A local intensity peak created by diffraction from dust or a clipped aperture, interference from ghost reflections, poor beam shaping or self-focusing in a high-power beam. Because damage depends on peak fluence, a beam whose average sits safely below an optic's damage threshold can still burn it where a hot spot lands. Beam profilers and burn paper are used to find them.
Average fluence is only half the coating spec, but there's a hot spot from that clipped iris, open it up before the next shot.
Also heard as
- hotspot
Related terms
Damage threshold
The maximum fluence or power density an optic can take before it is permanently damaged.
Clipping
A beam partly cut off by an aperture, mount or edge, causing power loss, diffraction rings and hot spots.
Beam profiler
An instrument, usually a camera or scanning slit, that measures a laser beam's intensity distribution and width.
Fluence
Pulse energy per unit area, usually in J/cm squared, the quantity that sets ablation and optical damage.
Burn paper
Paper that marks or darkens where a laser pulse hits it, giving a quick record of beam position and shape.
Same word, different worlds
Localized area of active corrosion on a pipeline, or the targeted anodes installed to protect just that spot.
Refractories & Furnace LiningsArea of a vessel or kiln shell running hotter than normal because the lining behind it is thin or gone.
Nuclear Safety & Radiation ProtectionA small spot on piping or equipment with a much higher dose rate than its surroundings.
Lighting & Color ScienceA distractingly bright patch in a beam or on a lit surface, brighter than its surroundings.