Laser Reflectance Detection Using Spatial Light Modulation
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Solution Overview
Problem
Existing laser processing methods risk damaging the workpiece during reflectance detection due to insufficient laser beam power and unclear configurations for acquiring reflectance while forming a modified layer.
Innovation Solution
A laser processing device with a spatial light modulator that lowers the power density of the laser light on the workpiece's surface for reflectance detection, using modulation patterns such as shift and spot deformation to minimize damage and optimize reflectance acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser beam is applied to a workpiece for reflectance detection, then the reflectance can be acquired, but the workpiece may be damaged due to high power density
Solution Approach 1:
The patent applies dynamic control of the laser beam by using a spatial light modulator to change the modulation pattern over time. The system alternates between a first modulation pattern (for focus detection with lower power density) and a second modulation pattern (for reflectance measurement), allowing the laser parameters to be dynamically adjusted to prevent damage while acquiring measurements
Solution Approach 2:
The patent changes the modulation pattern parameter of the laser beam through the spatial light modulator. By switching between different modulation patterns (first and second patterns), the system modifies the laser beam's power distribution on the workpiece surface, enabling safe reflectance detection without causing damage
2Measurement precision
If the laser beam output for reflectance detection is increased, then the measurement accuracy improves, but the damage to the workpiece increases
Solution Approach 1:
The system dynamically switches between different modulation patterns to optimize both measurement accuracy and safety. The spatial light modulator enables real-time adjustment of the laser beam profile, allowing the system to use higher power density only when necessary for accurate reflectance measurement while using lower power density for focus detection and positioning
Solution Approach 2:
The system uses feedback from the detection unit to monitor the workpiece state and adjust the laser beam modulation pattern accordingly. Based on the detected information, the control unit determines whether to switch between modulation patterns, ensuring that measurement accuracy is maintained while preventing workpiece damage through adaptive power 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
Enables the acquisition of reflectance while preventing damage to the workpiece by controlling the laser light's power density, expanding the dynamic range of measurable reflectance and ensuring accurate processing.
Implementation Method 1
a spatial light modulator configured to modulate the laser light according to a modulation pattern
Implementation Method 2
a converging unit configured to converge the laser light toward the first surface to form a converging point
Implementation Method 3
a camera configured to image reflected light of the laser light from the first surface
Data Source
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AI summary
Disclosed is a laser processing device including a laser light source configured to output laser light, a converging unit configured to converge the laser light toward a first surface to form a converging point, a camera configured to image reflected light of the laser light from the first surface, a spatial light modulator for modulating the laser light according to a modulation pattern, and a controller configured to execute acquisition processing of applying the laser light to the first surface by controlling the laser light source and imaging the reflected light by controlling the camera to acquire a reflectance of the first surface for the first wavelength.