JP-7855056-B2 - Fresnel reflection-based optical pick-off element for laser-based systems

Inventors

• アデマ，ダニエル
• モリソン，バンス・アール

Assignees

• グーグル エルエルシー

Dates

Publication Date

20260507

Application Date

20220810

Priority Date

20210811

Claims (19)

1. Photodetector and, A pick-off element comprising a first surface and a second surface opposite to the first surface, The aforementioned pick-off element is, A first interface is formed on the first surface between a first material having a first refractive index and a second material having a second refractive index, The second interface on the second surface between the first material and the second material, Furthermore, The first refractive index differs from the second refractive index, A laser projection system in which the pick-off element is configured to deflect a first portion of the received light from the first interface toward the photodetector via a first Fresnel reflection, and deflect a second portion of the received light from the second interface toward a second photodetector or optical scanner via a second Fresnel reflection.
2. The laser projection system according to claim 1, wherein the first material comprises at least one of N-BK7 borosilicate crown glass, fused silica, crown glass, flint glass, sapphire, diamond, barium fluoride, or calcium fluoride, and the second material comprises air.
3. The laser projection system according to claim 1, wherein the pick-off element is a prism, the first surface is the input surface of the prism, and the prism receives the received light at the input surface.
4. The laser projection system according to claim 1, wherein the pick-off element is a prism, the first surface is the output surface of the prism, and the prism outputs the received light through the output surface.
5. The laser projection system is An optical engine including multiple laser sources configured to generate multiple laser beams, The system further includes a beam combiner configured to combine the plurality of laser beams into a concentrated laser beam and to output the concentrated laser beam. The received light includes the concentrated laser beam, and the laser projection system is configured to determine the laser output of one or more of the plurality of laser sources of the optical engine. The laser projection system is The optical scanner is configured to receive the concentrated laser beam from the beam combiner after the concentrated laser beam has passed through the pick-off element, and to scan the concentrated laser beam. The laser projection system according to claim 1, further comprising: a waveguide configured to receive the scanned concentrated laser beam from the optical scanner and to project the scanned concentrated laser beam.
6. The first photodetector and The system includes a beam combiner configured to receive a first laser beam and a second laser beam, and to combine the first laser beam and the second laser beam into a concentrated laser beam, wherein the beam combiner A first pick-off interface configured to deflect a first portion of the concentrated laser beam toward the first photodetector via a first Fresnel reflection, A first primary index substrate comprising a first material having a first refractive index, The first secondary index substrate comprises a second material having a second refractive index different from the first refractive index, The first pick-off interface is a laser projection system positioned between the first primary index substrate and the first secondary index substrate.
7. The laser projection system according to claim 6, wherein the first material and the second material each comprise different materials selected from the group consisting of N- BK7 borosilicate crown glass, fused silica, crown glass, flint glass, sapphire, diamond, barium fluoride, and calcium fluoride .
8. The aforementioned beam combiner is A second primary index substrate comprising the first material having the first refractive index, The present invention further comprises a second pick-off interface disposed between the first secondary index substrate and the second primary index substrate, The second pick-off interface is configured to deflect a second portion of the concentrated laser beam toward the first photodetector via a second Fresnel reflection. The laser projection system according to claim 7 .
9. The laser projection system according to claim 8, wherein the first optical path of the first portion of the concentrated laser beam deflected by the first pick-off interface is separate from the second optical path of the second portion of the concentrated laser beam deflected by the second pick-off interface.
10. The laser projection system according to claim 8, wherein the first optical path of the first portion of the concentrated laser beam deflected by the first pick-off interface at least partially overlaps with the second optical path of the second portion of the concentrated laser beam deflected by the second pick-off interface.
11. The beam combiner further comprises a mirror positioned on the first side, The laser projection system according to claim 8, wherein the mirror reflects at least a portion of the first and second portions of the concentrated laser beam toward the first photodetector, and the first photodetector is located on the second side of the beam combiner opposite the first side.
12. The beam combiner further comprises an additional mirror positioned on the second side, The laser projection system according to claim 11, wherein the additional mirror receives the first and second portions of the concentrated laser beam from the mirror and reflects the first and second portions of the concentrated laser beam toward the first photodetector.
13. The laser projection system according to claim 11 , wherein the mirror completely reflects the first portion and the second portion of the concentrated laser beam.
14. The laser projection system according to claim 11, wherein the mirror partially reflects only the first portion and the second portion of the concentrated laser beam, thereby reflecting a first fragment of the first portion and the second portion of the concentrated laser beam toward the first photodetector, and passing a second fragment of the first portion and the second portion of the concentrated laser beam through the mirror .
15. The laser projection system according to claim 14, wherein the mirror is configured to have a wavelength-dependent reflectance profile that normalizes the non-uniform response profile of the first photodetector with respect to light reflected from the mirror onto the first photodetector.
16. The laser projection system according to claim 14, further comprising a second photodetector positioned on the first side of the beam combiner and configured to receive the second fragment of the first and second portions of the concentrated laser beam passing through the mirror.
17. The laser projection system according to claim 7 , wherein the first secondary index substrate is located at the first end of the beam combiner, and the concentrated laser beam exits the beam combiner through the first end.
18. The aforementioned beam combiner is The second photodetector, A third photodetector, A second primary index substrate containing the first material, A second secondary index substrate containing the second material, The present invention further comprises a second pick-off interface disposed between the first secondary index substrate and the second primary index substrate, wherein the second pick-off interface is configured to deflect only the first laser beam and the second laser beam toward the second photodetector via a second Fresnel reflection. The laser projection system according to claim 7, further comprising a third pick-off interface disposed between the second primary index substrate and the second secondary index substrate, wherein the third pick-off interface is configured to deflect only the first laser beam from the first and second laser beams toward the third photodetector via a third Fresnel reflection.
19. The first portion of the received light is deflected toward the photodetector via a first Fresnel reflection at the first interface between a first material having a first refractive index and a second material having a second refractive index, The second portion of the received light is redirected toward a second photodetector or optical scanner via a second Fresnel reflection at the second interface between the first material and the second material. A method comprising detecting the intensity of the first deflected portion of the received light with the photodetector.

Description

Background A projector is an optical device for displaying an image or video on another object (e.g., on the surface of another object, such as a projection screen) by projecting or illuminating a pattern of light onto that object. A laser projector is a projector whose light source is at least one laser, which is transiently modulated to give a pattern of laser light, which is then spatially distributed across the display area of another object (e.g., a screen or lens) to display an image or video. To better control the performance of a laser projector, it can be advantageous to monitor the laser output of the laser projector. For example, by accurately monitoring the laser output of a laser projector, the laser output can be controlled to adjust the white point and/or brightness of the display. By referring to the accompanying drawings, this disclosure can be better understood, and many of its features and advantages may become apparent to those skilled in the art. The use of the same reference numerals in different drawings indicates similar or identical items. This figure shows a display system having an integrated laser projection system according to several embodiments.This figure shows a laser projection system having an optical scanner, including an optical relay positioned between two scanning mirrors, according to one of several embodiments.This is a perspective view of a laser projector, according to several embodiments, which includes separate pick-off components for redirecting a portion of the laser light to a photodetector via Fresnel reflection.This figure shows an example of Fresnel reflection deflection of a portion of light from one or more laser beams passing through individual pick-off components, according to some embodiments.This is a perspective view of a laser projector having a beam combiner including a secondary indexing substrate interposed between two primary indexing substrates, according to some embodiments, wherein each primary indexing substrate has a first refractive index and the secondary indexing substrate has a second refractive index, and the difference between the first and second refractive indices causes the laser light beam to be partially reflected toward a photodetector at the interface between the primary and secondary indexing substrates.This figure shows an example in which the thickness of the secondary index substrate in Figure 5 is such that the first and second sets of laser light beams reflected at the input interface and output interface of the secondary index substrate do not overlap, according to several embodiments.This figure shows an example in which the thickness of the secondary index substrate in Figure 5 is such that the first and second sets of laser light beams reflected at the input interface and output interface of the secondary index substrate partially overlap, according to several embodiments.This is a perspective view of a laser projector having a beam combiner including a secondary index substrate interposed between two primary index substrates, according to one embodiment, wherein a mirror is positioned on the first side of the beam combiner to deflect the laser light beam toward a photodetector located on the second side of the beam combiner.This figure shows a perspective view of a laser projector having a beam combiner including a secondary index substrate interposed between two primary index substrates, according to one of several embodiments, wherein a first mirror is positioned on the first side of the beam combiner to deflect the laser light beam toward a photodetector, and a second mirror is positioned on the second side of the beam combiner to deflect the laser light beam toward a photodetector.This chart shows the wavelength response of photodetectors, such as the photodetector shown in Figures 8 and 9, according to several embodiments, as well as the wavelength-tunable reflectance profiles of the first and second partial reflection mirrors.This chart shows the first weighted wavelength response of a coupling between a first partial reflection mirror and a photodetector, and the second weighted wavelength response of a coupling between a second partial reflection mirror and a photodetector, according to several embodiments.This is a perspective view of a laser projector having a beam combiner including a secondary index substrate interposed between two primary index substrates, according to some embodiments, wherein a first beam splitter is positioned on the first side of the beam combiner to deflect the laser beam toward a first photodetector located on the second side of the beam combiner, and to allow a portion of the laser beam to pass through the first beam splitter toward a second photodetector located on the first side of the beam combiner.This is a perspective view of a laser projector having a beam combiner that includes a secondary index substrate positioned adjacent to a primary index substrate at the end of the be