Beam splitter, optical assembly and application thereof

Abstract

The invention discloses a beam splitter, an optical assembly and application thereof, the beam splitter comprises a microstructure array arranged on a substrate, the microstructure array comprises a plurality of microstructures, the microstructures are cylindrical, the axis direction of the cylinders is perpendicular to the surface of the substrate, the height h of the microstructures is greater than or equal to 670nm and less than or equal to 730nm; the diameter of the microstructure is d, and d is more than or equal to 110 nm and less than or equal to 200 nm or d is more than or equal to 210 nm and less than or equal to 310 nm. According to the beam splitter, through the micro-nano optical design on the substrate, the nano cylinders are formed on the surface of the substrate, and the microstructure array is formed, the collimation and beam splitting functions can be integrated, the number of optical elements is reduced, the structure of an optical assembly can be simplified, the performance of the optical assembly can be improved, and the beam splitter is suitable for large-scale production and application.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and more specifically, to a beam splitter, and also to an optical component with the beam splitter and application thereof. Background Art

[0002] Time of Flight (ToF) technology is often used in depth detection or three-dimensional detection. Currently, a mainstream trend in ToF solutions is to use a speckle projector to focus on projecting laser speckles. Different from the traditional projected area spot, the dotted spot (refer to Figure 1 As shown in the figure, the light source energy can be concentrated in the first speckle, which can avoid excessive energy divergence and thus improve the detection distance of the ToF system.

[0003] In the current dot matrix projection scheme (including speckle structured light and dToF), a diffractive optical element (DOE) is required. Its function is to use the microstructure pattern to diffract and replicate the incident light, thereby achieving the effect of beam splitting, and then combined with a collimator to achieve the speckle projection effect. Therefore, in the current scheme, an additional collimator is required, which increases the complexity and cost of the components.

[0004] Therefore, a new solution needs to be proposed to solve this problem. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a beam splitter, an optical component and applications thereof.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solution: a beam splitter, comprising a microstructure array arranged on a substrate, the microstructure array comprising a plurality of microstructures, the microstructure being cylindrical, the axial direction of the cylinder being perpendicular to the surface of the substrate, the height of the microstructure being h, 670nm≤h≤730nm; the diameter of the microstructure being d, 110nm≤d≤200nm or 210nm≤d≤310nm.

[0007] The present invention is further configured such that the height of the microstructure is h=700 nm.

[0008] The present invention is further configured such that diameters of at least two microstructures in the microstructure array are different.

[0009] The present invention is further configured such that the array directions of the microstructure array are mutually orthogonal x and y directions, and the array periods in the x and y directions are both 380-420 nm.

[0010] The present invention is further configured such that the array periods in the x direction and the y direction are equal.

[0011] The present invention is further configured such that the substrate is optical glass or optical resin.

[0012] The present invention also provides an optical component, comprising a light source and the beam splitter as described above, wherein the light source is a single beam of light, and the beam splitter is used to split the single beam of light into multiple beams of light distributed in arrays in the x-direction and the y-direction.

[0013] The present invention is further configured such that the wavelength of the single beam of light is 600-1000nm.

[0014] The present invention is further configured such that the wavelength of the single beam of light is 940 nm.

[0015] The present invention also provides application of the above optical component in depth detection or three-dimensional detection based on time of flight or structured light.

[0016] In summary, the present invention has the following beneficial effects:

[0017] In this solution, the beam splitter cooperates with a single-beam light source to achieve speckle projection, and has the optical effect of combining a diffraction optical element (DOE) with a collimator lens element in traditional optical elements, with a diffraction efficiency of >90%. The beam splitter, through micro-nano optical design on a substrate, arranges nano-cylinders on the surface of the substrate to form a microstructure array, which can realize integrated collimation and beam splitting functions, reduce the number of optical elements, simplify the structure of optical components, improve the performance of optical components, and is suitable for large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the dot-matrix light spot of current laser speckle projection;

[0019] Figure 2 is a schematic structural diagram of a microstructure array of a beam splitter in this embodiment;

[0020] Figure 3 is a cross-sectional view of a microstructure array of a beam splitter in this embodiment;

[0021] Figure 4 : is the correspondence between the diameter of the microstructure and the light field phase and transmittance in this embodiment.

[0022] Reference numerals: substrate 1 ; microstructure array 2 ; microstructure 21 . DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] This embodiment discloses a beam splitter, referring to Figure 2 , Figure 3 As shown, it includes a substrate 1 and a microstructure array 2 disposed on the substrate, the microstructure array 2 includes a plurality of microstructures 21, each microstructure 212 is cylindrical, and the axis direction of the cylinder is perpendicular to the substrate surface. In addition, the distribution state of each microstructure 21 is array distribution, and the parameters of the microstructure 21 are: the height of the microstructure 21 is h, 670nm≤h≤730nm; the diameter of the microstructure 21 is d, 110nm≤d≤200nm or 210nm≤d≤310nm.

[0025] In the microstructure array 2, the array directions are the x direction and the y direction which are orthogonal to each other. The array period ranges of the x direction and the y direction are both 380-420 nm.

[0026] Preferably, in the microstructure array 2, the height of the microstructure 21 is h=700 nm, and the array periods in the x direction and the y direction are equal, both of which are p, forming a square array distribution.

[0027] Reference Figure 4 As shown, the cylindrical microstructure 21 adopts different diameters, which will form corresponding phases and transmittances, wherein the phase has been normalized by 2*pi, and can be adjusted according to the projection effect according to the projection needs. As for transmittance, when the diameter of the microstructure 21 is in the range of 200-210nm, the transmittance performance has a resonance peak, and the transmittance is seriously reduced, so the parameters of the microstructure 21 in this range are not used; when the diameter of the microstructure 21 is in the range of 110-200 and 210-300nm, the transmittance performance is good, the transmittance>80%, and the phase space adjustment of 0-2*pi can be covered.

[0028] Preferably, when the diameter of the microstructure 21 is in the range of 110-190 nm and 220-300 nm, the transmittance performance is better, and the transmittance is greater than 90%. Therefore, the diameter parameter of the microstructure 21 is preferably in this range.

[0029] In this embodiment, the beam splitter can split a single beam of light into multiple beams of light, and the projection form of the multiple beams of light can be specifically set according to needs, for example, forming 3×5 multiple beams of light. The diameters of the microstructures 21 in the microstructure array 2 are different, and the diameter of each microstructure 21 is specifically set according to projection needs. The specific distribution form of the diameter of each microstructure 21 can be specifically adjusted according to the parameters of the simulation.

[0030] In this embodiment, the beam splitter is used with a single beam light source, for example, the single beam light source can be a vertical cavity surface emitting laser (VCSEL light source), and the wavelength of the single beam is 600-1000nm. Preferably, the wavelength of the single beam is 940nm.

[0031] The beam splitter in this embodiment has a substrate of optical glass or optical resin. Through micro-nano optical design on the substrate, nano-cylinders are arranged on the surface of the substrate to form a microstructure array 2, which can realize integrated collimation and beam splitting functions. Using semiconductor technology on a pure silicon wafer, photolithography and etching are combined to produce micro-nano structures that meet the above parameter requirements, forming the required microstructure array 2, and obtaining an optical element with a microstructure array 2. The beam splitter does not need to be used with a diffractive optical element (DOE), and can be directly used with a vertical cavity surface emitting laser (VCSEL light source) to directly realize integrated collimation and beam splitting functions, reduce the number of optical elements, and achieve structural simplification and cost control.

[0032] This embodiment also discloses an optical component, including a beam splitter and a vertical cavity surface emitting laser (VCSEL light source) as in the above embodiment. The beam splitter can split a single beam of light generated by the vertical cavity surface emitting laser (VCSEL light source) into multiple beams of light distributed in an array in the x-direction and the y-direction, for example, forming 3×5 multiple beams of light.

[0033] This embodiment also discloses a method for using the optical assembly in the above embodiment in depth detection or three-dimensional detection based on time of flight or structured light. The method can be implemented in various ways known in the art.

[0034] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A beam splitter, characterized in that: The invention comprises a microstructure array arranged on a substrate, wherein the microstructure array comprises a plurality of microstructures, wherein the microstructure is cylindrical, the axis direction of the cylinder is perpendicular to the surface of the substrate, the height of the microstructure is h, 670nm≤h≤730nm; the diameter of the microstructure is d, 110nm≤d≤200nm or 210nm≤d≤310nm.

2. A beam splitter according to claim 1, characterized in that: The height of the microstructure is h=700 nm.

3. A beam splitter according to claim 1, characterized in that: At least two microstructures in the microstructure array have different diameters.

4. A beam splitter according to claim 1, characterized in that: The array directions of the microstructure array are mutually orthogonal x and y directions, and the array periods in the x and y directions are both 380-420 nm.

5. A beam splitter according to claim 4, characterized in that: The array periods in the x-direction and the y-direction are equal.

6. A beam splitter according to claim 1, characterized in that: The substrate is optical glass or optical resin.

7. An optical component, characterized in that: It comprises a light source and a beam splitter as described in any one of claims 1 to 6, wherein the light source is a single beam of light, and the beam splitter is used to split the single beam of light into multiple beams of light distributed in arrays in the x-direction and the y-direction.

8. The optical component according to claim 7, characterized in that The wavelength of the single beam of light is 600-1000nm.

9. The optical component according to claim 8, characterized in that The wavelength of the single beam of light is 940 nm.

10. Use of the optical component according to claim 7 in depth detection or three-dimensional detection based on time of flight or structured light.

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