Darling, David David Darling Enterprises, Dundee, Angus, Scotland.
Show previous versions
- Units of photometry
- Modern photometers
- Calibration of photometers
- Photometers in photography
- Atomic absorption photometers
- Photometers as photon counters
- Additional Readings
An instrument used to measure the intensity of light or various optical properties of surfaces and substances. Strictly speaking, the term photometer applies only to devices that work in the visible region of the electromagnetic spectrum, at wavelengths from about 360 to 830 nm, and are calibrated so that they respond in the same way as the average human eye. However, the term is also more widely applied to instruments designed for use at infrared and ultraviolet wavelengths or for photon counting. Photometers come in a wide variety of forms to suit different applications (Figs. 1 and 2). Among the optical properties that they may measure are luminous intensity (the unit of which is the candela), luminous flux (measured in lumens), illuminance or luminous flux per unit area (measured in lumens per square meter), luminance or photometric brightness (measured in candelas per square meter), light distribution, light reflectance and transmittance, color, spectral distribution, and visibility. See also: Illuminance; Luminance; Luminous flux; Luminous intensity; Photometry
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 9000 highly qualified scientists and 43 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information