# Photometric Measurements

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

## Photometric Measurements

quantitative determinations of the values of quantities characterizing optical radiation (light in the broad sense) or such optical properties of materials as transparency and reflectivity. Photometric measurements can be made with instruments that contain optical detectors. In the simplest cases in the visible light range, the human eye is used as a detector in evaluating photometric quantities.

Table 1. Principal photometric qualities
QuantitySymbolDefining equationUnit
NameSymbol
Note: The subscript v of Φ indicates that Φv is a photometric quantity, in contrast to the radiometric quantity Φe(radiant flux); (t) time, (dΩ) infinitesimal solid angle through which the luminous flux is radiated, (dA) element of area of the surface, (θ) angle between the normal to the element of the surface and the direction in which the luminous flux is radiated (X) any photometric quantity
Luminous flux..................ϕv lumenlm
Luminous energyQQ = ʃϕvdtlumen-secondlm-s
Luminous intensity (of a light source in some direction) ..........ll=d Φv/dΩcandelacd
Luminous efficacy of radiant power ...........KK = Φvelumen per wattlm/w
Luminance (at a given point and in a given direction) ....Lcandela per square meter (formerly, nit) luxcd/m2
Illuminance (at a point of a surface).............EE = dϕv/dAluxlx
Luminous exitance...........MM=dϕv/dAlumen per square meterlm/m2
Exposure (quantity of illumination)..........HH=dQ/dA = ∫E dtlux-secondlx-s
Luminous pulse emittance .............θθ=⊄ldtcandale-sectioncd-s
Spectral concentration of a photometric quantity .....XλXλ = dx/dλ
References in periodicals archive ?
The FluxGage FG1500 performs fast, photometric measurements of assembled large LED systems, both during development and at the end of luminaire production.
Although some photometric measurements of 80 Sappho have been gathered, data from this event will help improve the asteroid's shape model.
Harris (1961) reviewed the early photometric measurements of Mercury.
Photometric Measurements: To take measurements of the distances (Zy-Zy and Go-Go), using photometry and ImageJ software version 1.42q (Rasband, 2009) standardized digital photographs of the subjects were taken with a Canon 400 D Digital using a 17-85mm lens, fixed to a height adjustable tripod at a fixed distance of 1.5 m from the individual to be photographed.
Photometric measurements of redness showed significant reductions on the treated side, compared with the untreated side and baseline, with reductions in the erythema index of 11.9%, 10.7%, and 13.6% at week 4, 8, and 12, respectively.
LBNL researchers evaluated energy savings, photometric measurements and occupants' satisfaction.
The IES announces the publication of two new testing procedures standards for fluorescent lamps: IES Approved Method for Life Testing of Single-Based Fluorescent Lamps (LM-65-14) and IES Approved Method for Electrical and Photometric Measurements of Single-Based Fluorescent Lamps (LM-66-14).
All photometric measurements were transforming to Heliocentric times.
Photometric measurements are of primary importance to comprehend if the novel source works correctly [16,17] and if it complies with the maritime signaling norms [9,10, 13].
IES LM-79 is an approved method for testing electrical and photometric measurements of solid-state lighting products.
The Figures show individual photometric measurements as a function of time through the predicted transit period.

Site: Follow: Share:
Open / Close