Optical system arrangement

Abstract

The present application provides an optical system device in which the contrast of a dot pattern is high even if light sources are arranged in a hexagonal pattern and lenses are quadrangular or have a shape similar thereto. In addition, the present application provides an optical system device in which the distance between a lens and a light source can be shortened. The present application provides an optical system device including: an optical element in which light of a wavelength λ passes through a lens having a width of P in an x direction and a width of (3)P / 2 in a y direction about an optical axis center, and the optical axis center is arranged in a regular hexagonal pattern at a pitch P in the x direction; and an irradiation section in which a light source that irradiates light of the wavelength λ to a plurality of the lenses is arranged in a regular hexagonal pattern at the pitch P in the x direction, and when a focal length of the lens is f and n is a natural number of 1 or more, a distance L1 from a focal point position of the optical element satisfies the following formula 1.

Description

Technical Field

[0001] This invention relates to an optical system device. Background Technology

[0002] Three-dimensional measurement sensors using the time-of-flight (TOF) method are used in portable devices, vehicles, robots, and more. They measure the distance to an object based on the time it takes for light from a light source to travel from the object to its reflection. If light from the light source illuminates a defined area of ​​the object uniformly, the distance to each illuminated point can be determined, allowing for the detection of the object's three-dimensional structure.

[0003] The sensor system includes a transmitter (Tx module) that illuminates an object with light, and a receiver (Rx module) that detects light reflected from various points on the object. The transmitter mainly includes an illumination unit that illuminates the light, and optical elements that control the light to illuminate a designated area. The receiver mainly includes a camera unit that receives the light, and a processing unit that calculates the distance to the object based on the signal received by the camera unit. Here, since the camera unit and processing unit of the receiver can use existing complementary metal-oxide-semiconductor (CMOS) imagers and central processing units (CPUs), the transmitter is the characteristic part of the system.

[0004] In the optical components of the transmitter, for example, there is a diffusion filter that shapes the light by allowing the light from the irradiation section to pass through, thereby uniformly irradiating an object within a specified range. As such a diffusion filter, a microlens array with randomly arranged lenses is used.

[0005] On the other hand, TOF requires long-distance measurement, and the illumination light needs to have an intensity or contrast corresponding to the capability for long-distance measurement. However, diffusion filters result in high uniformity of the illumination light, but correspondingly lower intensity or contrast, making them unsuitable for long-distance measurement.

[0006] Therefore, as a transmitter that can save power and send strong light signals, an optical system device is being researched that controls the light from the irradiation section into a distribution of multiple point-like lights, i.e., a point-like pattern, using optical elements for illumination. Compared with a diffusion filter, the point-like pattern has lower resolution, but higher light intensity or contrast at each point. As an optical system device for irradiating a point-like pattern, there is a device comprising an optical element including lenses arranged regularly at a predetermined spacing P, and an irradiation section disposed at a predetermined distance from the optical element. Here, the optical element and the irradiation section are configured such that when the wavelength of the light from the light source is set to λ, n is set to a natural number greater than or equal to 1, and the distance between the optical element and the light source of the irradiation section is set to L0, the following formula A is satisfied (for example, Patent Document 1).

[0007] [Formula 1]

[0008] Formula A

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: International Publication No. 2021 / 229848 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] In recent years, there has been a desire for miniaturization and thinning of optical systems. To achieve this, it is necessary to reduce the distance L0 between the microlens and the light source. To reduce this distance L0, according to Equation A, it is simply necessary to reduce the lens spacing P of the optical element.

[0014] On the other hand, since the lens spacing P is limited by the spacing of the light sources, the lens spacing depends on the spacing or arrangement of the light sources. Here, existing light sources use vertical-cavity surface-emitting lasers (VCSELs) that can predict high output with low power consumption. Hexagonal VCSELs are the mainstream arrangement, while quadrangular VCSELs are more expensive. Therefore, a hexagonal lens planar shape is considered; however, it is difficult to design a quadrilateral pattern of irradiated dots using a hexagonal lens planar shape. Therefore, a quadrilateral or similar shape is preferred for the lens planar shape.

[0015] As a VCSEL that arranges the light source in a hexagonal pattern and sets the lens planar shape to a quadrilateral, conventional methods have involved matching the short side of the lens with the minimum distance P of the light source and matching the long side with the second smallest distance (…). 3) A structure designed for P matching (refer to Figure 57 in reference 1). However, in this case, in order to make the minimum spacing P match the second smallest spacing ( 3) For both P and P to satisfy equation A, n in equation A must be a multiple of 3. As a result, the distance L0 increases, thus hindering the miniaturization and thinning of the optical system.

[0016] Therefore, the object of the present invention is to provide an optical system device that provides high contrast of dot pattern even when the light source is hexagonally arranged and the plane of the lens is quadrilateral or similar in shape, and can reduce the distance between the lens and the light source.

[0017] Technical means to solve the problem

[0018] To achieve the aforementioned objective, the optical system device of the present invention is characterized by comprising: an optical element that transmits light of wavelength λ, and has a width of P in the x-direction and a width of ( ) in the y-direction passing through the center of the optical axis. 3) A P / 2 lens is formed by arranging the optical axis centers in a regular hexagonal pattern with a spacing P in the x-direction; and an irradiation section is formed by irradiating light of wavelength λ onto the light sources of the plurality of lenses in a regular hexagonal pattern with a spacing P in the x-direction. When the focal length of the lens is set to f and n is set to a natural number greater than or equal to 1, the distance L1 between the irradiation section and the focal position of the optical element satisfies the following equation 1.

[0019] [Formula 2]

[0020] ... (Formula 1).

[0021] In this case, the shape of the xy plane of the lens in the optical element is preferably quadrilateral, for example, it can be set as a rectangle.

[0022] Furthermore, the distance L1 is preferably satisfied by the following equation 2.

[0023] [Formula 3]

[0024] ... (Equation 2).

[0025] Furthermore, the distance L1 is preferably satisfied by the following equation 3.

[0026] [Formula 4]

[0027] ... (Formula 3).

[0028] Furthermore, the distance L1 is preferably satisfied by the following equation 4.

[0029] [Formula 5]

[0030] ... (Formula 4).

[0031] The effects of the invention

[0032] The optical system device of the present invention provides an optical system device that provides high contrast of dot pattern even when the light source is hexagonally arranged and the lens is quadrilateral or similar in shape. Additionally, an optical system device that can shorten the distance between the lens and the light source can be provided. Attached Figure Description

[0033] [ Figure 1 [Illustration 1] is a schematic cross-sectional view of the optical system device of the present invention.

[0034] [ Figure 2 [Illustration 1] is a plan view showing the optical system device of the present invention.

[0035] [ Figure 3 [Illustration 1] is a plan view showing the optical system device of the present invention.

[0036] [ Figure 4 [Illustration 1] is a plan view showing the optical system device of the present invention.

[0037] [ Figure 5 [Illustration 1] is a plan view showing the optical system device of the present invention.

[0038] [ Figure 6 [ ] is a diagram showing the light distribution in the far field of the irradiation section used for simulation.

[0039] [ Figure 7 [A] is a schematic plan view of (a) the optical system device of the present invention and (b) a projection view in Simulation 1.

[0040] [ Figure 8 [A] is a schematic plan view of the existing optical system setup in Simulation 1, and [B] is a projection view.

[0041] [ Figure 9 [A] is a schematic plan view of (a) the optical system device of the present invention and (b) a projection view in Simulation 2.

[0042] [ Figure 10 [A] is a schematic plan view of the existing optical system setup in Simulation 2, and [B] is a projected view. Detailed Implementation

[0043] The optical system device of the present invention will now be described. Figure 1 As shown, the optical system device of the present invention mainly includes: an optical element 1, a periodic lens 11; and an irradiation unit 2, which has a periodic light source for irradiating light with wavelength λ.

[0044] Optical element 1 transmits light of wavelength λ, and its width in the x-direction passing through the center of the optical axis is P, and its width in the y-direction is ( ). 3) A P / 2 lens is an element that arranges the centers of the optical axis in a regular hexagonal pattern at a distance P along the x-direction. The term "lenses arranged in a regular hexagonal pattern" means, in other words, as... Figure 2 As shown, this refers to spacing P in the x-direction and spacing ( ) in the y-direction perpendicular to the x-direction. 3) The rows are arranged periodically in a P / 2 pattern, with the rows in the x-direction staggered by P / 2 from adjacent rows. Furthermore, for convenience in this specification, the direction of the optical axis of optical element 1 is defined as the z-direction, and the x, y, and z directions are defined as mutually perpendicular directions. Additionally, the center of the optical axis refers to the intersection of the xy plane and the optical axis.

[0045] Furthermore, lens 11 has a focal point at a predetermined distance f (f > 0) from lens 11. In addition, in this specification, the term focal length is as follows: Figure 1 The distance shown refers to the distance between the lens surface closest to the focal point and the focal point. Furthermore, lens 11 preferably has its focal point located on the illumination portion side of lens 11.

[0046] The shape of lens 11 can be freely designed according to the dot pattern. For example, the shape of lens 11 can be a spherical lens or an aspherical lens. In addition, the shape of lens 11 can also be a convex lens or a concave lens. Furthermore, as long as lens 11 functions as a lens, it can be any lens, such as a Fresnel lens, a diffraction optical element (DOE) lens, a meta-lens, etc.

[0047] Furthermore, the shape of the xy-plane of lens 11 (hereinafter referred to as the plane shape) can be arbitrary as long as it allows the optical axis centers of lens 11 to be arranged in a regular hexagonal pattern at a distance P in the x-direction. For example, as Figure 2 As shown, the planar shape of lens 11 can be set to a quadrilateral or a shape similar to it. Furthermore, when the planar shape of lens 11 is quadrilateral, a rectangle is preferred, but it can also be as shown... Figure 3 , Figure 4 As shown, it can be set as a parallelogram or a rhombus. Additionally, as a shape similar to a quadrilateral, such as... Figure 5 As shown, this is equivalent to setting the shape of the sides of the quadrilateral to a waveform shape such as a sine wave, a rectangular wave, a triangular wave, or a sawtooth wave.

[0048] Furthermore, as long as the optical element 1 can form a lens that transmits light of wavelength λ, any material can be used, such as resins like polydimethylsiloxane (PDMS) or glass. Additionally, as long as the optical element 1 can form the lens 11, it can be manufactured in any manner, for example, using conventionally known methods such as embossing or injection molding.

[0049] The irradiation section 2 is formed by arranging light sources 20, which illuminate multiple lenses 11 with wavelength λ, in a regular hexagonal pattern at a distance P along the x-direction. Furthermore, the irradiation section 2 and the optical element 1 are preferably configured such that the optical axis of the light source 20 in the irradiation section 2 coincides with the optical axis of the lens 11 in the optical element 1. The light source 20 can be any light source as long as it can illuminate the multiple lenses 11 with wavelength λ. A specific example of the irradiation section 2 is, for instance, a VCSEL (Vertical Cavity Surface Emitting Laser) that estimates high output with low power consumption. A VCSEL has multiple light sources 20 that can illuminate light in a direction perpendicular to the emitting surface.

[0050] [Positional relationship between the irradiation unit and optical elements]

[0051] like Figure 1 As shown, when the distance L1 between the irradiation unit 2 and the focal plane of the optical element 1 satisfies the following formula α, the incident light can be converted into a dot pattern with high contrast. Here, n refers to a natural number greater than or equal to 1, P refers to the distance between the lenses in the x-direction, λ refers to the wavelength of the light incident from the irradiation unit 2, f refers to the focal length of the lens 11, and a and b refer to coefficients representing the allowable error. Furthermore, the focal plane refers to the plane that is perpendicular to the optical axis (z-direction) of the lens 11 and located at the focal point of the lens 11. In addition, the distance L1 refers to the distance (optical path length) that the light travels in a vacuum in the same time as it travels in the medium, and when the refractive index of the medium is set to N and the actual distance is set to L, it is represented by their product NL.

[0052] [Formula 6]

[0053] ...(Equation α)

[0054] Here, the smaller the values ​​of the coefficients a and b in equation α, the better, preferably 1, 0.5, 0.3, and 0.1. When the coefficients of equation α are a=b=1, equation α becomes equation 1 below.

[0055] [Formula 7]

[0056] ...(Formula 1)

[0057] Furthermore, when the distance L1 satisfies Equation 2 below, where a=b=0, the light can be mutually enhanced to the greatest extent.

[0058] [Formula 8]

[0059] ... (Equation 2)

[0060] Furthermore, in equation α, the smaller the value of n, the smaller the distance L1 between the irradiation part 2 and the focal plane of the optical element 1. When n=1, it becomes equation β.

[0061] [Formula 9]

[0062] ...(Equation β)

[0063] Here, the smaller the values ​​of coefficients a and b in equation β, the better, preferably 1, 0.5, 0.3, and 0.1. When the coefficients of equation β are a=b=1, equation β becomes equation 3 below.

[0064] [Formula 10]

[0065] ... (Formula 3)

[0066] Furthermore, the distance L1 becomes the shortest distance between the irradiation part 2 and the focal plane of the optical element 1 when the following equation 4, which satisfies a=b=0, allows the light to enhance each other to the greatest extent.

[0067] [Formula 11]

[0068] ... (Formula 4)

[0069] Furthermore, if the spacing P is too small for the wavelength λ of the light from the light source 20, diffraction will be difficult to occur. Therefore, as long as the light distribution angle of the light source 20 includes a lens 11 sufficient to generate diffraction, the spacing P should be sufficiently large for the wavelength λ of the light from the light source 20, for example, more than 5 times, preferably more than 10 times.

[0070] [Simulation 1]

[0071] Simulations were performed on the optical system apparatus of the present invention and on a conventional optical system apparatus as a comparative example. In these simulations, the same irradiation unit was used in all optical system apparatuses. The irradiation unit is as follows: Figure 7 (a) Figure 8 As shown in (a), multiple light sources 20A are arranged in a regular hexagonal pattern with a spacing P in the x-direction. Furthermore, the light sources 20A in the irradiation section irradiate with a spacing P of 20 μm (P=20) and a wavelength of 940 nm (λ=0.94). Figure 6 The light distribution is as shown in the diagram for bat wings. Furthermore, the distance L1 between the irradiation section and the focal point of the optical element is calculated using the following formula 2.

[0072] [Formula 12]

[0073] ... (Equation 2)

[0074] The simulation used the optical simulation software BeamPROP (manufactured by Synopsys).

[0075] As an optical element 1A of the optical system device of the present invention, such as Figure 7 As shown in (a), an optical element is formed by arranging the optical axis centers in a regular hexagonal pattern with a spacing P along the x-direction using lenses 11A. The lenses 11A of the optical element 1A are configured to transmit light with a wavelength λ (λ=0.94), and have a width of 20 μm in the x-direction and a width of 10 μm in the y-direction passing through the optical axis centers. 3 μm. In addition, lens 11A is set with a refractive index of 1.5 and a focal length f of 10 μm.

[0076] The distance L1 between the irradiation part and the focal point 9 of the optical element 1A is set to the distance when n=2 in the above formula 2, which is 426um [L1=2×20 2 / (2 × 0.94) = 426.

[0077] Figure 7 (b) is the projected image 1 m in front of the optical element 1A. The average contrast at each point is 14.40.

[0078] As an optical element 1B in an existing optical system device, such as Figure 8 As shown in (a), lens 11B is used to make the optical axis center at a distance P in the x-direction and at a distance P in the y-direction. The optical element 1B is arranged in a four-corner configuration. The lens 11B of the optical element 1B is configured to transmit light with a wavelength λ (λ=0.94), and its width in the x-direction passing through the center of the optical axis is 20 μm, and its width in the y-direction is 20 μm. 3 μm. In addition, lens 11B is set with a refractive index of 1.5 and a focal length f of 12 μm.

[0079] The distance L1 between the irradiation part and the focal point 9 of the optical element 1B is set to the distance when n=2 in the above formula 2, which is 426um [L1=2×20]. 2 / (2 × 0.94) = 426.

[0080] Figure 8 (b) is the projected image 1 m in front of the optical element 1B. The average contrast at each point is 6.62.

[0081] When comparing the optical system device of the present invention with existing optical system devices, it can be seen that L1 is the same at 426 μm, but the average contrast of the optical system device of the present invention is higher than that of existing optical system devices, and the points of the projected image are clearer.

[0082] [Simulation 2]

[0083] Next, simulations were performed on the optical system apparatus of the present invention and a conventional optical system apparatus as a comparative example. In the simulations, it was assumed that the distance between the irradiation part and the focal position of the optical element was the same in any optical system apparatus. Furthermore, the distance L1 between the irradiation part and the focal position of the optical element was expressed using the following formula 2.

[0084] [Formula 13]

[0085] ... (Equation 2)

[0086] The simulation used the optical simulation software BeamPROP (manufactured by Synopsys).

[0087] As the irradiation section of the optical system device of the present invention, such as Figure 9 As shown in (a), an illumination section is formed by arranging multiple light sources 20B in a regular hexagonal pattern with a spacing P in the x-direction. The light sources 20B of the illumination section are configured such that the spacing P is 20... 3 μm (P=20) 3) Irradiation with a wavelength of 940 nm (λ=0.94) as... Figure 6 The light is as shown in the diagram, which is used for the light distribution of bat wings.

[0088] In addition, such as Figure 9 As shown in (a), the optical element 1C of the optical system device of the present invention is an optical element formed by arranging lenses 11C in a regular hexagonal pattern with a spacing P along the x-direction. The lenses 11C of the optical element 1C are configured to transmit light with a wavelength λ (λ=0.94), and have a width of 20 mm in the x-direction passing through the center of the optical axis. The lens has a width of 3 μm in the y-direction and a width of 30 μm in the y-direction. Additionally, the lens 11C has a refractive index of 1.5 and a focal length f of 10 μm.

[0089] The distance L1 between the irradiation part and the focal point 9 of the optical element 1C is set as the distance when n=2 in the above formula 2, which is 1277um [L1=2×(20 3) 2 / (2 × 0.94) = 1277.

[0090] Figure 9 (b) is the projected image 1 m in front of the optical element at a distance of 1 C. The average contrast at each point is 41.96.

[0091] As the illumination part of existing optical system devices, such as Figure 10As shown in (a), an irradiation section is formed by arranging multiple light sources 20A in a regular hexagonal pattern with a spacing P in the x-direction. The light sources 20A in the irradiation section are configured to have a spacing P of 20 μm (P=20) and a wavelength of 940 nm (λ=0.94), irradiating... Figure 6 The light is as shown in the diagram, which is used for the light distribution of bat wings.

[0092] In addition, such as Figure 10 As shown in (a), in the existing optical system device, optical element 1B uses lens 11B to make the optical axis center at a distance P in the x-direction and at a distance P in the y-direction. The optical element 1B is arranged in a four-corner configuration. The lens 11B of the optical element 1B is configured to transmit light with a wavelength λ (λ=0.94), and its width in the x-direction passing through the center of the optical axis is 20 μm, and its width in the y-direction is 20 μm. 3 μm. In addition, lens 11B is set with a refractive index of 1.5 and a focal length f of 12 μm.

[0093] The distance L1 between the irradiation unit 2 and the focal point 9 of the optical element 1B is set to the distance when n=6 in the above formula 2, which is 1277 μm [L1=6×20]. 2 / (2 × 0.94) = 1277.

[0094] Figure 10 (b) is the projected image 1 m in front of the optical element 1B. The average contrast at each point is 28.61.

[0095] When comparing the optical system device of the present invention with existing optical system devices, it can be seen that L1 is the same at 1277 μm, but the average contrast of the optical system device of the present invention is higher than that of existing optical system devices, and the points of the projected image are clearer.

[0096] Explanation of icon numbers

[0097] 1, 1A, 1B, 1C: Optical components

[0098] 2: Irradiation part

[0099] 9: Focus position

[0100] 10: Substrate

[0101] 11: Lens

[0102] 20: Light source

[0103] 51: Module

Claims

1. An optical system device, characterized in that... include: An optical element that transmits light of wavelength λ and has a width of P in the x-direction passing through the center of the optical axis, and a width of ( ) in the y-direction. 3) The P / 2 lens arranges the optical axis centers in a regular hexagonal pattern with a spacing P in the x-direction; as well as The illumination section is composed of light sources that illuminate multiple lenses at a distance P in a regular hexagonal arrangement along the x-direction, illuminating light of wavelength λ. When the focal length of the lens is set to f and n is set to a natural number greater than or equal to 1, the distance L1 between the irradiation part and the focal position of the optical element satisfies the following equation 1. [Formula 1] ... (Formula 1).

2. The optical system device according to claim 1, characterized in that, In the optical element, the xy plane of the lens is quadrilateral in shape.

3. The optical system device according to claim 1, characterized in that, In the optical element, the shape of the xy plane of the lens is rectangular.

4. The optical system apparatus according to any one of claims 1 to 3, characterized in that, The distance L1 satisfies the following equation 2 [Formula 2] ... (Equation 2).

5. The optical system apparatus according to any one of claims 1 to 3, characterized in that, The distance L1 satisfies the following equation 3 [Formula 2] ... (Formula 3).

6. The optical system apparatus according to any one of claims 1 to 3, characterized in that, The distance L1 satisfies the following equation 4 [Formula 2] ... (Formula 4).

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