What do pulse frequency, PPI, and repetition rate mean on a laser cutter?

ForEducators · Researchers · Students

Updated 1 October 2026 Sources checked · Not externally reviewed

Short answer

These terms describe how pulsed energy is delivered, but controllers do not always use them identically. Repetition rate is pulses per second. PPI is pulses per inch of travel. “Frequency” depends on the controller: on a galvo laser it is the pulse rate, while on some controllers it sets the power-modulation frequency. Combined with speed and power, they set how closely pulses are spaced and whether they overlap into a continuous line or cut.

The same pulse rate spreads pulses apart at a faster speed and overlaps them at a slower speed Two rows, each showing a path with an arrow and a line of circular pulse spots along it. A heading says the pulse rate is the same in both rows. In the top row, labeled faster travel, the spots are well separated, with a double arrow marking the spacing between two neighbors, and a note that the spots spread apart with little overlap. In the bottom row, labeled slower travel, the spots sit close together and overlap, with a note that they crowd together and overlap. Below, two boxes joined by an arrow separate what you set, a number in the machine’s units, from what physically happens: pulse spacing, overlap and heating. Sizes are exaggerated and no measurements are given. Same pulse rate in both rows Faster travel spacing spots spread apart, little overlap Slower travel spots crowd together and overlap What you set a number, in the machine’s units What physically happens pulse spacing, overlap, heating
Conceptual and exaggerated, with no values. Speed and pulse rate together set how far apart the pulses land and how much they overlap, which in turn affects heat input and edge texture. Controllers use words like frequency, repetition rate and PPI differently, so read your machine’s documentation, record the exact interface value and units, and do not carry a number from one machine to another.

Higher frequency does not simply mean more cutting power. It can change the edge finish on some materials and how even a mark looks. Interpret the control through that machine’s documentation and record the exact interface value and units. Do not transfer a PPI or frequency number between machines unless the underlying definitions and process have been validated.

Sources

  1. CORD / OP-TEC (NSF-funded photonics teaching module, 2008, hosted by UCF CREOL)Laser Material Removal: Drilling, Cutting, and MarkingA teaching module on how absorption at the laser's wavelength, reflectivity, beam quality, focus, pulses, speed, thickness and assist gas shape a cut; from 2008, with worked examples that are mostly metals. Link checked September 2026.
  2. LightBurn Software (laser control software documentation)Line ModeCovers scoring as a low-power surface line, passes, pulses per inch, PWM frequency and focus offset; one program's documentation, and the right values differ by machine. Link checked September 2026.
  3. LightBurn Software (laser control software documentation)Galvo-Specific Cut SettingsExplains frequency as the pulse rate on galvo lasers and that more pulses means less power in each; galvo lasers are mostly marking systems, not every cutter. Link checked September 2026.

Sources are checked by Laser TeamWork, not by an outside expert. General guidance: your machine’s manual and your school’s procedures come first. Report a correction.

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