Light Guide Optics Layout to Reduce LiDAR Stray Light
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Solution Overview
Problem
Existing distance measuring apparatuses face challenges in achieving accurate distance measurements due to the scattering of illumination light by scratches and foreign objects on optical surfaces, leading to unnecessary light generation and reduced measurement accuracy, particularly when using prisms for light reflection and shaping.
Innovation Solution
An optical apparatus with a light guide unit having non-parallel first and second surfaces, where illumination light is incident on a transmissive region without passing through other surfaces, allowing for shaping using a minimum number of optical surfaces, thereby reducing scattering and unnecessary light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If illumination light is reflected by the inner surface of a prism to shape the light, then the illumination light can be shaped, but part of the illumination light is scattered by scratches and foreign objects on each optical surface of the prism and incident on the light-receiving element as unnecessary light
Solution Approach 1:
The optical element is divided into distinct functional regions: a first surface for light entry, a second surface with a transmissive region for shaped light transmission, and a reflective region for reflected light redirection. This segmentation allows the illumination light to pass through only two optical surfaces (first and second surfaces) rather than multiple surfaces, reducing scattering from scratches and foreign objects while maintaining light shaping capability through the configured geometry of these surfaces
Solution Approach 2:
The patent extracts and eliminates the problematic intermediate optical surfaces that cause light scattering. By configuring the optical element so that illumination light passes directly from the first surface to the second surface without encountering other optical surfaces in between, the harmful scattering effect is removed while the light shaping function is preserved through the geometric configuration of the first and second surfaces
2Shape
If other optical elements are used to shape the illumination light, then the illumination light can be shaped, but the entire apparatus becomes complicated
Solution Approach 1:
The optical element performs multiple functions simultaneously: it guides illumination light from the light source to the deflection unit, shapes the illumination light through its geometric configuration, and redirects reflected light to the light-receiving element. By integrating light shaping, light guiding, and light redirection functions into a single optical element, the patent eliminates the need for separate optical components, thereby simplifying the apparatus structure while achieving favorable distance measurement accuracy
Solution Approach 2:
The patent merges the light shaping function with the light guiding function by configuring the optical element's geometry such that the first and second surfaces both guide and shape the illumination light. This merging of functions reduces the total number of optical components needed, simplifying the overall apparatus while maintaining effective light shaping capability
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 apparatus achieves favorable distance measurement accuracy by minimizing unnecessary light, ensuring accurate detection even at long distances with reduced complexity and size, and supports on-vehicle systems for object detection.
Implementation Method 1
a second surface including a transmissive region through which the illumination light from the first surface is transmitted
Implementation Method 2
a reflective region that reflects the reflected light from the deflection unit
Data Source
AI summary
An optical apparatus includes a deflection unit configured to deflect illumination light from a light source to scan an object and deflect reflected light from the object, and a light guide unit configured to guide the illumination light from the light source to the deflection unit and guide the reflected light from the deflection unit to a light-receiving element, wherein the light guide unit includes a first surface on which the illumination light from the light source is incident and a second surface including a transmissive region through which the illumination light from the first surface is transmitted and a reflective region that reflects the reflected light from the deflection unit, wherein the first and the second surfaces are non-parallel to each other, and wherein the illumination light from the first surface is incident on the transmissive region without passing through other surfaces.