniform illumination light source according to an embodiment of the present application.

Fig. 2 is a schematic diagram of a mathematical model of a free-form surface provided in an embodiment of the present application.

Fig. 3 is a schematic diagram of a light source output area not matching a grid when a projection method is used to project light source output light according to an embodiment of the present application.

Fig. 4 is a schematic view of a chebyshev grid provided in an embodiment of the present application.

Fig. 5 is a schematic view of free-form surface chebyshev point division according to an embodiment of the present application.

Fig. 6 is a schematic diagram of a 9-point differential method provided in an embodiment of the present application.

Fig. 7 (a) shows a free-form surface model obtained using a uniform mesh, and (b) shows a free-form surface model obtained using chebyshev mesh.

Fig. 8 is a light path diagram provided in an embodiment of the present application.

Fig. 9 (a) is a schematic view of the target surface irradiance obtained using a uniform grid, and (b) is a schematic view of the target surface irradiance obtained using a chebyshev grid.

Fig. 10 is a schematic diagram of obtaining illumination spots with different shapes according to an embodiment of the present application.

Fig. 11 is a schematic structural diagram of a design system of a uniform illumination source provided in the present application.

Fig. 12 is a schematic diagram of a terminal structure provided in an embodiment of the present application.

Fig. 13 is a schematic structural diagram of a storage medium according to an embodiment of the present application.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and intended for the purpose of explaining the present application and are not to be construed as limiting the present application.

In the description of the present application, it should be understood that the terms "upper," "lower," "horizontal," "inner," "outer," and the like indicate an orientation or a positional relationship based on that shown in the drawings, and are merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element in question must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

Example 1

Referring to fig. 1, a flowchart of steps of a method for designing a uniform illumination light source provided in the present application includes the following steps:

step S110: and constructing a mathematical model of the free-form surface to obtain the geometric relationship between the free-form surface and the light source.

In this embodiment, in the step of constructing a mathematical model of a free-form surface to obtain a geometric relationship between the free-form surface and a light source, the mathematical model of the free-form surface can be seen in fig. 2, and is specifically shown as follows:

wherein: w (w) ² ＝u ² +v ² ，ρ _uu Representing the second order bias of ρ in the u-direction, ρ _vv Representing the second order bias of ρ in the v direction, ρ _uv Representing the mixed bias of p in the u, v direction.

Specifically, first, it is obtained by the law of conservation of energy:

e represents irradiance of the target surface, and I represents light intensity of the outgoing light. w (w) ² ＝u ² +v ² ，u，v，t _x ，t _y Given in FIG. 2, ρ _uu Representing the second order bias of ρ in the u-direction, ρ _vv Representing the second order bias of ρ in the v direction, ρ _uv Representing the mixed bias of p in the u, v direction.

Transforming equations

|J(T)|E(t _x (u,v),t _y (u,v))＝I(u,v)(1+0.25w ² ) ^-2 (3)

Obtaining a Mone-Ampere elliptic equation

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Obtaining boundary conditions through snell's law

Finally, obtaining a mathematical model of the free-form surface:

step S120: and performing discrete processing on the mathematical model.

It will be appreciated that since the mathematical model is a partial differential equation set, only numerical analysis can be used. In the discrete method of the light source part, when the projection method is adopted to project the emergent light of the light source, the sampling grid is usually in a topological square shape or a topological rectangle shape, but the light source is usually provided with rotational symmetry, the corresponding emergent region is in a topological circular shape, and the two are not matched, and referring to fig. 3, a schematic diagram of the mismatch between the emergent region and the grid of the light source is shown.

In this embodiment, the chebyshev grid is used to perform discrete processing on the mathematical model, and according to the definition of chebyshev points, the chebyshev points can be understood as projections of equidistant points on the upper half unit circle on the horizontal axis, so that for the two-dimensional problem, the plane is divided along the X and Y directions respectively, as shown in fig. 4, which is a schematic diagram of the chebyshev grid.

Referring to fig. 5, a schematic diagram of free-form surface chebyshev point division is shown, and it can be seen from the figure that the free-form surface is divided by using the method, and the matching with the emergent projection of the light source is good.

Step S130: and solving the mathematical model after the discrete processing.

In this embodiment, the mathematical model is solved using a 9-point differencing method.

Please refer to fig. 6, which is a schematic diagram of a 9-point differential method.

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Step S140: and obtaining the surface shape of the free-form surface according to the solved mathematical model.

In this embodiment, the interpolation value point and the boundary point are carried into the B-spline curve by the ug software, so as to obtain the surface shape of the free-form surface.

Referring to fig. 7, where (a) is a free-form surface model obtained using a uniform mesh and (b) is a free-form surface model obtained using chebyshev mesh.

Step S150: and obtaining a uniform illumination light source according to the surface shape of the free curved surface.

In this example, 200 ten thousand ray traces were performed by introducing lighttools, and the light source was provided with a uniform light source having a diameter of 5mm and a thickness of 0.001 mm. The light path diagram is shown in fig. 8, and by adopting the method, a free curved surface and a receiving surface are placed, so that a uniform light spot is obtained. Fig. 9 (a) is a schematic view of the target surface irradiance obtained using a uniform grid, and fig. 9 (b) is a schematic view of the target surface irradiance obtained using a chebyshev grid.

The irradiance of the target surface can be found to be more than 98% through numerical analysis. However, the uniformity is reduced due to the limitation of the processing precision of the free curved surface, the reflectivity of the coating, the adjustment and the lambertian of the emergent light of the integrating sphere. To meet the detector requirements of different fields of view, differently shaped illumination spots can be obtained by defining boundary conditions, as shown in fig. 10.

Example 2

Referring to fig. 11, a schematic structural diagram of a design system of a uniform illumination light source provided in the present application includes: a model construction unit 110 for constructing a mathematical model of the free-form surface to obtain a geometric relationship between the free-form surface and the light source; a discrete processing unit 120, configured to perform discrete processing on the mathematical model; a computing unit 130, configured to solve the discrete processed mathematical model; a curved surface model construction unit 140, configured to obtain a surface model of the free-form surface according to the solved mathematical model; and a light source unit 150 for obtaining a uniform illumination light source according to the surface shape of the free-form surface. The detailed implementation manner of the method is already described in the above method description of the application, and is not repeated here.

Example 3

Fig. 12 is a schematic diagram of a terminal structure according to an embodiment of the present application. The terminal 50 includes a processor 51, a memory 52 coupled to the processor 51.

The memory 52 stores program instructions for implementing the described method of designing a uniform illumination source.

The processor 51 is arranged to execute program instructions stored in the memory 52 for controlling the design of the uniform illumination source.

The processor 51 may also be referred to as a CPU (Central Processing Unit ). The processor 51 may be an integrated circuit chip with signal processing capabilities. Processor 51 may also be a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

Example 4

Fig. 13 is a schematic structural diagram of a storage medium according to an embodiment of the present application. The storage medium of the embodiment of the present application stores a program file 61 capable of implementing all the methods described above, where the program file 61 may be stored in the storage medium in the form of a software product, and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to execute all or part of the steps of the methods of the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, randomAccess Memory), a magnetic disk, or an optical disk, or terminal devices, such as a computer, a server, a mobile phone, and a tablet.

The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and changes may be made to the present application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. which are within the spirit and principles of the present application are intended to be included within the scope of the claims of the present application.

Claims

1. A method of designing a uniform illumination source, comprising the steps of:

performing discrete processing on the mathematical model;

solving the mathematical model after discrete processing;

2. The method of claim 1, wherein in the step of constructing a mathematical model of a free-form surface to obtain a geometric relationship between the free-form surface and the light source, the mathematical model of the free-form surface is as follows:

3. The method of designing a uniform illumination source according to claim 1, wherein in the step of performing discrete processing on the mathematical model, the method specifically comprises the steps of:

the mathematical model is discretized using chebyshev grids.

4. A method of designing a uniform illumination source according to claim 3, comprising the steps of, in particular, solving the discrete processed mathematical model:

5. The method of claim 4, wherein the step of obtaining the surface shape of the free-form surface from the solved mathematical model comprises the steps of:

6. A system for designing a uniform illumination source, comprising:

7. A terminal, comprising: the terminal includes a processor, a memory coupled to the processor, wherein,

the memory stores program instructions for implementing the method of designing a uniform illumination source according to any one of claims 1 to 5;

8. A storage medium storing program instructions executable by a processor for performing the method of designing a uniform illumination source according to any one of claims 1 to 5.