LIDAR Enclosure Window with Silicone Composite for Chip Resistance
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Solution Overview
Problem
Existing enclosures for LIDAR sensors in automotive applications are vulnerable to damage from hard projectiles like gravel and road salt, and they do not effectively maintain optical and mechanical properties for reliable light transmission.
Innovation Solution
An enclosure with a housing made of an aluminum-based alloy and a window made of silicone-based polymeric material, specifically transparent polydimethylsiloxane, is designed with a thickness of at least 3 mm, using a silicone-based adhesive to accommodate thermal expansion mismatches, and optionally featuring anti-reflective coatings and a layered structure with a rigid transparent substrate for enhanced durability and light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid window material is used for durability, then resistance to damage from roadway debris is improved, but susceptibility to surface chipping from hard projectiles worsens
Solution Approach 1:
The patent applies composite materials by combining a rigid transparent substrate (such as glass or plastic) with a silicone-based polymeric material having Shore A durometer between 50 and 85. This composite structure allows the rigid substrate to provide durability and resistance to roadway debris, while the softer silicone layer absorbs impact from hard projectiles like gravel and road salt, preventing surface chipping. The composite design resolves the contradiction by distributing the protective functions across two material types with complementary properties.
Solution Approach 2:
The patent utilizes parameter changes by specifically controlling the Shore A durometer of the silicone-based polymeric material to be between 50 and 85. This parameter optimization ensures the material is soft enough to absorb impact from hard projectiles without being so soft as to compromise structural integrity. The thickness parameter is also optimized at greater than 0.5 mm to provide sufficient protective coverage while maintaining optical performance, directly addressing the contradiction between durability and chip resistance.
2Strength
If window thickness is increased to improve durability, then resistance to damage is improved, but light transmittance may be reduced
Solution Approach 1:
The composite structure allows the silicone-based polymeric material to be applied as a relatively thin layer (greater than 0.5 mm) over the rigid substrate. This thin coating provides sufficient protection against hard projectiles without creating a thick enough barrier to significantly block light. The rigid substrate maintains the primary light transmission function while the thin silicone layer provides protective functionality, resolving the contradiction between thickness for durability and thinness for light transmittance.
Solution Approach 2:
The patent applies local quality by providing enhanced protection only where needed - the silicone-based polymeric material is applied to the outer surface of the window where it directly contacts roadway debris and hard projectiles. The inner structure and bulk of the window maintain their original transparent properties for optimal light transmission. This localized application of protective material ensures durability enhancement without compromising overall light transmittance.
3Strength
If adhesive bonding is used to attach the window to the housing, then mechanical integrity is improved, but thermal expansion mismatch may cause bonding failure
Solution Approach 1:
The patent utilizes parameter changes by selecting a silicone-based adhesive whose thermal expansion characteristics are compatible with both the silicone-based polymeric window material and the aluminum-based alloy housing. The adhesive's durometer and thermal properties are specifically chosen to accommodate the different thermal expansion rates of the bonded materials, preventing bonding failure during temperature variations while maintaining strong mechanical attachment.
Solution Approach 2:
The silicone-based adhesive acts as an intermediary material between the window and housing, mediating the thermal expansion mismatch. The adhesive layer absorbs and distributes thermal stresses that arise from temperature changes, preventing direct stress transmission between the window and housing that would cause bonding failure. This intermediary function allows strong bonding while accommodating thermal incompatibility.
4Illumination intensity
If anti-reflective coatings are applied to enhance light transmittance, then optical performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functions into the silicone-based polymeric material layer itself. Rather than requiring separate anti-reflective coating layers, the silicone material is formulated to inherently provide both protective functions (chip resistance, durability) and optical functions (light transmittance enhancement). This merging eliminates the need for additional coating processes, reducing manufacturing complexity while maintaining improved light transmittance.
Solution Approach 2:
The patent utilizes parameter changes by optimizing the refractive index and optical properties of the silicone-based polymeric material during material formulation. By adjusting the material's inherent optical parameters, the coating naturally reduces reflections and enhances light transmittance without requiring additional anti-reflective coating layers. This material-level optimization achieves optical performance improvement while avoiding the manufacturing complexity of multi-layer coating processes.
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 enclosure provides superior resistance to damage from roadway debris and maintains high light transmittance (>80% at 1550 nm) while ensuring a strong bond and mechanical integrity, achieving a high chip resistance rating and enabling mounting on curved automobile surfaces.
Implementation Method 1
Clearances between edges of the window (14) and the housing (12) are determined based on differences in thermal coefficients of expansion (TCE) of both the window (14) and the housing (12), wherein the adhesive (22) accommodates a mismatch in the TCE
Implementation Method 2
The window (14) is configured to transmit light (26) originating from the LIDAR-sensor (16) to targets proximate to the automobile, as well as transmit the light (26) that is reflected back from the targets to the LIDAR-sensor (16)
Implementation Method 3
Anti-reflective coatings may also be applied to an interior-surface of the window (14) to further increase the transmittance (28)
Data Source
AI summary
An enclosure, includes a housing and a window. The housing is configured to retain a LIDAR-sensor. The window is attached to the housing within an opening defined by the housing. The window is configured to transmit light from the LIDAR-sensor. The window is comprised of a silicone-based polymeric material having a thickness of at least three millimeters. The window is characterized as having a transmittance of at least 80% of the light at a wavelength of 1550 nanometers.