CN209946429U - High-efficiency diffractive optical element for depth perception - Google Patents
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- CN209946429U CN209946429U CN201920812053.1U CN201920812053U CN209946429U CN 209946429 U CN209946429 U CN 209946429U CN 201920812053 U CN201920812053 U CN 201920812053U CN 209946429 U CN209946429 U CN 209946429U
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Abstract
The utility model relates to a high-efficiency diffraction optical element for depth perception, belonging to the technical field of optical elements; the high-efficiency diffractive optical element for depth perception comprises a substrate structure and a plurality of substructures supported by the substrate structure, wherein the substructures are arranged on the surface of a substrate in a matrix, the distance between coordinates of two adjacent substructures on the substrate is a fixed value in the row direction and the column direction of the matrix, the substructures have the same size and different rotation angles, and the rotation angles and the phases of the substructures have a determined relationship; the utility model uses the substructures with the same size and different corners to replace the step structures with different heights in the traditional diffraction optical element, and the heights are the same, so that the processing can be completed only by one-time processing, and the processing precision can be improved; the diffraction efficiency of the high efficiency diffractive optical element for depth perception is not limited by theory, since the rotation angle can vary continuously with phase, neglecting the loss of light in the material; namely the utility model discloses can improve diffraction efficiency and machining precision simultaneously.
Description
Technical Field
The utility model relates to a high efficiency diffraction optical element for degree of depth perception belongs to optical element technical field.
Background
In recent years, a depth-sensing diffractive optical element based on dot matrix projection has been proposed, which is based on the principle that a light spot array having depth information is generated by a diffractive optical element, projected onto the surface of a measurement object, and a three-dimensional profile of the measurement object is obtained by measuring a returned light spot array pattern.
The article Design and verification of differential optical elements for specific generation of 3-D range sensors and the article differential Element Design for generating Multi-Channel Structured Light Field relate to a Diffractive optical Element for generating Light lattice with depth information, the Diffractive optical Element is characterized by having step structures with different heights, and the phase corresponding to each height is a specific value in the range of 0-2 pi;
although this structure can produce an optical lattice with depth information, the step structure with different heights has the following problems:
first, since the height is a discrete value, the diffraction efficiency of such a diffractive optical element is limited theoretically, and the maximum diffraction efficiency of the two-step diffractive optical element is not more than 40.5% and the maximum diffraction efficiency of the four-step diffractive optical element is not more than 81% neglecting the loss of light in the material.
Second, although the diffraction efficiency can be improved to some extent by increasing the number of steps, the number of steps is 2nThe number of times of the required alignment of the diffractive optical element is n, and thus, the number of steps is increased, the number of times of the alignment is also increased, and the processing error is easy to accumulate, which brings difficulty to the improvement of the processing precision.
It is obvious that the improvement of the diffraction efficiency and the improvement of the processing precision are a pair of contradictory problems which are difficult to be considered at the same time.
SUMMERY OF THE UTILITY MODEL
The problem to traditional diffraction optical element can't improve diffraction efficiency simultaneously and improve the machining precision, the utility model provides a high efficiency diffraction optical element for degree of depth perception has adopted the size the same in this component, and the substructure that the corner is different replaces the not step structure of co-altitude in traditional diffraction optical element, not only can improve diffraction efficiency, can improve the machining precision moreover.
The purpose of the utility model is realized like this:
a high-efficiency diffraction optical element for depth perception is processed by single projection exposure, atomic layer deposition and etching processes and comprises a substrate structure and a plurality of substructures supported by the substrate structure, wherein the substructures are arranged on the surface of a substrate in a matrix mode, the distance between coordinates of two adjacent substructures on the substrate is a fixed value in the row direction and the column direction of the matrix, the substructures are identical in size and different in rotation angle, and the substructures meet the following relation between the rotation angle theta around the normal line of the substrate coordinates (x, y) and the corresponding phase phi (x, y) of the substructures at the substrate coordinates (x, y):
wherein m is an arbitrary integer, phiθ＝0The phase of the substructure at the substrate coordinate (x, y) is 0.
The above high efficiency diffractive optical element for depth perception has the following definitions:
the complex amplitude distribution g0(x, y) of the incident light at substrate coordinates (x, y) is:
wherein A is0(x, y) is the amplitude of the incident light at the substrate coordinates (x, y), φ0(x, y) is the phase of the incident light at the substrate coordinates (x, y), i is the imaginary unit;
the complex amplitude transmittance t (x, y) of the substructure is:
t(x,y)＝eiφ(x,y)
wherein, phi (x, y) is the phase distribution to be solved;
the complex amplitude distribution g (x, y) of the incident light after passing through the substructure is:
complex amplitude distribution u (x) of output plane1,y1And z) is:
wherein (x)1,y1) Is the coordinate of the output plane, z is the distance between the output plane and the plane of the substrate, λ is the free space wavelength, and r is the coordinate (x) on the output plane1,y1) The distance of the point of (a) to the center of the substrate;
light intensity distribution I (x) of output plane1,y1And z) is:
I(x1,y1,z)＝|u(x1,y1,z)|2
a method of calculating a corresponding phase phi (x, y) of a sub-structure at substrate coordinates (x, y), comprising the steps of:
step a, let phiinit(x,y)＝φ0(x, y) + φ (x, y) and, for φinit(x, y) is assigned, and phi after the assignment is carried outinit(x, y) as an initial phase distribution, constituting an initial complex amplitude distribution of the incident light after passing through the element
Step b, according to the complex amplitude distribution
To yield u (x)1,y1,z)；
Step c, light intensity distribution I of target light latticegoal(x1,y1And z) is:
Igoal(x1,y1,z)＝|ugoal(x1,y1,z)|2＝|Bgoal(x1,y1,z)|2，
wherein u isgoal(x1,y1Z) complex amplitude distribution of the target light lattice, Bgoal(x1,y1Z) is the real amplitude distribution of the target light lattice;
step d, using Bgoal(x1,y1Z) instead of u (x)1,y1Real amplitude in z) constitutes a new output plane complex amplitude distribution
Comprises the following steps:
step e, using the new output plane complex amplitude distribution obtained in step d
According to the following formula:
obtaining the complex amplitude distribution g (x, y) of new incident light after passing through the element;
the real amplitude of g (x, y) in step f and step e is the real amplitude A of the incident light0(x, y) instead, the phase part remains unchanged, and a new complex amplitude distribution of the incident light after passing through the element is formed
Comprises the following steps:
step g, calculating the real amplitude error delta of the incident lightgAnd the real amplitude error delta of the output planeuRespectively as follows:
step h, judging the real amplitude error delta of the incident lightgAnd the real amplitude error delta of the output planeuWhether each is less than a respective threshold, if:
is to distribute the complex amplitudeIs written into
Returning to the step b;
otherwise, the iteration is ended according to the following formula:
and calculating to obtain the corresponding phase phi (x, y) of the substructure at the substrate coordinate (x, y).
The above high efficiency diffractive optical element for depth perception if:
the incident light is visible light, the material of the substructure is titanium dioxide or gallium nitride, and the material of the substrate is silicon dioxide;
the incident light is infrared light, and the constituent materials of the substructure and the substrate are both silicon.
A method of determining an output plane intensity distribution of a high efficiency diffractive optical element for depth perception, comprising the steps of:
step a, determining the complex amplitude distribution g of incident light at substrate coordinates (x, y)0(x,y)
Complex amplitude distribution g of incident light at substrate coordinates (x, y)0(x, y) is:
wherein A is0(x, y) is the amplitude of the incident light at the substrate coordinates (x, y),φ0(x, y) is the phase of the incident light at the substrate coordinates (x, y), i is the imaginary unit;
step b, determining the complex amplitude transmittance t (x, y) of the substructure
The complex amplitude transmittance t (x, y) of the substructure is:
t(x,y)＝eiφ(x,y)
wherein, phi (x, y) is the phase distribution to be solved;
step c, determining the complex amplitude distribution g (x, y) of the incident light passing through the substructure
The complex amplitude distribution g (x, y) of the incident light after passing through the substructure is:
step d, determining the complex amplitude distribution u (x) of the output plane1,y1,z)
Complex amplitude distribution u (x) of output plane1,y1And z) is:
wherein (x)1,y1) Is the coordinate of the output plane, z is the distance between the output plane and the plane of the substrate, λ is the free space wavelength, and r is the coordinate (x) on the output plane1,y1) The distance of the point of (a) to the center of the substrate;
step e, determining the light intensity distribution I (x) of the output plane1,y1,z)
Light intensity distribution I (x) of output plane1,y1And z) is:
I(x1,y1,z)＝|u(x1,y1,z)|2
and (5) finishing the steps.
A method for computing the phase of a substructure in a depth-aware high efficiency diffractive optical element, comprising the steps of:
step a, let phiinit(x,y)＝φ0(x, y) + φ (x, y) and, for φinit(x, y) is assigned, and phi after the assignment is carried outinit(x, y) as an initial phase distribution, constituting an initial complex amplitude distribution of the incident light after passing through the element
Step b, according to the complex amplitude distribution
To yield u (x)1,y1,z)；
Step c, light intensity distribution I of target light latticegoal(x1,y1And z) is:
Igoal(x1,y1,z)＝|ugoal(x1,y1,z)|2＝|Bgoal(x1,y1,z)|2，
wherein u isgoal(x1,y1Z) complex amplitude distribution of the target light lattice, Bgoal(x1,y1Z) is the real amplitude distribution of the target light lattice;
step d, using Bgoal(x1,y1Z) instead of u (x)1,y1Real amplitude in z) constitutes a new output plane complex amplitude distribution
Comprises the following steps:
step e, using the new output plane complex amplitude distribution obtained in step d
According to the following formula:
obtaining the complex amplitude distribution g (x, y) of new incident light after passing through the element;
the real amplitude of g (x, y) in step f and step e is the real amplitude A of the incident light0(x, y) instead, the phase part remains unchanged, and a new complex amplitude distribution of the incident light after passing through the element is formed
Comprises the following steps:
step g, calculating the real amplitude error delta of the incident lightgAnd the real amplitude error delta of the output planeuRespectively as follows:
step h, judging the real amplitude error delta of the incident lightgAnd the real amplitude error delta of the output planeuWhether each is less than a respective threshold, if:
is to distribute the complex amplitude
Is written into
Returning to the step b;
otherwise, the iteration is ended according to the following formula:
and calculating to obtain the corresponding phase phi (x, y) of the substructure at the substrate coordinate (x, y).
Has the advantages that:
first, the present invention discloses a high efficiency diffractive optical element for depth perception, which comprises a substrate structure and a plurality of substructures supported by the substrate structure, wherein the substructures have the same size and different corners, that is, the substructures with the same size and different corners are used to replace the step structures with different heights in the conventional diffractive optical element; in this structure, the rotation angle θ and the corresponding phase φ (x, y) of the sub-structure at the substrate coordinates (x, y) satisfy the following relationship:
because the heights are the same, the machining can be finished only by one-time machining, so that the machining precision can be improved; the diffraction efficiency of the high efficiency diffractive optical element for depth perception is not limited by theory, since the rotation angle can vary continuously with phase, neglecting the loss of light in the material; it can be seen that this structure can improve both diffraction efficiency and machining accuracy.
Second, the utility model discloses in, provide a method for confirming high efficiency diffraction optical element output plane light intensity distribution who is used for degree of depth perception to a calculation method for the substructure phase place in high efficiency diffraction optical element who is used for degree of depth perception is provided, how to calculate the phase place according to output plane light intensity distribution has been realized, and then according to the basis
The continuously changing angle is obtained, so that the present invention not only stays in the envisaged phase, but actually provides a method for calculating the angle, ensuring that the skilled person can realize the method.
Drawings
Fig. 1 is a schematic structural diagram of a high-efficiency diffractive optical element for depth sensing according to the present invention.
Fig. 2 is a schematic diagram of a substructure of a high-efficiency diffractive optical element for depth perception according to the present invention.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings:
detailed description of the preferred embodiment
The present embodiment is an embodiment of a high efficiency diffractive optical element for depth perception.
The high-efficiency diffractive optical element for depth perception of the embodiment is processed by a single projection exposure, atomic layer deposition and etching process, and a schematic structural diagram is shown in fig. 1. The high-efficiency diffraction optical element for depth perception comprises a substrate structure and a plurality of substructures supported by the substrate structure, wherein the substructures are arranged on the surface of a substrate in a matrix, the distance between coordinates of two adjacent substructures on the substrate in the row direction and the column direction of the matrix is a fixed value, the substructures have the same size and different rotating angles, and the corresponding phases phi (x, y) of the substructures at the rotating angle theta around the normal of the coordinates (x, y) of the substrate and the coordinates (x, y) of the substructures at the positions of the coordinates (x, y) of the substrate satisfy the following relations:
wherein m is an arbitrary integer, phiθ＝0The phase of the substructure at the substrate coordinate (x, y) is 0.
Detailed description of the invention
The present embodiment is an embodiment of a high efficiency diffractive optical element for depth perception.
The high-efficiency diffractive optical element for depth perception of the present embodiment is further defined on the basis of the first specific embodiment as follows:
complex amplitude distribution g of incident light at substrate coordinates (x, y)0(x, y) is:
wherein A is0(x, y) is the amplitude of the incident light at the substrate coordinates (x, y), φ0(xY) is the phase of the incident light at the substrate coordinates (x, y), i is the imaginary unit;
the complex amplitude transmittance t (x, y) of the substructure is:
t(x,y)＝eiφ(x,y)
wherein, phi (x, y) is the phase distribution to be solved;
the complex amplitude distribution g (x, y) of the incident light after passing through the substructure is:
complex amplitude distribution u (x) of output plane1,y1And z) is:
wherein (x)1,y1) Is the coordinate of the output plane, z is the distance between the output plane and the plane of the substrate, λ is the free space wavelength, and r is the coordinate (x) on the output plane1,y1) The distance of the point of (a) to the center of the substrate;
light intensity distribution I (x) of output plane1,y1And z) is:
I(x1,y1,z)＝|u(x1,y1,z)|2
a method of calculating a corresponding phase phi (x, y) of a sub-structure at substrate coordinates (x, y), comprising the steps of:
step a, let phiinit(x,y)＝φ0(x, y) + φ (x, y) and, for φinit(x, y) is assigned, and phi after the assignment is carried outinit(x, y) as an initial phase distribution, constituting an initial complex amplitude distribution of the incident light after passing through the element
Step b, according to the complex vibrationDistribution of webs
To yield u (x)1,y1,z)；
Step c, light intensity distribution I of target light latticegoal(x1,y1And z) is:
Igoal(x1,y1,z)＝|ugoal(x1,y1,z)|2＝|Bgoal(x1,y1,z)|2，
wherein u isgoal(x1,y1Z) complex amplitude distribution of the target light lattice, Bgoal(x1,y1Z) is the real amplitude distribution of the target light lattice;
step d, using Bgoal(x1,y1Z) instead of u (x)1,y1Real amplitude in z) constitutes a new output plane complex amplitude distribution
Comprises the following steps:
step e, using the new output plane complex amplitude distribution obtained in step d
According to the following formula:
obtaining the complex amplitude distribution g (x, y) of new incident light after passing through the element;
the real amplitude of g (x, y) in step f and step e is the real amplitude A of the incident light0(x, y) instead, the phase part remains unchanged, and a new complex amplitude distribution of the incident light after passing through the element is formed
Comprises the following steps:
step g, calculating the real amplitude error delta of the incident lightgAnd the real amplitude error delta of the output planeuRespectively as follows:
step h, judging the real amplitude error delta of the incident lightgAnd the real amplitude error delta of the output planeuWhether each is less than a respective threshold, if:
is to distribute the complex amplitude
Is written intoReturning to the step b;
otherwise, the iteration is ended according to the following formula:
and calculating to obtain the corresponding phase phi (x, y) of the substructure at the substrate coordinate (x, y).
Detailed description of the preferred embodiment
The present embodiment is an embodiment of a high efficiency diffractive optical element for depth perception.
The high-efficiency diffractive optical element for depth perception of the present embodiment is further defined on the basis of the first embodiment or the second embodiment if:
the incident light is visible light, the material of the substructure is titanium dioxide or gallium nitride, and the material of the substrate is silicon dioxide;
the incident light is infrared light, and the constituent materials of the substructure and the substrate are both silicon.
Detailed description of the invention
The present embodiment is an embodiment of a method of determining an output plane light intensity distribution of a high efficiency diffractive optical element for depth perception.
A method of determining an output plane light intensity distribution of a high efficiency diffractive optical element for depth perception of the present embodiment comprises the steps of:
step a, determining the complex amplitude distribution g of incident light at substrate coordinates (x, y)0(x,y)
Complex amplitude distribution g of incident light at substrate coordinates (x, y)0(x, y) is:
wherein A is0(x, y) is the amplitude of the incident light at the substrate coordinates (x, y), φ0(x, y) is the phase of the incident light at the substrate coordinates (x, y), i is the imaginary unit;
step b, determining the complex amplitude transmittance t (x, y) of the substructure
The complex amplitude transmittance t (x, y) of the substructure is:
t(x,y)＝eiφ(x,y)
wherein, phi (x, y) is the phase distribution to be solved;
step c, determining the complex amplitude distribution g (x, y) of the incident light passing through the substructure
The complex amplitude distribution g (x, y) of the incident light after passing through the substructure is:
step d, determining the complex amplitude distribution u (x) of the output plane1,y1,z)
Complex amplitude distribution u (x) of output plane1Y1, z) is:
wherein (x)1,y1) Is the coordinate of the output plane, z is the distance between the output plane and the plane of the substrate, λ is the free space wavelength, and r is the coordinate (x) on the output plane1,y1) The distance of the point of (a) to the center of the substrate;
step e, determining the light intensity distribution I (x) of the output plane1,y1,z)
Light intensity distribution I (x) of output plane1,y1And z) is:
I(x1,y1,z)＝|u(x1,y1,z)|2
and (5) finishing the steps.
Detailed description of the preferred embodiment
The embodiment is an embodiment of a method for calculating a substructure phase in a depth-aware high-efficiency diffractive optical element.
The method for calculating the phase of the substructure in the high-efficiency diffractive optical element for depth perception of the embodiment comprises the following steps:
step a, let phiinit(x,y)＝φ0(x, y) + φ (x, y) and, for φinit(x, y) is assigned, and phi after the assignment is carried outinit(x, y) as an initial phase distribution, constituting an initial complex amplitude distribution of the incident light after passing through the element
Step b, according to the complex amplitude distribution
To yield u (x)1,y1,z)；
Step c, light intensity distribution I of target light latticegoal(x1,y1And z) is:
Igoal(x1,y1,z)＝|ugoal(x1,y1,z)|2＝|Bgoal(x1,y1,z)|2，
wherein u isgoal(x1,y1Z) is a complex amplitude distribution, Bgoal(x1,y1Z) is the real amplitude distribution of the target light lattice;
step d, using Bgoal(x1,y1Z) instead of u (x)1,y1Real amplitude in z) constitutes a new output plane complex amplitude distribution
Comprises the following steps:
step e, using the new output plane complex amplitude distribution obtained in step d
According to the following formula:
obtaining the complex amplitude distribution g (x, y) of new incident light after passing through the element;
the real amplitude of g (x, y) in step f and step e is the real amplitude A of the incident light0(x, y) instead, the phase part remains unchanged, and a new complex amplitude distribution of the incident light after passing through the element is formed
Comprises the following steps:
step g, calculating the real amplitude error delta of the incident lightgAnd output plane real vibrationAmplitude error deltauRespectively as follows:
step h, judging the real amplitude error delta of the incident lightgAnd the real amplitude error delta of the output planeuWhether each is less than a respective threshold, if:
is to distribute the complex amplitude
Is written into
Returning to the step b;
otherwise, the iteration is ended according to the following formula:
and calculating to obtain the corresponding phase phi (x, y) of the substructure at the substrate coordinate (x, y).
Claims (1)
1. A high-efficiency diffraction optical element for depth perception is processed by a single projection exposure, atomic layer deposition and etching process, and is characterized by comprising a substrate structure and a plurality of substructures supported by the substrate structure, wherein the substructures are arranged on the surface of a substrate in a matrix mode, the distance between coordinates of two adjacent substructures on the substrate in the row direction and the column direction of the matrix is a fixed value, the substructures have the same size and different rotation angles, and the substructures meet the following relationship between the rotation angle theta of the substructures around the normal line of the substrate coordinates (x, y) and the corresponding phase phi (x, y) of the substructures at the substrate coordinates (x, y):
wherein m is an arbitrary integer, phiθ＝0The phase of the substructure at the substrate coordinate (x, y) is 0.
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