What does photometer mean?
A photometer is an instrument that measures the intensity of light or another related optical property. It is used in photography to assess illumination, in laboratories to control experimental conditions, and in fields such as astronomy, architecture, and environmental monitoring. Different photometers may respond to illuminance, luminance, radiant power, or a specific range of wavelengths, so the precise reading depends on the instrument and its calibration. The word combines the Greek-derived element “photo-,” meaning light, with “-meter,” meaning a measuring device. In everyday technical contexts, a photometer may be called a light meter, although the more specific term is preferable when the exact optical quantity is known.
nounAn instrument for measuring the intensity of light. Depending on its design, it may measure illuminance, luminance, radiant power, or another optical quantity.
- An instrument used to measure the intensity or related optical properties of light.
"The photographer used a photometer to check the brightness of the studio lighting."
"The photometer recorded a sharp increase in light intensity when the shutters opened."
"Researchers calibrated the photometer before measuring the illumination in the laboratory."
The regular plural is used when referring to multiple instruments or different types of photometer.
"The laboratory owns several calibrated photometers for measuring visible light."
A photometer turns light into evidence: the brighter the light, the greater the reading that reveals its intensity.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does photometer come from?
The word was formed in the 18th century from Greek phōs, genitive phōtos, meaning “light,” and the combining form -meter, from Greek metron, meaning “measure.” The same Greek elements underlie related words such as photography, photometry, and photometric. Over time, photometer became associated with instruments for measuring the intensity of light.
Related word forms
How photometer is actually used
The term is chiefly technical and is common in photography, lighting, astronomy, laboratory work, and environmental monitoring. The precise quantity measured depends on the instrument's design and calibration.
Easily confused with photometer
A photometer measures particular properties of light, whereas a radiometer measures radiation more generally, including thermal radiation.