WO2022267836A1 - 衍射光学元件的设计方法以及分区匀光照明系统 - Google Patents

衍射光学元件的设计方法以及分区匀光照明系统 Download PDF

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WO2022267836A1
WO2022267836A1 PCT/CN2022/095969 CN2022095969W WO2022267836A1 WO 2022267836 A1 WO2022267836 A1 WO 2022267836A1 CN 2022095969 W CN2022095969 W CN 2022095969W WO 2022267836 A1 WO2022267836 A1 WO 2022267836A1
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light source
microstructure
optical element
diffractive optical
target
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PCT/CN2022/095969
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English (en)
French (fr)
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范真涛
宋昱铭
田克汉
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嘉兴驭光光电科技有限公司
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0012—Optical design, e.g. procedures, algorithms, optimisation routines
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
    • G02B27/0927—Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
    • G02B27/0938—Using specific optical elements
    • G02B27/0944—Diffractive optical elements, e.g. gratings, holograms

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  • the present invention generally relates to the technical field of laser display, and in particular to a design method of a diffractive optical element, a diffractive optical element, and a partitioned uniform lighting system.
  • the existing TOF (Time-Of-Flight) scheme in the mobile phone industry is Indirect Time-Of-Flight (Indirect Time-Of-Flight), which uses indirect schemes, such as the phase change of the emitted light field and the received light field, to calculate the distance of the target object , compared with the time-of-flight ranging of direct time stamps, the error of indirect measurement is larger. For example, when testing multiple targets, it will be converted into an average value to calculate a distance, and the environmental noise of indirect measurement has a great impact.
  • DTOF direct time-of-flight
  • Sensors designed for direct time-of-flight (DTOF) need to achieve uniform illumination of the target light field.
  • DTOF direct time-of-flight
  • VCSELs Vertical cavity surface emitting lasers
  • DOE diffractive optical elements
  • pincushion distortion occurs in the target light field area with a large field of view, and the larger the field of view, the more serious the pincushion distortion, which affects the Reconstruction of 3D information.
  • the present invention provides a design method of a diffractive optical element, wherein the design method includes:
  • S101 Determine the parameters of the light source and the target light field of the diffractive optical element
  • S102 Determine the distribution of a plurality of first microstructure pattern units on the diffractive optical element according to the parameters of the light source;
  • S103 Divide the target light field into multiple target maps, the multiple target maps are superimposed to form the target light field, and each of the first microstructure pattern units corresponds to one of the target maps;
  • the step S104 includes: respectively performing reverse correction for the pincushion distortion from a plane to a sphere on the plurality of target images.
  • the step S104 also includes:
  • Barrel correction is performed on the plurality of strip-shaped light fields, and the magnitude of the correction increases as the viewing angle increases.
  • the step S102 also includes:
  • the diffractive optical element is divided into a plurality of strip-shaped first microstructure pattern units, so that the plurality of strip-shaped VCSEL light source arrays and the plurality of strip-shaped VCSEL light source arrays are There is a one-to-one correspondence between the strip-shaped first microstructure pattern units, and each strip-shaped VCSEL light source array is irradiated on the corresponding strip-shaped first microstructure pattern unit.
  • step S102 also includes:
  • the first microstructure pattern unit is divided into a plurality of first microstructure subunits along the length direction of the strip.
  • step S105 includes:
  • the corresponding phase distribution of the first microstructure subunit is designed.
  • the diffractive optical element further includes arranging a plurality of second microstructure pattern units on the periphery of the plurality of first microstructure pattern units, so that all incident light spots from the light source are irradiated on the diffractive optical element.
  • the design method also includes:
  • the phase distribution of the corresponding second microstructure pattern unit is designed.
  • the design method further includes:
  • the present invention also provides a diffractive optical element designed using the above-mentioned design method.
  • the present invention also provides a homogeneous illumination system, comprising the above-mentioned diffractive optical element.
  • a preferred embodiment of the present invention provides a method for designing a diffractive optical element.
  • the diffractive optical element is divided into a plurality of first microstructure pattern units according to the VCSEL partition light source, and the plurality of first microstructure pattern units correspond to the VCSEL partition light source respectively.
  • One of the light source arrays and part of the target light field is used to design the phase distribution of the first microstructure pattern unit of the diffractive optical element according to the parameters of the light source array and the corrected part of the light field.
  • the invention also provides a design method for the diffractive optical element to prevent light leakage, and strengthens the target light field by using the projection of the stitching area.
  • the preferred embodiment of the present invention adopts the combination of VCSEL partitioned light source and diffractive optical element, which can project a clear and undistorted large field of view uniform light field; the diffractive optical element is applied to the partitioned uniform light illumination system, which is DTOF Uniform lighting required by the system provides technical support.
  • the diffractive optical element provided by the preferred embodiment of the present invention can also be arbitrarily combined into electronic devices that require uniform light projection, including but not limited to mobile phones, PADs, electronic locks, etc.
  • Fig. 1 shows the design method of the diffractive optical element according to a preferred embodiment of the present invention
  • Fig. 2 schematically shows a VCSEL partitioned light source according to a preferred embodiment of the present invention
  • Fig. 3A schematically shows a uniform light field according to a preferred embodiment of the present invention
  • Fig. 3B schematically shows that the uniform light field shown in Fig. 3A is divided into a plurality of strip light fields according to a preferred embodiment of the present invention
  • Fig. 4 schematically shows a diffractive optical element and its first microstructure pattern unit according to a preferred embodiment of the present invention
  • Fig. 5 schematically shows a VCSEL partitioned light source according to a preferred embodiment of the present invention
  • Fig. 6 schematically shows a bar target graph according to a preferred embodiment of the present invention
  • Fig. 7 schematically shows that pincushion distortion occurs in the target light field with a large viewing angle
  • FIG. 8 schematically shows barrel correction for the pincushion distortion shown in FIG. 7 according to a preferred embodiment of the present invention
  • Fig. 9 schematically shows the main area and the anti-leakage area of the diffractive optical element according to a preferred embodiment of the present invention.
  • Fig. 10 schematically shows the target diagram corresponding to some microstructure subunits in Fig. 9 and the coordinates of the eccentric light source;
  • Fig. 11 schematically shows a partition uniform lighting system according to a preferred embodiment of the present invention.
  • first and second are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features.
  • a feature defined as “first” or “second” may explicitly or implicitly include one or more of said features.
  • “plurality” means two or more, unless otherwise specifically defined.
  • connection should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection.
  • Connected, or integrally connected it can be mechanically connected, or electrically connected, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediary, and it can be the internal communication of two components or the interaction of two components relation.
  • a first feature being “on” or “under” a second feature may include that the first and second features are in direct contact, or may include the first and second features Not in direct contact but through another characteristic contact between them.
  • “on”, “above” and “above” the first feature on the second feature include that the first feature is directly above and obliquely above the second feature, or simply means that the level of the first feature is higher than that of the second feature.
  • "Below”, “below” and “under” the first feature to the second feature include that the first feature is directly above and obliquely above the second feature, or simply means that the first feature has a lower horizontal height than the second feature.
  • the present invention provides a method 10 for designing a diffractive optical element, including steps S101-S105.
  • step S101 the parameters of the light source and the target light field of the diffractive optical element are determined.
  • the preferred embodiment of the present invention adopts a vertical cavity surface emitting laser (VCSEL) partition light source 20, and the VCSEL partition light source 20 includes a plurality of light source arrays 20-1, 20-2, ..., 20-n, wherein for example Due to the limitations of the process, there is an interval between adjacent light source arrays, and there is a certain interval DS between the light source arrays in the first direction (horizontal direction in the figure).
  • VCSEL vertical cavity surface emitting laser
  • each white point inside each light source array represents a VCSEL light-emitting point
  • the interval between adjacent VCSEL light-emitting points is small, and the interval DS between adjacent light source arrays is usually large, Greater than the distance between VCSEL light-emitting points in the same light source array.
  • each light source array of the VCSEL partitioned light source can be lit separately, and each light source array can only uniformly illuminate the target light field when it is lit. Part of the target light field corresponding to the light source array, and it is necessary to ensure uniform illumination of the entire target light field when all light source arrays are turned on.
  • Figure 3A shows the uniform light field required for a DTOF sensor.
  • the uniform light field shown in FIG. 3A is divided according to the projection areas of the multiple light source arrays of the VCSEL partitioned light source 20 , and divided into multiple striped light fields as shown in FIG. 3B .
  • a corresponding strip light field is uniformly illuminated; when all light source arrays are lit, multiple strip light fields are spliced to form the target of the diffractive optical element light field.
  • step S102 the distribution of the plurality of first microstructure pattern units on the diffractive optical element is determined according to the parameters of the light source.
  • the diffractive optical element 40 has a plurality of first microstructure pattern units, and a plurality of first microstructure subunits with the same label in the figure constitute a first microstructure pattern unit, such as the number of subunits labeled "1".
  • a first microstructure subunit constitutes a first microstructure pattern unit... a plurality of first microstructure subunits labeled "6" constitute a first microstructure pattern unit ... a plurality of number "n"th subunits
  • a microstructure subunit constitutes a first microstructure pattern unit.
  • Each first microstructure pattern unit corresponds to a light source array of the VCSEL partition light source 20 shown in FIG.
  • a plurality of first microstructure subunits labeled "6" form a first microstructure pattern unit, corresponding to a light source array 20-6 of the VCSEL partitioned light source 20 ... labeled as
  • a plurality of “n” first microstructure subunits constitute a first microstructure pattern unit, corresponding to a light source array 20 - n of the VCSEL partitioned light source 20 .
  • each light source array of the VCSEL partitioned light source 20 shown in Figure 2 along the first direction i.e. the distance between the centerlines on the width direction of each light source array
  • the length along the second direction is L
  • the VCSEL partitioned light source The number of 20 light source arrays is n. According to the above-mentioned size characteristics of the VCSEL partitioned light source 20, the distribution of the multiple first microstructure pattern units on the diffractive optical element 40 as shown in FIG. 4 is determined.
  • each first microstructure pattern unit includes a plurality of first microstructure pattern units with the same label. Microstructural subunits, and uniform partitioning is preferred.
  • the width of each first microstructure pattern unit is d, and then the width of each first microstructure subunit is also d (as a plurality of first microstructure subunits labeled "1", "6", and "n")
  • the width of the cell is d). Assuming that the length of each first microstructure subunit is i, the choice of i has a certain degree of freedom, which can be d, or can be greater than or less than d.
  • Each first microstructure pattern unit corresponds to a light source array of the VCSEL partitioned light source shown in FIG. 2 , and corresponds to a part of the target light field projected by the light source array.
  • the integer multiple of the width of each first microstructure pattern unit is d, that is, the width of the first microstructure pattern unit is d/2, d/3...that is, in the above-mentioned embodiment
  • the first microstructure pattern unit is further divided, and a plurality of first microstructure pattern units jointly correspond to a light source array of the VCSEL partitioned light source shown in Figure 2, and correspond to the part of the target light field projected by the light source array Light field, this embodiment is also within the protection scope of the present invention.
  • the multiple light source arrays of the VCSEL partitioned light source have intervals along the first direction and the second direction.
  • the partitioned light source array 20 includes a plurality of light source arrays 20-1, 20-2, ..., 20-n, wherein adjacent light source arrays have a first interval DS1 along the first direction, and have a second interval DS2 along the second direction , where the first direction is perpendicular to the second direction.
  • each first microstructure pattern unit corresponds to a light source array of the VCSEL partition light source 20, and corresponds to the target light projected by the light source array Part of the light field in the field.
  • the multiple light source arrays of the VCSEL partitioned light source 20 are all turned on, the light fields projected by the multiple first microstructure pattern units of the diffractive optical element 40 are spliced to form the uniform light field required by the DTOF sensor.
  • Such an implementation manner is also within the protection scope of the present invention.
  • step S103 the target light field is divided into multiple target maps, and the target light field is formed after the multiple target maps are superimposed, and each first microstructure pattern unit corresponds to one of the target maps.
  • the diffractive optical element 40 as shown in FIG. 4 includes a plurality of first microstructure pattern units, which respectively correspond to a plurality of light source arrays spaced along the first direction of the VCSEL partitioned light source 20 shown in FIG. 2 , for The received light beams from the corresponding light source arrays are homogenized.
  • the phase distribution of the first microstructure pattern unit is designed to be able to project a point light source into at least one linear light field extending along the second direction.
  • the light source is defined as a point light source
  • the target figure is designed as a strip light field extending along the second direction (as shown in Figure 6 shown).
  • the strip light fields projected by the VCSEL light-emitting points in the edge areas of two adjacent light source arrays are spliced or overlapped with each other to form the uniform light field required by the DTOF sensor.
  • step S104 distortion pre-correction is performed on the multiple target images respectively.
  • the target light field will be deformed in a pincushion shape (as shown in Figure 7), which will affect the working quality of the DTOF system.
  • the barrel distortion is pre-introduced to compensate the pincushion distortion in the case of a large field of view, thereby ensuring that the target light field is roughly in the shape of a bar .
  • each light source array in the VCSEL partitioned light source corresponds to at least one first microstructure pattern unit of the diffractive optical element, for example, the diffractive optical element has the same number of light source arrays as the VCSEL partitioned light source.
  • the first microstructure pattern unit that is, the light source array is in one-to-one correspondence with the first microstructure pattern unit. Since the diffractive optical element will produce pincushion distortion in the case of large field of view projection, the light source array can be compared with the light source array according to the field of view area where the light field projected by each light source array is located on the overall target light field The corresponding first microstructure pattern unit performs pre-correction of pincushion distortion.
  • a corresponding barrel distortion is introduced for the target map of the strip light field to compensate for the pincushion distortion, and a curved strip with barrel distortion
  • the target map replaces the straight line target map, so as to achieve the purpose of pincushion distortion correction.
  • a curved bar with barrel distortion is used as the target map instead of a straight bar target map.
  • each light source array can also correspond to a plurality of first microstructure pattern units, that is, the first microstructure pattern units in the above embodiment are further divided, and for each further divided first microstructure pattern unit A microstructure pattern unit performs pincushion distortion pre-correction to achieve a more refined and optimized distortion correction result, thereby ensuring that the target light field is closer to a rectangular shape.
  • step S105 the phase distributions of the corresponding multiple first microstructure pattern units are respectively designed according to the corrected multiple target maps and the parameters of the light source. Specifically include:
  • the target light field on the target surface that is, the corrected target map, the parameters of the light source array of the corresponding VCSEL partition light source, the distance between the target light field and the VCSEL partition light source, and the projected field of view angle;
  • the diffractive optical element calculates the phase distribution of the first microstructure pattern unit of the diffractive optical element, so that the diffractive optical element can diverge and uniformly modulate the light beams emitted by the multiple light source arrays of the VCSEL partitioned light source, so that adjacent light source arrays project on the target surface Parts of the light fields in the first direction adjoin or overlap each other.
  • step S104 further includes: respectively performing inverse correction for pincushion distortion from a plane to a spherical surface on the multiple target images.
  • diffractive optical elements Since the design of diffractive optical elements is based on the theory of angular spectrum, it is necessary to calculate the amplitude and/or phase of the light wave on the angular spectrum, that is, it is necessary to calculate the propagation and superposition of the amplitude and/or phase of the light wave on the spherical surface, so when designing the diffraction
  • step S104 further includes: performing barrel correction on a plurality of strip-shaped light fields, and the magnitude of the correction increases as the field angle increases. (as shown in Figure 8)
  • the positional relationship between the working area and the area of the projected light field conforms to the lens principle.
  • the projected light field is located at the upper right corner of the target light field area. Therefore, when designing the phase distribution of the first microstructure pattern unit in the leftmost working area of the diffractive optical element 40, the rightmost target image in the target light field area should be used.
  • the strip light field correction is the target light field with barrel distortion bent to the right. After correction, the magnitude of field curvature of multiple strips increases with the increase of field angle.
  • step S102 further includes:
  • the diffractive optical element is divided into multiple strip-shaped first microstructure pattern units, so that multiple strip-shaped light source arrays and multiple strip-shaped first microstructure patterns
  • the units correspond to each other, and each strip-shaped light source array irradiates on the corresponding strip-shaped first microstructure pattern unit.
  • the diffractive optical element 40 is divided into a plurality of strip-shaped first microstructure pattern units along the first direction, and a plurality of first microstructure subunits with the same label in the figure form a strip-shaped first microstructure pattern unit.
  • Each strip-shaped first microstructure pattern unit corresponds to a strip-shaped light source array of the VCSEL partitioned light source 20 shown in FIG.
  • a plurality of first microstructure subunits form a strip-shaped first microstructure pattern unit; a strip-shaped light source array 20-6 of the VCSEL partitioned light source 20 irradiates on a plurality of first microstructure subunits labeled "6" On a strip-shaped first microstructure pattern unit; a strip-shaped light source array 20-n of the VCSEL partitioned light source 20 irradiates a plurality of first microstructure subunits labeled "n" to form a strip-shaped first microstructure pattern unit superior.
  • the plurality of strip-shaped first microstructure pattern units in the above embodiment are further divided along the first direction, so that some of the strip-shaped first microstructure pattern units jointly correspond to VCSEL partitions A strip-shaped light source array of the light source, and pre-correct the pincushion distortion for each further divided strip-shaped first microstructure pattern unit, so that the light field effect is more refined, and this embodiment is also included in the present invention within the scope of protection.
  • step S102 further includes:
  • the first microstructure pattern unit is divided into a plurality of first microstructure subunits along the length direction of the strip.
  • the diffractive optical element 40 is divided into a plurality of strip-shaped first microstructure pattern units along the first direction, and each strip-shaped first microstructure pattern unit is divided along the second direction (ie, the strip length direction). It is a plurality of first microstructure subunits. Multiple first microstructure subunits with the same number in the figure belong to the same strip-shaped first microstructure pattern unit.
  • a plurality of first microstructure subunits labeled "1" in the figure form a strip-shaped first microstructure pattern unit ...
  • a plurality of first microstructure subunits labeled "6" form a strip-shaped first microstructure pattern unit Structural pattern unit...
  • first microstructure subunits labeled "n" form a strip-shaped first microstructure pattern unit.
  • the first microstructure subunits with the same number correspond to the same light source array of the VCSEL partitioned light source and adopt the same target light field diagram.
  • step S105 further includes:
  • the phase distribution of the corresponding first microstructure subunit is designed.
  • the target light field on the target surface that is, the corrected target map, the parameters of the light source array of the corresponding VCSEL partition light source, the distance between the target light field and the VCSEL partition light source, and the projected field of view, calculate the first microstructure subunit phase distribution, so that the light beams emitted by the corresponding light source arrays are divergent and uniformly modulated along the direction, so that part of the light fields projected by adjacent light source arrays on the target surface adjoin or overlap each other in the first direction.
  • the diffractive optical element further includes arranging a plurality of second microstructure pattern units on the periphery of the plurality of first microstructure pattern units, so that the incident light spot from the light source All the light falls on the diffractive optical element.
  • the single-point spot size produced by the single-point light source in the VCSEL partitioned light source is, for example, 765um (the circular area in the figure), and the size of the first microstructure subunit of the diffractive optical element is 164um, then the single-point spot irradiation When it is on the first microstructure subunit at the edge of the main area (the square area in the center of the figure), light leakage occurs.
  • the design method 10 of the diffractive optical element further includes: designing the corresponding second microstructure pattern according to the target diagram and light source parameters of the first microstructure pattern unit adjacent to the second microstructure pattern unit The phase distribution of the unit.
  • the phase distribution is designed according to the target diagram and light source parameters of the first microstructure pattern unit adjacent to it, so that the light irradiated on the second microstructure pattern unit The light projects the same part of the target light field as that of the first microstructure pattern unit adjacent to the second microstructure pattern unit, which prevents light leakage and increases the intensity of the target light field.
  • the second microstructure pattern unit is divided into a plurality of second microstructure subunits of the same size as the first microstructure subunit, and the design method 10 is further include:
  • each second microstructure subunit and the first microstructure subunit closest to it calculate the coordinates of the off-center light source, and according to the coordinates of the off-center light source and the target map of the first microstructure subunit closest to it, respectively.
  • the phase distribution of each corresponding second microstructure subunit is designed.
  • An additional anti-leakage area is spliced outside the main area of the diffractive optical element.
  • a plurality of second microstructure subunits are arranged in the antileakage area.
  • the size of the plurality of second microstructure subunits is the same as
  • the dimensions of the multiple first microstructure subunits in the main area are the same.
  • the width of the first microstructure subunit be d
  • the length be i
  • the number of unilateral sides extending from the main area along the first direction of the anti-leakage area be kx
  • the number of unilateral sides extending from the main area along the second direction is ky, satisfying: d*kx>r, i*ky>r.
  • the eccentric divergent light design is carried out, as shown in Figure 9, taking the first microstructure subunit and the second microstructure subunit in the rectangular box in the lower right corner as an example: where
  • the same target diagram as that of the first microstructure subunit labeled "1" is used, and the offset of the light source coordinates is set.
  • the coordinates of the eccentric light source of the second microstructure subunit "1A" are (-0.164,0), the coordinates of the eccentric light source of the second microstructure subunit “1B” are (-0.328,0), and the coordinates of the second microstructure subunit “1B” are (-0.328,0).
  • the coordinates of the eccentric light source of 11 are (0,-0.164)
  • the coordinates of the eccentric light source of the second microstructure subunit 1C are (-0.164,-0.164)
  • the coordinates of the eccentric light source of the second microstructure subunit 1D are (-0.328,- 0.164).
  • FIG. 10 shows the first microstructure subunit and the second microstructure subunit with different labels, the corresponding corrected target light field, and the corresponding offset light source coordinates.
  • the present invention also provides a diffractive optical element, which is designed using the above-mentioned design method.
  • the present invention also provides a homogeneous illumination system 100 , including the diffractive optical element 40 as described above.
  • the partitioned uniform light projection system 100 includes a diffractive optical element 40 and a partitioned light source array 20 , wherein the partitioned light source array 20 includes multiple light source arrays (refer to FIG. 2 ), and the multiple light source arrays have intervals along the first direction.
  • the diffractive optical element 40 is arranged downstream of the optical path of the partitioned light source array 20, and can receive light beams emitted by multiple light source arrays and project a uniform light field on the target surface OB.
  • a preferred embodiment of the present invention provides a method for designing a diffractive optical element.
  • the diffractive optical element is divided into a plurality of first microstructure pattern units according to the VCSEL partition light source, and the plurality of first microstructure pattern units correspond to the VCSEL partition light source respectively.
  • One of the light source arrays and part of the target light field is used to design the phase distribution of the first microstructure pattern unit of the diffractive optical element according to the parameters of the light source array and the corrected part of the light field.
  • the invention also provides a design method for the diffractive optical element to prevent light leakage, and strengthens the target light field by using the projection of the stitching area.
  • the preferred embodiment of the present invention adopts the combination of VCSEL partitioned light source and diffractive optical element, which can project a clear and undistorted large field of view uniform light field; the diffractive optical element is applied to the partitioned uniform light illumination system, which is DTOF Uniform lighting required by the system provides technical support.
  • the diffractive optical element provided by the preferred embodiment of the present invention can also be arbitrarily combined into electronic devices that require uniform light projection, including but not limited to mobile phones, PADs, electronic locks, etc.

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Abstract

本发明提供了一种衍射光学元件的设计方法，包括：S101：确定光源的参数以及所述衍射光学元件的目标光场；S102：根据所述光源的参数，确定所述衍射光学元件上多个第一微结构单元的分布；S103：将所述目标光场划分为多个目标图，所述多个目标图叠加后形成所述目标光场，每个所述第一微结构单元对应其中一个所述目标图；S104：对所述多个目标图分别进行畸变预校正；和S105：根据校正后的所述多个目标图以及所述光源的参数，分别设计对应的所述多个第一微结构单元的相位分布。本发明的实施例采用VCSEL分区光源与衍射光学元件相结合，可投射出清晰、无畸变的大视场角匀光光场；将该衍射光学元件应用于分区匀光照明系统中，为DTOF系统所需的匀光照明提供了技术保障。

Description

衍射光学元件的设计方法以及分区匀光照明系统 技术领域
本发明大致涉及激光显示技术领域，尤其涉及一种衍射光学元件的设计方法、衍射光学元件以及分区匀光照明系统。
背景技术
目前手机行业现有的TOF(Time-Of-Flight)方案是间接飞行时间(Indirect Time-Of-Flight),利用间接的方案，例如发射光场和接收光场的相位变化，计算目标物体的距离，与直接时间戳的飞行时间测距对比，间接测量的误差较大，例如测试多目标时，会折合成平均值，算出一个距离，而且间接测量环境噪声影响大。直接利用时间戳进行飞行时间测距，可以解决这些问题。设计用于直接飞行时间(Direct Time-Of-Flight)的传感器，需要实现目标光场的分区均匀照明。此外，在其他很多的具体应用场景中，也需要提供一定范围内的均匀分布的光场。
垂直腔面发射激光器(VCSEL)是广泛使用的激光器。一些衍射光学元件(DOE)的匀光片是针对整个VCSEL芯片发射的光场进行匀光。但DOE工作于投射大视角的目标光场时，在视场角较大的目标光场区域，光场发生了枕形的畸变，且视场角越大，枕形畸变越严重，从而影响了3D信息的重建。
背景技术部分的内容仅仅是公开人所知晓的技术，并不当然代表本领域的现有技术。
发明内容
有鉴于现有技术的至少一个缺陷，本发明提供一种衍射光学元件的设计方法，其特征在于，所述设计方法包括：
S101：确定光源的参数以及所述衍射光学元件的目标光场；
S102：根据所述光源的参数，确定所述衍射光学元件上多个第一微结构图案单元的分布；
S103：将所述目标光场划分为多个目标图，所述多个目标图叠加后形成所述目标光场，每个所述第一微结构图案单元对应其中一个所述目标图；
S104：对所述多个目标图分别进行畸变预校正；和
S105：根据校正后的所述多个目标图以及所述光源的参数，分别设计对应的所述多个第一微结构图案单元的相位分布。
根据本发明的一个方面，其中所述步骤S104包括：对所述多个目标图分别进行从平面到球面的针对枕形畸变的反向校正。
根据本发明的一个方面，其中所述多个目标图包括多个条形光场，所述步骤S104还包括：
对所述多个条形光场进行桶形校正，校正的幅度随视场角增大而增大。
根据本发明的一个方面，其中所述光源包括多个条形VCSEL光源阵列，所述步骤S102还包括：
根据所述多个条形VCSEL光源阵列的位置分布，将所述衍射光学元件划分成多个条形的所述第一微结构图案单元，使得所述多个条形VCSEL光源阵列与所述多个条形第一微结构图案单元一一对应，每个条形VCSEL光源阵列照射在相对应的条形第一微结构图案单元上。
根据本发明的一个方面，其中，所述步骤S102还包括：
将所述第一微结构图案单元沿着条形的长度方向划分成多个第一微结构子单元。
根据本发明的一个方面，其中所述步骤S105包括：
根据所述校正后的目标图，设计对应的所述第一微结构子单元的相位分布。
根据本发明的一个方面，其中：
所述衍射光学元件还包括在所述多个第一微结构图案单元的外围设置多个第二微结构图案单元，使得来自所述光源的入射光斑全部照射在所述衍射 光学元件上。
根据本发明的一个方面，所述设计方法还包括：
根据所述第二微结构图案单元相邻的第一微结构图案单元的目标图和所述光源参数，设计对应的第二微结构图案单元的相位分布。
根据本发明的一个方面，其中所述第二微结构图案单元被划分成与所述第一微结构子单元相同尺寸的多个第二微结构子单元，所述设计方法还包括：
根据每个所述第二微结构子单元和与其最邻近的第一微结构子单元的相对位置，计算偏心光源坐标，并根据所述偏心光源坐标和所述最邻近的第一微结构子单元的目标图，分别设计对应的每个所述第二微结构子单元的相位分布。
本发明还提供一种衍射光学元件，使用如上文所述的设计方法设计。
本发明还提供一种匀光照明系统，包括如上文所述的衍射光学元件。
本发明的优选实施例提供了一种衍射光学元件的设计方法，根据VCSEL分区光源将衍射光学元件划分为多个第一微结构图案单元，多个第一微结构图案单元分别对应VCSEL分区光源的其中一个光源阵列以及部分目标光场，根据光源阵列的参数、校正后的部分光场，对衍射光学元件的第一微结构图案单元进行相位分布的设计。本发明还提供一种衍射光学元件防止漏光的设计方法，并利用拼接区域的投射对目标光场进行强化。本发明的优选实施例采用VCSEL分区光源与衍射光学元件相结合，可投射出清晰、无畸变的大视场角匀光光场；将该衍射光学元件应用于分区匀光照明系统中，为DTOF系统所需的匀光照明提供了技术保障。此外，本发明的优选实施例所提供的衍射光学元件，也可以任意结合到需要进行匀光投射的电子设备中，包括但不限于手机、PAD、电子锁等。
附图说明
附图用来提供对本发明的进一步理解，并且构成说明书的一部分，与本 发明的实施例一起用于解释本发明，并不构成对本发明的限制。在附图中：
图1示出了根据本发明的一个优选实施例的衍射光学元件的设计方法；
图2示意性地示出了根据本发明的一个优选实施例的VCSEL分区光源；
图3A示意性地示出了根据本发明的一个优选实施例的匀光光场；
图3B示意性地示出了根据本发明的一个优选实施例将图3A所示的匀光光场划分为多个条形光场；
图4示意性地示出了根据本发明的一个优选实施例的衍射光学元件及其第一微结构图案单元；
图5示意性地示出了根据本发明的一个优选实施例的VCSEL分区光源；
图6示意性地示出了根据本发明的一个优选实施例的条形目标图；
图7示意性地示出了大视场角的目标光场发生枕形畸变；
图8示意性地示出了根据本发明的一个优选实施例针对图7所示的枕形畸变进行桶型校正；
图9示意性地示出了根据本发明的一个优选实施例的衍射光学元件的主区域、防漏光区域；
图10示意性地示出了图9的部分微结构子单元对应的目标图及偏心光源坐标；
图11示意性地示出了根据本发明的一个优选实施例的分区匀光照明系统。
具体实施方式
在下文中，仅简单地描述了某些示例性实施例。正如本领域技术人员可认识到的那样，在不脱离本发明的精神或范围的情况下，可通过各种不同方式修改所描述的实施例。因此，附图和描述被认为本质上是示例性的而非限制性的。
在本发明的描述中，需要理解的是，术语"中心"、"纵向"、"横向"、"长度"、"宽度"、"厚度"、"上"、"下"、"前"、"后"、"左"、"右"、"竖直"、 "水平"、"顶"、"底"、"内"、"外"、"顺时针"、"逆时针"等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。此外，术语"第一"、"第二"仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有"第一"、"第二"的特征可以明示或者隐含地包括一个或者更多个所述特征。在本发明的描述中，"多个"的含义是两个或两个以上，除非另有明确具体的限定。
在本发明的描述中，需要说明的是，除非另有明确的规定和限定，术语"安装"、"相连"、"连接"应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接:可以是机械连接，也可以是电连接或可以相互通讯；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。
在本发明中，除非另有明确的规定和限定，第一特征在第二特征之"上"或之"下"可以包括第一和第二特征直接接触，也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且，第一特征在第二特征"之上"、"上方"和"上面"包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征"之下"、"下方"和"下面"包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度小于第二特征。
下文的公开提供了许多不同的实施方式或例子用来实现本发明的不同结构。为了简化本发明的公开，下文中对特定例子的部件和设置进行描述。当然，它们仅仅为示例，并且目的不在于限制本发明。此外，本发明可以在不同例子中重复参考数字和/或参考字母，这种重复是为了简化和清楚的目的，其本身不指示所讨论各种实施方式和/或设置之间的关系。此外，本发明提供了的各种特定的工艺和材料的例子，但是本领域普通技术人员可以意识到其 他工艺的应用和/或其他材料的使用。
以下结合附图对本发明的实施例进行说明，应当理解，此处所描述的实施例仅用于说明和解释本发明，并不用于限定本发明。
如图1所示，根据本发明一个优选实施例，本发明提供一种衍射光学元件的设计方法10，包括步骤S101-S105。
在步骤S101中，确定光源的参数以及衍射光学元件的目标光场。
如图2所示，本发明的优选实施例采用垂直腔面发射激光器(VCSEL)分区光源20，VCSEL分区光源20包括多个光源阵列20-1、20-2、…、20-n，其中例如由于工艺的限制，相邻的光源阵列之间具有间隔，在第一方向(图中的水平方向)上光源阵列之间具有一定的间隔DS。
如图2所示，在每个光源阵列内部每个白点都代表一个VCSEL发光点，相邻的VCSEL发光点之间的间隔较小，而相邻光源阵列之间的间隔DS通常较大，大于同一个光源阵列内VCSEL发光点之间的距离。为了配合DTOF传感器的工作，需要实现目标光场的分区匀光照明，即VCSEL分区光源的每个光源阵列可以被分别点亮，每个光源阵列被点亮时仅匀光照亮目标光场的与该光源阵列相对应的部分目标光场，并且需要保证在所有光源阵列都被点亮时整个目标光场的匀光照明。
图3A示出了DTOF传感器所需的匀光光场。将图3A所示的匀光光场，按照VCSEL分区光源20的多个光源阵列的投射区域进行划分，划分为如图3B所示的多个条形光场。VCSEL分区光源20的每个光源阵列单独点亮时，匀光照亮其对应的一个条形光场；所有光源阵列都被点亮时，多个条形光场拼接，形成衍射光学元件的目标光场。
在步骤S102中，根据光源的参数，确定衍射光学元件上多个第一微结构图案单元的分布。
如图4所示，衍射光学元件40具有多个第一微结构图案单元，图中标号相同的多个第一微结构子单元构成一个第一微结构图案单元，如标号为“1” 的多个第一微结构子单元构成一个第一微结构图案单元……标号为“6”的多个第一微结构子单元构成一个第一微结构图案单元……标号为“n”的多个第一微结构子单元构成一个第一微结构图案单元。每个第一微结构图案单元对应图2所示的VCSEL分区光源20的一个光源阵列，如标号为“1”的多个第一微结构子单元构成一个第一微结构图案单元，对应VCSEL分区光源20的一个光源阵列20-1……标号为“6”的多个第一微结构子单元构成一个第一微结构图案单元，对应VCSEL分区光源20的一个光源阵列20-6……标号为“n”的多个第一微结构子单元构成一个第一微结构图案单元，对应VCSEL分区光源20的一个光源阵列20-n。
如图2所示的VCSEL分区光源20的各个光源阵列沿第一方向的宽度(即各个光源阵列宽度方向上的中心线之间的距离)为d，沿第二方向长度为L，VCSEL分区光源20的光源阵列个数为n。根据VCSEL分区光源20的上述尺寸特征，确定如图4所示的衍射光学元件40上多个第一微结构图案单元的分布。
如图4所示，衍射光学元件40的主区域(图中带标号区域)沿第一方向划分n个第一微结构图案单元，每个第一微结构图案单元包括多个标号相同的第一微结构子单元，并优先选择均匀划分。每一个第一微结构图案单元的宽度为d，则每一个第一微结构子单元的宽度亦为d(如标号为“1”、“6”、“n”的多个第一微结构子单元的宽度均为d)。设每一个第一微结构子单元的长度为i，i的选择有一定自由度，可以为d，也可以大于或小于d。带标号的主区域内沿第二方向划分为m个区域，则优选i*m>L。每一个第一微结构图案单元对应图2中所示的VCSEL分区光源的一个光源阵列，并对应该光源阵列投射出的目标光场中的部分光场。
根据本发明的另一个优选实施例，每个第一微结构图案单元的宽度的整数倍为d，即第一微结构图案单元的宽度为d/2、d/3……即将上述实施例中的第一微结构图案单元进行进一步地分割，多个第一微结构图案单元共同对应图2中所示的VCSEL分区光源的一个光源阵列，并对应该光源阵列投射出的目标光场中的部分光场，这种实施方式也在本发明的保护范围之内。
如图5所示，VCSEL分区光源的多个光源阵列沿第一方向、第二方向均具有间隔。分区光源阵列20包括多个光源阵列20-1、20-2、…、20-n，其中相邻的光源阵列沿着第一方向具有第一间隔DS1，沿着第二方向具有第二间隔DS2，其中第一方向垂直于第二方向。对应设计衍射光学元件40，使得衍射光学元件40具有多个第一微结构图案单元，每个第一微结构图案单元对应VCSEL分区光源20的一个光源阵列，并对应该光源阵列投射出的目标光场中的部分光场。当VCSEL分区光源20的多个光源阵列均被点亮时，衍射光学元件40的多个第一微结构图案单元投射出的光场拼接形成DTOF传感器所需的匀光光场。此种实施方式也在本发明的保护范围之内。
在步骤S103中，将目标光场划分为多个目标图，多个目标图叠加后形成该目标光场，每个第一微结构图案单元对应其中一个目标图。
如图4所示的衍射光学元件40包括多个第一微结构图案单元，其分别与如图2所示的VCSEL分区光源20的多个沿第一方向间隔开的光源阵列相对应，用于对接收到的来自对应的光源阵列的光束进行匀化。对第一微结构图案单元的相位分布进行设计，将其设计成能够将一个点光源投射成延第二方向延伸的至少一条线形光场。例如，在利用计算机辅助软件设计衍射光学元件40的第一微结构图案单元的相位分布时，将光源定义为点光源，将目标图设计成延第二方向延伸的条形光场(如图6所示)。两个相邻光源阵列的边缘区域VCSEL发光点所投射出的条状光场相互拼接或重叠，从而形成DTOF传感器所需的匀光光场。
在步骤S104中，对多个目标图分别进行畸变预校正。
由于衍射光学元件在进行大视场投射的情况下会产生畸变，从而使得目标光场产生枕形的变形(如图7所示)，影响DTOF系统的工作质量。根据本发明的一个优选实施例，在设计衍射光学元件的相位分布时，预先引入桶形畸变，用于补偿大视场情况下的枕形畸变，从而保证了目标光场为大致的条形形状。
根据本发明的一个优选实施例，VCSEL分区光源中的每个光源阵列都对 应于衍射光学元件的至少一个第一微结构图案单元，例如，衍射光学元件具有与VCSEL分区光源的光源阵列个数相同的第一微结构图案单元，即光源阵列与第一微结构图案单元一一对应。由于衍射光学元件在进行大视场投射的情况下会产生枕形的畸变，可以根据每个光源阵列所投射出的光场在整体目标光场上所处的视场区域，对与该光源阵列相对应的第一微结构图案单元进行枕形畸变的预校正。例如，在设计衍射光学元件的第一微结构图案单元的相位分布时，针对条形光场的目标图引入相应的桶形畸变以对枕形畸变进行补偿，用具有桶形畸变的弯曲条形目标图代替直线条目标图，从而达到枕形畸变校正的目的。如图8所示，用具有桶形畸变的弯曲条形作为目标图代替直线条目标图。但本发明并不仅限于此，每个光源阵列还可以对应于多个第一微结构图案单元，即将上述实施例中的第一微结构图案单元进一步地分割，并针对每个进一步分割后的第一微结构图案单元进行枕形畸变预校正，实现更为精细优化的畸变校正结果，从而保证目标光场更为接近矩形形状。
在步骤S105中，根据校正后的多个目标图以及光源的参数，分别设计对应的多个第一微结构图案单元的相位分布。具体包括：
获得目标表面上的目标光场，即校正后的目标图，对应的VCSEL分区光源的光源阵列的参数，目标光场与VCSEL分区光源的距离，以及投射视场角；
计算衍射光学元件的第一微结构图案单元的相位分布，以使得衍射光学元件可将VCSEL分区光源的多个光源阵列发出的光束进行发散和匀光调制，使得相邻光源阵列在目标表面上投射的部分光场在第一方向上相互邻接或者重叠。
根据本发明的一个优选实施例，衍射光学元件的设计方法10中，步骤S104进一步包括：对多个目标图分别进行从平面到球面的针对枕形畸变的反向校正。
由于衍射光学元件的设计是基于角谱理论的，需要在角谱上进行光波振幅和/或相位的计算，即需要在球面上计算光波的振幅和/或相位的传播及叠加，因此在设计衍射光学元件时，需要将投射在目标平面上的预定平面光场 图案，即平面目标图，转换成相应的球面光场图案，即球面目标图。对多个目标图分别进行从平面到球面的针对枕形畸变的反向校正，然后基于该球面目标图、光源参数、投射工作距离及视场角等参数进行衍射光学元件的相位分布计算。
根据本发明的一个优选实施例，衍射光学元件的设计方法10中，步骤S104进一步包括：对多个条形光场进行桶形校正，校正的幅度随视场角增大而增大。(如图8所示)
在衍射光学元件进行投射的工作过程中，工作区域与投射光场区域的位置关系符合透镜原理。如图4所示，衍射光学元件40左下角方框内的工作区域，投射出的光场位于目标光场区域的右上角。因此，针对衍射光学元件40最左侧工作区域内的第一微结构图案单元进行相位分布设计时，应采用目标光场区域最右侧的目标图，经过预校正后，将条形光场校正为向右侧弯曲的具有桶形畸变的目标光场。校正后多个条形光场弯曲的幅度随视场角增大而增大。
根据本发明的一个优选实施例，衍射光学元件的设计方法10中，步骤S102进一步包括：
根据VCSEL分区光源的多个条形光源阵列的位置分布，将衍射光学元件划分成多个条形的第一微结构图案单元，使得多个条形光源阵列与多个条形第一微结构图案单元一一对应，每个条形光源阵列照射在相对应的条形第一微结构图案单元上。
如图4所示，衍射光学元件40沿第一方向划分为多个条形的第一微结构图案单元，图中标号相同的多个第一微结构子单元构成一个条形第一微结构图案单元。每个条形第一微结构图案单元对应图2中所示的VCSEL分区光源20的一个条形光源阵列，如VCSEL分区光源20的一个条形光源阵列20-1照射在标号为“1”的多个第一微结构子单元构成一个条形第一微结构图案单元上；VCSEL分区光源20的一个条形光源阵列20-6照射在标号为“6”的多个第一微结构子单元构成一个条形第一微结构图案单元上；VCSEL分区光源20 的一个条形光源阵列20-n照射在标号为“n”的多个第一微结构子单元构成一个条形第一微结构图案单元上。
根据本发明的另一个优选实施例，将上述实施例中的多个条形第一微结构图案单元沿第一方向进行进一步地分割，使得其中部分条形第一微结构图案单元共同对应VCSEL分区光源的一个条形光源阵列，并针对每个进一步分割后的条形第一微结构图案单元进行枕形畸变的预校正，使得光场效果更为精细化，这种实施方式也在本发明的保护范围之内。
根据本发明的一个优选实施例，衍射光学元件的设计方法10中，步骤S102进一步包括：
将第一微结构图案单元沿着条形的长度方向划分成多个第一微结构子单元。
如图4所示，衍射光学元件40沿第一方向划分为多个条形的第一微结构图案单元，每个条形第一微结构图案单元沿第二方向(即条形长度方向)划分为多个第一微结构子单元。图中标号相同的多个第一微结构子单元属于同一个条形第一微结构图案单元。如图中标号为“1”的多个第一微结构子单元构成一个条形第一微结构图案单元……标号为“6”的多个第一微结构子单元构成一个条形第一微结构图案单元……标号为“n”的多个第一微结构子单元构成一个条形第一微结构图案单元。标号相同的第一微结构子单元对应相同的VCSEL分区光源的光源阵列以及采用相同的目标光场图。
根据本发明的一个优选实施例，衍射光学元件的设计方法10中，步骤S105进一步包括：
根据校正后的目标图，设计对应的第一微结构子单元的相位分布。
根据目标表面上的目标光场，即校正后的目标图，对应的VCSEL分区光源的光源阵列的参数，目标光场与VCSEL分区光源的距离，以及投射视场角，计算第一微结构子单元的相位分布，以使得对应的光源阵列发出的光束沿着进行发散和匀光调制，使得相邻的光源阵列在目标表面上投射的部分光场在第一方向上相互邻接或者重叠。
根据本发明的一个优选实施例，衍射光学元件的设计方法10中：衍射光学元件还包括在多个第一微结构图案单元的外围设置多个第二微结构图案单元，使得来自光源的入射光斑全部照射在衍射光学元件上。
实际工作过程中，VCSEL分区光源与衍射光学元件具有一定的距离，单点光源照射到衍射光学元件上，形成为一个半径为r的圆。如图9所示，VCSEL分区光源中的单点光源产生的单点光斑大小例如为765um(图中圆形区域)，衍射光学元件的第一微结构子单元大小为164um，则单点光斑照射在主区域(图中中心的方框区域)边缘的第一微结构子单元上时，会发生漏光现象。因此，为了防止衍射光学元件漏光，需要在衍射光学元件的主区域外拼接额外的区域。通过在主区域外围设置多个第二微结构图案单元作为防漏光区域，使得来自光源的入射光斑全部照射在衍射光学元件上，并投射出目标光场。
根据本发明的一个优选实施例，衍射光学元件的设计方法10还包括：根据第二微结构图案单元相邻的第一微结构图案单元的目标图和光源参数，设计对应的第二微结构图案单元的相位分布。
对于拼接的防漏光区域内的第二微结构图案单元，根据与其相邻的第一微结构图案单元的目标图和光源参数进行相位分布的设计，以使得照射在第二微结构图案单元上的光，投射出与该第二微结构图案单元相邻的第一微结构图案单元相同的部分目标光场，在防止了漏光的同时，也提高了目标光场的强度。
根据本发明的一个优选实施例，衍射光学元件的设计方法10中，第二微结构图案单元被划分成与第一微结构子单元相同尺寸的多个第二微结构子单元，设计方法10进一步包括：
根据每个第二微结构子单元和与其最邻近的第一微结构子单元的相对位置，计算偏心光源坐标，并根据该偏心光源坐标和最邻近的第一微结构子单元的目标图，分别设计对应的每个第二微结构子单元的相位分布。
在衍射光学元件的主区域外拼接额外的防漏光区域，优选地，在防漏光区域内设置多个第二微结构子单元，为了便于工艺加工，该多个第二微结构 子单元的尺寸与主区域内的多个第一微结构子单元的尺寸相同。设第一微结构子单元的宽度为d，长度为i，防漏光区域沿第一方向从主区域延伸出的单边个数为kx，沿第二方向从主区域延伸出的单边个数为ky，满足：d*kx>r，i*ky>r。
对于拼接的防漏光区域内的第二微结构子单元进行偏心发散光设计，如图9所示，以右下角长方形框内的第一微结构子单元、第二微结构子单元为例：其中标号为“1”开头的第二微结构子单元进行相位分布的设计时，采用与标号为“1”的第一微结构子单元相同的目标图，并设置光源坐标的偏移。例如，第二微结构子单元“1A”的偏心光源坐标为(-0.164,0)，第二微结构子单元“1B”的偏心光源坐标为(-0.328,0)，第二微结构子单元11的偏心光源坐标为(0,-0.164)，第二微结构子单元1C的偏心光源坐标为(-0.164,-0.164),第二微结构子单元1D的偏心光源坐标为(-0.328,-0.164)……
图10示出了各个标号不同的第一微结构子单元、第二微结构子单元，对应的校正后的目标光场，及对应的进行偏移后的光源坐标。
根据本发明的一个优选实施例，本发明还提供一种衍射光学元件，使用如上文所述的设计方法设计。
如图11所示，根据本发明的一个优选实施例，本发明还提供一种匀光照明系统100，包括如上文所述的衍射光学元件40。
如图11所示，分区匀光投射系统100包括衍射光学元件40和分区光源阵列20，其中分区光源阵列20包括多个光源阵列(参考图2)，多个光源阵列沿第一方向具有间隔。衍射光学元件40设置在分区光源阵列20的光路下游，可接收多个光源阵列发射出的光束并在目标表面OB上投射出均匀的光场。
本发明的优选实施例提供了一种衍射光学元件的设计方法，根据VCSEL分区光源将衍射光学元件划分为多个第一微结构图案单元，多个第一微结构 图案单元分别对应VCSEL分区光源的其中一个光源阵列以及部分目标光场，根据光源阵列的参数、校正后的部分光场，对衍射光学元件的第一微结构图案单元进行相位分布的设计。本发明还提供一种衍射光学元件防止漏光的设计方法，并利用拼接区域的投射对目标光场进行强化。本发明的优选实施例采用VCSEL分区光源与衍射光学元件相结合，可投射出清晰、无畸变的大视场角匀光光场；将该衍射光学元件应用于分区匀光照明系统中，为DTOF系统所需的匀光照明提供了技术保障。此外，本发明的优选实施例所提供的衍射光学元件，也可以任意结合到需要进行匀光投射的电子设备中，包括但不限于手机、PAD、电子锁等。
最后应说明的是：以上所述仅为本发明的优选实施例而已，并不用于限制本发明，尽管参照前述实施例对本发明进行了详细的说明，对于本领域的技术人员来说，其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (11)

  1. 一种衍射光学元件的设计方法，其特征在于，包括：
    S101：确定光源的参数以及所述衍射光学元件的目标光场；
    S102：根据所述光源的参数，确定所述衍射光学元件上多个第一微结构单元的分布；
    S103：将所述目标光场划分为多个目标图，所述多个目标图叠加后形成所述目标光场，每个所述第一微结构单元对应其中一个所述目标图；
    S104：对所述多个目标图分别进行畸变预校正；和
    S105：根据校正后的所述多个目标图以及所述光源的参数，分别设计对应的所述多个第一微结构单元的相位分布。
  2. 如权利要求1所述的设计方法，其中所述步骤S104包括：对所述多个目标图分别进行从平面到球面的针对枕形畸变的反向校正。
  3. 如权利要求2所述的设计方法，其中所述多个目标图包括多个条形光场，所述步骤S104还包括：
    对所述多个条形光场进行桶形校正，校正的幅度随视场角增大而增大。
  4. 如权利要求1-3中任一项所述的设计方法，其中所述光源包括多个条形VCSEL光源阵列，所述步骤S102还包括：
    根据所述多个条形VCSEL光源阵列的位置分布，将所述衍射光学元件划分成多个条形的所述第一微结构单元，使得所述多个条形VCSEL光源阵列与所述多个条形第一微结构单元一一对应，每个条形VCSEL光源阵列照射在相对应的条形第一微结构单元上。
  5. 如权利要求4所述的设计方法，其中，所述步骤S102还包括：
    将所述第一微结构单元沿着条形的长度方向划分成多个第一微结构子单元。
  6. 如权利要求5所述的设计方法，其中所述步骤S105包括：
    根据所述校正后的目标图，设计对应的所述第一微结构子单元的相位分布。
  7. 如权利要求5中任一项所述的设计方法，其中：
    所述衍射光学元件还包括在所述多个第一微结构单元的外围设置多个第二微结构单元，使得来自所述光源的入射光斑全部照射在所述衍射光学元件上。
  8. 如权利要求7所述的设计方法，还包括：
    根据所述第二微结构单元相邻的第一微结构单元的目标图和所述光源参数，设计对应的第二微结构单元的相位分布。
  9. 如权利要求8所述的设计方法，其中所述第二微结构单元被划分成与所述第一微结构子单元相同尺寸的多个第二微结构子单元，所述设计方法还包括：
    根据每个所述第二微结构子单元和与其最邻近的第一微结构子单元的相对位置，计算偏心光源坐标，并根据所述偏心光源坐标和所述最邻近的第一微结构子单元的目标图，分别设计对应的每个所述第二微结构子单元的相位分布。
  10. 一种衍射光学元件，使用如权利要求1-9中任一项所述的设计方法设计。
  11. 一种分区匀光照明系统，包括如权利要求10所述的衍射光学元件。
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