Radiometry and Photometry: Review for Vision Optics

Published

January 1, 2000

Author(s)

Yoshihiro Ohno

Abstract

Radiometry is the measurement of optical radiation, which is electromagnetic radiation in the frequency range between 3 x 10¹¹ Hz and 3 x 10¹⁶ Hz. This range corresponds to wavelengths between 10 nm and 1000 m, and includes the regions commonly called the ultraviolet, the visible, and the infrared. Typical radiometric units include watt (radiant flux), watt per steradian (radiant intensity), watt per square meter (irradiance), and watt per square meter per steradian (radiance). Photometry is the measurement of light, which is defined as electromagnetic radiation detectable by the human eye. It is thus restricted to the visible region of the spectrum (wavelength range from 360 nm to 830 nm), and all the quantities are weighted by the spectral response of the eye. Photometry uses either optical radiation detectors constructed to mimic the spectral response of the eye, or spectroradiometry coupled with appropriate calculations for weighting by the spectral response of the eye. Typical photometric units include lumen (luminous flux), candela (luminous intensity), lux (illuminance), and candela per square meter (luminance). The difference between radiometry and photometry is that radiometry includes the entire optical radiation spectrum (and often involves spectrally resolved measurements), while photometry deals with the visible spectrum weighted by the response of the eye. This chapter provides some guidance in photometry and radiometry (Refs. 1 through 6 are available for further details). The terminology used in this chapter follows international standards and recommendations.^7-9

Citation

Radiometry and Photometry: Review for Vision Optics

Volume

Chap. 14

Publisher Info

OSA Handbook of Optics Book Chapter (14), OSA Handbook of Optics, Volume III Visual Optics and Vision,

Pub Type

Books

Keywords

candela, lumen, photometry, quantities, radiometry, spectroradiometry, unit, watt

Citation

Ohno, Y. (2000), Radiometry and Photometry: Review for Vision Optics, OSA Handbook of Optics Book Chapter (14), OSA Handbook of Optics, Volume III Visual Optics and Vision, (Accessed July 18, 2024)