A detector array for detecting incident angle based on the distance between adjacent diffraction points in a waveguide

Abstract

The present invention discloses a detector array for detecting the incident angle based on the distance between adjacent diffraction points in a waveguide, and relates to the field of angle measurement. The present invention includes a light source, a grating structure, a grating protection layer, an aperture, an optical waveguide, and an optical detector array; the grating structure is located on a surface at one end of the optical waveguide, and the optical detector array is located on the upper surface or the lower surface of the other end of the optical waveguide; the aperture is located on the upper surface or the lower surface of the optical waveguide and between the grating structure and the optical detector array; the incident angle and the diffraction angle of the light source are calculated by measuring the distance between adjacent diffraction points. The present invention can realize the angle measurement of incident light with high precision; the sub-wavelength one-dimensional grating structure integrated on the optical waveguide and the ultra-thin photodetectors arranged around the waveguide are used to realize angle perception based on the ultra-thin device.

Description

Technical Field

[0001] The invention relates to the field of angle measurement, and in particular to a detector array for detecting incident angles based on the distances between adjacent diffraction points in a waveguide. Background Art

[0002] Angle measurement is a part of basic geometric measurement and detection, especially high-precision angle measurement, which has a wide range of demands and applications in scientific fields such as precision machining and manufacturing of machinery, optical surface measurement, optical touch systems, and microelectronics manufacturing. With the continuous development and technological advancement of various fields, the accuracy requirements for angle detection are gradually increasing. At the same time, with the current trend of device manufacturing towards bendable and ultra-thin, thin and high-precision angle detector devices are becoming increasingly important.

[0003] Optical angle measurement methods are widely used in various fields due to their non-contact, long working distance and high precision. Traditional optical angle measurement methods include circular grating method, interferometry method, ring laser method and laser autocollimation, but these measurement devices are relatively bulky and difficult to integrate into ultra-thin devices.

[0004] Therefore, technicians in this field are committed to developing a detector array that detects the incident angle based on the distance between adjacent diffraction points in a waveguide, and providing an ultra-light and high-precision measurement device. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to achieve ultra-light and high-precision angle measurement.

[0006] To achieve the above-mentioned purpose, the present invention provides a detector array for detecting the incident angle based on the distance between adjacent diffraction points in a waveguide, comprising a light source, a grating structure, a grating protection layer, an aperture, an optical waveguide and a photodetector array; the grating structure is located on a surface at one end of the optical waveguide, and the photodetector array is located on the upper surface or the lower surface of the other end of the optical waveguide; the aperture is located on the upper surface or the lower surface of the optical waveguide and between the grating structure and the photodetector array; the incident angle and azimuth of the light source are calculated by measuring the distance between adjacent diffraction points.

[0007] Furthermore, when the incident light irradiates the grating structure, the optical signal to be measured falls between the detectors arranged at different positions of the optical waveguide frame, and the incident angle and azimuth are calculated according to the distance between the optical signal and the next optical signal that can distinguish the same mode; the distance D1 of the center point of the optical signal of the detector along the x-axis direction is:

[0008] D1=(m+1)·d1

[0009] Where: m is the number of signal centers detected between two optical signals along the x-axis, d1 is the distance between the centers of adjacent reflected light spots along the x-axis;

[0010] The angle of incidence is:

[0011]

[0012] Where: T is the grating period, n1 is the refractive index in the waveguide, λ is the wavelength of the incident light, k is the diffraction order, and h is the thickness of the waveguide.

[0013] Furthermore, the distance D2 of the center point of the optical signal of the detector along the y-axis direction is:

[0014] D2=(n+1)·d2

[0015] Where: n is the number of signal centers detected between two optical signals along the y-axis, and d2 is the distance between the centers of adjacent reflected light spots along the y-axis;

[0016] The azimuth angle α of the incident light is:

[0017]

[0018] Wherein: d1 is the distance between the centers of adjacent reflected light spots along the x-axis, d2 is the distance between the centers of adjacent reflected light spots along the y-axis, D1 is the distance between the center points of the optical signals of the detectors along the x-axis, and D2 is the distance between the center points of the optical signals of the detectors along the y-axis.

[0019] Furthermore, the diffraction angle can be changed by controlling the grating period and the incident angle.

[0020] Furthermore, the photodetector array can be attached to the upper and lower surfaces of the optical waveguide at the same time.

[0021] Furthermore, the aperture can limit the size of the light spot incident on the light detector array, and the centroids of adjacent reflected light spots can be identified by the light detector array even if they overlap.

[0022] Furthermore, the grating structure may be integrated on an optical waveguide.

[0023] Furthermore, the grating structure is a one-dimensional grating at a sub-wavelength scale, which can flexibly manipulate light waves at a nanometer scale.

[0024] Furthermore, ultra-thin photodetectors may be arranged around the optical waveguide.

[0025] Furthermore, the grating structure is composed of alternating medium-medium or medium-metal single or multilayer materials with different refractive indices; the position of the grating structure in the optical waveguide satisfies that the light diffracted by the grating structure enters the optical waveguide with maximum efficiency.

[0026] In a preferred embodiment of the present invention, the existing sensing technology for the spatial angle and azimuth of incident light is limited. The present invention can simultaneously measure the incident angle and azimuth of incident light. The non-zero-order diffraction angle of the grating will change with the change of the incident angle, and the change in the planar waveguide is the change in the distance between two adjacent diffraction points. Therefore, the incident angle and azimuth can be calculated by measuring the distance between adjacent diffraction points. The present invention can easily obtain the incident angle by measuring the distance of the center point of the reflection signal in the waveguide on the detector, and can realize the rapid measurement and perception of the change of the incident angle.

[0027] The existing incident light angle measurement is lacking in measurement accuracy. The present invention can achieve incident light angle measurement with high accuracy. The detector array can be attached to one surface of the waveguide alone, or to the upper and lower surfaces of the waveguide at the same time, which can further improve the angle detection accuracy. At the same time, a light-clearing aperture needs to be added to the front end of the detector. The aperture can limit the size of the light spot incident on the detector array, so that the centroids of adjacent reflected light spots can be recognized by the detector array even if they overlap, thereby further improving the detection accuracy. The present invention further improves the angle measurement accuracy through different detector array combinations and the role of light-clearing apertures.

[0028] Traditional optical angle measurement methods include circular grating method, interference method, ring laser method and laser self-collimation, but these types of measurement devices are relatively bulky and difficult to integrate into ultra-thin devices. The present invention utilizes a sub-wavelength one-dimensional grating structure integrated on an optical waveguide and ultra-thin photodetectors arranged around the waveguide to achieve angle perception based on ultra-thin devices. Sub-wavelength-scale one-dimensional gratings can achieve flexible manipulation of light waves at the nanoscale, including but not limited to directional coupling and other effects; at the same time, ultra-thin photodetectors, while achieving highly sensitive detection, also provide a good foundation for ultra-thin devices. The device of the present invention is small in size, thinner and lighter, and is easy to integrate into other devices.

[0029] Compared with the prior art, the present invention has the following obvious substantial features and significant advantages:

[0030] 1. Technical advantages: The detector array proposed in the present invention can simultaneously identify the spatial angle and azimuth angle of incident light, and has a fast response speed.

[0031] 2. Performance indicators: The existing detector arrays on the market can already achieve high-precision angle measurement, and the detection accuracy can be further improved under different arrangements. At the same time, sub-wavelength-scale optical films and ultra-thin detector arrays are conducive to their integration into other devices and reducing the size of the device.

[0032] 3. Production implementation: The grating optical film used in the present invention can utilize existing nanoimprinting, roll-to-roll imprinting and other technologies to achieve low-cost, mass-production goals. At the same time, the accuracy of existing detectors on the market can already meet the accuracy requirements for angle perception, providing a good implementation basis for the mass production of the entire device.

[0033] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of the geometric structure of the first embodiment of the waveguide angle sensor array based on the grating structure of the present invention;

[0035] Figure 2 is a schematic diagram of the geometric structure of a second embodiment of a waveguide angle sensor array based on a grating structure of the present invention;

[0036] Figure 3 is a schematic diagram of the geometric structure of a third embodiment of a waveguide angle sensor array based on a grating structure of the present invention;

[0037] Figure 4 It is a schematic diagram of a preferred embodiment of the present invention.

[0038] Among them, 1-optical waveguide, 2-grating structure, 3-grating protection layer, 4-photodetector array. DETAILED DESCRIPTION

[0039] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0040] In the drawings, components with the same structure are indicated by the same numerical reference numerals, and components with similar structures or functions are indicated by similar numerical reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0041] The coupling formula of grating waveguide is shown in formula (1) (2). Where T is the grating period, n0 is the refractive index of the incident medium, n1 is the refractive index in the waveguide, θ i is the incident angle, θ d is the diffraction angle, λ is the incident wavelength, k is the diffraction order, + represents transmission diffraction, and - represents reflection diffraction.

[0042] T·(n1sinθd ±n0sinθ i )=kλ,k=0,±1,±2……#(1)

[0043] The present invention is a transmission diffraction case with a + sign, so for the diffraction order, the diffraction angle satisfies:

[0044]

[0045] From formula (2), we can know that the diffraction angle can be changed by controlling the grating period and the incident angle. At the same time, we can also get the incident angle to satisfy the formula:

[0046]

[0047] like Figure 1 As shown in FIG. 1 , when the incident azimuth angle is 0, the distance D between the center points of the light spots reflected by different diffracted lights on the upper and lower surfaces of the waveguide can be obtained, wherein the relationship between the distance d between the center points of adjacent diffraction light spots and D is: D = (m+1) · d#(4)

[0048] In the formula, m is the number of signals between different diffraction points, and the relationship between the distance d between adjacent diffraction points, the thickness h of the optical waveguide and the diffraction angle is:

[0049]

[0050] From equations (3) and (4), we can get the relationship between the distance d between adjacent diffraction points and the incident angle θ: i Relationship:

[0051]

[0052] Example 1, the corresponding device is as follows Figure 1 As shown, the structure includes a light source with a wavelength of λ, a grating structure 2 with a period of T, a grating protection layer 3, an aperture, an optical waveguide 1 with a refractive index of n1 and a thickness of h, and a photodetector array 4. The grating structure 2 is located on a surface at one end of the optical waveguide 1, and the photodetector array 4 is located on the upper surface or the lower surface of the other end of the optical waveguide 1. The aperture is located on the upper surface or the lower surface of the optical waveguide 1 and between the grating structure 2 and the photodetector array 4. After the aperture is adjusted, the width of the incident light spot becomes smaller to facilitate the resolution of the reflected light spot signal on the detector. When the light source is incident from the air at an azimuth angle of 0, n0=1. According to formula (6), the incident angle can be obtained as:

[0053]

[0054] Example 2, the corresponding device is as follows Figure 2As shown, the structure includes a light source with a wavelength of λ, a grating structure with a period of T, a grating protection layer, an aperture, an optical waveguide with a refractive index of n1 and a thickness of h, and a photodetector array. When the light source has a wavelength of λ and is incident from the air at an azimuth angle of 0, n0=1. In order to improve the accuracy of angle measurement, the upper and lower surfaces of one end of the optical waveguide in the optical signal detection area are attached to the detector array. The grating structure is located on the upper surface or lower surface of the other end of the optical waveguide, and the aperture is located on the upper surface or lower surface of the optical waveguide and between the grating structure and the photodetector array. In this embodiment, the diffraction angle satisfies:

[0055]

[0056] The angle of incidence is:

[0057]

[0058] Example 3, the corresponding device is as follows Figure 3 As shown, the structure includes a light source with a wavelength of λ, a grating structure with a period of T, a grating protection layer, an aperture, an optical waveguide with a refractive index of n1, and a photodetector array. The grating structure is located on a surface at one end of the optical waveguide, and the photodetector array is located on the upper surface or the lower surface of the other end of the optical waveguide. The aperture is located on the upper surface or the lower surface of the optical waveguide and between the grating structure and the photodetector array. The thickness of the optical waveguide is h except for the light detection area, and it is a uniformly gradient slope in the light detection area, and the slope angle is β. When the light source is incident from the air with an azimuth angle of 0, n0=1, and the diffraction angle satisfies the relationship:

[0059]

[0060] The angle of incidence is:

[0061]

[0062] Example 4, the corresponding device is as follows Figure 4 As shown, the structure includes a light source with a wavelength of λ, a grating structure with a period of T, a grating protection layer, an aperture, an optical waveguide with a refractive index of n1, and a photodetector array. The grating structure is located on the upper surface of the planar optical waveguide, and the photodetector array is located on the upper surface or the lower surface around the planar optical waveguide. After the aperture is adjusted, the width of the incident light spot becomes smaller to facilitate the resolution of the reflected light spot signal on the detector. When the incident light is incident at a certain incident angle and azimuth, the distance D1 of the center point of the optical signal of the detector along the x-axis direction is:

[0063] D1=(m+1)·d1#(12)

[0064] Where: m is the number of signal centers detected between two optical signals along the x-axis, d1 is the distance between the centers of adjacent reflected light spots along the x-axis, then the incident angle can be obtained as:

[0065]

[0066] According to the distance D2 of the center point of the optical signal of the detector along the y-axis direction:

[0067] D2=(n+1)·d2#(14)

[0068] Where: n is the number of signal centers detected between two optical signals along the y-axis, d2 is the distance between the centers of adjacent reflected light spots along the y-axis, and the azimuth angle α of the incident light is:

[0069]

[0070] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A detector array for detecting incident angle based on the distance between adjacent diffraction points in a waveguide, characterized in that: The invention comprises a light source, a grating structure, a grating protection layer, an aperture, an optical waveguide and an optical detector array; the grating structure is located on a surface at one end of the optical waveguide, and the optical detector array is located on the upper surface or the lower surface of the other end of the optical waveguide; the aperture is located on the upper surface or the lower surface of the optical waveguide and between the grating structure and the optical detector array; the incident angle and the azimuth angle of the light source are calculated by measuring the distance between adjacent diffraction points; When the incident light irradiates the grating structure, the optical signal to be measured falls between the detectors arranged at different positions of the optical waveguide frame. The incident angle and azimuth are calculated based on the distance between the optical signal and the next optical signal that can distinguish the same mode; the distance D1 of the center point of the optical signal of the detector along the x-axis direction is: D1=(m+1)·d1 Where: m is the number of signal centers detected between two optical signals along the x-axis, d1 is the distance between the centers of adjacent reflected light spots along the x-axis; The angle of incidence is: Where: T is the grating period, n1 is the refractive index in the optical waveguide, λ is the wavelength of the incident light, k is the diffraction order, and h is the thickness of the optical waveguide; The distance D2 of the center point of the optical signal of the detector along the y-axis direction is: D2=(n+1)·d2 Where: n is the number of signal centers detected between two optical signals along the y-axis, and d2 is the distance between the centers of adjacent reflected light spots along the y-axis; The azimuth angle α of the incident light is: Wherein: d1 is the distance between the centers of adjacent reflected light spots along the x-axis, d2 is the distance between the centers of adjacent reflected light spots along the y-axis, D1 is the distance between the center points of the optical signals of the detectors along the x-axis, and D2 is the distance between the center points of the optical signals of the detectors along the y-axis.

2. The detector array for detecting the incident angle based on the distance between adjacent diffraction points in a waveguide as claimed in claim 1, characterized in that: The diffraction angle can be changed by controlling the grating period and the incident angle.

3. The detector array for detecting the incident angle based on the distance between adjacent diffraction points in a waveguide as claimed in claim 1, characterized in that: The photodetector array can be attached to the upper and lower surfaces of the optical waveguide at the same time.

4. The detector array for detecting the incident angle based on the distance between adjacent diffraction points in a waveguide as claimed in claim 1, characterized in that: The aperture can limit the size of the light spot incident on the light detector array, and the centroids of adjacent reflected light spots can be identified by the light detector array even if they overlap.

5. The detector array for detecting the incident angle based on the distance between adjacent diffraction points in a waveguide as claimed in claim 1, characterized in that: The grating structure may be integrated on an optical waveguide.

6. The detector array for detecting the incident angle based on the distance between adjacent diffraction points in a waveguide as claimed in claim 1, characterized in that: The grating structure is a one-dimensional grating at a sub-wavelength scale, which can flexibly control light waves at a nanometer scale.

7. The detector array for detecting the incident angle based on the distance between adjacent diffraction points in a waveguide as claimed in claim 1, characterized in that: Ultra-thin photoelectric detectors can be arranged around the optical waveguide.

8. The detector array for detecting the incident angle based on the distance between adjacent diffraction points in a waveguide as claimed in claim 1, characterized in that: The grating structure is composed of alternating single or multiple layers of medium-medium or medium-metal materials with different refractive indices; the position of the grating structure in the optical waveguide satisfies the requirement that the light diffracted by the grating structure enters the optical waveguide with maximum efficiency.

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