A handheld card with an upconverting or charge-up phosphor that emits visible light under near-infrared beams, letting people find and center invisible beams at 800, 1064 or 1550 nm. Cards have rated wavelength and power ranges and will burn or bleach above them. IR viewers, image-converter scopes, do a similar job from a distance, which keeps hands and faces out of the beam path.
Grab the IR card and check the spot on the second mirror, I think it's clipping the mount on the left side.
Hold the card at an angle so any specular glint goes down into the table, never back toward your face.
Also heard as
- viewer card
- detector card
Related terms
Burn paper
Paper that marks or darkens where a laser pulse hits it, giving a quick record of beam position and shape.
Walk the beam
To align a beam onto a path using two steering mirrors adjusted in turn against two targets or irises.
Clipping
A beam partly cut off by an aperture, mount or edge, causing power loss, diffraction rings and hot spots.
Doughnut mode
A ring-shaped laser mode with a dark center, usually a sign of misalignment or overheating in a TEM00 laser.