Automotive LiDAR Anti-Reflection Assembly for Sloped Windshields
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Solution Overview
Problem
LiDAR devices mounted behind sloped windshields in vehicles experience high reflectance of infrared radiation due to the angled incidence, leading to energy loss and increased power requirements, which current anti-reflective coatings are inefficient and costly to implement.
Innovation Solution
An anti-reflection unit with a specific absorption coefficient and wedge angle is integrated between the LiDAR device and the windshield, reducing the incident angle and improving the efficacy of the data provided by the technical solution, with a refractive index, and the anti-reflection unit is made of a refractive index, and the anti-reflection unit is coupled to the windshield, reducing the incident angle and enhancing infrared transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the LiDAR device is mounted behind a sloped windshield to protect it from environmental damage, then the device is protected from rain, hail, and impacts, but the incident angle of infrared radiation increases causing high reflectance and energy loss
Solution Approach 1:
An anti-reflection unit is introduced as an intermediary component between the LiDAR device and the sloped windshield. This unit has a first surface facing the LiDAR device and a second surface facing the windshield, with its normal forming a small angle with the incident infrared radiation. The anti-reflection unit acts as a mediator that redirects the infrared radiation at a favorable angle while maintaining the protective function of the sloped windshield.
Solution Approach 2:
The patent changes the angular parameter by positioning the anti-reflection unit such that its normal forms an angle of 0° to 30° with the incident infrared radiation. This parameter change ensures that the reflected radiation angle is minimized, thereby reducing reflectance according to Fresnel's law, while the sloped windshield maintains its protective function.
2Loss of energy
If anti-reflective coatings are applied to the windshield to reduce reflection, then infrared transmission is improved, but the manufacturing cost and complexity increase
Solution Approach 1:
Instead of applying complex multi-layer anti-reflective coatings directly to the windshield, the patent introduces a separate anti-reflection unit as an intermediary component. This unit can be made from materials with suitable optical properties and geometric configuration, simplifying the manufacturing process while achieving the same energy transmission improvement.
Solution Approach 2:
The anti-reflection function is segmented from the windshield structure and implemented as a separate, dedicated unit. This segmentation allows the anti-reflection unit to be optimized independently for infrared transmission without complicating the windshield manufacturing process, as the unit can be pre-fabricated and then integrated.
3Productivity
If the LiDAR device emits infrared radiation at a high incident angle to match the sloped windshield geometry, then the optical path is optimized for the windshield angle, but the reflectance increases significantly according to Fresnel's law
Solution Approach 1:
The anti-reflection unit serves as a mediator that decouples the optical path optimization from the windshield geometry. It provides an intermediate optical interface where the incident angle can be optimized for minimal reflectance, while the final transmission through the sloped windshield maintains its geometric optimization.
Solution Approach 2:
The patent changes the incident angle parameter from the high angle dictated by the sloped windshield geometry to a low angle (0° to 30°) at the anti-reflection unit interface. This parameter change dramatically reduces the reflected radiation fraction according to Fresnel's law, as reflectance increases continuously and very steeply for incident angles greater than 50°.
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 solution significantly reduces infrared radiation reflection, enhancing the efficacy and accuracy of LiDAR data transmission, thereby improving the performance of LiDAR systems in vehicles.
Implementation Method 1
An anti-reflection unit with a specific absorption coefficient and wedge angle is integrated between the LiDAR device and the windshield, reducing the incident angle and improving the efficacy of the data provided by the technical solution, with a refractive index
Implementation Method 2
An anti-reflection unit with a specific absorption coefficient and wedge angle is integrated between the LiDAR device and the windshield
Data Source
AI summary
An automotive vehicle having (a) a pane with a refractive index, n1, (b) a Light Detection and Ranging (LiDAR) device located in the interior environment and facing the inner surface of the pane, and (c) an anti-reflection unit, made of a material of refractive index, n3, coupling the LiDAR device to the inner surface of the transparent pane, and having a mean absorption coefficient (k) in the wavelength range from 750 nm to 1650 nm lower than 5 m−1 (i.e., k≤5 m−1). The anti-reflection unit also has an interfacial surface coupled in intimate contact with the inner surface of the transparent pane and a surface coupled to the LiDAR device, forming the angle θ with the interfacial surface and which normal forms the angle φ, with the incident axis (i0), where φ is between −30° and +30°.