Laser Scanner Drift Compensation for Subbeam Micromachining
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Solution Overview
Problem
Conventional laser beam deflectors and scanners fail to maintain the precise control of laser beam waists required for micromachining, as the position of laser beam waists must be controlled to within less than 1 μm over long periods, which is tighter than what is available with existing technologies.
Innovation Solution
A laser beam control system that includes a photodetector to receive subbeams produced by a diffractive beam splitter, a beam pointing controller to establish pointing errors, and a galvanometer scanner to adjust the propagation direction of subbeams, along with a scanning system that uses beam expanders and splitters to achieve precise subbeam spacing and pointing correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional beam deflectors or scanners are used, then the device complexity is reduced, but the manufacturing precision deteriorates (cannot maintain beam waist position within 1 μm over long periods)
Solution Approach 1:
The system employs a photodetector to continuously monitor the actual position of subbeams and feeds this information back to a beam pointing controller. The controller compares the measured position with the desired position and generates correction signals to the galvanometer scanner, creating a closed-loop feedback system that maintains beam waist position within 1 μm over long periods despite drift
Solution Approach 2:
The patent replaces conventional open-loop mechanical beam deflectors with a closed-loop system that uses photodetector sensing and electronic feedback control. This substitution transforms the purely mechanical positioning system into an electromechanical system with active compensation, enabling precision control that exceeds the capabilities of conventional mechanical scanners alone
2Manufacturing precision
If the position of laser beam waists is controlled to within less than 1 μm over long periods, then the manufacturing precision is improved, but the reliability of conventional scanners deteriorates (they cannot maintain this precision)
Solution Approach 1:
The photodetector continuously monitors subbeam positions and provides real-time feedback to the beam pointing controller, which adjusts the galvanometer scanner to compensate for drift. This closed-loop feedback mechanism ensures long-term position stability and reliability, maintaining beam waist position within 1 μm over extended periods
Solution Approach 2:
The system dynamically adjusts the galvanometer scanner parameters based on real-time photodetector measurements. By continuously modifying the scanner's operating parameters in response to detected position errors, the system maintains reliable precision control over long periods, overcoming the inherent drift limitations of conventional scanners
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 system enables precise control of laser beam positions, allowing for accurate micromachining by maintaining subbeam alignment and correcting pointing errors, thereby improving the precision of laser material processing beyond conventional capabilities.
Implementation Method 1
A photodetector is situated to receive a portion of at least one of a plurality of subbeams produced from a processing beam
Implementation Method 2
A beam splitter such as a diffractive beam splitter is situated to produce the plurality of subbeams
Data Source
AI summary
A scanned optical beam is divided so as to form a set of scanned subbeams. To compensate for scan errors, a portion of at least one subbeam is detected and a scan error estimated based on the detected portion. A beam scanner is controlled according to the estimated error so as to adjust a propagation direction of some or all of the set of scanned subbeams. The scanned subbeams with adjusted propagation directions are received by an f-theta lens and directed to a work piece. In typical examples, the portion of the at least one subbeam that is detected is obtained from the set of scanned subbeams prior to incidence of the scanned subbeams to the f-theta lens.