The beam profile produced by a laser running in TEM00, in which intensity across the beam follows a Gaussian function and the beam size is quoted where intensity drops to 1/e squared, about 13.5 percent of peak. It stays Gaussian as it propagates and passes through lenses, which makes its waist, Rayleigh range and divergence easy to calculate. Many applications reshape it into a top-hat for uniform processing.
With a Gaussian beam the center is twice the average intensity, so set the fluence off the peak or you'll ablate the middle.
Also heard as
- Gaussian
- TEM00 beam
Related terms
TEM00
The fundamental transverse mode of a laser: a single round spot with a Gaussian intensity profile.
Beam waist
The narrowest point of a focused or propagating laser beam, where its wavefront is flat.
Rayleigh range
The distance from a beam's waist to where its cross-sectional area has doubled, a measure of depth of focus.
Top-hat
Describes a beam with flat, uniform intensity across its width and steep edges, instead of a Gaussian peak.
M-squared
The beam quality factor: how many times worse a beam focuses and diverges than an ideal Gaussian of the same wavelength.