Polished Polygon Mirror Surfaces for Low-Scatter LiDAR Scanning
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Solution Overview
Problem
Traditional polygon mirrors in lidar systems are prone to surface scratches during machining, leading to unwanted light scattering and reduced accuracy in distance measurements.
Innovation Solution
Polygon mirrors made from materials like glass or glass ceramic, polished to achieve low surface roughness, eliminating the need for diamond-turning and reducing surface defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional metal polygon mirrors are machined using diamond-turning process, then manufacturing ease is improved, but surface roughness increases causing unwanted light scattering
Solution Approach 1:
The patent replaces the mechanical diamond-turning process with a polishing process that achieves superior surface finish. The metal polygon mirror is subjected to polishing treatment that removes tool marks and scratches, achieving an RMS surface roughness of 1.5 nm or less, thereby eliminating the harmful light scattering while maintaining manufacturing feasibility.
Solution Approach 2:
The patent changes the surface finish parameter through controlled polishing processes. By adjusting polishing parameters such as abrasive material, pressure, and polishing time, the surface roughness is reduced to 1.5 nm or less, transforming the surface quality from the scratchy state produced by diamond-turning to a mirror-quality finish that prevents light scattering.
2Strength
If traditional metal polygon mirrors are used, then structural strength is maintained, but density increases requiring more rotation energy
Solution Approach 1:
The patent changes the material density parameter by switching from traditional metal (aluminum) to glass or glass ceramic materials. These materials have lower density, reducing the mass of the polygon mirror and consequently the energy required for rotation, while still providing sufficient structural strength and optical properties for lidar system operation.
Solution Approach 2:
The patent employs glass or glass ceramic composite materials that combine optical transparency with mechanical strength. These materials offer a favorable density-strength ratio, providing the necessary structural integrity for the rotating mirror function while significantly reducing the mass compared to traditional metal mirrors, thereby lowering rotational energy requirements.
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 low surface roughness mirrors provide improved light reflection and reduced power consumption, enhancing measurement accuracy and efficiency in lidar systems.
Implementation Method 1
The polygon mirror rotates so that light from the light source reflects off the different reflective surfaces of the polygon mirror. The light is reflected outward, away from the lidar system, so that it scans an area for objects.
Data Source
AI summary
A polygon mirror that includes a top surface, a bottom surface, and a plurality of reflective surfaces disposed between the top surface and the bottom surface. Each reflective surface of the plurality of reflective surfaces forms an angle θ with an adjacent reflective surface. Additionally, each reflective surface of the polygon mirror has an RMS surface roughness of about 1.5 nm or less.