Diffractive optical element and design method, optical projection device and vehicle

Abstract

The present invention provides a design method for a diffractive optical element for projecting a starry sky effect, comprising: S101: generating a target map of the diffractive optical element according to a target light field range, wherein the target map comprises a background covering at least a portion of the target light field range, a first group of points in a first grayscale range, and a second group of points in a second grayscale range, wherein the first grayscale range is higher than the grayscale of the background, and the second grayscale range is higher than the first grayscale range; and S102: designing a phase distribution of a microstructure pattern unit of the diffractive optical element according to the target map.

Description

Technical Field

[0001] The present invention generally relates to the field of optical technology, and more particularly to a diffractive optical element capable of projecting a starry sky effect and a design method thereof, an optical projection device, and a vehicle comprising the same. Background Art

[0002] The existing lighting scheme for projecting starry sky effects usually uses diffractive optical elements (DOEs) to design regular dot arrays, such as 3*3, 5*5, and 7*7 regular dot arrays. Two DOEs are prepared on two surfaces of the same substrate and offset from each other by a certain angle by double-sided etching or double-sided transfer, forming a regular dot array such as Figure 1 The distribution of baby's breath is shown. However, the above conventional design has the following problems:

[0003] Firstly, since two regular dot matrices are transferred on both sides to form the light field FOV, the final light field of the starry sky field is the convolution sum of the two light field FOVs, which makes the final light field unable to be precisely controlled.

[0004] Secondly, the number of light spots and the degree of light and dark alternation cannot be designed accurately, and are highly dependent on processing. In addition, the parasitic points between the two are also prone to participate in convolution, which will make the points appear dense and deviate from the original design intention.

[0005] The contents of the background technology section are merely the technologies known to the public and do not necessarily represent the existing technologies in the field. Summary of the invention

[0006] In view of at least one defect of the prior art, the present invention provides a design method of a diffractive optical element for projecting a starry sky effect, comprising:

[0007] S101: generating a target map of the diffractive optical element according to a target light field range, wherein the target map includes a background covering at least a portion of the target light field range, a first group of points in a first grayscale range, and a second group of points in a second grayscale range, wherein the first grayscale range is higher than the grayscale of the background, and the second grayscale range is higher than the first grayscale range; and

[0008] S102: Designing the phase distribution of the microstructure pattern units of the diffractive optical element according to the target image.

[0009] According to one aspect of the present invention, step S101 includes randomly distributing the first group of points and the second group of points within the target light field.

[0010] According to one aspect of the present invention, the grayscale value range is set to 0-255, wherein the grayscale of the background is between 0-5, the first grayscale range is 20-50, and the second grayscale range is 100-255.

[0011] According to one aspect of the present invention, the design method further comprises adjusting the grayscale values ​​of the background, the first group of points and the second group of points according to computer simulation results to obtain a better starry sky effect.

[0012] According to one aspect of the present invention, the step S101 includes: generating a random number, and randomly distributing the first group of points and the second group of points within the target light field according to the random number.

[0013] The present invention also provides a diffractive optical element for projecting a starry sky effect, comprising:

[0014] at least one microstructure pattern unit capable of projecting a preset light field pattern;

[0015] The preset light field pattern has: a background covering at least a portion of the target light field range;

[0016] a first set of points in a first grayscale range; and

[0017] A second set of points in a second grayscale range,

[0018] The first grayscale range is higher than the grayscale of the background, and the second grayscale range is higher than the first grayscale range.

[0019] According to one aspect of the present invention, the first group of points and the second group of points are randomly distributed within the target light field.

[0020] According to one aspect of the present invention, the grayscale value range is set to 0-255, wherein the grayscale of the background is between 0-5, the first grayscale range is 20-50, and the second grayscale range is 100-255.

[0021] The present invention also provides an optical projection device, comprising:

[0022] a light source configured to emit a light beam;

[0023] The diffractive optical element as described above is arranged downstream of the light source to receive the light beam and project a preset light field pattern on a target plane, wherein the preset light field pattern includes a background, a first group of points in a first grayscale range, and a second group of points in a second grayscale range.

[0024] According to one aspect of the present invention, the optical projection device further comprises a collimating optical device, which is disposed between the light source and the diffractive optical element and is used to collimate the light beam emitted from the light source and project it onto the diffractive optical element.

[0025] The present invention also provides a vehicle, comprising:

[0026] The optical projection device as described above is installed inside the vehicle; and

[0027] The optical projection device is configured to project a preset light field pattern on the roof of the vehicle, wherein the preset light field pattern includes a background, a first group of points in a first grayscale range, and a second group of points in a second grayscale range.

[0028] The design method described in the embodiment of the present invention can obtain a diffractive optical element that projects a starry sky effect, with a nebula background (first level), weak starlight points (second level), and strong starlight points (third level) in the target light field. The strong starlight points and the weak starlight points can be randomly distributed in the target light field, or can be pre-set according to the actual starry sky effect diagram, or the strong starlight points and the weak starlight points can be respectively distributed symmetrically in the center of the target light field, wherein the grayscale or brightness of different strong starlight points can be randomly changed, and the grayscale or brightness of different weak starlight points can also be randomly changed, and the brightness of the strong starlight points is greater than the brightness of the weak starlight points. The nebula background covers at least part of the target light field, and the brightness of the nebula background gradually decreases from the center to the edge of the target light field. The brightness of the nebula background can also be randomly distributed in the target light field, and the brightness of the nebula background is less than the brightness of the weak starlight points. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 The projection of the starry sky image formed by the prior art is shown;

[0031] Figure 2 A design method of a diffractive optical element for projecting a starry sky effect according to an embodiment of the present invention is shown;

[0032] Figure 3 shows a target diagram of a diffractive optical element according to an embodiment of the present invention;

[0033] Figure 4 The figure shows the starry sky effect projected by irradiating the diffractive optical element designed and manufactured based on the above embodiment of the present invention with green laser light;

[0034] Figure 5 A diffractive optical element for projecting a starry sky effect according to an embodiment of the present invention is shown; and

[0035] Figure 6 An optical projection device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0036] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0038] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is lower in level than the second feature.

[0040] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0041] The embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0042] The present invention provides a diffractive optical element DOE for projecting a starry sky effect and a design method thereof, which can accurately control the FOV size, arbitrarily set the number of starry sky points, control the light and dark alternating effects of the number of light points, and form a projected light field with at least three levels of starry sky effects.

[0043] Figure 2 A design method 100 of a diffractive optical element for projecting a starry sky effect according to an embodiment of the present invention is shown and will be described in detail below with reference to the accompanying drawings.

[0044] In step S101: a target map of the diffractive optical element is generated according to a target light field range, wherein the target map includes a background covering at least a portion of the target light field range, a first group of points in a first grayscale range, and a second group of points in a second grayscale range, wherein the first grayscale range is higher than the grayscale of the background, and the second grayscale range is higher than the first grayscale range.

[0045] Figure 3 The target image of the diffractive optical element according to one embodiment of the present invention is shown. When used to project a starry sky effect inside a vehicle, the range of the target light field is, for example, the entire roof of the vehicle, and the background of the target image can occupy the entire target light field range or a part of the target light field range. The background can be a solid color background, or preferably, can have a preset pattern, for example, can simulate a nebula background in a starry sky effect.

[0046] like Figure 3 As shown, a plurality of weak starlight points (a first group of points) and a plurality of strong starlight points (a second group of points) are distributed on the background, wherein the grayscale or brightness of the weak starlight points is higher than the grayscale or brightness of the background, and the grayscale or brightness of the strong starlight points is higher than the grayscale or brightness of the weak starlight points.

[0047] The grayscale is used as an example for description. For example, the grayscale value range is set to 0-255, wherein the grayscale of the background may be between 0-5, the first grayscale range may be between 20-50, and the second grayscale range may be between 100-255.

[0048] In step S102: according to the target image, the phase distribution of the microstructure pattern unit of the diffractive optical element is designed. The surface of the diffractive optical element has one or more microstructure pattern units, and the microstructure pattern units include, for example, stepped micro-nano structures, and the heights of the micro-nano structures correspond to different phase delays, so that when the incident light is incident on the diffractive optical element, the micro-nano structures of different heights will be able to produce a certain phase delay on the incident light, modulate the incident light, and thus project a preset light field as a whole.

[0049] After obtaining the target image in step S101, the phase distribution of the microstructure pattern unit of the diffractive optical element can be designed by combining the parameters of the light source (such as the type and wavelength of the light source) and related size parameters (such as the distance between the light source and the diffractive optical element, the distance between the diffractive optical element and the target projection surface, etc.).

[0050] In step S101, the first group of points and the second group of points may be randomly distributed within the target light field or within the background. For example, a random number may be generated, and the first group of points and the second group of points may be randomly distributed within the target light field or within the background according to the random number, so as to achieve random distribution of the first group of points and the second group of points within the target light field. Alternatively, the first group of points and the second group of points may be distributed on the background or within the target light field according to a galaxy map.

[0051] According to a preferred embodiment of the present invention, after step S102, computer simulation can be performed to obtain a simulated light field projected by the diffractive optical element, and according to the result of the simulated light field, the grayscale value and distribution position of the background, the first group of points and the second group of points are adjusted to obtain a better starry sky effect.

[0052] The above described embodiment includes a first group of points and a second group of points, but the present invention is not limited thereto, and may further include a third group of points, the grayscale or brightness range of the third group of points being different from that of the first group of points and the second group of points, so as to simulate a more realistic starry sky effect. Alternatively, preferably, the second group of points is further subdivided into two groups of points, each having a different grayscale range or brightness range.

[0053] When designing a diffractive optical element according to the above method, the FOV can be set to 30°*30°. In addition, a 2-step design, a 4-step design, an 8-step design or a 16-step design can be adopted.

[0054] The design method described above can obtain a diffractive optical element that projects a starry sky effect, with a nebula background (first level), weak starlight points (second level), and strong starlight points (third level) in the target light field. The strong starlight points and the weak starlight points can be randomly distributed in the target light field, or can be pre-set according to the actual starry sky effect diagram, or the strong starlight points and the weak starlight points can be respectively distributed symmetrically in the center of the target light field, wherein the grayscale or brightness of different strong starlight points can be randomly changed, and the grayscale or brightness of different weak starlight points can also be randomly changed, and the brightness of the strong starlight points is greater than the brightness of the weak starlight points. The nebula background covers at least part of the target light field, and the brightness of the nebula background gradually decreases from the center to the edge of the target light field. The brightness of the nebula background can also be randomly distributed in the target light field, and the brightness of the nebula background is less than the brightness of the weak starlight points.

[0055] Figure 4 The figure shows the starry sky effect projected by irradiating the diffractive optical element designed and manufactured based on the above embodiment of the present invention with green laser.

[0056] Figure 5 FIG. 2 shows a diffractive optical element 200 for projecting a starry sky effect according to an embodiment of the present invention. Figure 5 As shown, there are multiple stepped micro-nano structures on the surface of the diffractive optical element, forming one or more microstructure pattern units, and the microstructure pattern unit is designed to project a preset light field pattern, such as Figure 3 and Figure 4 The pattern shown has a starry sky effect.

[0057] The preset light field pattern has a background that can cover at least a portion of the target light field range, a first group of points (such as Figure 3 The weak star points shown in FIG. 1 and the second group of points in the second grayscale range (or brightness range) (such as Figure 3 The first grayscale range is higher than the grayscale of the background, and the second grayscale range is higher than the first grayscale range.

[0058] The first group of points and the second group of points may be randomly distributed within the target light field.

[0059] Taking grayscale as an example, the grayscale value range is set to 0-255, wherein the grayscale of the background is preferably between 0-5, the first grayscale range is preferably 20-50, and the second grayscale range is preferably 100-255.

[0060] The present invention also relates to an optical projection device 30, such as Figure 6As shown, the optical projection device 30 includes a light source 301 and the diffractive optical element 20 as described above, wherein the light source 301 is configured to emit a light beam, and the diffractive optical element 20 is arranged downstream of the light source 301 to receive the light beam and project a preset light field pattern on a target surface 303, wherein the preset light field pattern includes a background, a first group of points in a first grayscale range, and a second group of points in a second grayscale range. After receiving the light emitted by the light source 301, the diffractive optical element 20 can modulate the light emitted by the light source and project the preset light field pattern on the target surface 303. The target surface 303 is, for example, a roof inside a vehicle or a wall of a building.

[0061] The light source 301 is preferably a laser light source, but it can also be other types of light sources, such as LED light sources. The light source is preferably configured to emit divergent light of non-plane waves.

[0062] According to a preferred embodiment of the present invention, the optical projection device 30 further includes a collimating optical device, which is disposed between the light source 301 and the diffractive optical element 20 and is used to collimate the light beam emitted from the light source and project it onto the diffractive optical element.

[0063] The present invention also relates to a vehicle, comprising the optical projection device 30 as described above, installed inside the vehicle, for example, installed on the A-pillar, B-pillar, C-pillar or elbow rest of the vehicle. The optical projection device is configured to project a preset light field pattern on the roof of the vehicle, wherein the preset light field pattern includes a background, a first group of points in a first grayscale range, and a second group of points in a second grayscale range. In addition, one or more optical projection devices 30 may be provided on the vehicle, each of which is configured to project a starry sky pattern in a local area of ​​the roof.

[0064] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A design method for a diffractive optical element for projecting a starry sky effect, comprising: S101: generating a target map of the diffractive optical element according to a target light field range, wherein the target map includes a background covering at least a portion of the target light field range, a first group of points in a first grayscale range, and a second group of points in a second grayscale range, wherein the first grayscale range is higher than the grayscale of the background, and the second grayscale range is higher than the first grayscale range; and S102: designing a phase distribution of a microstructure pattern unit of the diffractive optical element according to the target image; wherein the background has a preset pattern; The light source is configured to emit divergent laser light of a non-plane wave; The first group of points and the second group of points are randomly distributed within the background; The second group of points includes two further subdivided groups of points, and the two groups of points have different grayscale ranges or brightness ranges; The preset pattern of the background is a nebula background simulating a starry sky effect, and the brightness of the nebula background gradually decreases from the center to the edge of the target light field.

2. The design method as claimed in claim 1, wherein the step S101 comprises randomly distributing the first group of points and the second group of points within the target light field.

3. The design method as described in claim 1, wherein the grayscale value range is set to 0-255, wherein the grayscale of the background is between 0-5, the first grayscale range is 20-50, and the second grayscale range is 100-255.

4. The design method as described in claim 3 also includes adjusting the grayscale values ​​of the background, the first group of points and the second group of points according to computer simulation results to obtain a better starry sky effect.

5. The design method according to claim 2, wherein the step S101 comprises: Generate a random number, and randomly distribute the first group of points and the second group of points within the target light field according to the random number.

6. A diffractive optical element for projecting a starry sky effect, comprising: At least one microstructure pattern unit capable of projecting a preset light field pattern; The preset light field pattern has: a background covering at least a portion of the target light field range; A first set of points in a first grayscale range; and A second set of points in a second grayscale range, The first grayscale range is higher than the grayscale of the background, and the second grayscale range is higher than the first grayscale range; The background has a preset pattern; The light source is configured to emit divergent laser light of a non-plane wave; The first group of points and the second group of points are randomly distributed within the background; The second group of points includes two further subdivided groups of points, and the two groups of points have different grayscale ranges or brightness ranges; The preset pattern of the background is a nebula background in a simulated starry sky effect, and the brightness of the nebula background gradually decreases from the center to the edge of the target light field. 7 . The diffractive optical element of claim 6 , wherein the first group of points and the second group of points are randomly distributed within the target light field.

8. The diffractive optical element as claimed in claim 6, wherein the grayscale value range is set to 0-255, wherein the grayscale of the background is between 0-5, the first grayscale range is 20-50, and the second grayscale range is 100-255.

9. An optical projection device, comprising: a light source configured to emit a light beam; The diffractive optical element as described in any one of claims 6 to 8 is arranged downstream of the light source to receive the light beam and project a preset light field pattern on a target plane, wherein the preset light field pattern includes a background, a first group of points in a first grayscale range, and a second group of points in a second grayscale range.

10. The optical projection device according to claim 9, further comprising a collimating optical device, wherein the collimating optical device is disposed between the light source and the diffractive optical element, and is used to collimate the light beam emitted from the light source and project the light beam onto the diffractive optical element.

11. A vehicle comprising: The optical projection device according to claim 9 or 10, installed inside the vehicle; and The optical projection device is configured to project a preset light field pattern on the roof of the vehicle, wherein the preset light field pattern includes a background, a first group of points in a first grayscale range, and a second group of points in a second grayscale range.

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