Optical Waveguide Grating Radial Scanning
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Solution Overview
Problem
Conventional optical scanning methods using laser beams are limited by mechanical structures, which are slow, large, and expensive, and face challenges in controlling the phase of laser light due to the small wavelength of light compared to radio waves, making it difficult to form wavefronts with submicron spacing.
Innovation Solution
An optical device with a light source, an optical waveguide element, and a control circuit that includes a first grating causing laser light to propagate radially and a second grating for emission, with a transparent member and a polarization rotator to control the direction and polarization of light, enabling efficient scanning without mechanical structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical structures are used for optical scanning, then the scanning system can be implemented, but the scanning speed is slow and the device size is large
Solution Approach 1:
The patent replaces mechanical scanning structures with an optical waveguide element that uses gratings to control light propagation. The first grating converts incident laser light into radially propagating guided light, and the second grating converts it back to emitted light, eliminating the need for mechanical moving parts while achieving fast scanning speeds.
Solution Approach 2:
The patent transitions from mechanical rotation in physical space to phase modulation in optical space. By controlling the phase of laser light through grating structures and polarization rotation, the system achieves scanning without mechanical movement, effectively moving the operation from one dimension (mechanical rotation) to another (optical phase control).
2Measurement precision
If the wavelength of light is small compared to radio waves, then the resolution is improved, but it becomes difficult to control the phase and form wavefronts with submicron spacing
Solution Approach 1:
The patent introduces a polarization rotator as an intermediary device between the light source and the waveguide element. This polarization rotator controls the polarization state of incident light, which in turn controls the phase and direction of guided light propagation through the grating structures, enabling precise phase control without directly manipulating the light wavefronts.
Solution Approach 2:
The patent controls the phase and direction of light by changing the polarization parameter of the incident laser light. By rotating the polarization state before light enters the waveguide element, the system achieves precise control over the guided light's propagation characteristics, converting a difficult-to-control parameter (phase) into an easier-to-control parameter (polarization state).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The optical device enables efficient and precise scanning of objects within a field of view by controlling the direction and polarization of laser light, reducing the need for mechanical structures and improving scanning speed and accuracy.
Implementation Method 1
a first grating that includes a plurality of portions arranged in a radial direction of a virtual circle centered on a point where the laser light is incident and having mutually different refractive indices, and that causes a portion of the laser light that is incident to be propagated in the radial direction within the optical waveguide element as propagation light
Implementation Method 2
having mutually different refractive indices
Implementation Method 3
a second grating that includes a plurality of portions arranged outside the first grating, arranged in the radial direction, and having mutually different refractive indices, and that causes a portion of the propagation light to be emitted from the optical waveguide element as emission light
Implementation Method 4
having mutually different refractive indices
Implementation Method 5
The emission light is incident on the first transparent member from the bottom surface or the side surface, and is emitted from the side surface
Data Source
AI summary
An optical device includes: a light source that emits laser light; an optical waveguide element positioned on the optical path of the laser light; a first member positioned on the optical path, and has a bottom surface that faces the optical waveguide element, and a side surface that is rotationally symmetric about the optical path; and a control circuit. The optical waveguide element includes: a first grating that includes a plurality of portions arranged in the radial direction and having mutually different refractive indices, and that causes a portion of the laser light that is incident to be propagated in the radial direction within the optical waveguide element; and a second grating that includes a plurality of portions arranged outside the first grating, arranged in the radial direction, and having mutually different refractive indices, and that causes light to be emitted from the optical waveguide element.