NIR Light-Scattering Coatings for Low-Haze LiDAR Detection
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Solution Overview
Problem
Existing coatings do not effectively enhance the diffuse reflection of near-infrared (NIR) light, particularly from dark and clear objects, while maintaining minimal visible light scattering and absorption, which limits the visibility of objects to LIDAR systems in autonomous vehicles.
Innovation Solution
A coating composition comprising nanoparticles of noble metals or their alloys/oxides with an average diameter of 20 nm to <500 nm, used in a range of 0.01 wt.% to 10.0 wt.% in a basecoat or clearcoat, along with a water and/or organic solvent content of at least 30 wt.%, to achieve diffuse NIR scattering without significant visible light haze or color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coatings are applied to substrates for improved durability and aesthetics, then the coating provides protective and visual properties, but the coating does not sufficiently diffuse reflect near-IR light for LIDAR visibility
Solution Approach 1:
The patent changes the particle size parameter of the scattering agents to sub-visual dimensions (20-500 nm), which fundamentally alters how light interacts with the coating. These nanoparticle dimensions enable effective NIR scattering while remaining invisible to the human eye, thus improving LIDAR visibility without compromising aesthetic appearance or generating visual haze.
Solution Approach 2:
The patent employs composite material structures combining multiple scattering agents (TiO2, SiO2, ZrO2) in specific ratios within the coating matrix. This composite approach optimizes the scattering properties across the NIR spectrum while maintaining coating integrity, adhesion, and visual clarity, thereby achieving enhanced LIDAR detection without sacrificing other coating functions.
2Reliability
If particles are added to the coating to scatter NIR light, then LIDAR detection capability is improved, but visible light haze and color changes occur
Solution Approach 1:
The patent utilizes the wavelength-dependent scattering properties of nanoparticles by precisely controlling particle size (20-500 nm) and composition. This parameter optimization creates a scattering effect that is selective to NIR wavelengths while being transparent to visible light, thus improving LIDAR detection without causing visible haze or color changes.
Solution Approach 2:
The patent assigns different functional properties to different components of the scattering system. Specifically, TiO2 provides strong scattering in both visible and NIR regions, SiO2 provides refractive index contrast for NIR scattering with minimal visible effect, and ZrO2 enhances NIR scattering. This local functional differentiation allows the coating to scatter NIR light effectively while maintaining visible light transmission.
3Measurement precision
If specular reflection is used for LIDAR detection, then detection at specific angles is achieved, but detection at all angles is limited
Solution Approach 1:
The patent employs spherical or near-spherical nanoparticle shapes rather than flat or irregular geometries. These spherical particles scatter light uniformly in all directions (isotropic scattering), enabling LIDAR detection at any angle of incidence or observation. This spherical geometry fundamentally differs from specular reflection surfaces that only reflect at specific angles, thereby providing omnidirectional detection capability.
4Reliability
If multiple coating layers are applied to achieve NIR reflection, then LIDAR visibility is improved, but application complexity and time increase
Solution Approach 1:
The patent combines multiple scattering agents (TiO2, SiO2, ZrO2) and functional components into a single integrated coating composition that can be applied in one layer. This merged formulation achieves superior NIR scattering performance without requiring multiple sequential coating layers, thereby simplifying the application process and improving productivity while maintaining or enhancing LIDAR visibility.
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 coating composition enables enhanced NIR visibility by diffuse scattering, allowing detection at all angles, with minimal visible light absorption and haze, suitable for LIDAR applications and automotive refinishing with reduced layer application requirements.
Implementation Method 1
The coating composition enables enhanced NIR visibility by diffuse scattering, allowing detection at all angles
Implementation Method 2
with minimal visible light absorption and haze
Data Source
AI summary
Disclosed herein is a coating composition being a basecoat or a clearcoat composition and including at least one polymer as a film-forming binder (A), nanoparticles (B) containing at least one noble metal and/or at least one alloy and/or oxide thereof, as well as water and/or at least one organic solvent as component (C) being present in the coating composition in an amount of at least 30 wt.-%, based on the total weight of the composition. Further disclosed herein are a coating film and a coating obtainable from the coating composition, a method of forming a coating film and a coating at least partially onto at least one surface of a substrate, and an at least partially coated substrate obtainable by the method.