Facebook Technologies, LLC

Meta Platforms Technologies, LLC

Kavous Jorabchi

Austin Lane

Matthieu Charles Raoul Leibovici

Wanli Chi

Yang Yang

Peter Topalian

Janee Ashley McNeil

Marvin Dion Alim

A device for determining coplanarity of two surfaces includes an illumination system for providing first light to a first surface and providing second light to a second surface. The first surface redirects at least a portion of the first light and the second surface redirects at light a portion of the second light. The device also includes an optical detector positioned to receive an overlap of the redirected portion of the first light and the redirected portion of the second light. An image of the overlap of the redirected portion of the first light and the redirected portion of the second light indicates coplanarity of the first surface and the second surface.

Optical alignment for ultra-high coplanarity of two planes

A grating coupler may be fabricated by exposing a photopolymer layer to grating forming light for forming periodic refractive index variations in the photopolymer layer. The photopolymer layer may be exposed to apodization light for reducing an amplitude of the periodic refractive index variations in a spatially-selective manner. The apodization may also be achieved or facilitated by subjecting outer surface(s) of the photopolymer layer to a chemically reactive agent that causes the refractive index contrast to be reduced near the surface(s) of application. The apodized refractive index profile of the gratings facilitates the reduction of optical crosstalk between different gratings of the grating coupler.

Apodization of refractive index profile in volume gratings

A waveguide, e.g. an image-replicating waveguide, is provided. The waveguide includes a substrate having two outer surfaces, for propagating a beam of image light in the substrate by reflecting the beam from the outer surfaces. A diffraction grating is supported by the substrate and configured for diffracting the impinging beam. A partial reflector is disposed in the substrate between and parallel to the first and second surfaces. The partial reflector is configured for splitting the impinging beam, increasing the number of beam portions in the waveguide, thereby improving output pupil density.

Waveguide having partial reflector

A monitoring system monitors changes in an index of refraction of the grating over a time interval that includes the period of time. The monitoring system includes a light source assembly, a probing assembly, a power meter (e.g., a diffraction and/or a transmittance power meter), and a controller. The light source assembly emits a probe beam. The scanning assembly scans the probe beam over an area of the grating. The power meter measures power of a portion of the probe beam that interacts (e.g., is transmitted by or diffracted from) with the area of the grating. The controller determines changes in grating parameters (may be as a function of time) for the grating being formed based in part on measured power readings over the time interval.

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Bellevue, WA, United States of America

Kavous Jorabchi