Patent ID: 12253694

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It should be understood that the number of any elements/components is merely for illustration, and it does not intend to limit the present disclosure.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Still further, when a number or a range of numbers is described with “about”, “approximate,” and the like, the term is intended to encompass numbers that are within a reasonable range including the number described, such as within +/−10% of the number described or other values as understood by person skilled in the art. For example, the term “about 5 nm” encompasses the dimension range from 4.5 nm to 5.5 nm.

Hereinafter, several embodiments of the present invention will be disclosed with the accompanying drawings. Many practical details will be described in the following description for a clear description. However, it should be understood that these practical details should not be used to limit the present invention. That is, in some embodiments of the present invention, these practical details are unnecessary. In addition, in order to simplify the drawings, some conventional structures and elements will be shown in the drawings in a simple schematic manner.

When a beam enters into a light-guide lens or a glass through various optical elements, RGB lights would have different optical paths. Therefore, the RGB lights transmission to the viewer's eyes will shift. In order to solve this transmission imaging problem caused by the RGB lights having different optical paths, a plurality of grating coupler and/or a plurality of optical elements were used to achieve the same optical paths for imaging. For example, three separate high refractive index glasses were used for separately multiplexing three wavelengths (such as RGB wavelengths of lights) of an external light, and each of the glasses had at least one grating coupler, thereby transmitting the RGB wavelengths along the same optical paths. However, three separate high refractive index glasses would increase the thickness of the optical device and also increase the cost of manufacturing the optical device.

The optical systems of the present disclosure adjusts incident angles of three separated RGB images emitted from different positions, and then couple the RGB images with one deflector, one grating coupler, and one light-guide lens. In addition, the present disclosure provides optical systems including variation structures of a deflector. The deflector could include a meta-grating structure having multiple longitudinal units, a meta-grating structure having multiple cylinder units, a n-step grating structure, a blazed grating structure, a slanted grating structure. The deflector also could include three quartz cubes with a blue dichroic filter, a green dichroic filter, and a red dichroic filter. The optical system of the present disclosure could reduce the thickness of an optical device and provide high efficiencies of RGB lights (images). The present disclosure may be applied in smart glasses such as augmented reality (AR) and virtual reality (VR).

FIG.1is a schematic view of a pair of smart glasses100in accordance with some embodiments of the present disclosure. The pair of smart glasses100includes an arm110, an optical device120, a grating coupler structure130, and a light-guide lens140. The arm110and the optical device120extend along a direction Y, and the optical device120is disposed in the arm110. The grating coupler structure130is disposed around an end of the arm110. The light-guide lens140extends along a direction X.

FIG.2is a partial top view of the pair of smart glasses100inFIG.1. The optical device120includes several elements.FIG.2merely illustrates a deflector121including a grating structure1212and a substrate1214for clarity. The detailed drawing of the optical device120will be discussed inFIG.3below. The grating coupler structure130is disposed at the intersection of the end of the arm110and the end of the light-guide lens140. Specifically, the grating coupler structure130is disposed on a surface of the light-guide lens140.

FIG.3is a schematic view of an optical system300in accordance with some embodiments of the present disclosure. The optical system300includes a projector122, a polarizer123, a collimator124, a filter125, the deflector121, the grating coupler structure130, the light-guide lens140, and a light absorber150. The projector122could emit three beams having different wavelengths. Specifically, the three beams extend along the direction Y. The beams emitting from the projector122are not limited to three beams, and it also may emit polychromatic light. The three beams may be a blue light BL, a green light GL, and a red light RL. It should be understood that “the three beams” below refer to the blue light BL, the green light GL, and the red light RL. The projector122is configured to decouple an overlapped colored image500(please refer toFIG.5D) into three separated RGB images (please refer toFIG.5AtoFIG.5C). In some embodiments, the projector122may be an organic light-emitting diode (OLED) projector so that the blue light BL, the green light GL, and the red light RL may be broadband lights. The polarizer123is disposed below the projector122. Specifically, the polarizer123is disposed between the projector122and the deflector121. The polarizer123is configured to filter out transverse electric (TE) modes or transverse magnetic (TM) modes of the three beams emitting from the projector122. The collimator124is disposed below the polarizer123and is configured to confine incident angles of the three beams emitting from the projector122. The filter125is disposed below the collimator124and is configured to narrow the wavebands of the three beams emitting from the projector122. In some embodiments, the filter125includes a blue narrow bandpass filter for the blue light BL, a green narrow bandpass filter for the green light GL, and a red narrow bandpass filter for the red light RL. In some embodiments, the arranged sequence of the polarizer123, the collimator124, and the filter125may be interchangeable.

FIG.4is a schematic view of wavebands of the three beams emitting from the projector122after the three beams transmitting through the filter125inFIG.3. Specifically, after the blue light BL, the green light GL, and the red light RL transmitting through the filter125, wavebands of the blue light BL, the green light GL, and the red light RL will be narrowed. In some embodiments, after the blue light BL transmitting through the filter125, the wavelength of the blue light BL may be in a range from 430 nm to 491 nm, such as about 440, 446, 457, 465, 473, or 488 nm. In some embodiments, after the green light GL transmitting through the filter125, the wavelength of the green light GL may be in a range from 510 nm to 581 nm, such as about 515, 520, 532, 543, or 560 nm. In some embodiments, after the red light RL transmitting through the filter125, the wavelength of the red light RL may be in a range from 590 nm to 671 nm, such as about 630, 633, 637, or 658 nm. It is understood that the blue light BL, the green light GL, and the red light RL shown inFIG.3also may include other color lights. In some embodiments, the blue light BL, the green light GL, and the red light RL include three separated RGB images.

Please refer toFIG.3again. The deflector121is disposed below the filter125. The deflector121includes the grating structure1212and the substrate1214. The grating structure1212is disposed on the substrate1214. The substrate1214includes a blue region BR, a green region GR, and a red region RR. The blue region BR and the red region RR are separated by the green region GR, as shown inFIG.3. The grating structure1212includes a first grating deflector structure1212adisposed on the blue region BR of the substrate1214and a second grating deflector structure1212bdisposed on the red region RR of the substrate1214. In other words, there are no any grating structures disposed on the green region GR of the substrate1214. It should be understood that the grating structure1212shown inFIG.2andFIG.3merely illustrates for clarity. The detailed arrangements of the grating structure1212will be discussed inFIG.6toFIG.14, and the variation structures of the grating structure1212will be discussed inFIG.17AtoFIG.17C. In some embodiments, a refractive index of each of the first grating deflector structure1212aand the second grating deflector structure1212bis in a range from 1.7 to 3.5, such as 1.8, 2.2, 2.6, 3.0, or 3.4. In some embodiments, each of the first grating deflector structure1212aand the second grating deflector structure1212bmay be made by Al2O3, TiO2, Nb2O5, Si3N4, or Ta2O5. In some embodiments, the substrate1214may be transparent substrate and may be made of glass, fused silica, sapphire, ceramic, polymer resin, or plastic. In some embodiments, a refractive index of the substrate1214may be in a range from 1.3 to 2.0, such as 1.4, 1.5, 1.7, or 1.9.

InFIG.3, the grating coupler structure130and the light-guide lens140are disposed below the deflector121. The grating coupler structure130includes a first grating coupler structure130aand a second grating coupler structure130b. The first grating coupler structure130aand the second grating coupler structure130bare connected to the light-guide lens140. The first grating coupler structure130ais below the deflector121and is configured to couple the three beams (such as the blue light BL, the green light GL, and the red light RL) into the light-guide lens140, such that the three beams travel the same optical path within the light-guide lens140. The light-guide lens140is configured to transmit the three beams. The deflector121is configured to change incident angles of the three beams and to focus the three beams at the same region of the first grating coupler structure130aof the grating coupler structure130. Specifically, after the blue light BL passes through the deflector121, a blue deflected angle θBof the blue light BL to the first grating coupler structure130ais formed. Similarity, after the red light RL passes through the deflector121, a red deflected angle θRof the red light RL to the first grating coupler structure130ais formed. The second grating coupler structure130bof the grating coupler structure130is disposed on the light-guide lens140and is configured to enable the three beams departing from the light-guide lens140after the three beams have traveled the same optical path. In some embodiments, the structure and the material of the first grating coupler structure130aare the same as the second grating coupler structure130b. In some embodiments, the light absorber150is disposed below the grating coupler structure130. In some embodiments, the light absorber150is optional. The light absorber150is configured to absorb non-ideal lights, such as zero-order light or higher-order diffraction lights (of the blue light BL, the green light GL, and the red light RL) other than the first-order diffraction lights.

FIG.5A,FIG.5B, andFIG.5Care schematic views of original images of three separated beams (the blue light BL, the green light GL, and the red light RL).FIG.5Dis a schematic view of an optical image of the overlapped colored image500. Specifically, please refer toFIG.3, after the three beams transmit through the deflector121, the three beams would change their travel directions, and then the three beams would focus on the same region of the first grating coupler structure130aof the grating coupler structure130. Therefore, the three beams couple into the light-guide lens140. Next, the three beams would travel the same optical path within the light-guide lens140along the direction X. Finally, the three beams would couple out through the second grating coupler structure130bof the grating coupler structure130, so that the three beams are separated to form the overlapped colored image500shown inFIG.5D.

FIG.6is an enlargement view of the deflector121inFIG.3. Both the first grating deflector structure1212aand the second grating deflector structures1212bof the grating structure1212shown inFIG.6are meta-grating structures. In other words, the first grating deflector structure1212ainFIG.3could be understood as the first meta-grating structure1212aminFIG.6, and the second grating deflector structure1212binFIG.3could be understood as the second meta-grating structure1212bminFIG.6. It should be understood that the “meta-grating structure” herein means the units in the grating structure are different and widths of the units are increased or decreased regularly. As shown inFIG.6, a plurality of first meta-grating structures1212amare disposed on the blue region BR of the substrate1214. In some embodiments, the number of the first meta-grating structures1212amis in a range from 125 to 8000, for example, about 200 to 4000. In some embodiments, a period PBof the first meta-grating structure1212amis in a range from 1000 to 8000 nm, for example, about 2000 to 5000 nm. In some embodiments, a height HBof the first meta-grating structure1212amis in a range from 20 to 2000 nm, for example, about 100 to 1000 nm. Similarity, a plurality of second meta-grating structures1212bmare disposed on the red region RR of the substrate1214. In some embodiments, the number of the second meta-grating structures1212bmis in a range from 125 to 8000, for example, about 200 to 4000. In some embodiments, a period PR of the second meta-grating structure1212bmis in a range from 1000 to 8000 nm, for example, about 2000 to 5000 nm. In some embodiments, a height HR of the second meta-grating structure1212bmis in a range from 20 to 2000 nm, for example, about 100 to 1000 nm. In some embodiments, each of a width WBRof the blue region BR, a width WGRof the green region GR, and a width WRRof the red region RR of the substrate1214is in a range from 1 to 8 mm. In some embodiments, a spacing S between the blue region BR and the green region GR, and a spacing S between the green region GR and the red region RR are in a range from 100 nm to 2 mm, for example, about 10 to 200 μm.

FIG.7andFIG.8are top views of the deflector121,121A inFIG.6in accordance with some embodiments of the present disclosure. Specifically, the view along a line L1-L1′ of the deflector121inFIG.7isFIG.6, and the view along a line L2-L2′ of the deflector121A inFIG.8also isFIG.6. Please refer toFIG.7, the shapes of the first meta-grating structure1212amand the second meta-grating structure1212bmof the grating structure1212are longitudinal. Please refer toFIG.8, the shapes of the first meta-grating structure1212amand the second meta-grating structure1212bmof the grating structure1212are cylinders. Whether the deflector121inFIG.7or the deflector121A inFIG.8, the cross-sectional views are the same, as shown inFIG.6.

FIG.9AandFIG.9Brespectively are enlargement views of the first meta-grating structure1212amand the second meta-grating structure1212bminFIG.6. Please refer toFIG.9A, the first meta-grating structure1212amincludes a first longitudinal unit U1Bhaving a first width W1B, a second longitudinal unit U2Bhaving a second width W2B, a third longitudinal unit U3Bhaving a third width W3B, a t−1thlongitudinal unit Ut−1Bhaving a t−1thwidth Wt−1B, a tthlongitudinal unit UtBhaving a tthwidth WtB, and W1B≤W2B≤W3B≤Wt−1B≤WtB. In other words, the plurality of longitudinal units of the first meta-grating structure1212amare gradational in width. The first meta-grating structure1212amcould include t longitudinal units, and t≥4, such as 5, 6, 8, or 10. Specifically, the period PBof the first meta-grating structure1212amand the number t define a pitch PB/t, as shown inFIG.9A. Please refer toFIG.6andFIG.9A, the first longitudinal unit U1B, the second longitudinal unit U2B, and the third longitudinal unit U3Bsequentially are disposed along an outer surface of the blue region BR of the substrate1214to an inner surface of the blue region BR of the substrate1214.

Please refer toFIG.9B, the second meta-grating structure1212bmincludes a first longitudinal unit U1Rhaving a first width W1R, a second longitudinal unit U2Rhaving a second width W2R, a third longitudinal unit U3Rhaving a third width W3R, a m−1thlongitudinal unit Um−1Rhaving a m−1thwidth Wm−1R, a mthlongitudinal unit UmRhaving a m width WmR, and W1R≤W2R≤W3R≤Wm−1R≤WmR. In other words, the plurality of longitudinal units of the second meta-grating structure1212bmare gradational in width. The second meta-grating structure1212bmcould include m longitudinal units, and m Z4, such as 5, 6, 8, or 10. Specifically, the period PRof the second meta-grating structure1212bmand the number m define a pitch

PRm,
as shown inFIG.9B. Please refer toFIG.6andFIG.9B, the first longitudinal unit U1R, the second longitudinal unit U2R, and the third longitudinal unit U3Rsequentially are disposed along an outer surface of the red region RR of the substrate1214to an inner surface of the red region RR of the substrate1214.

FIG.10AandFIG.10Brespectively are enlargement views of variation structures for the first meta-grating structure1212amand the second meta-grating structure1212bminFIG.9AandFIG.9B. Same features are labeled by the same numerical references, and descriptions of the same features are not repeated in the following figures. The differences betweenFIG.9AandFIG.10Aare that the first meta-grating structure1212aminFIG.10Afurther includes a t+1thlongitudinal unit Ut+1Bhaving a t+1thwidth Wt+1Band a t+2thlongitudinal unit Ut+2Bhaving a t+2thwidth Wt+2B, in which WtB≥Wt+1B≥Wt+2B. The t+1thlongitudinal unit Ut+1Bis next to the tthlongitudinal unit UtB, and the t+2thlongitudinal unit Ut+2Bis next to the t+1thlongitudinal unit Ut+1B.

The differences betweenFIG.9BandFIG.10Bare that the second meta-grating structure1212bminFIG.10Bfurther includes a m+1thlongitudinal unit Um+1Rhaving a m+1thwidth Wm+1Rand a m+2thlongitudinal unit Um+2Rhaving a m+2thwidth Wm+2R, in which WmR≥Wm+1R≥Wm+2R. The m+1thlongitudinal unit Um+1Ris next to the mthlongitudinal unit UmR, and the m+2thlongitudinal unit Um+2Ris next to the m+1thlongitudinal unit Um+1R.

FIG.11is a top view of a variation structure of the first meta-grating structure1212amof the deflector121A inFIG.8. Specifically, the cross-sectional view of the first meta-grating structure1212aminFIG.11could refer to theFIG.10A. The first meta-grating structure1212aminFIG.11are cylinders and has a plurality of circle shapes when viewed from X-Z section. As shown inFIG.11, the first meta-grating structure1212amincludes a first cylinder unit U1Bhaving a first diameter D1B, a second cylinder unit U2Bhaving a second diameter D2B, a third cylinder unit U3Bhaving a diameter width D3B, a t−1thcylinder unit Ut−1Bhaving a t−1thdiameter Dt−1B, a tthcylinder unit UtBhaving a tthdiameter DtB, and D1B≤D2B≤D3B≤Dt−1B≤DtB. The first meta-grating structure1212aminFIG.11further includes a t+1thcylinder unit Ut+1Bhaving a t+1thdiameter Dt+1Band a t+2thcylinder unit Ut+2Bhaving a t+2thdiameter Dt+2B, in which DtB≥Dt+1B≥Dt+2B. The t+1thcylinder unit Ut+1Bis next to the tthcylinder unit UtB, and the t+2thcylinder unit Ut+2Bis next to the t+1thcylinder unit Ut+1B. It is understood that the arrangements and positions of the first meta-grating structure1212aminFIG.11could be similar to the arrangements positions of the first meta-grating structure1212aminFIG.8, and the details thereof are not repeatedly described. In addition, a variation structure of the second meta-grating structure1212bmcould be a mirror structure in a lateral symmetry of the first meta-grating structure1212amshown inFIG.11.

Please refer toFIG.6,FIG.9A, andFIG.9Bagain. All of the longitudinal/cylinder units U1B, U2B, U3B, Ut−1B, UtBhave the same height HB. All of the longitudinal/cylinder units U1R, U2R, U3R, Um−1R, UmRhave the same height HR. In some embodiments, as shown inFIG.6, the height HBof the first meta-grating structure1212amis the same as the height HR of the second meta-grating structure1212bm. In some embodiments, the period PBof the first meta-grating structure1212amis the same as the period PR of the second meta-grating structure1212bm, as shown inFIG.6.

FIG.12,FIG.13, andFIG.14are cross-sectional views of a deflector121B,121C,121D in accordance with some alternative embodiments of the present disclosure. In some embodiments, as shown in the deflector121B ofFIG.12, the height HBof the first meta-grating structure1212amis different from the height HRof the second meta-grating structure1212bm. In some embodiments, as shown in the deflector121C ofFIG.13and the deflector121D ofFIG.14, the period PBof the first meta-grating structure1212amis different from the period PRof the second meta-grating structure1212bm. Specifically, inFIG.13, the number of the longitudinal units of the first meta-grating structure1212amis greater than the number of the longitudinal units of the second meta-grating structure1212bm. InFIG.14, the pitch

PBt
between the longitudinal units of the first meta-grating structure1212amis smaller than the pitch

PRt
between the longitudinal units of the second meta-grating structure1212bm.

FIG.15is a cross-sectional view of the light-guide lens140with the grating coupler structure130inFIG.3. The grating coupler structure130includes the first grating coupler structure130aand the second grating coupler structure130b. The grating coupler structure130shown inFIG.15is a slanted grating coupler structure. Specifically, the grating coupler structure130is defined by the positons of a bottom left point BL, a bottom right point BR, an upper left point UL, and an upper right point UR. In some embodiments, a period PGCof the grating coupler structure130is in a range from 300 nm to 500 nm. In some embodiments, a height HGCof the grating coupler structure130is in a range from 100 nm to 600 nm. In some embodiments, a refractive index of the grating coupler structure130is in a range from 1.7 to 3.5, such as 1.8, 2.5, 2.9, or 3.4. In some embodiments, a refractive index of the light-guide lens140is the same as or similar to a refractive index of the grating coupler structure130.

Please refer to Tables 1-3 below andFIG.3,FIG.7, andFIG.15. It shows experimental example 1 under the conditions that the shapes of the first meta-grating structure1212amand the second meta-grating structure1212bmof the grating structure1212are longitudinal, and the filter125is under the TM mode.

TABLE 1meta-grating structures of the deflectorblue light =green light =red light =TM488 nm532 nm620 nmPBt⁢or⁢PRm596.1 nm—504.9 nmW1Bor W1R154.9 nm—0 nmW2Bor W2R174.9 nm—0 nmW3Bor W3R190.2 nm—120.2 nmW4Bor W4R249.9 nm—158.9 nmW5Bor W5R390.7 nm—196.8 nmW6Bor W6R428.5 nm—248.5 nmW7Bor W7R477.5 nm—331.8 nmHBor HR791.5 nm—770.7 nmθBor θR5.87°—11.81°

TABLE 2slanted grating coupler structurerefractive index (n)1.9PGC430nmbottom left point BL−77.5nmbottom right point BR115nmupper left point UL−213.8nmupper right point UR−15.4nmHGC500nm

TABLE 3efficiencyTMblue lightgreen lightred lightdeflector76.79%100%85.03%slanted grating coupler structure80.77%95.59%72.94%total62.02%95.59%62.02%

In the experimental example 1, it can be seen from Table 3 that the total efficiency of the blue light BL was 62.02%, the total efficiency of the green light GL was 95.59%, and the total efficiency of the red light RL was 62.02%. It is considered that this example had good efficiencies of RGB lights.

Please refer to Tables 4-6 below andFIG.3,FIG.7, andFIG.15. It shows experimental example 2 under the conditions that the shapes of the first meta-grating structure1212amand the second meta-grating structure1212bmof the grating structure1212are longitudinal, and the filter125is under the TE mode.

TABLE 4meta-grating structures of the deflectorblue light =green light =red light =TE488 nm532 nm620 nmPBt⁢or⁢PRm596.1 nm—504.9 nmW1Bor W1R120.0 nm—120.2 nmW2Bor W2R120.0 nm—120.3 nmW3Bor W3R122.8 nm—444.8 nmW4Bor W4R336.9 nm—394.5 nmW5Bor W5R351.9 nm—0W6Bor W6R374.3 nm—0W7Bor W7R411.5 nm—161.4 nmHBor HR775.5 nm—800.0 nmθBor θR5.87°—11.81°

TABLE 5slanted grating coupler structurerefractive index (n)1.9PGC430nmbottom left point BL−65.2nmbottom right point BR115nmupper left point UL−215.0nmupper right point UR−80.7nmHGC355.5nm

TABLE 6efficiencyTEblue lightgreen lightred lightdeflector56.40%100%48.69%slanted grating coupler structure83.51%86.42%92.18%total47.10%86.42%44.88%

In the experimental example 2, it can be seen from Table 6 that the total efficiency of the blue light BL was 47.10%, the total efficiency of the green light GL was 86.42%, and the total efficiency of the red light RL was 44.88%. It is considered that this example had good efficiencies of RGB lights.

Please refer to Tables 7-9 below andFIG.3,FIG.8, andFIG.15. It shows experimental example 3 under the conditions that the shapes of the first meta-grating structure1212amand the second meta-grating structure1212bmof the grating structure1212are cylindrical, and the filter125is under the TE mode.

TABLE 7meta-grating structures of the deflectorblue light =green light =red light =TE460 nm530 nm620 nmPBt⁢or⁢PRm471.0 nm—494.0 nmW1Bor W1R120.5 nm—0 nmW2Bor W2R146.6 nm—0 nmW3Bor W3R171.9 nm—181.0 nmW4Bor W4R187.6 nm—236.1 nmW5Bor W5R212.5 nm—281.3 nmW6Bor W6R0—342.5 nmW7Bor W7R0—418.4 nmHBor HR848.2 nm—790.1 nmθBor θR9.37°—12.08°

TABLE 8slanted grating coupler structurerefractive index (n)1.9PGC430nmbottom left point BL−8.8nmbottom right point BR215nmupper left point UL−193.5nmupper right point UR−55.7nmHGC236.5nm

TABLE 9efficiencyTEblue lightgreen lightred lightdeflector83.54%100%83.96%slanted grating coupler structure80.73%88.80%80.33%total67.44%88.80%67.44%

In the experimental example 3, it can be seen from Table 9 that the total efficiency of the blue light BL was 67.44%, the total efficiency of the green light GL was 88.80%, and the total efficiency of the red light RL was 67.44%. It is considered that this example had good efficiencies of RGB lights.

FIG.16is a schematic view of an optical system1600in accordance with some embodiments of the present disclosure.FIG.17Ais an enlargement view of the first grating deflector structure1212ainFIG.16.FIG.17BandFIG.17Care enlargement views of variation structures for the first grating deflector structure1212ainFIG.16. The first grating deflector structure1212aof the grating structure1212inFIG.16may be the 3-step grating structure1212a1shown inFIG.17A, a blazed grating structure1212a2shown inFIG.17B, a slanted grating structure1212a3shown inFIG.17C, or combinations thereof.

The difference between the optical system1600inFIG.16and the optical system300inFIG.3is the grating structure1212. Specifically, the first grating deflector structure1212aand the second grating deflector structures1212bof the grating structure1212inFIG.3are meta-grating structures. In some embodiments, the first grating deflector structure1212aand the second grating deflector structures1212bof the grating structure1212inFIG.16are 3-step grating structures1212a1(please refer toFIG.17A). It is understood that the number of the 3-step grating structures inFIG.16is merely for illustration, and it does not intend to limit the present disclosure.

Please refer toFIG.17A, the 3-step grating structure1212a1includes multiple vertical sidewalls173,175and multiple horizontal surfaces172,174. The horizontal surface174adjoins the vertical sidewalls173,175. The grating structure1212a1shown inFIG.17Ais a 3-step grating structure, however, it may be a n-step grating structure, and n≥3. Please refer toFIG.17B, the blazed grating structure1212a2includes an oblique sidewall176. The oblique sidewall176extends from a top of the blazed grating structure1212a2to a bottom of the blazed grating structure1212a2, and a width of the blazed grating structure1212a2gradually increases from the top of the blazed grating structure1212a2to the bottom of the blazed grating structure1212a2. Please refer toFIG.17C, the slanted grating structure1212a3includes oblique sidewalls177,178and a top surface179. The top surface179adjoins the oblique sidewalls177,178. Each of the oblique sidewalls177,178of the slanted grating structure1212a3has a first slope and a second slope. In some embodiments, the first slope is the same as the second slope. In some embodiments, the first slope is less than the second slope. In addition, variation structures of the second grating deflector structure1212bcould be mirror structures in a lateral symmetry of the first grating deflector structure1212ashown inFIG.17AtoFIG.17C.

FIG.18is a partial top view of the pair of smart glasses100inFIG.1. The differences between the smart glasses100inFIG.2and the smart glasses100A inFIG.18are the optical devices120,120a. The detailed drawing of the optical device120awill be discussed inFIG.19below. Same features are labeled by the same numerical references, and descriptions of the same features are not repeated in the following figures.

FIG.19is a schematic view of an optical system1900in accordance with some embodiments of the present disclosure. The optical system1900includes the projector122, the polarizer123, the collimator124, the filter125, a deflector121E, a light absorber1910, the grating coupler structure130, the light-guide lens140, and the light absorber150. The deflector121E includes a blue dichroic filter1922for the blue light BL, a green dichroic filter1924for the green light GL, and a red dichroic filter1926for the red light RL. The blue dichroic filter1922, the green dichroic filter1924, and the red dichroic filter1926could be understood as filter coatings for reflecting lights.

FIG.20is a partial view of the deflector121E inFIG.19. The deflector121E includes a quartz1932having a first oblique surface OSBand a first bottom surface BSB, a quartz1934having a second oblique surface OSGand a second bottom surface BSG, a quartz1936having a third oblique surface OSRand a third bottom surface BSR. The first bottom surface BSBof the quartz1932, the second bottom surface BSGof the quartz1934, and the third bottom surface BSRof the quartz1936are parallel to each other. The quartz1932has a first angle θ1 between the first oblique surface OSBand the first bottom surface BSBof the quartz1932. The quartz1934has a second angle θ2 between the second oblique surface OSGand the second bottom surface BSGof the quartz1934. The quartz1936has a third angle θ3 between the third oblique surface OSRand the third bottom surface BSRof the quartz1936. In some embodiments, the second angle θ2 is 45 degrees, and θ1<θ2<θ3, as shown inFIG.20.

Still refer toFIG.20. The blue dichroic filter1922is disposed on the first oblique surface OSB, the green dichroic filter1924is disposed on the second oblique surface OSG, and the red dichroic filter1926is disposed on the third oblique surface OSR. It is understood that the blue dichroic filter1922is aligned between the quartz1932and a quartz1933and assembled as a blue deflector cube. The green dichroic filter1924is aligned between the quartz1934and a quartz1935and assembled as a green deflector cube. The red dichroic filter1926is aligned between the quartz1936and a quartz1934and assembled as a red deflector cube. In some embodiments, a thickness of each of the blue deflector cube, the green deflector cube, and the red deflector cube is in a range from 1 to 10 mm. In some embodiments, the transmittance of a light smaller than 400 nm wavelength for the blue deflector cube is greater than 90%, and the reflection of a light greater than 400 nm wavelength for the blue deflector cube is greater than 90%. In some embodiments, the transmittance of alight smaller than 500 nm wavelength for the green deflector cube is greater than 90%, and the reflection of a light greater than 500 nm wavelength for the green deflector cube is greater than 90%. In some embodiments, the transmittance of a light smaller than 585 nm wavelength for the red deflector cube is greater than 90%, and the reflection of a light greater than 585 nm wavelength for the red deflector cube is greater than 90%. The blue deflector cube, the green deflector cube, and the red deflector cube are configured to adjust the incident angles of the three beams (three separated RGB images, refer toFIG.5AtoFIG.5C) and expose on the same region of the of the first grating coupler structure130a(refer toFIG.19) as an merged color image (refer toFIG.5D).

Please refer toFIG.19again. The light absorber1910is disposed aside (the right side ofFIG.19) the deflector121E. The light absorber1910is configured to absorb beams which are not reflected by the blue dichroic filter1922, the green dichroic filter1924, and the red dichroic filter1926of the optical device120a(seeFIG.18). The grating coupler structure130, the light-guide lens140, and the light absorber150are disposed below (the bottom side ofFIG.19) the deflector121E. The three beams (the blue light BL, the green light GL, and the red light RL) emitting from the projector122would be reflect by the blue dichroic filter1922, green dichroic filter1924, and the red dichroic filter1926and then the three beams change incident angles and focus at the same region of the first grating coupler structure130aof the grating coupler structure130.

The optical systems of the present disclosure adjusts incident angles of three separated RGB images emitted from different positions, and then couple the RGB images with one deflector, one grating coupler, and one light-guide lens. In addition, the present disclosure provides optical systems including variation structures of the deflector. The deflector could include a meta-grating structure having multiple longitudinal units, a meta-grating structure having multiple cylinder units, a n-step grating structure, a blazed grating structure, a slanted grating structure. The deflector also could include three quartz cubes with a blue dichroic filter, a green dichroic filter, and a red dichroic filter. The optical system of the present disclosure could reduce the thickness of an optical device and provide high efficiencies of RGB lights (images).

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.