The present invention relates to substrate-guided optical devices, and particularly to devices which include a plurality of reflecting surfaces carried by a common light-transmissive substrate, also referred to as a light-guide optical element (LOE).
The invention can be implemented to advantage in a large number of imaging applications, such as, for example, head-mounted and head-up displays, cellular phones, compact displays, 3-D displays, compact beam expanders as well as non-imaging applications such as flat-panel indicators, compact illuminators and scanners.
One of the important applications for compact optical elements is in head-mounted displays, wherein an optical module serves both as an imaging lens and a combiner, in which a two-dimensional display is imaged to infinity and reflected into the eye of an observer. The display can be obtained directly from either a spatial light modulator (SLM) such as a cathode ray tube (CRT), a liquid crystal display (LCD), an organic light emitting diode array (OLED), or a scanning source and similar devices, or indirectly, by means of a relay lens or an optical fiber bundle. The display comprises an array of elements (pixels) imaged to infinity by a collimating lens and transmitted into the eye of the viewer by means of a reflecting or partially reflecting surface acting as a combiner for non-sec-through and see-through applications, respectively. Typically, a conventional, free-space optical module is used for these purposes. Unfortunately, as the desired field-of-view (FOV) of the system increases, such a conventional optical module becomes larger, heavier, bulkier, and therefore, even for a moderate performance device, is impractical. This is a major drawback for all kinds of displays, but especially in head-mounted applications, wherein the system must necessarily be as light and as compact as possible.
The strive for compactness has led to several different complex optical solutions, all of which, on one hand, are still not sufficiently compact for most practical applications, and, on the other hand, suffer major drawbacks in terms of manufacturability. Furthermore, the eye-motion-box (EMB) of the optical viewing angles resulting from these designs is usually very small—typically less than 8 mm. Hence, the performance of the optical system is very sensitive, even to small movements of the optical system relative to the eye of the viewer, and do not allow sufficient pupil motion for conveniently reading text from such displays.
The teachings included in Publication Nos. WO01/95027, WO03/081320, WO2005/024485, WO2005/024491. WO2005/024969, WO2005/124427, WO2006/013565, WO2006/085309. WO2006/085310, WO2006/087709, WO2007/054928, WO2007/093983. WO2008/023367, WO2008/129539, WO2008/149339, WO2013/175465, IL 232197, IL 235642, IL 236490 and IL 236491, all in the name of Applicant, are herein incorporated by references.
The present invention facilitates the design and fabrication of very compact LOEs for, amongst other applications, head-mounted displays. The invention allows relatively wide FOVs together with relatively large eye-motion-box values. The resulting optical system offers a large, high-quality image, which also accommodates large movements of the eye. The optical system offered by the present invention is particularly advantageous because it is substantially more compact than state-of-the-art implementations, and yet it can be readily incorporated even into optical systems having specialized configurations.
A further application of the present invention is to provide a compact display with a wide FOV for mobile, hand-held applications such as cellular phones. In today's wireless internet-access market, sufficient bandwidth is available for full video transmission. The limiting factor remains the quality of the display within the device of the end-user. The mobility requirement restricts the physical size of the displays, and the result is a direct-display with poor image viewing quality. The present invention enables a physically very compact display with a very large virtual image. This is a key feature in mobile communications, and especially for mobile internet access, solving one of the main limitations for its practical implementation. The present invention thereby enables the viewing of the digital content of a full format internet page within a small, hand-held device, such as a cellular phone.
The broad object of the present invention is therefore to alleviate the drawbacks of state-of-the-art compact optical display devices and to provide other optical components and systems having improved performance, according to specific requirements.
In accordance with the present invention there is therefore provided an optical device, comprising a light-transmitting substrate having an input aperture, an output aperture, at least two major surfaces and edges, an optical element for coupling light waves into the substrate by total internal reflection, at least one partially reflecting surface located between the two major surfaces of the light-transmitting substrate for partially reflecting light waves out of the substrate, a first transparent plate, having at least two major surfaces, one of the major surfaces of the transparent plate being optically attached to a major surface of the light-transmitting substrate defining an interface plane, and a beam-splitting coating applied at the interface plane between the substrate and the transparent plate, wherein light waves coupled inside the light-transmitting substrate are partially reflected from the interface plane and partially pass therethrough.
The invention is described in connection with certain preferred embodiments, with reference to the following illustrative figures so that it may be more fully understood.
With specific reference to the figures in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention. The description taken with the drawings are to serve as direction to those skilled in the art as to how the several forms of the invention may be embodied in practice.
In the drawings:
As can be seen in
The trapped rays arrive at the reflecting surface from the second direction 30 after an odd number of reflections from the substrate surfaces 26 and 27, where the off-axis angle is α′in =180°-αin and the incident angle between the trapped ray and the normal to the reflecting surface is:
wherein the minus sign denotes that the trapped ray impinges on the other side of the partially reflecting surface 22.
As illustrated in
An important issue that must be considered is the actual active area of each reflecting surface. A potential non-uniformity in the resulting image might occur due to the different reflection sequences of different rays that reach each selectively reflecting surface: some rays arrive without previous interaction with a selectively reflecting surface; other rays arrive after one or more partial reflections. This effect is illustrated in
It is difficult to fully compensate for such differences in multiple-intersection effects nevertheless, in practice, the human eye tolerates significant variations in brightness, which remain unnoticed. For near-to-eye displays, the eye integrates the light which emerges from a single viewing angle and focuses it onto one point on the retina, and since the response curve of the eye is logarithmic, small variations, if any, in the brightness of the display will not be noticeable. Therefore, even for moderate levels of illumination uniformity within the display, the human eye experiences a high-quality image. The required moderate uniformity can readily be achieved with the element illustrated in
Since the “darker” portions of the partially reflecting surfaces 22 contribute less to the coupling of the trapped light waves out of the substrate, their impact on the optical performance of the LOE can be only be negative, namely, there will be darker portions in the output aperture of the system and dark stripes will exist in the image. The transparency of each one of the reflecting surfaces is, however, uniform with respect to the light waves from the external scene. Therefore, if overlapping is set between the reflective surfaces to compensate for the darker portions in the output aperture, then rays from the output scene that cross these overlapped areas will suffer from double attenuations, and darker stripes will be created in the external scene. This phenomenon significantly reduces the performance not only of displays which are located at a distance from the eye, such as head-up displays, but also that of near-eye displays, and hence, it cannot be utilized.
As illustrated in
Since the trapped angle αin can be varied as a function of the FOV, it is important to know with which angle to associate each reflecting surface 22n, in order to calculate its active aperture.
As seen in
T=d−Dn·cot(αsur) (5)
As illustrated in
As illustrated in
This occurrence of dark or bright stripes due to the structure of the partially reflective surfaces in the LOE is not limited to the surface which creates this phenomenon. As illustrated with reference to
Another source for unevenness of the image can be the non-uniformity of the image waves which are coupled into the LOE. Usually, when two edges of a light source have slightly different intensities this will hardly be noticed by the viewer, if at all. This situation is completely different for an image which is coupled inside a substrate and gradually coupled-out, like in the LOE. As illustrated in
As illustrated in
Similarly, as illustrated in
As illustrated in
A difficulty still existing is that the LOE 20 is assembled from several different components. Since the fabrication process usually involves cementing optical elements, and since the required angular-sensitive reflecting coating is applied to the light-guide surface only after the body of the LOE 20 is complete, it is not possible to utilize the conventional hot-coating procedures that may damage the cemented areas. Novel thin-film technologies, as well as ion-assisted coating procedures, can also be used for cold processing. Eliminating the need to heat parts, allows cemented parts to be safely coated. An alternative is that the required coating can simply be applied to transparent plate 120, which is adjacent to the LOE 20, utilizing conventional hot-coating procedures and then cementing it at the proper place. Clearly, his alternative approach can be utilized only if the transparent plate 120 is not too thin and hence might be deformed during the coating process.
There are some issues that should be taken into consideration while designing a beam splitting mechanism as illustrate above:
All the various parameters of the above embodiments, such as, the thickness and the optical material of the plate 120, the exact nature of the beam-splitting coating, the number of the beam-splitting surfaces and location of the partially reflecting surface inside the LOE, could have many different possible values. The exact values of these factors are determined according to the various parameters of the optical system as well as the specific requirements for optical quality and fabrication costs.
So far, it was assumed that the light waves are coupled out from the substrate by partially reflecting surfaces, which are oriented at an oblique angle in relation to the major surfaces, and usually coated with a dielectric coating. As illustrated in
Number | Date | Country | Kind |
---|---|---|---|
IL237337 | Feb 2015 | IL | national |
Number | Name | Date | Kind |
---|---|---|---|
4720189 | Heynen et al. | Jan 1988 | A |
5208800 | Isobe et al. | May 1993 | A |
5235589 | Yokomori et al. | Aug 1993 | A |
5341230 | Smith | Aug 1994 | A |
6264328 | Williams | Jul 2001 | B1 |
6671100 | McRuer | Dec 2003 | B1 |
6799859 | Kozo | Oct 2004 | B1 |
6805490 | Levola | Oct 2004 | B2 |
6880931 | Moliton et al. | Apr 2005 | B2 |
6927694 | Smith et al. | Sep 2005 | B1 |
7405881 | Shimizu et al. | Jul 2008 | B2 |
7457040 | Amitai | Nov 2008 | B2 |
7570859 | DeJong | Aug 2009 | B1 |
7589901 | DeJong et al. | Sep 2009 | B2 |
7613373 | DeJong | Nov 2009 | B1 |
7653268 | DeJong | Jan 2010 | B1 |
7724441 | Amitai | May 2010 | B2 |
7839575 | DeJong et al. | Nov 2010 | B2 |
7949214 | DeJong | May 2011 | B2 |
8369019 | Baker | Feb 2013 | B2 |
8391668 | DeJong | Mar 2013 | B2 |
8432614 | Amitai | Apr 2013 | B2 |
8472119 | Kelly | Jun 2013 | B1 |
8531773 | DeJong | Sep 2013 | B2 |
8649099 | Schultz | Feb 2014 | B2 |
8873148 | Gupta et al. | Oct 2014 | B1 |
9541762 | Mukawa et al. | Jan 2017 | B2 |
9766459 | Alton et al. | Sep 2017 | B2 |
9798061 | Hsiao et al. | Oct 2017 | B2 |
10302957 | Sissom | May 2019 | B2 |
10317679 | Ayres et al. | Jun 2019 | B2 |
10437068 | Weng et al. | Oct 2019 | B2 |
10558044 | Pan | Feb 2020 | B2 |
10564430 | Amitai et al. | Feb 2020 | B2 |
11054581 | Ayres et al. | Jul 2021 | B2 |
11262564 | Tanaka | Mar 2022 | B2 |
20020176173 | Song | Nov 2002 | A1 |
20030165017 | Amitai | Sep 2003 | A1 |
20040032660 | Amitai | Feb 2004 | A1 |
20040033528 | Amitai | Feb 2004 | A1 |
20050078388 | Amitai | Apr 2005 | A1 |
20050083592 | Amitai | Apr 2005 | A1 |
20050180687 | Amitai | Aug 2005 | A1 |
20070070859 | Hirayama | Mar 2007 | A1 |
20070091445 | Amitai | Apr 2007 | A1 |
20070097513 | Amitai | May 2007 | A1 |
20070155277 | Amitai | Jul 2007 | A1 |
20070165192 | Prior | Jul 2007 | A1 |
20080025667 | Amitai | Jan 2008 | A1 |
20080106775 | Amitai et al. | May 2008 | A1 |
20080151379 | Amitai | Jun 2008 | A1 |
20080186604 | Amitai | Aug 2008 | A1 |
20080192239 | Otosaka | Aug 2008 | A1 |
20080198471 | Amitai | Aug 2008 | A1 |
20080278812 | Amitai | Nov 2008 | A1 |
20080285140 | Amitai | Nov 2008 | A1 |
20090010023 | Kanade et al. | Jan 2009 | A1 |
20090052046 | Amitai | Feb 2009 | A1 |
20090052047 | Amitai | Feb 2009 | A1 |
20090059380 | Moliton et al. | Mar 2009 | A1 |
20090097127 | Amitai | Apr 2009 | A1 |
20090122414 | Amitai | May 2009 | A1 |
20090153437 | Aharoni | Jun 2009 | A1 |
20100027289 | Aiki et al. | Feb 2010 | A1 |
20100053148 | Khazeni et al. | Mar 2010 | A1 |
20100171680 | Lapidot et al. | Jul 2010 | A1 |
20100278480 | Vasylyev | Nov 2010 | A1 |
20100291489 | Moskovits et al. | Nov 2010 | A1 |
20110176218 | Noui | Jul 2011 | A1 |
20120044572 | Simmonds | Feb 2012 | A1 |
20120081789 | Mukawa | Apr 2012 | A1 |
20120179369 | Lapidot et al. | Jul 2012 | A1 |
20130163089 | Bohn | Jun 2013 | A1 |
20130229717 | Amitai | Sep 2013 | A1 |
20130242392 | Amirparviz | Sep 2013 | A1 |
20130250430 | Robbuns et al. | Sep 2013 | A1 |
20130250431 | Robbins | Sep 2013 | A1 |
20130276960 | Amitai | Oct 2013 | A1 |
20130279017 | Amitai | Oct 2013 | A1 |
20130334504 | Thompson et al. | Dec 2013 | A1 |
20140118813 | Amitai et al. | May 2014 | A1 |
20140118836 | Amitai et al. | May 2014 | A1 |
20140118837 | Amitai et al. | May 2014 | A1 |
20140126051 | Amitai et al. | May 2014 | A1 |
20140126052 | Amitai et al. | May 2014 | A1 |
20140126056 | Amitai et al. | May 2014 | A1 |
20140126057 | Amitai et al. | May 2014 | A1 |
20140126175 | Amitai et al. | May 2014 | A1 |
20140192418 | Suzuki | Jul 2014 | A1 |
20150138451 | Amitai | May 2015 | A1 |
20150198805 | Mansharof et al. | Jul 2015 | A1 |
20150205140 | Mansharof et al. | Jul 2015 | A1 |
20150205141 | Mansharof et al. | Jul 2015 | A1 |
20150219834 | Nichol et al. | Aug 2015 | A1 |
20150277127 | Amitai | Oct 2015 | A1 |
20150293360 | Amitai | Oct 2015 | A1 |
20160116743 | Amitai | Apr 2016 | A1 |
20160170212 | Amitai | Jun 2016 | A1 |
20160170213 | Amitai | Jun 2016 | A1 |
20160170214 | Amitai | Jun 2016 | A1 |
20160187656 | Amitai | Jun 2016 | A1 |
20160313567 | Kurashige | Oct 2016 | A1 |
20160314564 | Jones et al. | Oct 2016 | A1 |
20160341964 | Amitai | Nov 2016 | A1 |
20160349518 | Amitai et al. | Dec 2016 | A1 |
20170003504 | Vallius | Jan 2017 | A1 |
20170023761 | Dural et al. | Jan 2017 | A1 |
20170045744 | Amitai | Feb 2017 | A1 |
20170052376 | Amitai | Feb 2017 | A1 |
20170052377 | Amitai | Feb 2017 | A1 |
20170122725 | Yeoh | May 2017 | A1 |
20170276947 | Yokoyama | Sep 2017 | A1 |
20170336636 | Amitai et al. | Nov 2017 | A1 |
20170357095 | Amitai | Dec 2017 | A1 |
20170363799 | Ofir et al. | Dec 2017 | A1 |
20180039082 | Amitai | Feb 2018 | A1 |
20180067315 | Amitai et al. | Mar 2018 | A1 |
20180101087 | Shiohara | Apr 2018 | A1 |
20180157057 | Gelberg et al. | Jun 2018 | A1 |
20180210202 | Danziger | Jul 2018 | A1 |
20180267317 | Amitai | Sep 2018 | A1 |
20180275384 | Danziger et al. | Sep 2018 | A1 |
20180292592 | Danziger | Oct 2018 | A1 |
20180292599 | Ofir et al. | Oct 2018 | A1 |
20180373039 | Amitai | Dec 2018 | A1 |
20190011710 | Amitai | Jan 2019 | A1 |
20190056600 | Danziger et al. | Feb 2019 | A1 |
20190064518 | Danziger | Feb 2019 | A1 |
20190155035 | Amitai | May 2019 | A1 |
20190170327 | Eisenfeld et al. | Jun 2019 | A1 |
20190208187 | Danziger | Jul 2019 | A1 |
20190212487 | Danziger et al. | Jul 2019 | A1 |
20190227215 | Danziger et al. | Jul 2019 | A1 |
20190278086 | Ofir | Sep 2019 | A1 |
20190285900 | Amitai | Sep 2019 | A1 |
20190293856 | Danziger | Sep 2019 | A1 |
20190339530 | Amitai | Nov 2019 | A1 |
20190346609 | Eisenfeld | Nov 2019 | A1 |
20190361240 | Gelberg | Nov 2019 | A1 |
20190361241 | Amitai | Nov 2019 | A1 |
20190377187 | Rubin et al. | Dec 2019 | A1 |
20190391408 | Mansharof | Dec 2019 | A1 |
20200033572 | Danziger et al. | Jan 2020 | A1 |
20200041713 | Danziger | Feb 2020 | A1 |
20200089001 | Amitai et al. | Mar 2020 | A1 |
20200110211 | Danziger et al. | Apr 2020 | A1 |
20200120329 | Danziger | Apr 2020 | A1 |
20200133008 | Amitai | Apr 2020 | A1 |
20200150330 | Danziger et al. | May 2020 | A1 |
20200183159 | Danziger | Jun 2020 | A1 |
20200183170 | Amitai et al. | Jun 2020 | A1 |
20200200963 | Eisenfeld et al. | Jun 2020 | A1 |
20200209667 | Sharlin et al. | Jul 2020 | A1 |
20200225476 | Urness et al. | Jul 2020 | A1 |
20200241308 | Danziger et al. | Jul 2020 | A1 |
20200249481 | Danziger et al. | Aug 2020 | A1 |
20200278557 | Greenstein et al. | Sep 2020 | A1 |
20200285060 | Amitai | Sep 2020 | A1 |
20200292417 | Lobachinsky et al. | Sep 2020 | A1 |
20200292744 | Danziger | Sep 2020 | A1 |
20200292819 | Danziger et al. | Sep 2020 | A1 |
20200310024 | Danziger et al. | Oct 2020 | A1 |
20200326545 | Amitai et al. | Oct 2020 | A1 |
20200371311 | Lobachinsky et al. | Nov 2020 | A1 |
20210003849 | Amitai et al. | Jan 2021 | A1 |
20210018755 | Amitai | Jan 2021 | A1 |
20210033773 | Danziger et al. | Feb 2021 | A1 |
20210033862 | Danziger et al. | Feb 2021 | A1 |
20210033872 | Rubin et al. | Feb 2021 | A1 |
20210055218 | Aldaag et al. | Feb 2021 | A1 |
20210055466 | Eisenfeld et al. | Feb 2021 | A1 |
20210055561 | Danziger et al. | Feb 2021 | A1 |
20210063733 | Ronen | Mar 2021 | A1 |
20210072553 | Danziger et al. | Mar 2021 | A1 |
20210099691 | Danziger | Apr 2021 | A1 |
20210109351 | Lumus | Apr 2021 | A1 |
20210116367 | Gelberg et al. | Apr 2021 | A1 |
20210141141 | Danziger et al. | May 2021 | A1 |
20210157150 | Amitai | May 2021 | A1 |
20210165231 | Gelberg et al. | Jun 2021 | A1 |
20210239898 | Danziger et al. | Aug 2021 | A1 |
20210271006 | Ronen et al. | Sep 2021 | A1 |
20220003914 | Danziger et al. | Jan 2022 | A1 |
20220004001 | Danziger et al. | Jan 2022 | A1 |
20220004014 | Ronen et al. | Jan 2022 | A1 |
20220019018 | Gilo et al. | Jan 2022 | A1 |
20220030205 | Danziger | Jan 2022 | A1 |
20220043269 | Maziel | Feb 2022 | A1 |
20220043272 | Amitai | Feb 2022 | A1 |
Number | Date | Country |
---|---|---|
103837988 | Jun 2014 | CN |
1514977 | Jun 1978 | GB |
H09258062 | Oct 1997 | JP |
2006145644 | Jun 2006 | JP |
2010044172 | Feb 2010 | JP |
2012058404 | Mar 2012 | JP |
2012123936 | Jun 2012 | JP |
2016028275 | Feb 2016 | JP |
2015012280 | Jan 2015 | WO |
2018013307 | Jan 2018 | WO |
Entry |
---|
S.Chattopadhyay el al: “Anti-reflecting and pholonic nanostruclures”, Materials Science and Engineering: R: Repots, ol. 69, No. 1-3, Jun. 20, 2010, pp. 1-35. |
Petros Stavroulakis et al: Suppression of backscattered diffraction from sub-wavelenght “moth-eye” arrays References and Links/ Optics Express 1, Endeavour Nanotechnology Zoolog_ Sci_ Philos_ Trans_ J_ Mod_ Opt Appl ppt. Opt. Acta {Lond.) Appl. Opt. Appl. Opt. Opt. Lett. Jpn.□Appl. Pjys. J. Ceram. Soc. Jpn. Opt. Commun. App;. Opt ppt. Lett. Nanotechno, Jan. 1, 1967, pp. 79-84. |
Piaoyin Yang et al.: “Antireflection effects at nanostructured material interfaces and the suppression of thin-film nterference”, Nanotechnology, vol. 24, No. 23, May 15, 2013, p. 235202. |
Chih-Hao Chang, et al ;“Nanostructured gradient-index antireflection diffractive optics”, in 354 Optics Letters / vol. 36, No. 12 / Jun. 15, 2011. https://sites.utexas.edu/chang/files/2015/02/Chang_OL_GRINGrating.pdf. |
R. J. Weiblen et al; “Optimized moth-eye anti-reflective structures for As2S3 chalcogenide optical fibers” in Optics Express vol. 24, Issue 10, pp. 10172-10187 (2016) ⋅https://doi.org/10.1364/OE.24.010172. |
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20210018755 A1 | Jan 2021 | US |
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