Free-form lensing phase modulator optimization
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Solution Overview
Problem
Current light projector technologies face challenges in achieving high luminance levels while maintaining energy efficiency and computational efficiency, particularly in generating desired light fields with high contrast and dynamic range, often requiring computationally expensive methods that are difficult to parallelize.
Innovation Solution
The method involves configuring a free-form lens using a phase modulator by defining non-overlapping source and display regions, adjusting their areas to match target light intensity ratios, and optimizing the phase surfaces to redirect light efficiently, employing algorithms like the Shift'n'scale algorithm and limited memory Broyden-Fletcher-Goldfarb-Shanno optimization for efficient light redistribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If optimal transportation methods are used to determine light field mapping, then image quality and contrast are improved, but computational cost increases significantly requiring hours of computation
Solution Approach 1:
The patent segments the continuous optimal transportation problem into discrete bin assignments. By dividing the light field into discrete bins and using combinatorial optimization to assign source bins to target bins, the method achieves high image quality while reducing computational complexity compared to continuous optimal transportation methods that require hours of computation.
Solution Approach 2:
The patent replaces the continuous mathematical optimization framework with a discrete combinatorial optimization approach. This substitution transforms the problem from requiring continuous gradient-based optimization (which is computationally expensive and difficult to parallelize) to a discrete assignment problem that can be solved more efficiently and parallelized across multiple processors.
2Manufacturing precision
If continuous optimization methods are used for light field generation, then image quality is improved, but the computation is difficult to parallelize
Solution Approach 1:
The patent divides the light field into discrete bins that can be independently processed. Each bin assignment can be computed separately and then combined, enabling parallelization across multiple processors or GPUs while maintaining high image quality through the discrete optimization framework.
Solution Approach 2:
The patent replaces continuous optimization algorithms with discrete combinatorial optimization. This substitution enables the use of parallel computing architectures that can evaluate multiple bin assignments simultaneously, dramatically improving computational efficiency while preserving image quality.
3Illumination intensity
If light steering is used to achieve high luminance levels, then peak luminance is improved, but power consumption increases
Solution Approach 1:
The patent uses computational methods to create a virtual light steering effect through discrete bin assignments rather than physical light moving parts. This computational copying of the light steering function achieves high peak luminance through precise light field control while avoiding the energy consumption associated with mechanical light steering devices.
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 creation of high-luminance light fields with deep black levels and wide contrast ranges, achieving peak luminance levels up to 45 times that of uniformly illuminated projectors while reducing energy consumption and computational complexity.
Implementation Method 1
controlling a phase modulator to provide the phase surfaces for the source regions
Implementation Method 2
generating a phase surface for each of the source areas, the phase surface configured to redirect light incident on the source area onto the corresponding display area
Data Source
Figure 1~2B
Figure 3A~3B
Figure 4~5
AI summary
A method for controlling a phase modulator to display an image defined by image data, the method comprising: providing a model of a two-dimensional light source comprising a plurality of non-overlapping source regions, each of the source regions having a boundary, a corresponding source light intensity value and a source area and being associated with a corresponding display region of a display, each of the display regions having a corresponding display area; based on the image data, assigning a light intensity value to each of the display regions; setting a target source area for each of the source regions such that a ratio of the target source area of the source region to the display area of the corresponding display region is proportional to a ratio of the light intensity value assigned to the corresponding display region to the source light intensity value for the source region; performing an optimization to determine configurations for the boundaries of the source regions which best satisfy an objective function which quantifies aggregate deviations of the areas of the source regions from the target source areas corresponding to the source regions; based on the configurations of the source region boundaries after the optimization, determining a normal vector for each of the source regions; integrating the normal vectors to yield a solution phase function relating a phase of the phase modulator to position in two dimensions.