A product and method for expanding the field of view of an optical waveguide

Abstract

The present application relates to a kind of products and methods for expanding the field of view of optical waveguide, the product includes waveguide sheet, coupling-in prism, array reflection film and optical wedge array;After the incident light enters the waveguide sheet as central field of view light after the coupling-in prism, the array reflection film is arranged in the inside of the waveguide sheet;The angle between the array reflection film and the total reflection surface of the waveguide sheet is θ, by changing the angle of the coupling-in prism, so that the incident angle β of the central field of view light in waveguide sheet is >2θ;The optical wedge array is arranged at the total reflection surface of the waveguide sheet exit;The optical wedge array is used to make the light of central field of view perpendicular to the total reflection surface of the waveguide sheet when entering human eye, in line with the viewing habits of human eye;The optical wedge array is composed of multiple single optical wedges in succession.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of augmented reality (AR) technology, and in particular to a product and method for expanding the field of view of an optical waveguide. BACKGROUND

[0002] The following merely represents the background art mastered by the inventor, and is not the prior art available to the public.

[0003] In the field of AR, the field of view angle is an important parameter affecting the effect of AR glasses. For today's optical waveguide modules, in order to make the central field of view of the light machine enter the human eye after passing through the waveguide sheet also a central field of view, the incident central field of view light in the waveguide sheet is made to have an incident angle equal to twice the angle between the array reflection surface and the total reflection surface of the waveguide sheet, so that the central field of view of the light machine is perpendicular to the exit after passing through the waveguide sheet. In this way, limited by the total reflection condition of the waveguide sheet, the angle range that the waveguide sheet can be applied is also determined and limited within a certain range.

[0004] As shown in Figure 1 , the incident angle (2θ) of the central field of view of the incident light 4 (central field of view light) in the waveguide sheet 1 is twice the angle (θ) between the array reflection film 3 in the waveguide sheet and the total reflection surface (5, 6) of the waveguide sheet; at this time, the direction of the central field of view light exiting the waveguide sheet is perpendicular to the total reflection surface of the waveguide sheet. When θ is fixed, assuming that the refractive index of the waveguide sheet is n1, then limited by the total reflection condition, the angle range of the incident light in the waveguide sheet is F1=2*[2θ-arcsin(1 / n1)]. Figure 1 In the figure, reference numeral 2 represents a coupling-in prism. SUMMARY

[0005] The present application aims to provide a product and method for expanding the field of view of an optical waveguide, and the technical problem to be solved is how to expand the field of view of an AR optical module while ensuring that the exit light of the central field of view is perpendicular to the total reflection surface of the waveguide sheet, in line with the viewing habits of the human eye.

[0006] On the other hand, the technical problem to be solved by the present application also includes how to ensure that the product has a relatively thin thickness, and a relatively small volume and weight.

[0007] The present application aims to solve the problems of the prior art and provide a product for expanding the field of view of an optical waveguide, comprising a waveguide sheet, a coupling-in prism, an arrayed reflecting film and an array of optical wedges; incident light enters the waveguide sheet as central field of view light after passing through the coupling-in prism, and the arrayed reflecting film is arranged inside the waveguide sheet; the angle between the arrayed reflecting film and the total reflection surface of the waveguide sheet is θ, the angle of the coupling-in prism is changed so that the incident angle β of the central field of view light in the waveguide sheet is greater than 2θ; the array of optical wedges is arranged at the total reflection surface of the waveguide sheet; the array of optical wedges is used to make the central field of view light perpendicular to the total reflection surface of the waveguide sheet when entering the human eye, in line with the viewing habits of the human eye; the array of optical wedges is composed of a plurality of single optical wedges connected end to end.

[0008] Preferably, assuming that the refractive index of the waveguide sheet is n1, the angle range of the incident light satisfying the total reflection condition in the waveguide sheet is F2=2*[β-arcsin(1 / n1)].

[0009] Preferably, a predetermined gap is left between the array of optical wedges and the waveguide sheet, for ensuring the total reflection condition of the waveguide sheet.

[0010] Preferably, assuming that the total length of the arrayed reflecting film of the waveguide sheet is L1, the length of the array of optical wedges is greater than L2, and the array of optical wedges covers the length range of L1; wherein L2>L1.

[0011] Further preferably, the wedge angle of the single optical wedge is φ, and assuming that the refractive index of the single optical wedge is n2, φ=(n2-1)*arcsin[n1*sin(2β-4θ)].

[0012] Further preferably, assuming that the minimum thickness of the single optical wedge is h1 and the minimum length of the single optical wedge is S, the maximum thickness of the single optical wedge is h=h1+S*tanφ.

[0013] The present application also provides a method for expanding the field of view of an optical waveguide, comprising the following steps:

[0014] Firstly, the angle of the coupling-in prism is changed so that the incident angle β of the central field of view light in the waveguide sheet is greater than 2θ; when the angle θ between the arrayed reflecting film and the total reflection surface of the waveguide sheet is fixed, assuming that the refractive index of the waveguide sheet is n1, the angle range of the incident light satisfying the total reflection condition in the waveguide sheet is F2=2*[β-arcsin(1 / n1)]; the field of view angle of the waveguide sheet is expanded;

[0015] Second step, add a light wedge array at the total reflection surface of the waveguide sheet; the light wedge array is used to make the light of the central field of view vertical to the total reflection surface of the waveguide sheet when entering the human eye, in line with the viewing habit of the human eye; the light wedge array is composed of a plurality of single light wedges in a head-to-tail manner.

[0016] Advantages

[0017] Compared with the prior art, the advantages of the present application are:

[0018] The product and method for expanding the field of view range of the light waveguide of the present application adopt the mode that the incident central field of view light has an incident angle greater than 2 times the included angle between the array reflection surface and the total reflection surface of the waveguide sheet, at this time the central field of view is offset in the direction of increasing the incident angle in the waveguide sheet, and then the field of view range angle transmitted in the waveguide sheet is increased, so as to expand the field of view range of the AR light module; a light wedge array is added outside the waveguide sheet to ensure that the outgoing light of the central field of view is perpendicular to the total reflection surface of the waveguide sheet, in line with the viewing habit of the human eye. At the same time, the light wedge array can ensure the direction of the corrected light beam and also ensure a relatively thin thickness, and the volume and weight are relatively small. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings are included to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification, and together with the specific embodiments of the present application, serve to explain the technical solutions of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0020] Figure 1 is a schematic diagram of a general setting mode of the waveguide sheet in the background art.

[0021] Figure 2 is a schematic diagram of the structure of the product for expanding the field of view range of the light waveguide according to the present application.

[0022] Figure 3 is an enlarged schematic diagram of the single light wedge according to the present application. DETAILED DESCRIPTION

[0023] The present application is described in more detail below to help understand the present application.

[0024] As shown in Figure 2 and Figure 3 , the product for expanding the field of view range of the light waveguide according to the present application comprises a waveguide sheet 1, a coupling-in prism 2, an array reflection film 3 and a light wedge array 7; the incident light enters the waveguide sheet 1 as central field of view light 4 after passing through the coupling-in prism 2, and the array reflection film 3 is arranged inside the waveguide sheet 1; the included angle between the array reflection film 3 and the total reflection surface of the waveguide sheet 1 is θ, and by changing the angle of the coupling-in prism, the incident angle β of the central field of view light 4 in the waveguide sheet is greater than 2θ.

[0025] In this way, when θ is fixed, assuming that the refractive index of the waveguide sheet is n1, the angle range of the incident light satisfying the total reflection condition in the waveguide sheet is F2=2*[β-arcsin(1 / n1)]=F1+2(β-2θ)>F1; obviously, the field angle of the waveguide sheet is increased.

[0026] In the above manner of the present application, the light of the central field of view is not perpendicular to the total reflection surface of the waveguide sheet when it is emitted from the waveguide sheet, which does not conform to the viewing habit of the human eye; therefore, an optical wedge array 7 is added at the total reflection surface 5 of the waveguide sheet; assuming that the total length of the array reflection film 3 of the waveguide sheet is L1, the length of the optical wedge array should be greater than L2 and cover the length range of L1; in addition, a certain gap (between 0.1mm and 1mm) is left between the optical wedge array and the waveguide sheet to ensure the total reflection condition of the waveguide sheet.

[0027] The optical wedge array 7 is composed of a plurality of single optical wedges 8 connected end to end. Figure 3 As shown in the enlarged view of the optical wedge array, the wedge angle of the single optical wedge 8 is denoted as φ, and assuming that the refractive index of the single optical wedge is n2, φ=(n2-1)*arcsin[n1*sin(2β-4θ)].

[0028] Based on the consideration of the processing technology, assuming that the minimum thickness of the single optical wedge is h1 and the minimum length of the single optical wedge can be S, the maximum thickness of the single optical wedge is h=h1+S*tanφ. Since S is much smaller than L2, the value of h is very small, so that the thickness, volume and weight of the single optical wedge and the optical wedge array are small, which conforms to the lightweight design concept of AR; after passing through the optical wedge array, the light of the central field of view is perpendicular to the total reflection surface of the waveguide sheet when it enters the human eye, which conforms to the viewing habit of the human eye.

[0029] The value of L2 can be greater than L1.

[0030] The present application also provides a method for expanding the field of view of an optical waveguide, comprising the following steps:

[0031] Firstly, the angle of the coupling-in prism is changed so that the incident angle β of the light of the central field of view in the waveguide sheet is greater than 2θ; when the included angle θ between the array reflection film 3 and the total reflection surface of the waveguide sheet is fixed, assuming that the refractive index of the waveguide sheet is n1, the angle range of the incident light satisfying the total reflection condition in the waveguide sheet is F2=2*[β-arcsin(1 / n1)]; the field angle of the waveguide sheet is increased;

[0032] Second step, add a light wedge array 7 at the exit total reflection surface 5 of the waveguide sheet; the light wedge array is used to make the central field of view light vertical to the total reflection surface of the waveguide sheet when entering the human eye, in line with the viewing habits of the human eye; the light wedge array is composed of a plurality of single light wedges in end-to-end connection.

[0033] The product and method for expanding the field of view range of the light waveguide of the present application adopts the mode that the incident central field of view light has an incident angle greater than twice the angle between the reflection surface and the total reflection surface of the waveguide sheet array in the waveguide sheet, offsets the central field of view to the direction of increasing the incident angle in the waveguide sheet, and further increases the field of view range angle transmitted in the waveguide sheet, thereby expanding the field of view range of the AR light module. An additional light wedge array is added outside the waveguide sheet to ensure that the exit light of the central field of view is perpendicular to the total reflection surface of the waveguide sheet, in line with the viewing habits of the human eye. At the same time, the light wedge array can ensure the correction of the light beam direction while also ensuring a relatively thin thickness, and the volume and weight are relatively small.

[0034] The above describes the preferred embodiments of the present application, but is not intended to limit the present application. Those skilled in the art can make improvements and changes to the embodiments disclosed herein without departing from the scope and spirit of the present application.

Claims

1. A product for expanding the field of view of an optical waveguide, characterized in that, The product for expanding the field of view of the light waveguide includes a waveguide sheet, a coupling-in prism, an array reflection film and a light wedge array; the incident light enters the waveguide sheet as central field of view light after passing through the coupling-in prism, and the array reflection film is arranged inside the waveguide sheet; the included angle between the array reflection film and the total reflection surface of the waveguide sheet is θ ; by changing the angle of the coupling-in prism, the incident angle of the central field of view light in the waveguide sheet is β > 2 θ ; the light wedge array is arranged at the total reflection surface of the waveguide sheet; the light wedge array is used for making the central field of view light perpendicular to the total reflection surface of the waveguide sheet when entering the human eye, and conforming to the viewing habit of the human eye; the light wedge array is composed of a plurality of single light wedges connected in head-to-tail mode.

2. The product of claim 1, wherein, The refractive index of the waveguide sheet is n1, and the angle range of the incident light satisfying the total reflection condition in the waveguide sheet is F2=2 [ β -arcsin(1 / n1)].

3. The product of claim 1, wherein, The optical wedge array is spaced apart from the waveguide sheet by a predetermined gap to ensure total reflection of the waveguide sheet.

4. The product of claim 1, wherein, The total length of the array reflection film of the waveguide sheet is L1, the length of the optical wedge array is greater than L2, and the optical wedge array covers the length range of L1; wherein L2>L1.

5. The product of claim 1, wherein, The wedge angle of the single optical wedge is denoted as φ , and the refractive index of the single optical wedge is n2, then φ = (n2-1) arcsin[n1 sin(2 β -4 θ )] 6. The product of claim 5, wherein, The minimum thickness of the single optical wedge is h1, and the minimum length of the single optical wedge is S, so the maximum thickness of the single optical wedge is h = h1 + S tan φ .

7. A method of expanding the field of view of an optical waveguide using a product according to any one of claims 1 to 6, characterized in that, The method for expanding the field of view of the optical waveguide includes the following steps: The first step, change the angle of the coupling-in prism, so that the incident angle of the central field of view light in the waveguide sheet β >2 θ ; when the angle between the array reflection film and the total reflection surface of the waveguide sheet is fixed, assuming the refractive index of the waveguide sheet is n1, the angle range of the incident light satisfying the total reflection condition in the waveguide sheet is F2=2 θ [ β -arcsin(1 / n1)]; the field of view angle of the waveguide sheet is increased;​ Secondly, an optical wedge array is added at the total reflection exit surface of the waveguide sheet; the optical wedge array is used to make the light of the central field of view perpendicular to the total reflection surface of the waveguide sheet when entering the human eye, in line with the viewing habits of the human eye; the optical wedge array is composed of a plurality of single optical wedges connected end to end.

8. The method of claim 7, wherein, The optical wedge array is spaced apart from the waveguide sheet by a predetermined gap to ensure total reflection of the waveguide sheet.

9. The method of claim 7, wherein, The total length of the array reflection film of the waveguide sheet is L1, the length of the optical wedge array is greater than L2, and the optical wedge array covers the length range of L1; wherein L2>L1.

10. The method of claim 9, wherein, The wedge angle of the single optical wedge is recorded as φ The refractive index of the single optical wedge is n2, then φ = (n2-1) arcsin[n1 sin(2 β -4 θ )]; when the minimum thickness of the single optical wedge is h1, the minimum length of the single optical wedge is S, then the maximum thickness of the single optical wedge is h = h1+S tan φ .

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