1. A design method of a random micro-lens array structure is characterized by comprising the following steps:

(1) generating a regular lattice, wherein the coordinate of any one array point in the lattice in an xy coordinate system is (x, y), wherein x is (1-r) dr, y is (1-c) dc, and r, c, dr and dc are the row number, column number, row spacing and column spacing of the lattice respectively;

(2) and taking the connecting line direction from all array points to the center of the dot matrix in the dot matrix as an offset direction, and generating corresponding x-direction offset distance dx and y-direction offset distance dy for each array point according to the distance from each array point to the center of the dot matrix, wherein:

dx＝s*sqrt(DDX/(DDX+DDY))，dy＝s*sqrt(DDY/(DDX+DDY))

DDX＝(x-Xavg)^2，DDY＝(y-Yavg)^2，

Xavg＝max(x)/2+min(x)/2，Yavg＝max(y)/2+min(y)/2，

s is a random number generated in the interval (0-dmax), dmax is an allowed maximum offset, max (x), min (x) are respectively a maximum value and a minimum value of an x coordinate of any array point, and max (y) and min (y) are respectively a maximum value and a minimum value of a y coordinate of any array point;

(3) shifting the lattice position of each array point in the lattice according to the shift direction and the shift distance given in the step (2), and further updating the coordinates of any one of the array points to (x ', y'), x ═ x + dx, y ═ y + dy;

(4) using each array point in the shifted dot matrix obtained in the step (3) as the central position of the corresponding sub-lens, and generating the boundary of each sub-lens by using a Thiessen polygon method;

(5) and (4) using the x and y coordinates of each array point in the dot matrix in the boundary of the sub-lens obtained in the step (3) as the position of the coverage area of the corresponding sub-lens to generate the surface type of the micro-lens array.

2. The design method according to claim 1, wherein: in the step (1), the number of rows and the number of columns of the dot matrix are both odd numbers.

3. The design method according to claim 1, wherein: in the step (2), the direction close to the center of the lattice is a negative offset direction, and the direction far from the center of the lattice is a positive offset direction.

4. A random microlens array structure designed by the method of any one of claims 1 to 3.

5. A method of designing an optical element, comprising:

designing a random microlens array structure using the method of any one of claims 1-3, and distributing the random microlens array structure over the first surface of the optical element; and

the second surface of the optical element is set to be a DOE structure, and the first surface and the second surface are a light-in surface and a light-out surface of the optical element respectively.

6. The design method of claim 5, wherein the first surface is disposed opposite the second surface.

7. The design method of claim 5, wherein the optical element comprises a shim.

8. An optical element designed by the method of any one of claims 5 to 6.

9. An illumination device comprising a light source and a light homogenizing mechanism, characterized in that: the light unifying mechanism comprising the optical element of claim 8.

10. A lighting device as recited in claim 9, wherein: the light source comprises a laser light source, and laser emitted by the laser light source sequentially passes through the first surface and the second surface of the optical element.

Background

Microlens array elements are a class of micro-optical elements that can transform an input beam into a specific output beam, and with the use of microlens array elements, a specific desired spot shape and energy distribution can be generated.

Regular microlens array elements are currently on the market for uniform spot illumination. Each sub-lens unit in the regular array element has the same shape and size, and is characterized by simple arrangement structure and easy design and processing detection, but the interference effect is obvious when a coherent light source passes through a periodically repeated structure, and the corrugated light spot non-uniform effect is often generated in practical application, thereby generating adverse effect on the practical application. An existing improvement is to use a random lens-shaped microlens array to achieve a uniform light spot effect, and the dodging slice of the structure has a good uniform light effect, but is only suitable for scenes with small angle requirements (for example, FOV < 120 °).

Disclosure of Invention

The main objective of the present invention is to provide a random microlens array structure, a design method thereof and applications thereof, so as to overcome the deficiencies in the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

the embodiment of the invention provides a design method of a random micro-lens array structure, which comprises the following steps:

(1) generating a regular lattice, wherein the coordinate of any one array point in the lattice in an xy coordinate system is (x, y), wherein x is (1-r) dr, y is (1-c) dc, and r, c, dr and dc are the row number, column number, row spacing and column spacing of the lattice respectively;

(2) and taking the connecting line direction from all array points to the center of the dot matrix in the dot matrix as an offset direction, and generating corresponding x-direction offset distance dx and y-direction offset distance dy for each array point according to the distance from each array point to the center of the dot matrix, wherein:

dx＝s*sqrt(DDX/(DDX+DDY))，dy＝s*sqrt(DDY/(DDX+DDY))

DDX＝(x-Xavg)^2，DDY＝(y-Yavg)^2，

Xavg＝max(x)/2+min(x)/2，Yavg＝max(y)/2+min(y)/2，

s is a random number generated in the interval (0-dmax), dmax is an allowed maximum offset, max (x), min (x) are respectively a maximum value and a minimum value of an x coordinate of any array point, and max (y) and min (y) are respectively a maximum value and a minimum value of a y coordinate of any array point;

(3) shifting the lattice position of each array point in the lattice according to the shift direction and the shift distance given in the step (2), and further updating the coordinates of any one of the array points to (x ', y'), x ═ x + dx, y ═ y + dy;

(4) using each array point in the shifted dot matrix obtained in the step (3) as the central position of the corresponding sub-lens, and generating the boundary of each sub-lens by using a Thiessen polygon method;

(5) and (4) using the x and y coordinates of each array point in the dot matrix in the boundary of the sub-lens obtained in the step (3) as the position of the coverage area of the corresponding sub-lens to generate the surface type of the micro-lens array.

Further, in the step (1), the number of rows and the number of columns of the dot matrix are both odd.

Further, in the step (2), a direction close to the center of the lattice is a negative offset direction, and a direction away from the center of the lattice is a positive offset direction.

The embodiment of the invention also provides a random micro-lens array structure which is designed and formed by adopting any one of the methods.

The embodiment of the invention also provides a design method of the optical element, which comprises the following steps:

adopting any one of the methods of the invention to design and form a random micro-lens array structure, and distributing the random micro-lens array structure on the first surface of the optical element; and

the second surface of the Optical element is provided with a DOE (discrete Optical elements) structure, and the first surface and the second surface are a light incident surface and a light emitting surface of the Optical element respectively.

Further, the first surface and the second surface are arranged oppositely.

Further, the optical element includes a light homogenizing plate, but is not limited thereto.

The embodiment of the invention also provides an optical element which is designed and formed by adopting any one of the methods.

The embodiment of the invention also provides the lighting equipment which comprises a light source and the light evening mechanism, wherein the light evening mechanism comprises the optical element.

Further, the light source comprises a laser light source, and laser emitted by the laser light source sequentially passes through the first surface and the second surface of the optical element.

Further, the light source also includes other types of light sources, such as tungsten lamp, LED, etc., and is not limited thereto.

Compared with the prior art, the random micro-lens array structure provided by the embodiment of the invention effectively eliminates the problems of repeated sub-lens periods, light spot ripple of the regularly arranged micro-lens array and the like, simultaneously lightens the sensitivity of the light source installation tolerance of the illumination system, and particularly can realize the uniform speckle projection effect with a large wide angle by matching with the DOE surface, so that the random micro-lens array structure can meet the requirements of various application scenes.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

The embodiment provides a design method of a random microlens array structure, which may specifically include:

(1) the regular lattice is generated by an algorithm, which may be any suitable algorithm known in the art. For example, one way to generate a structured lattice arrangement includes: given the number of rows r, the number of columns c, the row spacing dr, and the column spacing dc of the lattice, a distribution of array points can be generated with coordinates (x, y), where x (1 to r) dr and y (1 to c) dc. The number of rows and columns of the matrix of the lattice is odd, for example 13 × 17. In this embodiment, the interval between the array dots in the dot matrix is set to be between 50 μm and 200 μm.

(2) And taking the connecting line direction from all array points to the center of the dot matrix in the dot matrix as an offset direction, taking the direction close to the center of the dot matrix as a negative direction, taking the direction far away from the center of the dot matrix as a positive direction, and generating the offset distance according to the size of the array point distance through a certain relation. In this embodiment, dmax is an allowable maximum offset, s is a random number generated in an interval from (0) to dmax, and a maximum value and a minimum value are taken for all x in step (1) to calculate an average value, which is denoted as Xavg ═ max (x)/2+ min (x)/2, and a maximum value and a minimum value are taken for all y in step (1) to calculate an average value, which is denoted as Yavg ═ max (y)/2+ min (y)/2. Thus, for any array point (x, y) generated in step (1), DDX ═ x-Xavg ^2, DDY ═ y-Yavg ^2 are obtained. Then, the offset dx ═ s ═ sqrt (DDX/(DDX + DDY)), dy ═ s ═ sqrt (DDY/(DDX + DDY)) can be calculated.

(3) And (3) updating the coordinates of each array point in the dot matrix into a new dot matrix position according to the offset direction and the offset distance determined in the step (2). Specifically, the coordinates of any one of the array points may be updated to (x ', y'), x '═ x + dx, y' ═ y + dy).

(4) Each array point in the shifted lattice is used as the center position of the corresponding sub-lens (i.e. the coordinates (x ', y') of the array point, when the polygon boundary is generated by using the coordinates, the points can be regarded as the center point of each polygon), and the boundary is generated by using the Thiessen polygon method according to the position, so that the effective aperture of the sub-lens can be utilized to the maximum.

(5) The face shape of the microlens array is generated using the central lattice (i.e., the coordinates (x ', y') of the array points as the locations of the coverage areas of the sub-lenses.

The random arrangement distribution generated by the algorithm mechanism is used, and then the generated random micro-lens array is filled, so that the embodiment has excellent light equalizing effect, can eliminate the interference fringe problem of the regular micro-lens array, and can reduce the sensitivity of the light source installation tolerance of the lighting system.

Further, the random microlens array structure can be applied to various optical elements.

In an application of this embodiment, the random microlens array structure can be applied to a light uniformizing sheet. Specifically, the random microlens array structure may be disposed on a first surface of the light uniformizing sheet, the first surface being a light incident surface, and the second surface of the light uniformizing sheet being a DOE surface, the second surface being a light emergent surface. Further, the second surface may be constituted by a binary DOE structure.

When applying to this even light piece and carrying out the homogenization to laser, the laser through first surface will be by first homogenization, and rethread second surface is by further homogenization, enlarges the exit angle simultaneously to effectively solve current even light piece and be difficult to realize the problem that the even facula of wide-angle throws, realize better optics plastic effect.

The random microlens array structure and the corresponding optical element Of the present embodiment can be used for uniform laser light, and can also be used in any other scenes requiring uniform light illumination, including but not limited to 3D ToF (Time Of light) module, lighting, projector, tv backlight, etc.

It is to be understood that the above-described embodiments are part of the present invention, and not all embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.