Combined diffractive optical element, design method and application thereof
Through combined diffraction optical elements, the phase structure and position relationship of multiple DOE devices are used to realize three-dimensional regulation of laser beam, solving the problems of complex systems, difficult integration and low incident optical power threshold in the prior art, and having a wide range of lasers Technology application potential.
Patent Information
- Application Number
- CN202411542067.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-01-07
AI Technical Summary
The existing laser beam scanning systems have problems such as complex system, difficulty in integrating, limited regulation dimensions and low incident light power thresholds, and are particularly difficult to achieve two-dimensional and three-dimensional control of the beam.
A combined diffraction optical element is designed, including a sequentially arranged first DOE, a second DOE and a third DOE, and controls the spot position and focus position of the incident light by adjusting its relative position relationship, and combines periodic phase planes Construct gradient grating and lens phases to achieve three-dimensional control of the beam.
Dynamic three-dimensional spatial regulation of the beam is achieved through the optical moiré effect and spatial beat frequency effect between multiple DOE devices with periodic phase structures, and is suitable for the fields of lidar, laser weapons and laser processing.
Smart Images
Figure CN119270447A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of optical elements, systems or instruments, and in particular to a combined diffractive optical element, a design method and application thereof. Background Art
[0002] Laser beam scanning system is the core technology in the fields of laser radar, laser weapons and laser processing. The existing laser beam scanning system is mainly based on micro-electromechanical systems (MEMS), liquid crystal optical technology and optical waveguide technology. In actual operation, the liquid crystal optical phased array can control the refractive index change of the liquid crystal through voltage, thereby further changing the beam deflection angle. This has a relatively mature application in spatial light modulation.
[0003] However, in the prior art, two-dimensional scanning often requires cascading two liquid crystal optical phased arrays, and the positioning of liquid crystal molecules requires a long response time. Although MEMS phased array systems have the advantages of stability and low power consumption, they also have similar problems in practical applications, that is, sufficient adjustment time is required to achieve the switching of the beam deflection angle. In addition, the liquid crystal or silicon-based materials used in the above optical phased array platform have limited power tolerance and are not suitable for high-power laser systems. At the same time, they cannot well achieve three-dimensional control of the beam in space.
[0004] Diffractive Optical Element (DOE) is a device that can precisely control the phase and amplitude of light at the micro-nano scale. It makes it possible to miniaturize laser beam scanning systems. It can also greatly increase the intensity threshold of incident light by selecting materials with different wavelength windows as DOE carriers. It provides technical support for laser beam three-dimensional scanning, lidar, and laser processing. Summary of the invention
[0005] The present invention solves the problems existing in the prior art and provides a combined diffractive optical element, a design method and its application, which solve the problems existing in the laser beam scanning system, such as complex system, difficult integration, limited control dimension and low incident light power threshold.
[0006] The technical solution adopted by the present invention is a combined diffractive optical element, comprising a first DOE, a second DOE and a third DOE arranged in sequence; the second DOE is fixed, and the position of the spot of the incident light in the focal plane is controlled by adjusting the relative position relationship between the first DOE and the second DOE, and the focusing position of the incident light in the z-axis direction is controlled by adjusting the relative position relationship between the third DOE and the second DOE.
[0007] Preferably, the phase distributions of the first DOE and the second DOE are respectively Where A is a constant, (x, y) is the coordinate in the rectangular coordinate system, is the direction angle and a is a constant.
[0008] Preferably, the phase distribution of the third DOE is
[0009] Preferably, a plurality of phases are stacked in conjunction with the second DOE to shape the incident light.
[0010] Preferably, the shaping includes beam homogenization, superposition of structured light patterns and beam splitting.
[0011] A method for designing a combined diffractive optical element, the method comprising the following steps:
[0012] S1 constructs a gradient grating with adjustable period by combining two conjugated periodic phase planes to control the deflection angle of the incident light;
[0013] S2 combines two conjugated periodic phase planes to achieve the control of the incident light in the z-axis direction;
[0014] S3 juxtaposes the two combinations in S1 and S2, and takes one of them as the second DOE, the other element of the combination in S1 is the first DOE, and the other element of the combination in S2 is the third DOE.
[0015] Preferably, in S1, the phase distribution of the combination satisfies Where (x, y) is the coordinate in the rectangular coordinate system, and A is a constant;
[0016] The first DOE is displaced by d in the x and y directions. x With d y After that, the phase distribution of the combination is obtained as follows:
[0017]
[0018] Preferably, in S2, the phase distribution of the combination satisfies in, is the direction angle, a is a constant;
[0019] After the third DOE rotates around the center by an angle of θ, the phase distribution of the combination is obtained as follows:
[0020]
[0021] An application of the combined diffractive optical element is applied to dynamic three-dimensional control of light beams.
[0022] Preferably, by changing the displacement of the first DOE on the x-axis and y-axis, the blazed grating phases of different periods and directions are obtained, thereby realizing the regulation of the deflection direction of the incident light. By changing the rotation θ value of the third DOE on the z-axis relative to the second DOE, the lens phases of different focal lengths are obtained, thereby realizing the regulation of the incident light in the z-axis direction.
[0023] The invention relates to a combined diffractive optical element, a design method and an application thereof, comprising a first DOE, a second DOE and a third DOE which are arranged in sequence; the second DOE is fixed, and the position of the spot of the incident light on the focal plane is controlled by adjusting the relative position relationship between the first DOE and the second DOE, and the focusing position of the incident light in the z-axis direction is controlled by adjusting the relative position relationship between the third DOE and the second DOE; the method constructs a gradient grating with adjustable period by combining two conjugated periodic phase planes to realize the control of the deflection angle of the incident light, and realizes the regulation of the incident light in the z-axis direction by combining two conjugated periodic phase planes, and juxtaposes the two groups of conjugated periodic phase planes to set the first DOE, the second DOE and the third DOE; and the method is applied to the dynamic three-dimensional regulation of light beams.
[0024] The beneficial effect of the present invention lies in that, by designing multiple DOE devices with periodic phase structures, the optical moiré effect generated between DOEs is used to achieve three-dimensional adjustability of the light beam, by introducing changes such as mechanical deformation, rotation or displacement between layers, new periodic interference fringes are formed by utilizing the spatial beat frequency effect between periodic structures, the position of the second DOE element in the middle is fixed, and the phase spatial position of the first DOE and the third DOE is adjusted to achieve changes in the propagation direction and focal length of the incident light, thereby achieving dynamic three-dimensional spatial regulation of the light beam; the present invention can also realize the shaping of the incident light by superimposing an additional phase on the second DOE, such as light splitting, beam homogenization, etc., and has great potential application value in the fields of laser radar, laser weapons and laser processing. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a schematic structural diagram of a combined diffractive optical element of the present invention;
[0026] Figure 2 is a flow chart of the design method of the present invention;
[0027] Figure 3 It is a schematic diagram of the adjustable grating and the adjustable lens in the present invention;
[0028] Figure 4 It is a simulation result diagram of the combined diffractive optical element of the present invention. DETAILED DESCRIPTION
[0029] The present invention is further described in detail below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto.
[0030] The present invention relates to a combined diffractive optical element, a design method and application thereof. The technology of the present invention is specifically described below.
[0031] First, a design method of a combined diffractive optical element involved in the present invention is described. In order to achieve three-dimensional control of incident light, a combination of a blazed grating phase and a lens phase is used. By changing the period and direction of the blazed grating, the position of the light spot on the xy two-dimensional plane is controlled. By changing the focal length of the lens phase, the incident light can be arbitrarily controlled in the z-axis direction. The xy two-dimensional plane is perpendicular to the incident light, and the z-axis is consistent with the direction of the incident light.
[0032] (1) A periodically adjustable gradient grating is constructed by combining two conjugated periodic phase planes (DOEs) to control the deflection angle of the incident light;
[0033] The combined phase distribution satisfies,
[0034]
[0035] Where (x, y) is the coordinate in the rectangular coordinate system, and A is a constant;
[0036] A phase plane (second DOE) is fixed, and the first DOE is displaced by d in the x and y directions. x With d y After that, the phase distribution of the combination is obtained as follows:
[0037]
[0038] When constant A = 50, and The phase distribution of Figure 3 (a) with Figure 3 As shown in (b), when and When relative displacement occurs in the x and y directions respectively, the output phase after superposition is as follows: Figure 3 (e) with Figure 3 (f) As shown in the figure, it can be seen that by changing d x With d y The blazed grating phases of different periods and directions can be obtained, thereby realizing the deflection direction of the incident light, that is, realizing arbitrary control of the incident light in a two-dimensional plane.
[0039] (2) In order to obtain a lens phase with adjustable focal length, two conjugate periodic phase planes are combined to achieve the control of the incident light in the z-axis direction;
[0040] The combined phase distribution satisfies,
[0041]
[0042] in, is the direction angle, a is a constant;
[0043] After fixing a phase plane (the second DOE) and rotating the third DOE around the center by an angle of θ, the phase distribution of the combination is obtained as follows:
[0044]
[0045] When the constant a=500, and The phase distribution of Figure 3 (c) with Figure 3 As shown in (d), when and When the relative rotation angle is θ, the output phase after superposition is as follows: Figure 3 (g) with Figure 3 As shown in (h), it can be seen from the results in the figure that by changing the size of θ, the lens phase of different focal lengths can be obtained, thereby realizing the regulation of the incident light in the z-axis direction.
[0046] Based on this, (3) juxtapose the two combinations in (1) and (2), and take one of them as the second DOE, the other element of the combination in S1 as the first DOE, and the other element of the combination in S2 as the third DOE.
[0047] Here, a combined diffractive optical element according to the present invention is obtained, such as Figure 1 As shown, it includes a first DOE, a second DOE and a third DOE arranged in sequence; the second DOE is fixed, so as to adjust the relative position relationship between the first DOE and the second DOE to control the position of the spot of the incident light in the focal plane, and to adjust the relative position relationship between the third DOE and the second DOE to control the focusing position of the incident light in the z-axis direction.
[0048] In particular, the phase distributions of the first DOE and the second DOE are Where A is a constant, (x, y) is the coordinate in the rectangular coordinate system, is the direction angle, a is a constant; the phase distribution of the third DOE is
[0049] A plurality of phases are stacked in conjunction with the second DOE to shape the incident light.
[0050] The shaping includes beam homogenization, superposition of structured light patterns and beam splitting.
[0051] To be precise, an additional phase is superimposed on the second DOE to shape the incident light, including but not limited to beam shaping schemes such as beam homogenization, superimposed structured light patterns, and beam splitting.
[0052] Finally, the present invention also relates to an application of the combined diffractive optical element, which is applied to dynamic three-dimensional control of light beams.
[0053] By changing the displacement of the first DOE on the x-axis and y-axis, the blazed grating phases of different periods and directions are obtained, thereby realizing the regulation of the deflection direction of the incident light. By changing the rotation θ value of the third DOE on the z-axis relative to the second DOE, the lens phases of different focal lengths are obtained, thereby realizing the regulation of the incident light in the z-axis direction.
[0054] In order to verify the feasibility of the combined diffractive optical element, Figure 4 The propagation of the light beam along the z-axis under different control conditions:
[0055] Figure 4 (a) is a cross-sectional view of the beam propagation along the z-axis when the second DOE and the third DOE are stationary and the first DOE moves to different positions. It can be seen that the propagation direction of the beam changes;
[0056] Figure 4 (b) is a cross-sectional view of the beam propagating along the z-axis when the first DOE and the second DOE are stationary and the third DOE is rotated at different angles. It can be seen that the focal position of the beam has changed;
[0057] Figure 4 (c) is a cross-sectional diagram of the light beam propagating along the z-axis after the second DOE remains stationary and the first and third DOEs move in the x and y directions and rotate around the z-axis to different positions. It can be seen that the propagation direction and focal position of the light beam are changed at the same time, that is, the light beam is controlled in three dimensions.
[0058] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0059] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. A combined diffractive optical element, characterized in that: It includes a first DOE, a second DOE and a third DOE which are arranged in sequence; the second DOE is fixed, so as to adjust the relative position relationship between the first DOE and the second DOE to control the position of the light spot of the incident light in the focal plane, and to adjust the relative position relationship between the third DOE and the second DOE to control the focusing position of the incident light in the z-axis direction.
2. A combined diffractive optical element according to claim 1, characterized in that: The phase distributions of the first DOE and the second DOE are Among them, A is a constant, (x, y) is the coordinate in the rectangular coordinate system, is the direction angle and a is a constant.
3. A combined diffractive optical element according to claim 2, characterized in that: The phase distribution of the third DOE is 4. The combined diffractive optical element according to claim 1, characterized in that: A plurality of phases are stacked in conjunction with the second DOE to shape the incident light.
5. The combined diffractive optical element according to claim 4, characterized in that: The shaping includes beam homogenization, superposition of structured light patterns and beam splitting.
6. A method for designing a combined diffractive optical element according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1 constructs a gradient grating with adjustable period by combining two conjugated periodic phase planes to control the deflection angle of the incident light; S2 combines two conjugated periodic phase planes to achieve the control of the incident light in the z-axis direction; S3 juxtaposes the two combinations in S1 and S2, and takes one of them as the second DOE, the other element of the combination in S1 is the first DOE, and the other element of the combination in S2 is the third DOE.
7. The design method according to claim 6, characterized in that: In S1, the combined phase distribution satisfies Where (x, y) is the coordinate in the rectangular coordinate system, and A is a constant; The first DOE is displaced by d in the x and y directions. x With d y After that, the phase distribution of the combination is obtained as follows:
8. The design method according to claim 6, characterized in that: In S2, the combined phase distribution satisfies in, is the direction angle, a is a constant; After the third DOE rotates around the center by an angle of θ, the phase distribution of the combination is obtained as follows:
9. An application of the combined diffractive optical element according to any one of claims 1 to 5, characterized in that: Applied to dynamic three-dimensional control of light beams.
10. The use according to claim 9, characterized in that: By changing the displacement of the first DOE on the x-axis and y-axis, the blazed grating phases of different periods and directions are obtained, thereby realizing the regulation of the deflection direction of the incident light. By changing the rotation θ value of the third DOE on the z-axis relative to the second DOE, the lens phases of different focal lengths are obtained, thereby realizing the regulation of the incident light in the z-axis direction.