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
G01J1/10—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void
G01J1/16—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void using electric radiation detectors
G01J1/1626—Arrangements with two photodetectors, the signals of which are compared
Landscapes
Physics & Mathematics
(AREA)
General Physics & Mathematics
(AREA)
Spectroscopy & Molecular Physics
(AREA)
Spectrometry And Color Measurement
(AREA)
Investigating Or Analysing Materials By Optical Means
(AREA)