Active Alignment of Lens Stack Arrays for Array Camera Modules
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Solution Overview
Problem
Array cameras face challenges in aligning lens stack arrays with focal planes due to manufacturing tolerances, leading to variations in focal lengths and image quality issues, as each optical channel may have different axial optimum image locations, making it difficult to achieve optimal spatial arrangement and image focus across multiple cameras.
Innovation Solution
The method involves actively aligning a lens stack array with an array of focal planes by varying their spatial relationship, capturing images of a known target, scoring them based on Modulation Transfer Function (MTF) scores, and selecting a spatial relationship that maximizes focus and minimizes variance across multiple focal planes, allowing for the formation of an array camera module that can capture images exceeding threshold quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional manufacturing methods are used to assemble lens stack arrays with focal planes, then manufacturing simplicity is maintained, but manufacturing precision deteriorates due to tolerances causing variations in focal lengths and image quality
Solution Approach 1:
The patent applies preliminary action by pre-assembling lens stacks into arrays with predetermined spatial relationships before final assembly with the focal plane array. This preliminary arrangement allows for pre-adjustment and pre-alignment, ensuring that when the complete module is assembled, the optical components are already in optimal positions, thereby achieving high manufacturing precision without requiring complex final alignment procedures
Solution Approach 2:
The patent replaces traditional mechanical alignment methods with an active electronic alignment system. Instead of using mechanical fixtures and manual adjustment mechanisms to achieve precise alignment, the system uses electronic sensors and control algorithms to detect misalignment and automatically adjust the lens stack array position, substituting complex mechanical alignment processes with electronic measurement and control
2Manufacturing precision
If active alignment processes are implemented to improve manufacturing precision, then alignment accuracy is improved, but productivity decreases due to additional alignment steps and time requirements
Solution Approach 1:
The patent performs preliminary alignment and adjustment of lens stacks within arrays before final module assembly. This preliminary action ensures that complex alignment tasks are completed when components are more accessible and can be adjusted more easily, preventing the need for time-consuming rework during final assembly and thereby maintaining high productivity while achieving precise spatial arrangement
Solution Approach 2:
The patent implements self-service alignment through automated feedback systems that use sensors to detect alignment status and automatically control adjustment mechanisms. The system monitors its own alignment state and makes real-time corrections without requiring external intervention or complex manual procedures, achieving high precision alignment while minimizing additional processing time and maintaining manufacturing throughput
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
This approach enables the construction of an array camera module capable of recording images with improved on-axis and off-axis performance by strategically disabling underperforming cameras and optimizing the spatial alignment of lens stacks, thereby reducing the detrimental impact of manufacturing variations on image quality.
Implementation Method 1
each lens stack forms separate optical channels for each focal plane in the sensor; capturing images of a known target using a plurality of active focal planes
Data Source
AI summary
Systems and methods in accordance with embodiments of the invention actively align a lens stack array with an array of focal planes to construct an array camera module. In one embodiment, a method for actively aligning a lens stack array with a sensor that has a focal plane array includes: aligning the lens stack array relative to the sensor in an initial position; varying the spatial relationship between the lens stack array and the sensor; capturing images of a known target that has a region of interest using a plurality of active focal planes at different spatial relationships; scoring the images based on the extent to which the region of interest is focused in the images; selecting a spatial relationship between the lens stack array and the sensor based on a comparison of the scores; and forming an array camera subassembly based on the selected spatial relationship.