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KR-102965167-B1 - ejection pupil dilator

KR102965167B1KR 102965167 B1KR102965167 B1KR 102965167B1KR-102965167-B1

Abstract

According to an exemplary embodiment of the present invention, an Exit Pupil Expander (EPE) grating divided into at least two segments is provided, wherein the EPE grating comprises a plurality of grating bars in a first segment and a plurality of grating bars in a second segment, wherein the plurality of grating bars of the first segment are oriented in the same direction as the plurality of grating bars of the second segment and may be misaligned in a direction perpendicular to the direction of the grating bars.

Inventors

  • 라주넨, 한나
  • 사스타모이넨, 토니

Assignees

  • 디스페릭스 오와이

Dates

Publication Date
20260513
Application Date
20210525
Priority Date
20200529

Claims (18)

  1. As an injection pupil dilator grating (EPE grating) divided into at least two segments, The above EPE grating includes a plurality of grating bars in a first segment and a plurality of grating bars in a second segment, and A plurality of grating bars of the first segment are oriented in the same direction as a plurality of grating bars of the second segment, and are misaligned in a direction perpendicular to the direction of the grating bars, An EPE grating characterized in that a plurality of grating bars of the first segment and a plurality of grating bars of the second segment are misaligned so that a light ray propagating along a different path in the EPE grating undergoes a different phase shift.
  2. delete
  3. In Article 1, EPE grating characterized in that each of the plurality of grating bars in the second segment is offset by a certain distance relative to the corresponding grating bar in the first segment in a direction perpendicular to the direction of the grating bar.
  4. In Paragraph 3, EPE grating characterized in that the first grating bar of the first segment is a grating bar corresponding to the first grating bar of the second segment, and the second grating bar of the first segment is a grating bar corresponding to the second grating bar of the second segment.
  5. In Paragraph 3, An EPE grating characterized by the above distance being smaller than the period of the EPE grating.
  6. In Paragraph 3, An EPE grating characterized in that each of the plurality of bars within the second segment is offset by the distance in the lateral direction from the corresponding grating bar within the first segment.
  7. In Paragraph 3, An EPE grating characterized in that each of the plurality of bars in the second segment is offset by the distance in the vertical direction from the corresponding grating bar in the first segment.
  8. In Article 1, The above EPE grating is characterized by being doubly periodic.
  9. In Article 1, An EPE grating characterized in that the first segment of the EPE grating is arranged to cause a first phase shift with a ray deflected from the first segment, and the second segment of the EPE grating is arranged to cause a second phase shift with a ray deflected from the second segment.
  10. In Article 9, An EPE grating characterized in that the first phase shift is different from the second phase shift.
  11. In Article 9, EPE grating characterized in that the amplitude of the deflected light ray in the first segment is the same as the amplitude of the deflected light ray in the second segment.
  12. In Article 1, An EPE grating characterized in that the second segment above follows the first segment for a beam guided to the EPE grating.
  13. In Article 1, The EPE grating further comprises a plurality of grating bars within a third segment, wherein each of the plurality of bars within the third segment is offset by a certain distance in a direction perpendicular to the direction of the grating bar from a corresponding grating bar within the first segment.
  14. In Article 1, EPE grating characterized in that the distance between consecutive grating bars of the first segment is the same as the distance between consecutive grating bars of the second segment.
  15. In Article 1, The EPE grating is characterized by being arranged to diffuse and combine light from the EPE grating.
  16. In Article 1, The EPE grating is characterized by being arranged to maintain the amplitude of light rays propagating through different paths within the EPE grating without changing.
  17. In an optical waveguide device for displaying an image, - Optical waveguide; - An in-coupling grating for diffractively coupling the above image into the optical waveguide; - An out-coupling grating for diffractively coupling the image out of the optical waveguide; and - EPE grating according to Article 1; Includes, An optical waveguide device characterized in that the above EPE grating exists between the out-coupling grating and the in-coupling grating, which expands the exit pupil of the image on the out-coupling grating.
  18. A personal display device comprising an optical waveguide device according to claim 17.

Description

ejection pupil dilator [0001] Embodiments of the present invention generally relate to an exit pupil expander (EPE), and more specifically to an exit pupil expander for an optical waveguide device, such as a waveguide-based display. [0002] Generally, there is a need to provide improvements related to the exit pupil dilator (EPE). Light rays typically interfere with the EPE grating and thus cause non-uniformity in the out-coupled image. Therefore, there is a need to reduce interference caused by light rays interfering with the EPE grating. [0003] For example, US 2018/0052501 A1 discusses EPE, which represents wave interference caused by uniform grating in an orthogonal pupil expander (OPE). Wave interference can be reduced, and luminance uniformity of the output image can be increased, for example, by changing the grating parameters or material at different locations. [0010] FIG. 1 illustrates an exemplary system according to at least some embodiments of the present invention. [0011] FIG. 2a illustrates an example of an optical waveguide device according to at least some embodiments of the present invention. [0012] FIG. 2b illustrates an example of an in-coupling grating, an out-out pupil dilator, and an out-coupling grating according to at least some embodiments of the present invention. [0013] FIG. 3 illustrates an example of an injection pupil dilator according to at least some embodiments of the present invention. [0014] FIG. 4 illustrates a first example of offset grating bars according to at least some embodiments of the present invention. [0015] FIGS. 5a and FIGS. 5b illustrate a second example of offset grating bars according to at least some embodiments of the present invention. [0016] FIG. 6 illustrates an example of a phase shift according to at least some embodiments of the present invention. [0017] FIGS. 7a and 7b illustrate an example of an offset two-dimensional grating bar according to at least some embodiments of the present invention. [0018] FIG. 8 illustrates an exemplary distribution of distances moved in different segments according to at least some embodiments of the present invention. [0019] Embodiments of the present invention relate, for example, to an Exit Pupil Expander (EPE) for an optical waveguide device. More specifically, embodiments of the present invention provide an EPE grating that reduces interference effects caused by interfering light rays in an EPE grating. According to an embodiment of the present invention, the EPE grating is divided into at least two segments having different phase shifts. Each of the at least two segments may include a plurality of grating bars, and the grating bars of each segment may be arranged to cause different phase shifts, such as different phase shifts controlled according to Lohmann's detour-phase principle, when a light ray propagates along a different path through the segment. Thus, the EPE grating may not be altered to maintain the same amplitude of light rays propagating along different paths, that is, to provide more degrees of freedom to modify the operation of the optical waveguide. For example, interference caused by light rays interfering with the EPE grating can be reduced. [0020] An EPE grating may include a plurality of grating bars in a first segment and a plurality of grating bars in a second segment, wherein the plurality of grating bars in the first segment are misaligned compared to the plurality of grating bars in the second segment. That is, the grating bars of the first and second segments may not be in-line, and each of the plurality of bars in the second segment may be offset from the corresponding grating bar in the first segment by a distance in a direction perpendicular to the direction of the grating bars. That is, the offset may mean a distance at which one grating bar is not aligned with the corresponding grating bar. [0021] FIG. 1 illustrates an exemplary system according to at least some embodiments of the present invention. The system may include at least one light source (140). The at least one light source (140) may include, for example, a laser or a light-emitting diode (LED) light source, wherein the laser source has the advantage of being more strictly monochromatic than the LED. Embodiments of the present invention may be implemented using two or more types of light sources (140) without being limited to any specific light source. The at least one light source (140) together with an optional mirror (130) may be arranged to generate a light field in an angular space that can be used to cause a waveguide-based display to generate its image. [0022] An image may be encoded within a light field. The light field is schematically illustrated in FIG. 1 as a field (100). In some embodiments, a physical primary display may display an image of the light field (100), whereas in other embodiments, the system may not include a physical primary display, and the image is encoded only in the light field (100) distribute