Lidar Optical Window with Scratch-Resistant Multilayer Coating
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Solution Overview
Problem
LIDAR systems face performance degradation due to window damage from environmental impacts and microwave radiation interference, with existing windows failing to provide adequate durability and optical filtering for infrared and visible spectra.
Innovation Solution
A window design featuring alternating high and low refractive index layers on both outer and inner surfaces, including a scratch-resistant layer and optional absorption layers or transparent conductive oxide layers, configured to achieve high infrared transmittance and low visible transmittance, while providing microwave shielding and tunable color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a window is placed to protect the laser and sensor from environmental impacts, then protection from rocks and objects is improved, but the window becomes susceptible to scratching and damage that scatters laser beams
Solution Approach 1:
The window employs a composite structure with a glass substrate and multiple deposited layers including silicon nitride, silicon oxide, and other materials. This composite construction provides both environmental protection and enhanced scratch resistance, resolving the contradiction between protection and durability.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the window surface through controlled deposition of multiple layers with specific thicknesses (e.g., 50-200 nm for silicon nitride, 100-500 nm for silicon oxide). These parameter changes enhance hardness and scratch resistance while maintaining optical performance.
2Use of energy by moving object
If the window provides high transmittance in the infrared spectrum for LIDAR operation, then LIDAR effectiveness is improved, but visible light transmittance may interfere with aesthetics and visibility
Solution Approach 1:
The window exhibits different optical properties at different wavelength ranges. The layered structure is specifically designed to provide high transmittance in the infrared spectrum (905 nm and 1550 nm wavelengths) while providing low transmittance in the visible spectrum, achieving local quality optimization for different spectral regions.
Solution Approach 2:
The window's optical properties are tuned to appear colored or tinted in the visible spectrum while remaining transparent to infrared radiation. This color characteristic improves aesthetics and reduces visible light interference while maintaining LIDAR effectiveness.
3Ease of manufacture
If the window structure is simplified for ease of manufacture, then manufacturing cost is reduced, but durability and optical filtering performance may be compromised
Solution Approach 1:
The window manufacturing process is segmented into discrete deposition steps, with each layer (silicon nitride, silicon oxide, etc.) deposited separately with controlled thicknesses. This segmentation enables precise control of optical and mechanical properties while maintaining manufacturability through standardized processes.
Solution Approach 2:
The patent specifies precise parameter ranges for each layer thickness (e.g., silicon nitride: 50-200 nm, silicon oxide: 100-500 nm) that can be controlled during deposition. These parameter specifications enable consistent manufacturing of durable windows with optimized optical filtering 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
The window design enhances durability against environmental impacts, maintains high infrared transmittance, minimizes visible light transmission, and offers effective microwave shielding, thereby improving LIDAR system performance and aesthetics.
Implementation Method 1
The outer layered film comprises a plurality of alternating high index and low index layers. The inner layered film comprises a plurality of alternating high index and low index layers. Each of the high index layers has a refractive index greater than a refractive index of each of the low index layers.
Implementation Method 2
The quantity, thicknesses and materials of the plurality of alternating high index and low index layers of the outer layered film and the inner layered film are configured so that the window exhibits an average transmittance of greater than 85% within ±25 nm of at least one wavelength within the infrared spectrum
Implementation Method 3
The outer layered film comprises a scratch resistant layer having a thickness from about 0.5 μm to about 10 μm. The outer layered film exhibits a hardness of at least 11 GPa, as measured with a Berkovich Indenter Hardness Test from the outermost surface of the outer layered film to a depth of 1 μm.
Implementation Method 4
The inner layered film or the outer layered film comprises a transparent conductive oxide layer
Data Source
AI summary
A window for a sensing system is provided that includes: a substrate comprising an outer and an inner primary surface; an outer layered film disposed on the outer primary surface; and an inner layered film disposed on the inner primary surface. Each of the outer and inner layered films comprises alternating high index and low index layers. The outer layered film comprises a scratch resistant layer having a thickness from about 0.5 μm to about 10 μm, and exhibits a hardness of at least 11 GPa, as measured with a Berkovich Indenter Hardness Test. The window exhibits an average transmittance of greater than 85% within ±25 nm of at least one wavelength within the infrared spectrum from 900 nm to 1600 nm and an average transmittance of less than 5% in the visible spectrum from 420 nm to 650 nm, each at an angle of incidence<15°.