Multi-Image Laser Beam Focus Correction for Accurate Beam Profiling
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Solution Overview
Problem
Existing laser beam profilers face focal errors due to incomplete overlap of the laser beam with the imaging device's focal planes, leading to erroneous beam characterization results.
Innovation Solution
A method and apparatus for focus correction that determine the in-focus and out-of-focus modulation transfer functions, capture images, divide them into slices, calculate distances from the focal plane, and deconvolve each slice to resolve out-of-focus transfer functions, allowing for accurate computation of beam parameters like beam waist size and angular divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple images of Rayleigh scatter are acquired to measure beam quality parameters, then comprehensive beam characterization is achieved, but focal errors occur when the laser beam does not completely overlap the focal planes of the imaging devices
Solution Approach 1:
The patent applies parameter changes by modifying the mathematical processing of image data through deconvolution operations. The system changes the state of the measured parameters by applying transfer functions and point spread functions to correct focal errors, transforming inaccurate beam parameter measurements into accurate ones through computational parameter adjustment
Solution Approach 2:
The patent replaces mechanical alignment adjustments with a computational correction system. Instead of mechanically repositioning imaging devices to achieve perfect focal overlap, the system uses digital image processing and mathematical deconvolution to substitute for the mechanical alignment that would otherwise be required
2Adaptability or versatility
If digital processing of multiple images is performed to compute beam parameters, then beam characterization capability is enhanced, but computational complexity increases requiring sophisticated correction algorithms
Solution Approach 1:
The patent applies segmentation by dividing the complex image processing task into distinct computational stages. The system segments the processing into: capturing multiple images at different positions, determining point spread functions for each image, performing deconvolution operations on each image separately, and finally combining results to compute beam parameters. This segmentation makes the complex processing manageable and systematic
Solution Approach 2:
The patent introduces intermediary mathematical functions (transfer functions and point spread functions) that mediate between the raw image data and the final beam parameters. These intermediary functions serve as computational bridges that facilitate the transformation from scattered light images to accurate beam characterization, simplifying the overall processing complexity
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 accurate computation of beam parameters by correcting for focus errors, ensuring precise characterization and control of high-power laser beams in materials processing applications.
Implementation Method 1
acquire multiple images of the Rayleigh scatter of the beam
Data Source
AI summary
The present application discloses a method and apparatus for compensation of focal errors in laser beam measurement instruments that characterize beam parameters by analyzing images of Rayleigh scatter taken at multiple angles around the beam axis. If the laser beam is not precisely positioned, these images may not be in focus, and the instrument will not report accurate results. This method and apparatus finds the longitudinal axis of the beam by analyzing the beam location in at least two images. All images are subdivided into slices and distances from the beam axis to the focal plane for each slice are calculated and used to find an out-of-focus transfer function for each slice, which is used in combination with the modulation transfer function of the system to deconvolve the slice. Images formed by reassembling the deconvolved slices can then be analyzed to obtain the correct beam parameters.