Laser Machining Device Output Control via Q Switch and Driving Current
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Solution Overview
Problem
Existing laser machining devices face challenges in stabilizing low-output laser settings without deteriorating laser characteristics, particularly when adjusting output on the high-output side, due to overheating of wavelength conversion elements and thermal lens effects.
Innovation Solution
A laser machining device with a Q switch that pulse-oscillates third harmonic laser light based on set pulse frequency and duty ratio, and an excitation light source with a correspondence relation table to adjust driving current for precise output control, switching between driving current and duty ratio adjustments based on target output levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the driving current is reduced to lower laser output, then the output of laser light decreases, but the driving current becomes unstable and the laser output becomes unstable
Solution Approach 1:
The patent dynamically switches between two control methods (driving current control and duty ratio control) based on the target output level. For high output levels, driving current is adjusted; for low output levels, duty ratio is adjusted while keeping driving current constant, ensuring stability across the entire output range.
Solution Approach 2:
The patent changes the control parameter from driving current to duty ratio depending on the output level. By keeping the driving current constant at an optimal value and using duty ratio modulation for low output control, the system maintains both low output capability and output stability.
2Power
If the duty ratio is increased to raise laser output on the high-output side, then the laser output increases, but the wavelength conversion element overheats and laser characteristics deteriorate
Solution Approach 1:
The patent dynamically adjusts the driving current based on the target output level. For high output requirements, it increases the driving current while maintaining an appropriate duty ratio, thereby controlling the average power and heat generation while still achieving the required peak output.
Solution Approach 2:
The patent changes the primary control parameter from duty ratio to driving current for high output levels. This allows the system to achieve high output through increased excitation power rather than extended pulse duration, reducing thermal accumulation in the wavelength conversion element.
3Reliability
If the driving current is increased to improve low-output stability, then the output stability improves, but the wavelength conversion element overheats when operating on the high-output side
Solution Approach 1:
The patent dynamically adjusts the driving current based on the target output level. For high output requirements, it increases the driving current while maintaining an appropriate duty ratio, thereby controlling the average power and heat generation while still achieving the required peak output.
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 configuration allows for stable low-output settings and prevents laser characteristic deterioration on the high-output side by optimizing output control through the Q switch and driving current adjustments, ensuring appropriate output without thermal issues.
Implementation Method 1
a Q switch configured to pulse-oscillate the third harmonic generated by the second wavelength conversion element on the basis of a pulse frequency set as one of the machining conditions and a duty ratio related to a ratio of a period in which the Q switch is switched to an OFF state and a period in which the Q switch is switched to an ON state
Implementation Method 2
a first wavelength conversion element on which the fundamental wave generated by the laser medium is made incident, the first wavelength conversion element generating a second harmonic having a frequency higher than a frequency of the fundamental wave
Implementation Method 3
a second wavelength conversion element on which the second harmonic generated by the first wavelength conversion element is made incident, the second wavelength conversion element generating a third harmonic having a frequency higher than the frequency of the second harmonic
Implementation Method 4
a laser medium configured to generate a fundamental wave on the basis of the excitation light generated by the excitation-light generating section
Implementation Method 5
an excitation light source configured to generate excitation light corresponding to a driving current supplied from an outside
Data Source
AI summary
To appropriately change an output of laser light without deteriorating laser characteristics. A control section of a laser machining device controls, when a target output is larger than a predetermined threshold, an output of laser light by changing a driving current supplied to an excitation light source and, on the other hand, controls, when the target output is equal to or smaller than the threshold, the output of the laser light by changing a duty ratio of a Q switch while keeping the driving current supplied to the excitation light source substantially fixed.