G
PHYSICS
G01
MEASURING; TESTING
G01J
MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
G01J1/00
Photometry, e.g. photographic exposure meter
G01J1/42
using electric radiation detectors