Bonding Glass Lenses to Low CTE Substrates for Thermal Stability
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Solution Overview
Problem
Array cameras face performance issues due to temperature-dependent thermal expansion, which causes variations in the spatial relationships between optical elements, leading to pitch and refractive index changes that affect image quality and camera functionality.
Innovation Solution
Implementing a robust optical system with a low coefficient of thermal expansion carrier substrate and glass lens elements bonded to it, along with polymer lens elements, to stabilize optical characteristics across temperature variations, and using aperture-defining masks and air gaps for optical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymer lens elements are used in array cameras, then manufacturing cost and ease of manufacture are improved, but thermal stability and optical characteristic consistency deteriorate due to high coefficient of thermal expansion
Solution Approach 1:
The patent employs a composite material structure where a glass lens element (providing thermal stability) is bonded to a polymer carrier substrate (providing ease of manufacture). This combination allows the optical system to benefit from both the low thermal expansion of glass and the manufacturing advantages of polymer materials.
Solution Approach 2:
The invention applies different materials to different functional requirements: the glass lens element specifically addresses thermal stability where optical performance is critical, while the polymer carrier substrate handles structural support and manufacturing requirements. This localized material assignment resolves the contradiction between ease of manufacture and thermal stability.
2Reliability
If glass lens elements are used in array cameras, then thermal stability and optical characteristic consistency are improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines glass lens elements with polymer carrier substrates, allowing the glass to provide thermal stability while the polymer simplifies manufacturing. The bonding process integrates these materials into a unified structure that achieves both thermal performance and manufacturing efficiency.
Solution Approach 2:
The invention segments the optical system into distinct functional components: the glass lens element for thermal stability and the polymer carrier for manufacturing ease. This segmentation allows each component to be optimized for its specific function while being integrated into a complete optical system.
3Stability of the object's composition
If lens elements are rigidly bonded to carrier substrate, then structural stability is improved, but optical isolation and thermal expansion management deteriorate
Solution Approach 1:
The patent introduces an intermediary bonding layer between the glass lens element and polymer carrier substrate. This intermediate layer has thermal expansion properties that bridge the gap between the two materials, allowing structural stability while accommodating differential thermal expansion without causing stress or distortion.
Solution Approach 2:
The invention carefully selects and controls the thermal expansion parameters of the bonding layer to match the average expansion characteristics of the glass and polymer materials. This parameter optimization allows the assembly to maintain structural stability across temperature variations while managing thermal expansion effects.
Data Source
AI summary
Systems and methods in accordance with embodiments of the invention implement optical systems incorporating lens elements formed separately and subsequently bonded to low coefficient of thermal expansion substrates. Optical systems in accordance with various embodiments of the invention can be utilized in single aperture cameras, and multiple-aperture array cameras. In one embodiment, a robust optical system includes at least one carrier characterized by a low coefficient of thermal expansion to which at least a primary lens element formed from precision molded glass is bonded.