Apple Inc.
Grating-based spatial mode filter for laser scanning

Abstract:

An optical device includes a laser light source configured to emit a collimated beam of light, and a scanning mirror, which is configured to reflect and scan the beam of light over a predefined angular range. The optical device further includes a volume holographic grating (VHG), which is positioned to receive and reflect the collimated beam emitted by the laser light source toward the scanning mirror by Bragg reflection at a predefined Bragg-angle, while transmitting the beam reflected from the scanning mirror over a part of the angular range that is outside a cone containing the Bragg-angle.