spectrophotometer (spektrofotometer)

[NL. spectrum + E. photometer.] An instrument used to compare the intensities of two spectra (as from the limb and center of the sun), or the intensity of a given color with that of the corresponding color in a standard spectrum. It is based upon the fact that the eye is very sensitive to slight differences of intensity between two similar colors when brought side by side. It consists e entially of a spectroscope arranged with total reflecting prisms, so that, for example, the spectra to be compared can be brought into immediate juxtaposition, while Nicol prisms in the path of the pencil of rays make it po ible to diminish the intensity of the brighter light until the two exactly correspond. The angular position of the analyz ing prism gives the means of deducing the required relation in intensity.