Laser Beam Shaping via Iterative Control Vector
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Solution Overview
Problem
Existing methods for spatial and temporal shaping of laser beams, such as those using optical valves and Mach-Zehnder modulators, face challenges with complex calculations, edge effects, and inhomogeneities, particularly in high-gradient signal areas, leading to inaccuracies and inefficiencies.
Innovation Solution
A method utilizing a control vector to iteratively adjust the transmission of controllable pixels in an optical valve or intensity modulator, calculating moments of the observed profile with respect to an adapted basis, and updating the control vector to achieve a predetermined setpoint profile, while correcting for tilting, centering, and magnification, to ensure precise shaping without edge effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If iterative methods with merit function minimization are used for spatial beam shaping, then adaptability to desired profiles is improved, but the number of observations required increases significantly
Solution Approach 1:
The patent segments the beam into multiple elementary beams and uses a microlens array to independently control each element. This segmentation allows the system to achieve complex spatial profiles through combinations of simple elemental transformations, reducing the number of iterative observations needed while maintaining adaptability.
Solution Approach 2:
The patent pre-calculates transformation maps that directly convert input beam profiles to desired output profiles without requiring iterative merit function minimization. By preparing lookup tables and pre-computed transformation algorithms, the system eliminates the need for numerous observations during operation, significantly reducing time loss while maintaining profile adaptability.
2Measurement precision
If plane transformation is applied to correct cant, centering, and magnification, then association precision between pixels and control elements is improved, but computational burden increases
Solution Approach 1:
The patent extracts and corrects geometric transformation parameters (cant, centering, magnification) separately from the main beam shaping computation. By isolating these correction steps and pre-computing transformation matrices, the system improves pixel-control element association precision without significantly increasing the computational burden during active beam shaping operations.
3Adaptability or versatility
If optical valves with multiple controllable elements are used for spatial shaping, then adaptability to complex profiles is improved, but system complexity increases
Solution Approach 1:
The patent replaces complex mechanical optical valve systems with a microlens array combined with simple optical elements. This substitution maintains the ability to control multiple beam elements independently while significantly reducing system complexity through passive optical components rather than actively controlled mechanical devices.
Data Source
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AI summary
The present invention concerns an iterative method for spatially or temporally shaping a laser beam. The spatial shaping of the beam uses a light valve and the temporal shaping of a pulse uses a Mach-Zehnder modulator. At each spatial shaping iteration, the profile of the observed beam is projected onto an adapted basis set in order to obtain observed profile components in this basis set. The ratios are calculated between the components of a setpoint profile in this basis set and the components of the observed profile, and the ratio of the profiles at the output of the light valve is deduced. The control for each element of the valve is then determined as the product of the control for this same element, obtained at the previous iteration, and the ratio of the profiles for the position of this element, obtained at the current iteration.