Zeiss LSM 880 Operating Manual page 677

Glossary
Aperture angle of a microscope objective
a
AU Airy unit (diameter of Airy disc)
dpix Pixel size in the object plane
FWHM Full width at half maximum of an intensity
distribution (e.g. optical slice)
n
Refractive index of an immersion liquid
NA Numerical aperture of a microscope objective
PH Pinhole; diaphragm of variable size arranged in
the beam path to achieve optical sections
PMT Photomultiplier tube (detector used in LSM)
PSF
Point spread function
RU Rayleigh unit
SNR Signal-to-noise ratio
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