Instrument for measuring fluorescence; it projects light tailored in color to the excitation spectrum of a particular fluorescent compound, and observes light at a longer wavelength corresponding to the emission spectrum of that compound. One commonly observed compound is Chlorophyll a, excited in the blue portion of the spectrum and emitting in the red portion.
A fluorometer is identical in function to a scatterometer, except that a scatterometer receives light at the same wavelength it transmits.
Fluorescence stimulated by natural light may also be measured passively with a spectroradiometer.