LiDAR Optical System Beam Waist Control
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Solution Overview
Problem
LiDAR devices face challenges in achieving high-speed and wide-range optical scanning with high angular resolution while maintaining detection distance, as longer focal lengths required for high angular resolution result in larger beam waist diameters that may not fit on downsized movable mirrors, leading to reduced radiation intensity and shorter detectable distances.
Innovation Solution
An optical system with a first optical element to control the divergence angle of the laser beam from a VCSEL device, combined with a second optical element to focus the beam onto a movable mirror, ensuring a small beam waist diameter and sufficient radiation intensity, even on smaller mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focal length of the focus lens is increased to achieve high angular resolution, then the angular resolution is improved, but the beam waist diameter becomes wider and requires a larger movable mirror
Solution Approach 1:
The patent changes the divergence angle parameter of the laser beam by introducing a first optical element (beam expanding element) between the VCSEL device and the focus lens. By controlling the divergence angle to be within a specific range (5 degrees to 30 degrees), the system achieves high angular resolution without requiring an excessively long focal length, thus avoiding the need for a large movable mirror while maintaining measurement precision.
Solution Approach 2:
The first optical element acts as an intermediary component that mediates between the VCSEL device and the focus lens. This beam expanding element adjusts the beam parameters (divergence angle and beam waist diameter) before the light reaches the focus lens, enabling the system to achieve high angular resolution with a more compact movable mirror by optimizing the intermediate beam state.
2Measurement precision
If the focal length is made longer to increase angular resolution, then the angular resolution is improved, but the radiation intensity of light for optical scanning decreases
Solution Approach 1:
The patent optimizes the divergence angle parameter by introducing a beam expanding element that controls the beam's angular spread. By maintaining the divergence angle within 5 to 30 degrees, the system achieves high angular resolution while preserving sufficient radiation intensity on the movable mirror, avoiding the intensity loss that would occur with excessively long focal lengths.
Solution Approach 2:
The first optical element performs preliminary beam expansion and divergence angle control before the light reaches the focus lens and movable mirror. This preliminary action ensures that the beam has optimal parameters (appropriate divergence angle and beam waist) when it reaches the scanning system, thereby maintaining high radiation intensity while achieving high angular resolution.
3Measurement precision
If the size of the light-emitting area of the VCSEL is reduced to increase angular resolution, then the angular resolution is improved, but the output power of the VCSEL device decreases
Solution Approach 1:
The patent employs a VCSEL device with multiple light-emitting elements (segments) that can be independently controlled. By segmenting the light source into multiple elements arranged in specific patterns, the system achieves high angular resolution through the spatial distribution of these segments while maintaining high output power through the combined emission of all segments. The first optical element further processes each segment's beam to optimize the overall system performance.
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 enables high-speed and wide-range optical scanning with high angular resolution without compromising detection distance, by reducing the beam waist diameter and maintaining radiation intensity on smaller movable mirrors.
Implementation Method 1
an optical element to control the divergence angle of the laser beam emitted from the VCSEL device
Implementation Method 2
a second optical element to focus the laser beam that has passed through the first optical element onto a to-be-scanned surface of the scanner
Implementation Method 3
The VCSEL device performs lasing in a direction perpendicular to the substrate
Data Source
AI summary
An optical device includes a light source provided with a plurality of surface-emitting laser elements to emit a laser beam, a scanner to scan the laser beam emitted from the light source, and an optical system disposed in an optical path between the light source and the scanner and to guide the laser beam to the scanner. The optical system includes a first optical element to control a divergence angle of the laser beam emitted from the light source and a second optical element to concentrate the laser beam that has passed through the first optical element onto a to-be-scanned surface of the scanner.