Variable Focal Length Lens for Wide Field Depth Imaging
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Solution Overview
Problem
Current depth imaging technologies face challenges in consumer electronics due to size, weight, cost, and power consumption constraints, particularly in maintaining accurate image acquisition across a wide field of view without increasing focal length, which leads to uneven light distribution and increased error in depth measurements.
Innovation Solution
A machine-vision system with a modulated light source, imaging pixel array, and a lens system where the focal length decreases with increasing angle of observation, ensuring a constant effective aperture size over a wide range of field angles, thereby directing more photons to peripheral pixels and improving light collection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the focal length of the lens system is increased to capture a wider field of view, then the field of view is improved, but the depth measurement accuracy deteriorates due to increased error bars
Solution Approach 1:
The lens system employs a variable focal length design where the focal length dynamically changes based on the angle of observation. Specifically, the focal length decreases as the angle of observation increases relative to the optical axis. This dynamic adjustment compensates for the increased error bars that would otherwise occur at wider field angles, thereby maintaining depth measurement accuracy across the entire field of view while capturing a wider area.
2Measurement precision
If the focal length is kept constant to maintain depth accuracy, then measurement precision is improved, but the field of view is limited and light distribution becomes uneven
Solution Approach 1:
The lens system applies local quality by having different focal lengths for different regions of the field of view. Central regions (smaller observation angles) use longer focal lengths for high depth accuracy, while peripheral regions (larger observation angles) use shorter focal lengths to maintain accuracy and expand coverage. This spatially varying focal length property allows the system to optimize for both accuracy and wide field of view simultaneously.
3Adaptability or versatility
If a wider field of view is captured, then adaptability is improved, but light collection efficiency deteriorates due to reduced effective aperture size
Solution Approach 1:
The lens system dynamically adjusts the effective aperture size based on the angle of observation. By decreasing the focal length at larger observation angles, the system maintains a relatively constant effective aperture size across the field of view. This dynamic adjustment ensures that peripheral pixels receive sufficient photons for accurate depth measurement, thereby maintaining light collection efficiency while capturing a wide field of view.
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 configuration balances error bars in 3D imaging, making the acquired data more usable for computer systems while introducing minimal distortion, which can be corrected post-processing, and allows for more accurate depth mapping across a broader field of view.
Implementation Method 1
a modulated light source configured to project light onto a subject
Implementation Method 2
The imaging pixel array is configured to receive the light reflected from a locus of the subject and indicate distance to the locus
Implementation Method 3
The lens system is configured to receive the light reflected from the subject and refract such light onto the imaging pixel array
Data Source
AI summary
A machine-vision system includes a modulated light source, an imaging pixel array, and a lens system. The modulated light source is configured to project light onto a subject. The imaging pixel array is configured to receive the light reflected from a locus of the subject and indicate distance to the locus. The lens system is configured to receive the light reflected from the subject and refract such light onto the imaging pixel array. The focal length of the lens system decreases with increasing angle of observation relative to a shared optical axis of the lens system and the imaging pixel array.