5. Laser Peak Fluence, Intensity and Peak Power

Laser-Induced Damage Threshold (LIDT) is frequently expressed in units of laser peak fluence or laser peak power density. Let us take a closer look how it is evaluated.

Laser fluence describes the energy delivered per unit (or effective) area. Within the community of laser scientists and technicians, it is very common to define fluence in units of J/cm2. To calculate fluence use the following equation or download free app Lidaris Calc:


In the case of Gaussian beams, effective focal spot area is registered by CCDs. Then it is converted to the units of square centimeters at the I0/e level of maximal intensity. See figure below for more details. Sometimes (in other communities) intensity of laser peak power density is used instead of fluence:

intensity can be used instead of laser peak fluenceWhile laser peak power is defined as:

Laser peak power definition

It should be noted, that Laser-Induced Damage Threshold (LIDT) expressed as laser peak fluence is always quoted with the pulse duration used for the testing. Thus, laser peak power value can be always calculated, if necessary. Want to learn more on LIDT measurements and evaluation? Check out different testing regimes at Laser-Induced Damage Threshold (LIDT) Testing.

Gaussian shape beam profile














Have a question on your mind? Don’t hesitate to ask Lidaris team. Contact: gintare@lidaris.com

<< Back to Glossary