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January 1, 2026Fiber Laser Frequency Setting Explained: For Coin Engraving & Beyond
1. Introduction and Background
When first starting out with fiber lasers, frequency is often the most confusing setting, especially if you’re transitioning from CO2 or diode lasers where frequency isn’t something you have to consider. In this article, the author explains what frequency is, how it affects engraving, and provides a practical demonstration comparing different frequency settings on engraving projects.
2. What is Frequency?
Frequency refers to the number of pulses your fiber laser emits per second, measured in kilohertz (kHz). For example:
50 kHz means the laser emits 50,000 pulses per second.
100 kHz means 100,000 pulses per second.
The laser operates in a pulsed system, meaning each laser firing is a “flash” rather than a continuous beam. The frequency controls how fast these flashes occur.
3. How Frequency Affects Engraving
Low Frequency (e.g., 20 kHz): Each pulse carries more energy with bigger gaps between pulses, which is good for deep engraving and material removal.
High Frequency (e.g., 200 kHz): Each pulse carries less energy with less time between pulses, making it ideal for fine marking, color marking, annealing, and polishing. It leads to heat accumulation on the material’s surface.
4. Low Frequency vs. High Frequency
Low Frequency: Best for deep engraving and material removal. The large gaps between pulses allow the material to cool slightly before each new pulse, making the removal more effective.
High Frequency: Best for fine marking, coloring, and polishing. The smaller gaps between pulses result in more heat accumulation, making it ideal for gentle treatments like color marking or polishing.
5. Impact of Frequency on Pulse Power and Pulse Overlap
Pulse Power: At low frequency, each pulse carries more energy; at high frequency, each pulse carries less energy.
Pulse Overlap: At low frequency, the pulses are spaced further apart, allowing for better cooling of the material between pulses. At high frequency, pulses overlap, causing heat to accumulate on the surface of the material, making it more effective for polishing or coloring.
6. Laser Type and Its Impact on Frequency
Non-MOPA Lasers: These have a narrower frequency range, usually from 20 kHz to 100 kHz.
MOPA Lasers: These can operate at a much wider range of frequencies, from 1 kHz to 4000 kHz or higher, which is why MOPA lasers tend to be more expensive.
7. Practical Demonstration
Testing three different frequency settings:
45 kHz: Lower frequency, results in rougher, more textured engraving with noticeable background noise, suitable for deeper engraving.
80 kHz: Mid-range frequency, the background is smoother, but there’s still some texture. Good for balancing depth and fine detail.
200 kHz: Higher frequency, the background is very smooth, making it great for fine marking and polishing with minimal heat buildup. Surprisingly, the engraving depth isn’t much different from the lower frequency results.
8. Conclusion
The choice of frequency significantly affects engraving depth, smoothness, and fine detail.
Low frequencies are best for deep engraving and material removal, while high frequencies are ideal for fine marking, coloring, and polishing.
The frequency setting should be adjusted based on material, desired effect, and the capabilities of your laser system.
