Beam Analysis Feedback for AOD Laser Spot Control
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Solution Overview
Problem
Laser-processing systems face challenges in controlling the precise timing of laser pulses and acoustic wavefronts in acousto-optic deflectors (AODs), leading to poor spot position displacement and quality, which affects the accuracy and feature quality of processed workpieces.
Innovation Solution
A laser processing apparatus with a beam analysis system that measures and transmits data to a controller to adjust the operation of AODs, ensuring precise timing and correction of beam characteristics, such as spot size and astigmatism, through closed-loop control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If AODs are used to diffract the laser-processing beam, then beam deflection and spot position control are achieved, but precise timing control between laser pulse and acoustic wavefront becomes difficult, resulting in poor spot position displacement and quality
Solution Approach 1:
The patent implements a feedback mechanism where a beam analysis system measures actual beam characteristics (spot position, spot size, astigmatism) and feeds this information back to the controller. The controller then adjusts AOD timing and parameters based on this feedback to correct deviations, thereby achieving precise spot position control despite the difficulty of direct timing control.
Solution Approach 2:
The patent replaces direct mechanical/timing control of AODs with an optical measurement and feedback-based control system. Instead of relying solely on precise timing commands, the system uses beam analysis measurements to infer and correct timing deviations, substituting direct timing control with an indirect measurement-based approach.
2Measurement precision
If characterization of the processing beam is performed, then beam quality assessment is achieved, but the process becomes time-consuming and may not provide the precise control required
Solution Approach 1:
The patent implements continuous or near-continuous beam analysis measurements during the laser processing operation. Rather than performing separate, time-consuming characterization steps before processing, the system continuously monitors beam characteristics (spot position, spot size, astigmatism) and uses this information for real-time control adjustments, eliminating idle characterization time.
Solution Approach 2:
The beam analysis system serves dual purposes: it characterizes the beam for quality assessment and simultaneously provides control data for real-time adjustment. This self-service approach means the same measurement system that evaluates beam quality also directly enables corrective action, eliminating the need for separate characterization and control setup phases.
3Ease of operation
If incorrect timing between control commands for the AOD and the laser source is used, then system operation is simplified, but spot position displacement and spot quality deteriorate, reducing overall system accuracy and feature quality
Solution Approach 1:
The system uses beam analysis feedback to detect timing deviations between AOD and laser source commands. The controller receives measurement data about actual spot position and quality, compares it to expected values, and automatically adjusts timing parameters to correct deviations, maintaining precision without requiring manual timing calibration.
Solution Approach 2:
The patent dynamically changes control parameters (timing offsets, AOD frequencies) based on measured beam characteristics. When timing deviations are detected through beam analysis, the controller adjusts these parameters in real-time to optimize spot position and quality, transforming static timing settings into adaptive, measurement-based parameter control.
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
Improves the accuracy and quality of laser processing by enabling precise control of beam characteristics, enhancing system performance, throughput, and yield.
Implementation Method 1
an acousto-optic deflector (AOD) arranged within the beam path and is operative to diffract the beam of laser energy
Data Source
AI summary
Numerous embodiments of a laser-processing apparatus are disclosed. In one embodiment, the laser-processing apparatus includes a laser source operative to generate a beam of laser energy, an acousto-optic deflector (AOD) arranged within a beam path, a controller coupled to the AOD, and a beam analysis system operative to measure characteristics of the beam, generate measurement data representative of the measured beam characteristics, and transmit the measurement data to a controller operative to control the operation of the AOD based on that measurement data. In another embodiment, the laser-processing apparatus includes a system for characterization of cross-axis wobble of a galvanometer mirror, comprising a reference laser source configured to emit a reference laser beam, a reflective surface formed on the galvanometer mirror and configured to reflect the reference laser beam to a sensor configured to output a signal representative of the position of the reference beam to a controller.