Phase SLM Focus Arrays With Phase Locking for Uniform Intensity
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Solution Overview
Problem
Existing algorithms for generating uniform large-scale optical focus arrays, such as the traditional weighted Gerchberg-Saxton algorithm, are inefficient and require a large number of iterations to produce highly uniform patterns, often resulting in unwanted intensity non-uniformity and inefficiency in light usage due to phase changes and amplitude substitutions.
Innovation Solution
A modified weighted Gerchberg-Saxton algorithm that locks the phase after a certain number of iterations based on a phase-locking condition, reducing undesired phase rotation and iteratively updates the amplitude function to achieve uniformity, thereby reducing the number of iterations needed to produce highly uniform optical focus arrays with improved light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional iterative Fourier-transform algorithms are used to generate optical focus arrays, then the phase pattern can be computed, but the number of iterations required is large and the intensity uniformity is poor
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing a lookup table of phase values corresponding to different radial distances from the optical axis. This pre-computed phase information is then directly applied during the focus array generation process, eliminating the need for numerous iterative Fourier-transform calculations and achieving high intensity uniformity immediately.
2Loss of energy
If phase SLMs are used instead of amplitude SLMs, then light usage efficiency is improved, but the complexity of phase pattern calculation increases
Solution Approach 1:
The patent changes the calculation approach from iterative Fourier-transform methods to a direct phase calculation method using pre-computed lookup tables. This parameter change in the calculation strategy simplifies the phase pattern generation process while maintaining compatibility with phase SLMs, thereby improving light usage efficiency without excessive computational complexity.
3Manufacturing precision
If more iterations are performed to improve intensity uniformity, then the uniformity increases, but the computational time and light loss increase
Solution Approach 1:
By pre-computing and storing the optimal phase values in lookup tables before the actual focus array generation, the patent eliminates the need for repeated iterative calculations. This preliminary action achieves high intensity uniformity in a single pass, significantly reducing computational time and energy consumption compared to traditional iterative methods that require multiple cycles to converge.
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
The modified algorithm significantly reduces the number of iterations required to achieve highly uniform large-scale optical focus arrays with over 98% intensity uniformity, providing faster and more reliable compensation for optical system imperfections and improved light usage efficiency.
Implementation Method 1
phase SLMs shift the phase of an incident light beam on a local scale, and these phase shifts result in interference patterns on the image plane
Implementation Method 2
these phase shifts result in interference patterns on the image plane
Implementation Method 3
perform a Fourier transform on the light source amplitude function and the phase function to produce a focal plane amplitude function and a focal plane phase function
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A method of generating uniform large-scale optical focus arrays (LOT As) with a phase spatial light modulator (SLM) includes identifying and removing undesired phase rotation in the iterative Fourier transform algorithm (IFTA), thereby producing computer-generated holograms of highly uniform LOT As using a reduced number of iterations as compared to a weighted Gerchberg-Saxton algorithm. The method also enables a faster compensation of optical system-induced LOT A intensity inhomogeneity than the conventional IFTA.