Optical waveguide

Abstract

The utility model discloses an optical waveguide, which is characterized in that an optical machine is connected with a coupling-in prism and is used for providing a projection image to the coupling-in prism; the coupling-in prism is arranged at the end side of the transverse prism and is used for turning a light beam into the transverse prism, and the light beam is transversely propagated in the transverse prism through total reflection and is propagated to the first turning surface and the second turning surface; the first turning surface and the second turning surface respectively turn light beams downwards to enter the first diffraction grating and the second diffraction grating; and a light beam is extended by the first diffraction grating and the second diffraction grating and is finally coupled out by the first coupling-out prism array and the second coupling-out prism array. The coupling-in prism is arranged on the end side and realizes transverse transmission through the transverse prism, so that the problems that a waveguide sheet model is unrelated and the nose bridge end is thick and heavy are solved, and the lighting effect is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of AR display, in particular to an optical waveguide. Background Art

[0002] The optical module of AR is mainly divided into two parts. The first part is the micro display module, including micro display (LCD screen, LCOS / DLP display panel, uLED / uOLED, and other micro projectors). The second part is the waveguide that enters the eye, including prism waveguide (prism method, the main companies are Epson and Nadejia), array waveguide (a spectroscopic device composed of multiple grating sheets glued together, the main manufacturers are Shanghai Lipai, Longjing Optoelectronics, etc.), diffraction waveguide (nano-imprinting method to transfer nanometer-level micro stripes on silicon-based glass, and propagate light by diffraction), and other waveguide solutions.

[0003] Although the waveguide model and AR glasses in the existing technology can realize a one-to-two dual-eye display with a single optical engine in the middle, the biggest flaw is that in actual use, because the optical engine is in the middle, the glasses will be very thick at the bridge of the nose (the thickness of the optical engine), which seriously affects the aesthetics of wearing. At the same time, because the optical engine is on the side of the bridge of the nose, the weight of the optical engine is at the end of the bridge of the nose, which will make the nose bear a relatively large weight, affecting the wearing comfort.

[0004] In summary, the prior art lacks an optical waveguide that is easy to use.

[0005] It should be noted that the information disclosed in the above background technology section is only used to understand the background of this application, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Utility Model Content

[0006] The utility model provides an optical waveguide, which can solve at least one technical problem in the prior art.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] An optical waveguide includes a coupling-in prism, a transverse prism, a first turning surface and a second turning surface arranged in the transverse prism, a first diffraction grating and a second diffraction grating respectively arranged corresponding to the first turning surface and the second turning surface, and a first outcoupling prism array and a second outcoupling prism array for coupling out light beams; an optical engine is connected to the coupling-in prism and is used to provide a projected image to the coupling-in prism; the coupling-in prism is arranged at the end side of the transverse prism and is used to bend the light beam into the transverse prism, and the light beam propagates laterally through total internal reflection within the transverse prism and propagates to the first turning surface and the second turning surface; the first turning surface and the second turning surface respectively bend the light beam downward to enter the first diffraction grating and the second diffraction grating; the light beam expands through the first diffraction grating and the second diffraction grating and is finally coupled outward through the first outcoupling prism array and the second outcoupling prism array.

[0009] Preferably, the coupling-in prism, the first turning surface, the second turning surface, the first coupling-out prism array, and the second coupling-out prism array are all arrayed optical waveguides.

[0010] Preferably, the bevel angle of the coupling prism is as follows: define the xyz coordinate axis, the z axis is the thickness direction of the coupling prism, which belongs to the longitudinal direction, and xy is the coordinate of the direction of the plane perpendicular to the z axis; the angle between the bevel of the coupling prism and the y axis is θ1y; the range of θ1y is: 30°~70°; the angle between the bevel of the coupling prism and the z axis is θ1z; the range of θ1z is: 30°~70°.

[0011] Preferably, the lateral prism is a rectangular parallelepiped, comprising a first layer, a second layer and a third layer from top to bottom; the distance from the first turning surface to the coupling-in prism is closer than the distance from the second turning surface to the coupling-in prism; the first turning surface is arranged on the third layer; the second turning surface is arranged on the second layer; the two surfaces in contact with the second layer and the third layer include a first part and a second part; the first part is a part close to the coupling-in prism, used to reflect the light beam; the second part is used to transmit the light beam to the first turning surface; the two surfaces in contact with the first layer and the second layer include a third part and a fourth part; the third part is a part close to the coupling-in prism, used to reflect the light beam; the fourth part is used to transmit the light beam to the second turning surface.

[0012] Preferably, the reflectivity of the first portion and the third portion is R≥95%; and the transmittance of the second portion and the fourth portion is T≥95%.

[0013] Preferably, the first turning surface and the second turning surface are reflective, and the angle of the inclined surface is θ3y; wherein the relationship between θ3y and θ1y is:

[0014] 90°-θ3y=1 / 2*θ1y.

[0015] Preferably, the widths of the first layer and the second layer of the transverse prism are a and b respectively, and the ratio of a to b is in the range of:

[0016] a:b=1 / 2~2.

[0017] Preferably, the number of the first turning surfaces and the second turning surfaces is 2 to 30 respectively to form a first turning surface array and a second turning surface array.

[0018] Preferably, a third diffraction grating and a fourth diffraction grating are provided, respectively used to receive light beams from the first turning surface array and the second turning surface array; the third diffraction grating and the fourth diffraction grating are two-dimensional gratings, respectively including gratings in two directions, and form a K-space vector closure under the superposition of different grating vectors.

[0019] Preferably, the lateral prism is a rectangular parallelepiped, comprising a first layer, a second layer, and a third layer from top to bottom; the distance between the first turning surface array and the coupling-in prism is closer than the distance between the second turning surface array and the coupling-in prism; the first turning surface array and the second turning surface array are arranged in the third layer; the coating of the two contacting surfaces of the first layer and the second layer has a transmittance T of 20% to 70%; the two contacting surfaces of the second layer and the third layer include a seventh part, an eighth part, and a ninth part; the seventh part and the ninth part correspond to binoculars respectively, and the eighth part is arranged between the seventh and ninth parts; the coating of the seventh part has a transmittance T of 25% to 50%; the coating of the eighth part has a transmittance T of less than 1%; and the coating of the ninth part has a transmittance T of 50% to 70%.

[0020] The utility model has the beneficial effects:

[0021] In the preferred technical solution, the coupling prism is arranged at the end side to realize lateral transmission through the lateral prism, thereby improving the problem of the waveguide plate model being unreliable and the thick nose end.

[0022] Furthermore, the present invention utilizes an arrayed waveguide as its main component, resulting in high optical efficiency. Furthermore, because all light propagates within the waveguide, the diffraction grating is designed to achieve lossless propagation. Therefore, the present invention effectively improves optical efficiency through the use of geometric array waveguides and diffraction waveguides. Combined with a transverse prism, this creates a single-lens binocular solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of an optical waveguide according to an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of an in-coupling prism according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of a transverse prism according to an embodiment of the present invention.

[0026] Figure 4 FIG. 4 is a schematic diagram of another transverse prism according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of a first diffraction grating according to an embodiment of the present invention.

[0028] Figure 6 This is a schematic diagram of a first diffraction grating K space according to an embodiment of the present invention.

[0029] Figure 7 This is a schematic diagram of a second diffraction grating according to an embodiment of the present invention.

[0030] Figure 8 This is a schematic diagram of a first outcoupling prism array according to an embodiment of the present invention.

[0031] Figure 9 FIG. 4 is a schematic diagram of another optical waveguide according to an embodiment of the present invention.

[0032] Figure 10 FIG. 4 is a schematic diagram of another coupling-in prism according to an embodiment of the present invention.

[0033] Figure 11 FIG. 4 is a schematic diagram of another optical waveguide according to an embodiment of the present invention.

[0034] Figure 12 This is a schematic diagram of another first diffraction grating according to an embodiment of the present invention.

[0035] Figure 13 This is a schematic diagram of another first diffraction grating K space according to an embodiment of the present invention.

[0036] Figure 14 FIG. 4 is a schematic diagram of another optical waveguide according to an embodiment of the present invention.

[0037] Figure 15 This is a schematic diagram of another first diffraction grating according to an embodiment of the present invention.

[0038] Figure 16 This is a schematic diagram of another second diffraction grating according to an embodiment of the present invention.

[0039] Figure 17 This is a schematic diagram of another first diffraction grating K space according to an embodiment of the present invention.

[0040] Figure 18 FIG. 4 is a schematic diagram of another optical waveguide according to an embodiment of the present invention.

[0041] Figure 19 This is a K-space schematic diagram of another diffraction grating according to an embodiment of the present invention.

[0042] Figure 20 Schematic diagram of the coating of the lateral prism according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is merely illustrative and is not intended to limit the scope and application of the present invention. In the absence of conflict, the embodiments and features in the embodiments of the present invention may be combined with each other.

[0044] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for both fixing and coupling or communication.

[0045] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0047] See Figure 1One embodiment of the present invention provides an optical waveguide 1, which is an integral array assembly. The optical waveguide 1 includes an incoupling prism 11, a transverse prism 12, a first turning surface 151 and a second turning surface 152 disposed within the transverse prism 12, a first diffraction grating 131 and a second diffraction grating 132 disposed corresponding to the first turning surface 151 and the second turning surface 152, respectively, and a first outcoupling prism array 141 and a second outcoupling prism array 142 for outcoupling light beams.

[0048] The optical engine 2 is connected to the coupling prism 11 and is used to provide a projection image to the coupling prism 11;

[0049] The coupling-in prism 11 is provided at the end side of the transverse prism 12 and is used to deflect the light beam into the transverse prism 12. The light beam propagates laterally inside the transverse prism 12 by total internal reflection and propagates to the first deflection surface 151 and the second deflection surface 152.

[0050] The first turning surface 151 and the second turning surface 152 respectively turn the light beam downward into the first diffraction grating 131 and the second diffraction grating 132; the light beam expands through the first diffraction grating 131 and the second diffraction grating 132 and is finally coupled outward through the first outcoupling prism array 141 and the second outcoupling prism array 142.

[0051] The sum of the grating vectors of the first diffraction grating 131 and the second diffraction grating 132 is both 0.

[0052] It is understandable that the coupling-in prism 11 in the present invention can be arranged on the left side or the right side of the transverse prism 12 . The following description takes the arrangement on the right side as an example, which is not restrictive.

[0053] Continue as Figure 1 As shown, after the light beam enters through the coupling-in prism 11, the light is turned and enters the inside of the transverse prism 12. The first turning surface 151 and the second turning surface 152 are used to turn the light beam propagating in the transverse prism 12 downward and enter the first diffraction grating 131 and the second diffraction grating 132 respectively. The first diffraction grating 131 and the second diffraction grating 132 are used to expand the light beam, and then couple it outward through the first coupling-out prism array 141 and the second coupling-out prism array 142 respectively.

[0054] In a specific embodiment, the first diffraction grating 131 and the second diffraction grating 132 are embossed on the surface of the waveguide 1; the coupling-in grating 11, the lateral prism 12, the first turning surface 151, the second turning surface 152, the first diffraction grating 131, the second diffraction grating 132, the first outcoupling prism array 141, and the second outcoupling prism array 142 are connected in sequence.

[0055] In an embodiment of the present invention, the coupling-in prism 11 , the first turning surface 151 , the second turning surface 152 , the first coupling-out prism array 141 , and the second coupling-out prism array 142 are all arrayed optical waveguides.

[0056] The coupling-in grating of the utility model is arranged at the end side to realize lateral transmission through a lateral prism, thereby improving the problem of the waveguide plate model being loose and the nose bridge being thick.

[0057] Furthermore, the present invention utilizes an arrayed waveguide as its main component, resulting in high optical efficiency. Furthermore, because all light propagates within the waveguide, the diffraction grating is designed to achieve lossless propagation. Therefore, the present invention effectively improves optical efficiency through the use of geometric array waveguides and diffraction waveguides. Combined with a transverse prism, this creates a single-lens binocular solution.

[0058] Furthermore, the main structure of the present invention is simple to process, has a high yield rate and low cost.

[0059] like Figure 2 As shown, the slope angle S11R of the coupling-in prism 11 is as follows:

[0060] Define xyz coordinate axes, where the z axis is the thickness direction of the coupling prism 11 and is longitudinal, and xy is the coordinate of the direction of the plane perpendicular to the z axis;

[0061] The angle between the inclined surface of the coupling-in prism 11 and the y-axis is θ1y; the range of θ1y is: 30°~70°;

[0062] The included angle between the inclined surface of the coupling-in prism 11 and the z-axis is θ1z; the range of θ1z is 30° to 70°.

[0063] like Figure 3 As shown, the transverse prism 12 is a rectangular parallelepiped, including a first layer, a second layer and a third layer from top to bottom;

[0064] The distance between the first turning surface 151 and the coupling-in prism 11 is shorter than the distance between the second turning surface 152 and the coupling-in prism 11;

[0065] The first turning surface 151 is provided on the third layer; the second turning surface 152 is provided on the second layer;

[0066] The two surfaces of the second layer and the third layer in contact include a first portion S21 and a second portion S22; the first portion S21 is close to the coupling prism 11 and is used to reflect the light beam; the second portion S21 is used to transmit the light beam to the first turning surface 151;

[0067] The two contacting surfaces of the first layer and the second layer include a third portion S23 and a fourth portion S24; the third portion S23 is a portion close to the coupling prism 11 and is used to reflect the light beam; the fourth portion S24 is used to transmit the light beam to the second turning surface.

[0068] In a specific embodiment, the first turning surface 151 and the second turning surface 152 are reflective;

[0069] The angle between the first turning surface 151 and the second turning surface 152 is θ3y; wherein the relationship between θ3y and θ1y is:

[0070] 90°-θ3y=1 / 2*θ1y.

[0071] In another specific embodiment, the bottom surface S25 of the transverse prism 12 is connected to the first diffraction grating 131 and the second diffraction grating 132. The first portion S21 and the third portion S23 are reflective, with a reflectivity of R ≥ 95%; the third portion S23 and the fourth portion S24 are transmissive, and can transmit light that is turned downward by the first turning surface 151 and the second turning surface 152, with a transmittance of T ≥ 95%.

[0072] like Figure 4 As shown, the widths of the first layer and the second layer of the transverse prism 12 are a and b respectively, and the ratio of a to b is in the range of:

[0073] a:b=1 / 2~2.

[0074] By adjusting the ratio of a and b, the light intensity distribution of the left and right eyes can be adjusted.

[0075] In one embodiment of the present invention, the vertical distances between the first turning surface 151 and the second turning surface 152 and the central axis of the transverse prism 12 are equal. As previously described, the first turning surface 151 and the second turning surface 152 are respectively disposed on the third and second layers of the transverse prism 12. The vertical distances between the first turning surface 151 and the second turning surface 152 and the central axis of the transverse prism 12 are defined herein. The following description will be divided into three cases.

[0076] In a specific embodiment, the first turning surface 151 and the second turning surface 152 are respectively arranged on the inner sides of both eyes, that is, both are arranged near the bridge of the nose.

[0077] like Figure 5 As shown, the first diffraction grating 131 and the second diffraction grating 132 are mirror-symmetrical; the first diffraction grating 131 includes a coupling grating portion 131a and an extended grating portion 131b;

[0078] Define xyz coordinate axes, where the z axis is the thickness direction of the coupling prism 11 and is longitudinal, and xy is the coordinate of the direction of the plane perpendicular to the z axis;

[0079] The coupling grating portion 131a is arranged corresponding to the first turning surface 151, and is used to couple the light beam from the first turning surface 151 into the first diffraction grating 131; and the angle with the negative direction of the x-axis is θ131y, and the grating direction of the extended grating portion 131b is consistent with the direction of the coupling grating portion 131a; in one embodiment, the angle range of θ131y is: 15°~75°.

[0080] The grating period of the first diffraction grating 131 and the second diffraction grating 132 is 200 nm to 600 nm.

[0081] like Figure 6 As shown, the coupling grating portion 131a and the extended grating portion 131b in the K-space structure of the first diffraction grating 131 have the same period, but the vector directions of the gratings are opposite. Therefore, the grating vectors of the coupling grating portion 131a and the extended grating portion 131b are superimposed, and the sum of the vectors is 0, forming a closed loop.

[0082] The diffraction efficiency of the coupled-in grating portion 131a is: 0th order light <10%, 1st order light >90%;

[0083] The diffraction efficiency of the extended grating part 131b is: 0th order light: 10%~90%, 1st order light: 90%~10%

[0084] like Figure 7 As shown, it can be understood that the second diffraction grating 132 has a structure similar to that of the first diffraction grating 131, exhibits mirror symmetry, and also includes a coupling grating portion 132a and an extended grating portion 132b; the angle with the negative direction of the x-axis is θ132y, and the grating direction of the extended grating portion 132b is consistent with the direction of the coupling grating portion 132a; in one embodiment, the angle range of θ132y is: 15°~75°.

[0085] like Figure 8 As shown, the first outcoupling prism array 141 and the second outcoupling prism array have the same structure, the number of arrays is 5 to 20, the angle between the inclined plane of the array and the z-axis is θ4z, and the relationship between θ4z and θ1z is:

[0086] θ1z=θ4z

[0087] The reflectivity range of the coating on the inclined surface of the array is R: 2%~30%.

[0088] like Figure 9 As shown, Figure 1The embodiment shown is different. Figure 9 The inclined surface of the coupling prism 11 reflects the light upwards. Figure 1 As shown in FIG, the light reflected by the oblique surface of the coupling prism 11 is directed downward. It is understood that if the light reflected by the oblique surface of the coupling prism 11 is directed upward or downward, it will only cause the image to be inverted. The inverted image can be reversed by projecting an inverted image on the optical engine 2. Therefore, the light reflected by the oblique surface of the coupling prism 11 can be directed upward or downward.

[0089] like Figure 10 As shown, when the inclined surface of the coupling prism 11 reflects light upward, the coordinate system is defined as described above. The angle of the inclined surface S11R of the coupling prism 11a is θ1y with the y-axis, and θ1z with the z-axis. The range of θ1y is 30°~70°, and the range of θ1z is 30°~70°.

[0090] like Figure 11 As shown below, a second grating structure is described. In this case, the first turning surface 151 and the second turning surface 152 are respectively positioned in the middle of the left and right eyes. The first turning surface 151 and the second turning surface 152 respectively bend the light beam downward from the middle to enter the first diffraction grating 131 and the second diffraction grating 132. It can be understood that in this case, the structures of the first diffraction grating and the second diffraction grating need to be adaptively changed.

[0091] The first diffraction grating 131 and the second diffraction grating 132 expand the light beam from the center to both sides.

[0092] like Figure 12 As shown, the first diffraction grating 131 and the second diffraction grating 132 have the same structure; the first diffraction grating 131 includes a first portion 131c, a middle portion 131d, and a second portion 131e, which are arranged in sequence and have the same grating period. The middle portion 131d is arranged corresponding to the first turning surface 151 to form a two-dimensional grating; the first portion 131c and the second portion 131e expand the light beam to both sides and propagate downward; the grating vectors of the middle portion 131d, the first portion 131c, and the second portion 131e are superimposed, and the vector sum is 0, forming a closed loop.

[0093] Similarly, the second diffraction grating 132 is also configured as described above to receive the grating of the second turning surface, which will not be described in detail here.

[0094] In one specific embodiment, the middle portion 131d is a two-dimensional grating. Upon entering, light is diffracted to the left and right, respectively, before being diffracted by 131c and 131e and propagating downward. In one specific embodiment, the grating period of the first portion 131c, the middle portion 131d, and the second portion 131e is 200 nm to 600 nm.

[0095] like Figure 13 As shown, the three gratings in the K-space structure of first diffraction grating 131, namely, first portion 131c, middle portion 131d, and second portion 131e, have the same period. Middle portion 131d is a two-dimensional grating. A portion of middle portion 131d forms a closed loop with first portion 131c, and a portion of middle portion 131d forms a closed loop with first portion 131e. Consequently, the sum of the grating vectors of first portion 131c and second portion 131e is zero, forming a closed loop.

[0096] The diffraction efficiency of the middle portion 131d is: 0th order light: ≤20%, 1st order light: ≥80%;

[0097] The diffraction efficiency of the first part 131c is: 0th order light: 10%~90%, 1st order light: 90%~10%

[0098] The diffraction efficiency of the second part 131e is: 0th order light: 10%~90%, 1st order light: 90%~10%

[0099] In a specific embodiment, the angle θ131y between the first portion 131c and the y-circumference is in the range of 15° to 75°, and the second portion 131e can be adaptively set.

[0100] like Figure 14 The figure shows a third configuration of the first and second turning surfaces 151, 152. The first and second turning surfaces 151, 152 are positioned outside the eyes, with the light beams deflecting downward from the edges. Compared to the first configuration of the present invention, the grating shapes of the first and second diffraction gratings 131, 132 are swapped, yet the mirror symmetry is maintained.

[0101] like Figure 15 As shown, the first diffraction grating 131 includes a coupling grating portion 131a and an extended grating portion 131b;

[0102] Define xyz coordinate axes, where the z axis is the thickness direction of the coupling prism and belongs to the longitudinal direction, and xy is the coordinate of the direction of the plane perpendicular to the z axis;

[0103] The coupling grating portion 131a is provided corresponding to the first turning surface 151 and is used to couple the light beam from the first turning surface 151 into the first diffraction grating 131; and the angle with the negative direction of the x-axis is θ131y, and the grating direction of the extended grating portion 131b is consistent with the direction of the coupling grating portion 131a;

[0104] The grating period of the first diffraction grating 131 and the second diffraction grating 132 is 200 nm to 600 nm.

[0105] like Figure 16 As shown, the second diffraction grating 132 is adaptively arranged with the first diffraction grating 131 , which will not be described in detail here.

[0106] like Figure 17 As shown, in the K space of the first diffraction grating 131, the sum of the superimposed grating vectors is 0, forming a closed loop; in the K space of the second diffraction grating 132, the sum of the superimposed grating vectors is 0, forming a closed loop; this is the same as the first case and will not be repeated here.

[0107] In the present invention, the number of reflective surfaces of the first turning surface 151 and the second turning surface 152 is not limited to only one, and can be 2-30.

[0108] like Figure 18 As shown, the first turning surfaces 151 and the second turning surfaces 152 are respectively provided in a number of 2 to 30 to form a first turning surface array 151a and a second turning surface array 152a;

[0109] A third diffraction grating 1312 and a fourth diffraction grating 1322 are provided to receive the light beams 152a from the first turning surface array 151a and the second turning surface array respectively;

[0110] The third diffraction grating 1312 and the fourth diffraction grating 1322 are two-dimensional gratings, each including gratings in two directions. When different grating vectors are superimposed, a K-space vector closure is formed.

[0111] like Figure 19 As shown, the third diffraction grating 1312 and the fourth diffraction grating 1322 have the same shape, wherein the grating period of the third diffraction grating 1312 is 200nm~600nm, and the angle θ1312y with the y-axis ranges from 15° to 75°; the diffraction efficiency of the third diffraction grating 1312 is: 0th order light: 20%~80%, 1st order light: 80%~20%; the gratings in two directions of the third diffraction grating 1312 can form K-space vector closure under the superposition of different grating vectors.

[0112] like Figure 20 As shown, the coating of the lateral prism 12 of this embodiment also needs to be adaptively changed.

[0113] The transverse prism 12 is a rectangular parallelepiped, and includes a first layer, a second layer, and a third layer from top to bottom;

[0114] The distance between the first turning surface array 151a and the coupling-in prism 11 is closer than the distance between the second turning surface array 152a and the coupling-in prism 11;

[0115] The first turning surface array 151a and the second turning surface array 152a are arranged on the third layer; the coating of the two surfaces S26 contacting the first layer and the second layer has a transmittance T of 20% to 70%;

[0116] The two surfaces where the second layer and the third layer contact each other include a seventh part S27, an eighth part S28 and a ninth part S29; the seventh part S27 and the ninth part S29 correspond to the two eyes respectively, the seventh part S27 is the area directly above the right eye 151a, and the ninth part S29 is the area directly above the left eye 152a. The eighth part S28 is arranged between the seventh part S27 and the ninth part S29; the coating of the seventh part S27 has a transmittance T of 25~50%; the coating of the eighth part S28 has a transmittance T<1%; and the coating of the ninth part S29 has a transmittance T of 50%~70%.

[0117] In a specific embodiment of the present invention, the coating of the surfaces of the first turning surface array 151 a and the second turning surface array 152 a has a transmittance T of ≤5%.

[0118] The above content is a further detailed description of the present invention in conjunction with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, they can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be considered to belong to the scope of protection of the present invention. In the description of this specification, the reference terms "one embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in an appropriate manner in any one or more embodiments or examples. Without mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the scope of protection of the patent application.

Claims

1. An optical waveguide, characterized in that: The optical system comprises an incoupling prism, a transverse prism, a first turning surface and a second turning surface arranged in the transverse prism, a first diffraction grating and a second diffraction grating respectively arranged corresponding to the first turning surface and the second turning surface, and a first outcoupling prism array and a second outcoupling prism array for outcoupling light beams; The optical engine is connected to the coupling-in prism and is used to provide a projection image to the coupling-in prism; The coupling-in prism is arranged at the end side of the transverse prism, and is used to deflect the light beam into the transverse prism, and the light beam propagates laterally inside the transverse prism through total reflection and propagates to the first deflection surface and the second deflection surface; The first turning surface and the second turning surface respectively turn the light beam downward to enter the first diffraction grating and the second diffraction grating; the light beam is expanded by the first diffraction grating and the second diffraction grating and is finally coupled outward through the first outcoupling prism array and the second outcoupling prism array.

2. The optical waveguide according to claim 1, wherein: The coupling-in prism, the first turning surface, the second turning surface, the first coupling-out prism array, and the second coupling-out prism array are all arrayed optical waveguides.

3. The optical waveguide according to claim 1, wherein: The bevel angles of the coupling-in prism are as follows: Define xyz coordinate axes, where the z axis is the thickness direction of the coupling prism and belongs to the longitudinal direction, and xy is the coordinate of the direction of the plane perpendicular to the z axis; The angle between the inclined surface of the coupling prism and the y-axis is θ1y; the range of θ1y is: 30°~70°; The included angle between the inclined surface of the coupling-in prism and the z-axis is θ1z; the range of θ1z is: 30°~70°.

4. The optical waveguide according to claim 3, wherein: The transverse prism is a rectangular parallelepiped, comprising a first layer, a second layer and a third layer from top to bottom; The distance between the first turning surface and the coupling-in prism is shorter than the distance between the second turning surface and the coupling-in prism; The first turning surface is provided on the third layer; the second turning surface is provided on the second layer; The two surfaces of the second layer and the third layer in contact include a first portion and a second portion; the first portion is a portion close to the coupling prism, and is used to reflect the light beam; the second portion is used to transmit the light beam to the first turning surface; The two surfaces where the first layer and the second layer contact each other include a third part and a fourth part; the third part is the part close to the coupling prism and is used to reflect the light beam; the fourth part is used to transmit the light beam to the second turning surface.

5. The optical waveguide according to claim 4, wherein: The reflectivity of the first portion and the third portion is R≥95%; the transmittance of the second portion and the fourth portion is T≥95%.

6. The optical waveguide according to claim 4, wherein: The first turning surface and the second turning surface are reflective, and the angle of the inclined surface is θ3y; wherein the relationship between θ3y and θ1y is: 90°-θ3y=1 / 2*θ1y.

7. The optical waveguide according to claim 4, wherein: The widths of the first layer and the second layer of the transverse prism are a and b respectively, and the ratio of a to b is in the range of: a:b=1 / 2~2.

8. The optical waveguide according to claim 3, wherein: The number of the first turning surfaces and the number of the second turning surfaces are 2 to 30 respectively to form a first turning surface array and a second turning surface array.

9. The optical waveguide according to claim 8, wherein: Setting a third diffraction grating and a fourth diffraction grating, respectively used to receive the light beams from the first turning surface array and the second turning surface array; The third diffraction grating and the fourth diffraction grating are two-dimensional gratings, each including gratings in two directions, and form a K-space vector closure under the superposition of different grating vectors.

10. The optical waveguide according to claim 9, wherein: The transverse prism is a rectangular parallelepiped, comprising a first layer, a second layer and a third layer from top to bottom; The distance between the first turning surface array and the coupling-in prism is closer than the distance between the second turning surface array and the coupling-in prism; The first turning surface array and the second turning surface array are arranged on the third layer; The coating of the two surfaces in contact with the first layer and the second layer is: transmittance T: 20%~70%; The two surfaces where the second layer and the third layer contact each other include a seventh part, an eighth part, and a ninth part; the seventh part and the ninth part correspond to the binoculars respectively, and the eighth part is arranged between the seventh part and the ninth part; the coating of the seventh part has a transmittance T of 25% to 50%; the coating of the eighth part has a transmittance T of less than 1%; and the coating of the ninth part has a transmittance T of 50% to 70%.

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