Purchasing laser safety protection is impacted by if the laser is continuous or pulsed. Below, we illustrate generally how although the average power of a laser may be the same, a pulsed laser has peaks that require more protection (as it becomes necessary to protect from the peaks).
Continuous Wave Lasers are defined as having a pulsed length > 0.25s. The calculation is relatively simple, and all that is needed is the average power of the laser.
Repetitive Pulse Lasers – Have higher peak energies and therefore are more complicated to calculate a Maximum Permissible Exposure (“MPE”). To determine the MPE with a repetitive pulse laser, you must have the following:
- Wavelength (measured in nm, µm)
- Pulse repetition frequency (F – measured in Hertz or Hz)
- Duration of a single pulse or pulse width (time – measured in seconds or s)
- Energy per Pulse (J)
Find below the four types of lasers (defined by pulse frequency) mentioned in EN guidance.
Continuous Wave (cw) with constant average power.
Pulsed Length: > 0.25 seconds
I: Pulsed: short single or periodic energy emission
> 1µs to 0.25s
R: Giant Pulsed: very short single or periodic energy mission
1 µs to 1ns
M: Mode locked.
< 1 ns (pico and femtosecond)