Optical Device Tip Tilt Alignment for Depth of Focus
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Solution Overview
Problem
As camera performance requirements increase, such as wider field-of-view and smaller pixels, the use of aspherical lens elements increases sensitivity to lens fabrication and assembly errors, leading to suboptimal alignment of optical devices relative to image sensors, which affects modulation transfer function (MTF) optimization.
Innovation Solution
A system and method for evaluating optical devices that determine the optimal tip and tilt of optical components relative to the image sensor plane to maximize depth of focus, rather than aligning peaks of modulation transfer function curves, using metrics from images of calibration patterns to predict and optimize depth of focus across the field-of-view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If aspherical lens elements are used to reduce optical device size and meet wider field-of-view requirements, then the optical device can achieve better imaging performance, but the sensitivity to lens fabrication and assembly errors increases, leading to suboptimal alignment
Solution Approach 1:
The patent applies preliminary action by measuring and determining the optimal tip and tilt alignment parameters before final assembly and manufacturing. The system evaluates multiple candidate alignments and selects the optimal one in advance, compensating for expected fabrication and assembly errors in aspherical lens elements. This allows the optical device to achieve optimal performance despite manufacturing variations.
2Ease of operation
If traditional MTF peak alignment method is used, then the alignment process is straightforward, but it does not maximize depth of focus and is sensitive to fabrication errors
Solution Approach 1:
The patent implements feedback by measuring the actual modulation transfer function across multiple field locations and using this measurement data to determine and adjust the optimal tip and tilt alignment. The system continuously evaluates alignment quality and adjusts parameters to maximize depth of focus, providing feedback-driven optimization that compensates for fabrication errors and ensures reliable performance.
3Reliability
If depth of focus optimization is pursued instead of MTF peak alignment, then robustness to fabrication and assembly errors is enhanced, but the evaluation and alignment process becomes more complex
Solution Approach 1:
The patent applies parameter changes by shifting the optimization criterion from MTF peak alignment to depth of focus maximization. This involves changing the evaluation parameters from single-point MTF measurements to multi-location depth of focus assessments. The system adjusts alignment parameters (tip and tilt) to optimize depth of focus across the field, providing robustness to manufacturing variations despite increased evaluation complexity.
Data Source
AI summary
Systems and methods for evaluating an optical device include a pattern source that provides a pattern suitable for use in the evaluating the optical device. The optical device images the pattern to provide an image. The optical device has an optical device and an image sensor, with an associated image sensor plane. An image analysis system determines, from the image, a tip and a tilt for a component of the optical device relative to the image sensor plane that maximizes a depth of focus for the optical device.