phosphoroscope

from The Century Dictionary.

• noun An instrument for. measuring the duration of evanescent, phospho' resceuce in different substances.
• noun A philosophical toy consisting of glass tubes containing different phosphorescent substances and arranged in a box.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Physics) An apparatus for observing the phosphorescence produced in different bodies by the action of light, and for measuring its duration.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun physics, chemistry Any of several devices used to measure phosphorescence, and to distinguish it from fluorescence