Radiometry And Photometry

introduction to colour science
nice page explaining the xyz color space, teh CIE chromaticity diagram and a couple other things.
konica minolta spectrophotometers
Highly precise portable and bench top spectrophotometers.
photometry menu
Photometry at NIST. Get your instruments calibrated.
radiometry and photometry faq
PDF FAQ from the University of Arizona that authoritatively covers the basics of measuring light.
the light measurement handbook
A giude provided by a maker of equipment that dicusses practical considerations of photometry and radiometry.