Multi-Image Laser Beam Focus Correction for Accurate Profiling
Find Innovative SolutionsGenerate Solutions
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 characterization results.
Innovation Solution
A method for focus correction that involves capturing images of the laser beam, dividing them into slices, determining the distance from the beam axis to the focal plane for each slice, deconvolving each slice using the corresponding transfer function, and reassembling the deconvolved slices to compute accurate beam parameters such as beam waist size, location, and propagation ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple images of Rayleigh scatter are acquired to measure beam parameters, then beam quality characterization is enabled, but focal errors occur when the beam does not completely overlap the focal planes of the imaging devices
Solution Approach 1:
The patent divides the measurement problem into segments by acquiring multiple images at different focal planes and processing them separately. Each image is analyzed for specific beam parameters, and the results are combined to compute comprehensive beam characteristics. This segmentation allows the system to overcome the limitation of a single focal plane and accurately measure parameters even when the beam does not completely overlap any single focal plane.
2Device complexity
If the laser beam does not completely overlap the focal planes of the imaging devices, then device complexity is reduced, but focal errors lead to erroneous beam characterization results
Solution Approach 1:
The patent applies preliminary action by acquiring multiple images at different focal planes before processing. The system proactively captures data across the entire beam propagation range, ensuring that all necessary information is collected before computation. This preliminary multi-plane imaging prevents focal errors from affecting the final measurement accuracy, as the beam parameters can be derived from the collective data set rather than requiring perfect overlap with a single focal plane.
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 ensures accurate computation of laser beam parameters by correcting for focal errors, thereby improving the reliability of laser beam characterization and process control in materials processing applications.
Implementation Method 1
One technique used to measure the quality of a focused laser beam is to acquire multiple images of the Rayleigh scatter of the beam
Data Source
Figure 1
Figure 2
Figure 3A~3B
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.