Laser Processing Apparatus Stabilizing Pulsed Light Output Power
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Solution Overview
Problem
Laser processing apparatuses face challenges in stabilizing pulsed light output power due to variations in repetition frequency and excitation energy, leading to inconsistent processing quality, especially when ambient temperature or aging affects the excitation semiconductor laser.
Innovation Solution
A laser processing apparatus with an optical amplifying fiber, a seed light source, and an excitation light source, where control conditions are set to maintain consistent excitation energy during both emitting and non-emitting times, using a storage unit and control unit to adjust excitation light power based on detected output, ensuring stable pulsed light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the excitation semiconductor laser is continuously driven at high power, then the optical amplifying fiber is sufficiently excited, but the energy of the output pulse immediately after the start of light emission becomes excessively large
Solution Approach 1:
The excitation semiconductor laser is driven in a periodic manner with different power levels during emitting and non-emitting time periods. During non-emitting time periods, the excitation power is reduced to a level that prevents excessive energy accumulation, while during emitting time periods, the excitation power is increased to ensure sufficient amplification. This periodic modulation of excitation power stabilizes the output pulse energy at the start of light emission.
2Object-generated harmful factors
If the excitation semiconductor laser is pulse-driven in synchronization with signal light, then ASE is reduced, but the excitation energy remaining in the optical amplifying fiber varies with the interval between excitation light pulses
Solution Approach 1:
The excitation semiconductor laser is pulse-driven in synchronization with the signal light, creating a periodic excitation pattern. By carefully controlling the pulse width and interval of the excitation light, the system reduces ASE while maintaining stable output power. The key is to set the excitation power during non-emitting time periods at a level that prevents excessive energy accumulation, ensuring that the excitation energy remaining in the optical amplifying fiber remains consistent across different pulse intervals.
3Productivity
If the power of the continuous light from the first excitation semiconductor laser is not appropriately controlled, then the quality of laser processing deteriorates due to unstable output pulse energy
Solution Approach 1:
The control unit monitors the output pulse energy and adjusts the excitation power of the excitation semiconductor laser accordingly. When the output pulse energy deviates from the desired level, the control unit modifies the excitation power during non-emitting time periods to correct the deviation. This feedback mechanism ensures stable output pulse energy and maintains high laser processing quality.
Solution Approach 2:
The excitation semiconductor laser is operated with periodic power modulation, where the power is reduced during non-emitting time periods and increased during emitting time periods. This periodic action prevents excessive energy accumulation in the optical amplifying fiber, ensuring that the output pulse energy at the start of light emission remains stable, thereby maintaining high laser processing quality.
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 stabilizes the power of pulsed light output, maintaining consistent processing quality regardless of changes in repetition frequency or environmental factors like temperature, and reduces the impact of aging on the excitation semiconductor laser.
Implementation Method 1
an optical amplifying fiber (1) that amplifies seed light using excitation light
Implementation Method 2
an excitation semiconductor laser that generates excitation light
Data Source
Figure 1
Figure 2(A)~2
Figure 3
AI summary
A technology for stabilizing the power of pulsed light that is output from a laser processing apparatus is provided. A laser processing apparatus (100) includes optical amplifying fibers (1, 8) that amplify seed light using excitation light, a seed LD (2) that generates seed light in a pulsed manner, and excitation LDs (3, 9A, 9B) that generate excitation light. The conditions for the excitation light during a non-emitting time period during which the seed light is not generated can be varied based on conditions relating to laser light that is output from the laser processing apparatus (100). The control apparatus (20) varies the conditions for the excitation light during the non-emitting time period by controlling drivers (22, 23A, 23B). This makes it possible to stabilize the energy of pulsed light that is output from the laser processing apparatus regardless of the length of the non-emitting time period.