Definition of "photometer" [pho•tom•e•ter]

• An instrument for measuring a property of light, especially luminous intensity or flux. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "To accomplish this mission, a space-based photometer is being developed that employs a 0. 95m aperture Schmidt telescope coupled to a very large focal plane array (FPA) measuring 14” (L) x 14” (W) x 10” (D)."
• "If the photometer were analog, you could remove the cover and feel the position of the needle."
• "Anyone who wants to make sure their sunglasses have adequate protection can have them tested by a machine called a photometer in an ophthalmologist's or optician's office."