LiDAR Optical Path Layout to Prevent Stray Light Saturation
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Solution Overview
Problem
Existing LiDAR systems face challenges in accurately measuring the distance to objects due to signal saturation caused by unnecessary light, particularly when distinguishing between reflected light from short-distance objects and unnecessary light.
Innovation Solution
The optical apparatus includes a deflector and a light guide that directs illumination light and reflected light to specific detectors, with an optical element having a tilted or eccentric surface to separate unnecessary light from the principal ray of illumination, thereby preventing signal saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical system and light receiving element are used to detect illumination timing and measure emission light amount, then the ability to detect illumination timing and measure emission light amount is improved, but unnecessary light is generated inside the apparatus and saturates the signal of the light receiving element
Solution Approach 1:
The optical system is divided into separate optical paths: one for distance measurement (through the deflector to the first light receiving element) and another for illumination timing detection (through the light guide to the second light receiving element). This segmentation allows each subsystem to function independently, preventing unnecessary light from one path from interfering with the other.
Solution Approach 2:
The unnecessary light (stray light) generated inside the apparatus is extracted and directed away from the light receiving element used for distance measurement. The light guide system separates the illumination timing detection path from the distance measurement path, removing the harmful effect of internal stray light from the measurement path.
2Measurement precision
If the reflected light from a short-distance object is received, then the distance measurement capability is improved, but the reflected light cannot be distinguished from unnecessary light causing signal saturation
Solution Approach 1:
The detection system is segmented into two separate light receiving elements: the first for distance measurement and the second for illumination timing detection. This segmentation enables the system to distinguish between reflected light from objects and unnecessary internal light, as each element receives light through a dedicated optical path.
Solution Approach 2:
The light guide acts as an intermediary that directs illumination light to the second light receiving element for timing detection, while the deflector and associated optics serve as intermediaries for directing reflected light to the first light receiving element for distance measurement. These intermediary components ensure that each detector receives only the intended light signal.
3Ease of operation
If a light guide is used to direct illumination light to the deflector and light receiving element, then the optical path control is improved, but unnecessary light may still reach the light receiving element causing saturation
Solution Approach 1:
The optical path is segmented into distinct segments: the light guide for illumination timing detection and the deflector system for distance measurement. This segmentation ensures that unnecessary light generated in one segment does not contaminate the other segment's detection process.
Solution Approach 2:
The light guide system extracts and directs a portion of the illumination light to the second light receiving element, separating this function from the main distance measurement path. This extraction prevents the unnecessary light that would otherwise reach the first light receiving element from causing signal saturation.
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
This configuration effectively reduces the reception of unnecessary light by the light receiving elements, allowing for accurate distance measurement even in the presence of short-distance objects, thereby enhancing the precision of LiDAR systems.
Implementation Method 1
an optical element having an optical surface provided between the light guide and the second light receiving element. The optical surface tilts or is eccentric to a principal ray of the illumination light
Implementation Method 2
a deflector configured to deflect illumination light from a light source unit so as to scan an object and configured to deflect reflected light from the object
Implementation Method 3
a light guide configured to guide part of the illumination light from the light source unit to the deflector, another part to a first light receiving element
Implementation Method 4
the reflected light from the deflector to a second light receiving element
Data Source
AI summary
An optical apparatus includes a deflector configured to deflect illumination light from a light source unit so as to scan an object and configured to deflect reflected light from the object, a light guide configured to guide part of the illumination light from the light source unit to the deflector, another part to a first light receiving element, and the reflected light from the deflector to a second light receiving element, and an optical element having an optical surface provided between the light guide and the second light receiving element. The optical surface tilts or is eccentric to a principal ray of the illumination light.