3D TOF Micro Lens Array With Variable Height and Shift
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Solution Overview
Problem
Existing Time-of-Flight (TOF) pixel-based 3D cameras face decreased modulation efficiency due to inefficiencies in conventional micro lens array designs that focus backscattered light, particularly as image height increases, leading to reduced volumetric optic power and photon hit rates.
Innovation Solution
A 3D TOF camera with a micro lens array configured for variable height and shift, where micro lens heights decrease and shifts increase with radial distance from the image lens axis, optimizing volumetric optic power by maximizing the photon hit rate across various image heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional micro lens array designs are used, then the device structure is simple and easy to manufacture, but modulation efficiency decreases with increasing image height
Solution Approach 1:
The patent applies local quality by varying the height of individual micro lenses based on their position in the array. Specifically, micro lenses at different image heights have different heights, with taller lenses at the center and shorter lenses at the periphery. This local variation optimizes light focusing for each region, maintaining high modulation efficiency across the entire field of view while avoiding the need for a completely complex redesign of the entire lens array system.
Solution Approach 2:
The patent implements dynamics by introducing positional variation into the micro lens array structure. Instead of a static uniform design, the lens heights dynamically adapt to different image heights, creating a gradient structure that responds to the optical path requirements at different positions. This dynamic structural adaptation resolves the contradiction by allowing the system to maintain optimal performance across varying conditions without requiring complex active control mechanisms.
2Manufacturing precision
If uniform micro lens heights are used across the array, then manufacturing is simplified, but volumetric optic power and photon hit rates decrease at peripheral pixels
Solution Approach 1:
The patent resolves this contradiction by applying local quality through position-dependent micro lens heights. The manufacturing process is designed to create lenses with varying heights based on their location in the array, with the height being a function of the image height. This approach maintains manufacturing feasibility through systematic variation while significantly improving the volumetric optic power hit rate at peripheral pixels compared to uniform height designs.
3Reliability
If micro lens heights are increased to improve light focusing, then modulation efficiency improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by implementing a controlled gradient in micro lens heights rather than uniformly increasing all lens heights. This approach improves modulation efficiency by optimizing each lens's height for its specific position in the array, while the systematic nature of the variation allows for streamlined manufacturing processes that can handle the gradient structure more efficiently than arbitrary complex designs.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying the height parameter of micro lenses based on their position in the array. This controlled parameter variation optimizes optical performance across different image heights while maintaining manufacturability through a predictable, systematic pattern that can be incorporated into standard fabrication processes rather than requiring complex custom manufacturing for each lens.
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 enhances modulation efficiency by ensuring optimal focusing of backscattered light onto pixels, increasing the volumetric optic power hit rate and improving depth data accuracy across the camera's field of view.
Implementation Method 1
micro lens array (MLA) configured with variable ML height and variable ML shift... configured to direct backscattered light that is transmitted through an image lens into corresponding pixels
Implementation Method 2
array of pixels that generate photoelectric signals when stricken with the backscattered light
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
A three-dimensional time-of-flight (3D TOF) camera having a micro lens (ML) array configured with variable ML height and variable ML shift. The ML array includes micro lens that are configured to direct backscattered light that is transmitted through an image lens into corresponding pixels. Heights of individual micro lenses within the ML array vary according to image height. For example, the height of micro lenses at the center of the ML array, near the axis of the image lens, may be relatively larger than the height of other micro lenses toward the perimeter of the ML array. Furthermore, the shift of individual micro lenses with respect to corresponding pixels may also vary according to the image height. For example, the shift of micro lenses at the center of the ML array may be relatively smaller than the shift of the other micro lenses toward the perimeter of the ML array.