Customizable Spacers for Optical Module Tilt and Focal Length Control
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Solution Overview
Problem
Manufacturing irregularities in optical modules for array cameras, such as variations in focal lengths and thermal expansion, lead to inferior image quality, while adhesive issues cause tilt and reduced image quality.
Innovation Solution
A wafer-level fabrication process with customized spacers for focal length adjustment and thermal stability, using a single transparent cover and strategically designed adhesive application to minimize tilt and protect wiring, thereby improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is applied to attach the lens barrel or optical assembly, then the components are fixed in place, but uneven adhesive distribution causes tilt and reduces image quality
Solution Approach 1:
The patent introduces a spacer as an intermediary component between the optical assembly and the image sensor. This spacer serves as a mechanical mediator that provides precise positioning and support, eliminating the need for adhesive to provide both attachment and alignment functions. The spacer's rigid structure ensures uniform support across the optical assembly, preventing tilt while maintaining secure attachment.
2Strength
If adhesive is used to attach optical components, then components are secured, but adhesive migration to the image sensor renders the module unusable
Solution Approach 1:
The patent extracts the alignment and positioning function from the adhesive and transfers it to a dedicated spacer component. By separating these functions, the adhesive is only required to provide attachment strength, reducing the risk of migration. The spacer physically confines the adhesive to specific areas and prevents it from reaching the image sensor's active region.
3Device complexity
If thermal expansion is not compensated, then the structure remains simple, but optical channels shift laterally and become tilted
Solution Approach 1:
The patent addresses thermal expansion by carefully selecting materials with matched thermal expansion coefficients. The spacer and surrounding structure are made from materials that expand and contract at similar rates, minimizing differential expansion that would cause misalignment. This parameter matching approach maintains optical precision without requiring complex compensation mechanisms.
4Ease of manufacture
If focal length variations occur due to manufacturing irregularities, then production is simpler, but the focal plane lies off the image sensor plane
Solution Approach 1:
The patent incorporates preliminary focal length adjustment during the assembly process. The spacer is designed with adjustable features that allow fine-tuning of the distance between the optical assembly and the image sensor. This preliminary adjustment ensures that focal plane variations from manufacturing are corrected before final assembly, guaranteeing proper focus without requiring complex post-manufacturing adjustments.
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 process reduces focal length variations, minimizes thermal expansion effects, and prevents adhesive migration, resulting in improved image quality and mechanical stability for array cameras.
Implementation Method 1
Another problem that can arise, for example, in array cameras is shifting of the optical axes of the various optical channels as a result of thermal expansion of the lens stacks.
Data Source
Figure 1
Figure 1A~1C
Figure 2A~2B
AI summary
Optical modules are made using customizable spacers to reduce variations in the focal lengths of the optical channels, to reduce the occurrence of tilt of the optical channels, and/or prevent adhesive from migrating to active portions of an image sensor.