阅读说明：本技术 包括多层波导的光学设备 (Optical device comprising multilayer waveguide ) 是由 奥克萨那·什拉姆科娃 瓦尔特·德拉齐克 阿诺·舒伯特 于 2019-05-28 设计创作，主要内容包括：提出了一种用于将多色图像传递到眼眶的光学设备,该眼眶位于佩戴所述光学设备的用户的眼睛前方的区域。该光学设备的显著之处在于它包括：光引擎,用于传递所述多色图像,所述光引擎能够生成n个不同的单色光图像光束[C-1,...,C-i,...,C-n],所述n个不同的单色光图像光束的组合对应于所述多色图像,每个单色光图像C-j与波长λ-j相关联,并且其中对于所有所述i∈[1,n],λ-(i+1)＞λ-i,并且其中如果j是奇数的,则所述单色光图像光束C-j处于横向电模式,并且如果j是偶数的,则所述单色光图像光束C-j处于横向磁模式；n-波导元件,彼此堆叠,n是大于或等于三的整数,除了较靠近用户的所述眼睛的波导元件之外,每个波导元件包括衍射光栅、第一输出和第二输出,所述衍射光栅能够通过全内反射仅使所述n个单色光图像之一在该波导元件中偏转,所述第一输出向所述眼眶递送偏转的光,所述第二输出向后一波导元件递送波导元件未偏转的光,其中所述第二输出包括消色差半波片,并且其中较靠近所述用户的所述眼睛的所述波导元件也包括衍射光栅和输出,所述衍射光栅能够通过全内反射仅使所述n个单色光图像之一在该波导元件中偏转,所述输出向所述眼眶递送偏转的光,其中所述光学设备的每个衍射光栅与不同的波长相关联,并且其中所述n-波导的布置顺序根据波长值从最小到最高来完成的,最小波导元件位于较靠近所述光引擎的位置。(An optical device for delivering a multicoloured image to an eyebox located in an area in front of an eye of a user wearing the optical device is presented. The optical device is remarkable in that it comprises: a light engine for delivering the multi-color image, the light engine capable of generating n different monochromatic light image beams [ C ] 1 ，...，C i ，...，C n ]A combination of said n different monochromatic light image beams corresponding to said polychromatic image, each monochromatic light image C j And wavelength lambda j And wherein for all of said i e [1, n ∈]，λ i+1 ＞λ i And wherein if j is an odd number, the monochromatic light image lightBundle C j In transverse electric mode, and if j is an even number, the monochromatic light image beam C j In a transverse magnetic mode; n-waveguide elements stacked on one another, n being an integer greater than or equal to three, each waveguide element, except for the waveguide element closer to the eye of the user, comprising a diffraction grating capable of deflecting only one of the n monochromatic light images in the waveguide element by total internal reflection, a first output delivering deflected light to the eyebox, and a second output delivering light undeflected by the waveguide element to a next waveguide element, wherein the second output comprises an achromatic half-wave plate, and wherein the waveguide element closer to the eye of the user also comprises a diffraction grating capable of deflecting only one of the n monochromatic light images in the waveguide element by total internal reflection, and an output delivering deflected light to the eyebox, wherein each diffraction grating of the optical device is associated with a different wavelength, and wherein the order of placement of the n-waveguides is done according to wavelength values from smallest to highest, the smallest waveguide element being located closer to the light engine.)

1. An optical device for delivering a multicoloured image to an eyebox, said eyebox being an area located in front of an eye of a user wearing the optical device, characterized in that it comprises:

a light engine for delivering the multi-color image (101; 201; 501), the light engine being capable of generating n different monochromatic light image beams [ C ]₁，...，C_i，...，C_n]A combination of said n different monochromatic light image beams corresponding to said polychromatic image, each monochromatic light image C_jAnd wavelength lambda_jAnd wherein for all of said i e [1, n ∈]，λ_i+1＞λ_iAnd wherein if j is an odd number, then the monochromatic light image beam C_jIn transverse electric mode, and if j is an even number, the monochromatic light image beam C_jIn a transverse magnetic mode;

n-waveguide elements (102, 103, 104; 202, 203, 204; 502, 503, 504) stacked on each other, n being an integer greater than or equal to three, each waveguide element comprising, in addition to the waveguide element closer to the eye of the user, a diffraction grating capable of deflecting only one of the n monochromatic light images in the waveguide element by total internal reflection, a first output delivering deflected light to the eyebox, and a second output delivering light undeflected by the waveguide element to a next waveguide element, wherein the second output comprises an achromatic half-wave plate (105, 106; 205, 206; 506, 507), and wherein the waveguide element closer to the eye of the user also comprises a diffraction grating capable of deflecting only one of the n monochromatic light images in the waveguide element by total internal reflection and an output, the output delivers deflected light to the eyebox, wherein each diffraction grating of the optical device is associated with a different wavelength, and wherein the order of arrangement of the n-waveguides is done from smallest to highest according to wavelength value, with the smallest waveguide element (102; 202; 502) located closer to the light engine,

wherein each of said diffraction gratings is embedded in a layer having a first refractive index n₁Each cell being located in a region having a refractive index n₄Wherein each unit cell has a length equal to d, wherein each unit cell comprises a bi-material structure having a rectangular cross-section, wherein each unit cell comprises a bi-material structure having a second refractive index n₂And a first portion made of a first material having a third refractive index n₃Wherein the cross-section of the bi-material structure comprises a second portion of a second material equal to W₂+W₃Width W, W of₂Is the width of the first portion and W₃Is the width of the second portion and the first portion has a first height H₂And the second portion has a second height H₃And wherein the length d of the unit cell is greater than the width W.

2. The optical device of claim 1, wherein n equals three, and wherein the first waveguide element is associated with blue, the second waveguide element is associated with green, and the third waveguide element is associated with red.

3. The optical device of claim 1 or 2, wherein the first height H₂And said second height H₃Are equal.

4. The optical apparatus of any of claims 1-4, wherein the first width W₂And the second width W₃Are equal.

5. The optical device according to claim 1 or 2, wherein the waveguide element associated with blue has a diffraction grating with the following values: w₂＝80nm，W₃＝112nm，H₂＝170nm，H₃＝130nm，n₂＝1.5，n₃＝2.1，n₄＝n₃，n₁1.0 and d 367 nm.

6. The optical device according to claim 1 or 2, wherein the waveguide element associated with the green color has a diffraction grating with the following values: w₂＝140nm，W₃＝140nm，H₂＝300nm，H₃＝180nm，n₂＝1.5，n₃＝2.1，n₄＝n₃，n₁1.0 and d 424 nm.

7. The optical device according to claim 1 or 2, wherein the waveguide element associated with the red color has a diffraction grating with the following values: w₂＝180nm，W₃＝150nm，H₂＝360nm，H₃＝220nm，n₂＝1.5，n₃＝2.1，n₄＝n₃，n₁1.0 and d 500 nm.

8. Optical device according to claim 1 or 2, wherein said n different monochromatic light image beams [ C ]₁，...，C_i，...，C_n]Satisfies the following properties:ε is about 10 nm.

Technical Field

The present disclosure relates to the field of augmented reality glasses. More specifically, it relates to an in-coupler (in-coupler) that deflects a picture or image from a light engine into a waveguide where the picture is transferred to an extraction region by Total Internal Reflection (TIR).

Background

This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

The improvement of augmented reality glasses is a positive research topic. In fact, there is still ongoing research for reducing the power consumption of these devices, for extending the field of view, for providing better image quality, etc.

Examples of the structure and improvements of these devices are described in the following documents: in the context of US 9,383,582, there is provided,

it should be noted that augmented reality glasses typically comprise a light source or light engine (as a white light source, such as a white LED illuminating a Liquid Crystal Display (LCD) displaying an image to a user, or a technique as described in document WO 2018-102582).

Furthermore, these devices also comprise an incoupling or incoupling element made of a diffraction grating and also for a limited wavelength range (see, for example, WO2017116637 or titled "by Jiasheng Xiao et al"Design of achromatic surface microstructure for near-eye display with diffractive waveguide(Article for the design of achromatic surface microstructures for near-eye displays with diffractive waveguides) ". If a polychrome picture is necessary to produce a true color virtual image superimposed over the field of view, it is necessary to have as many waveguides as the number of primary colors used by the light engine.

Typically, a single diffraction grating is customized to one wavelength. Therefore, the design of waveguide systems for true color images is important for these kinds of devices.

In document US 8,885,997, a technique has been proposed for conveying multicoloured images or pictures using several waveguides. More precisely, fig. 32 of document US 8,885,997 shows a schematic diagram and the principle of two wavelengths. When green light strikes the first diffraction grating with TE (transverse electric) polarization, it is coupled into the first waveguide. Meanwhile, red TM (transverse magnetic) polarized light passes through, and its polarization is converted from TM to TE by the phase retarder after the first waveguide. Thus, the red TE light will couple into the second diffraction grating. The system works as long as there are only two color bands. However, if there are more than two waveguides and ribbons, the embodiment of fig. 33 shows an architecture intended to provide a solution for this situation. All wavelengths at the input must be polarized in the TM mode. Then, the wavelength λ₁Is polarized only byThe first component behind the projection lens changes to TE mode while the polarization of the other color bands does not change. The first color band polarized TE is then coupled into the first waveguide. After the first waveguide, there is another phase retarder, which will only have the wavelength λ₂The polarization state of the light is converted into the TE mode without touching the state of other wavelengths. And the process is repeated until the last color band. However, with this approach, there is a problem. In fact, no wave retarder can selectively change the polarization state of one band while leaving the rest of the spectrum in an unchanged polarization state. Therefore, the technique of document US 8,885,997 is only valid for two color channels.

Therefore, there is a need to provide a solution that can be used with more than two color channels. In addition, contrary to the technique of document US 8,885,997, it would be interesting to obtain a technical solution that does not impose requirements as regards the polarization of the light.

The proposed technique is an alternative to the solution of document US 8,885,997, which does not have these drawbacks.

Disclosure of Invention

References in the specification to "one embodiment," "an example embodiment," indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

The present disclosure relates to an optical device for delivering a multi-color image to the eye socket (eye box), which is the area located in front of the eye of the user wearing the optical device. The optical device is remarkable in that it comprises:

a light engine for delivering the multi-color image, the light engine capable of generating n different monochromatic light image beams [ C ]₁，...，C_i，...，C_n]A combination of said n different monochromatic light image beams corresponding to said polychromatic image, each monochromatic light image C_jAnd wavelength lambda_jAnd wherein for all of said i e [1, n ∈]，λ_i+1＞λ_iAnd wherein if_jIs odd, the monochromatic light image beam C_jIn transverse electric mode, and if j is an even number, the monochromatic light image beam C_jIn a transverse magnetic mode;

n-waveguide elements stacked on one another, n being an integer greater than or equal to three, each waveguide element, except for the waveguide element closer to the eye of the user, comprising a diffraction grating capable of deflecting only one of the n monochromatic light images in the waveguide element by total internal reflection, a first output delivering deflected light to the eyebox, and a second output delivering light undeflected by the waveguide element to a next waveguide element, wherein the second output comprises an achromatic half-wave plate, and wherein the waveguide element closer to the eye of the user also comprises a diffraction grating capable of deflecting only one of the n monochromatic light images in the waveguide element by total internal reflection, and an output delivering deflected light to the eyebox, wherein each diffraction grating of the optical device is associated with a different wavelength, and wherein the order of placement of the n-waveguides is done according to wavelength values from smallest to highest, the smallest waveguide element being located closer to the light engine.

Wherein each of said diffraction gratings is embedded in a layer having a first refractive index n₁Is defined by a series of unit cells, each cell being located at a position having a refractive index n₄Wherein each unit cell has a length equal to d, wherein each unit cell comprises a bi-material structure having a rectangular cross-section, wherein each unit cell comprises a bi-material structure having a second refractive index n₂And a first portion made of a first material having a third refractive index n₃Wherein the cross-section of the bi-material structure comprises a second portion of a second material equal to W₂+W₃The width W of (a) is,W₂is the width of the first portion and W₃Is the width of the second portion and the first portion has a first height H₂And the second portion has a second height H₃And wherein the length d of the unit cell is greater than the width W.

The present disclosure relates to a technique that uses n waveguides one above the other, each waveguide for a particular color band, and the overall system is optimized in such a way that:

-coupling each image associated with each color band into a specific waveguide;

-transferring the image in its bands to the eye with maximum efficiency;

-avoiding rejection of the ribbon;

the best angular efficiency in each band is also ensured.

In one embodiment of the invention it is proposed to use the diffraction grating described in european patent application 17306763 in one or several waveguide elements.

In a variant, the optical device is notable in that n is equal to three, and in which the first waveguide element is associated with blue, the second waveguide element with green and the third waveguide element with red.

In another embodiment of the invention it is proposed to use the diffraction grating described in european patent application 18305263 in one or several waveguide elements. In such an embodiment of the present disclosure, the waveguide element comprises a structure having the sequence of bi-material structures shown in fig. 8(a), 8(b), 9(a) and 9(b) of european patent application 18305263. In another embodiment of the present invention, the bi-material structure includes a first portion having a single material and a second portion having a single and different material. The first and second portions have different widths and heights, as described in detail later.

In a variant, the optical device is notable in that said first height H₂And said second height H₃Are equal.

In a variant, theThe optical device is notable in that the first width W₂And the second width W₃Are equal.

In a variant, the optical device is notable in that the waveguide element associated with the blue color has a diffraction grating having the following values: w₂＝80nm，W₃＝112nm，H₂＝170nm，H₃＝130nm，n₂＝1.5，n₃＝2.1，n₄＝n₃，n₁1.0 and d 367 nm.

In a variant, the optical device is notable in that the waveguide element associated with the color green has a diffraction grating having the following values: w₂＝140nm，W₃＝140nm，H₂＝300nm，H₃＝180nm，n₂＝1.5，n₃＝2.1，n₄＝n₃，n₁1.0 and d 424 nm.

In a variant, the optical device is notable in that the waveguide element associated with the red color has a diffraction grating having the following values: w₂＝180nm，W₃＝150nm，H₂＝360nm，H₃＝220nm，n₂＝1.5，n₃＝2.1，n₄＝n₃，n₁1.0 and d 500 nm.

In a variant, the optical device is notable in that the n different monochromatic light image beams [ C ]₁，...，C_i，...，C_n]Satisfies the following properties:ε is about 10 nm.

Drawings

The above and other aspects of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:

figure 1 presents a part of an optical device (such as augmented reality glasses) according to one embodiment of the present disclosure;

figure 2 presents in the left part a schematic view corresponding to the features of figure 1 (but not referenced) and in the right part a schematic view corresponding to the features of an optical device according to an embodiment of the present disclosure for delivering an image to a second eye of a user;

figure 3 shows an example of a diffraction grating for use in a waveguide element according to one embodiment of the present disclosure;

figure 4 shows an example of a diffraction grating for use in a waveguide element according to another embodiment of the present disclosure;

fig. 5 shows a part of an optical device (such as augmented reality glasses) according to another embodiment of the present disclosure.

Detailed Description

As mentioned in document WO2018102834, augmented reality and virtual reality devices use a waveguide device comprising an input grating. The present disclosure relates to a technique that may be implemented within an input grating for multi-color image input. The role of an input grating according to one embodiment of the present disclosure is to take an image from a light engine (referred to as a field of view on the figure) and deflect the light beam in such a way that it tunnels into the waveguide (which is a flat glass plate) by TIR.

Fig. 1 presents a portion of an optical device (such as augmented reality glasses) according to one embodiment of the present disclosure. The purpose of such an optical device is to direct a polychromatic image represented by light rays or beams 101 produced by a light engine.

The first waveguide element 102 receives these light rays or light beams 101. The first waveguide element 102 comprises a diffraction grating (not shown) which deflects only the blue component in said optical beam 101. The light beam associated with the blue component is reflected within the first waveguide element 102 so as to reach a first output which passes the deflected "blue" light towards said eyebox 107 of the user. The other components of the light beam 101 (i.e. all other colour components except the blue component colour) are transmitted to the second waveguide element 103 via the second output 105 of the diffraction grating without changing the propagation direction (i.e. the same direction of the light beam 101). However, the second output includes an achromatic half-wave plate for modifying the polarization of the remaining light. In one embodiment of the present disclosure, the diffraction grating structure in the first waveguide comprises the diffraction grating and the second output.

The second waveguide element 103 receives these light rays or light beams which do not comprise the blue light component. The second waveguide element 103 comprises a diffraction grating (not shown) which deflects only the green component within the received light beam. The light beam associated with the green component is reflected within the second waveguide element 103 so as to reach a first output which delivers deflected "green" light towards said eye socket 107 of the user. The other components of the optical beam 101 (i.e. all other colour components except the blue and green component colours) are transmitted to the third waveguide element 104 via the second output 106 of the diffraction grating without changing the direction of propagation (i.e. the same direction of the optical beam 101). In addition, the second output 106 includes an achromatic half-wave plate for changing the polarization of the remaining light transmitted to the other waveguide element.

The third waveguide element 104 receives these light rays or light beams that do not include the blue and green light components.

The third waveguide element 104 includes a diffraction grating (not shown) that deflects only the red component within the received light beam. The light beam associated with the red component is reflected within the third waveguide element 104 so as to reach a first output which delivers deflected "red" light towards the eye socket 107 of the user.

Thus, the third waveguide element 104 does not include an achromatic half-wave plate.

Fig. 2 presents in the left part a schematic view corresponding to the features of fig. 1 (but without reference signs) and in the right part a schematic view corresponding to the features of the optical device according to an embodiment of the present disclosure for delivering an image to a second eye of the user.

The purpose of such an optical device is to direct a polychromatic image represented by light rays or beams 201 produced by a light engine.

The first waveguide element 202 receives these light rays or light beams 201. The first waveguide element 202 comprises a diffraction grating (not shown) which deflects only the blue component within the optical beam 201. The light beam associated with the blue component is reflected within the first waveguide element 202 so as to reach a first output which delivers the deflected "blue" light towards said eye-box 207 of the user. The other components of the light beam 201 (i.e. all other colour components except the blue component colour) are transmitted to the second waveguide element 203 via the second output 205 of the diffraction grating without changing the propagation direction (i.e. the same direction of the light beam 201). Further, the second output 205 comprises an achromatic half-wave plate for changing the polarization of the remaining light transmitted to the other waveguide element.

The second waveguide element 203 receives these light rays or light beams which do not comprise the blue light component. The second waveguide element 203 comprises a diffraction grating (not shown) which deflects only the green component within the received light beam. The light beam associated with the green component is reflected within the second waveguide element 203 so as to reach a first output which delivers deflected "green" light towards the eye socket 207 of the user. The other components of the optical beam 201 (i.e., all other color components except the blue and green component colors) are transmitted to the third waveguide element 204 via the second output 206 of the diffraction grating without changing the propagation direction (i.e., the same direction of the optical beam 201). Further, the second output 206 comprises an achromatic half-wave plate for changing the polarization of the remaining light transmitted to the other waveguide element.

The third waveguide element 204 receives these light rays or light beams that do not include the blue and green light components.

The third waveguide element 204 includes a diffraction grating (not shown) that deflects only the red component within the received light beam. The light beam associated with the red component is reflected within the third waveguide element 204 so as to reach a first output that delivers deflected "red" light towards the eye socket 207 of the user.

The multilayer waveguide element in the left part of fig. 1 and 2 comprises a 1 st order diffraction grating, while the multilayer waveguide element in the right part of fig. 2 comprises a 1 st order diffraction grating.

Figure 3 illustrates an example of a diffraction grating for use in a waveguide element according to one embodiment of the present disclosure.

Such diffraction gratings are also described in detail in european patent application 18305263.

Fig. 4 illustrates an example of a diffraction grating for use in a waveguide element according to another embodiment of the present disclosure.

In such an embodiment, in contrast to the embodiment of fig. 3, the refractive index n is increased₂Of a single material and having a refractive index n₃The dimensions of the components made of a single material vary.

Fig. 5 illustrates a portion of an optical device (such as augmented reality glasses) according to another embodiment of the present disclosure.

In another embodiment of the present disclosure, the light engine used to deliver the light beams 101 and 201 may generate a light beam having n color components C₁，...，C_i，...，C_n]Is marked 501, each color component C_jAnd wavelength lambda_jAnd wherein for all these i e [1, n ∈]，λ_i+1＞λ_iAnd wherein the polarization of the color component satisfies the following properties: pol (C) if i is 2k +1_i) TE, otherwise pol (C)_i)＝TM。

In addition, the wavelength should satisfy the following characteristics:ε is about 10 nm.

Thus, in one embodiment of the present disclosure, the optical device comprises n waveguide elements (stacked on top of each other as in the embodiments of fig. 1 and 2, with three waveguide elements), and only the waveguide element 502 that can deflect the smallest wavelength is positioned closer to the light engine. The arrangement of the n waveguide elements follows the n color components C₁，…，C_i，...，C_n]The order of (a). Thus, the i-waveguide element labeled 503 can only deflect the color component C_iAnd transmits a color component [ C_i+1，...，C_n]. The last waveguide element, which is located closer to the user's eye 505, has only the color component C of the received light beam_nDeflection。

As in the embodiment of fig. 1 and 2, the waveguide element in fig. 5 includes a diffraction grating as previously described, and further includes achromatic half waveplates, such as achromatic half waveplate 506 and achromatic half waveplate 507.