The Terminology of Illumination and VisionH.M. Stationery Office, 1926 |
Contents
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Common terms and phrases
500 watt Lamps absorption factor angle of cut-off aperture approximately axis B.Sc Background Brightness bowl C. J. W. Grieveson centre colour Curves of Reflector daylight factor diagram diameter direct light distance effect equal Festoon Filament filament lamp foot-candles given glare glass height horizontal Illumination Research Committee ILLUMINATION RESEARCH TECHNICAL Industrial Research installation integrating sphere light distribution light source lumens luminous efficiency luminous energy luminous flux luminous intensity mean spherical candle-power Model Gallery National Physical Laboratory normal observers obstruction obtained Old Queen Street opal Optical Instruments orange glass paint perfectly diffusing photometer head photometric integrator picture wall plane polar curve position reflected flux reflection factor RESEARCH TECHNICAL PAPER retina Ring Filament roof Scientific and Industrial screen shown in Fig sill ratio solid angle sphere surface sphere window sub-standard sunlight Table test lamp threshold Transmission Factor unit variation vertical visible volts
Popular passages
Page 5 - Theoretical photometry makes use of two general laws of radiation; first, that the intensity of illumination of a surface is inversely proportional to the square of its distance from the light source...
Page 10 - A perfectly diffusing surface is one for which the luminous intensity per unit area in any direction varies as the cosine of the angle between that direction and the normal to the surface, so that it appears equally bright whatever be the direction from which it is viewed.
Page 4 - The unit of luminous flux is the Lumen. It is equal to the flux emitted in unit solid angle by a uniform point source of one international candle.
Page 6 - A complete list, showing prices, may be obtained upon application to the Department, 16, Old Queen Street, Westminster, SWI...
Page 1 - Luminous Flux is the rate of passage of radiant energy evaluated by reference to the luminous sensation produced by it. Although luminous flux should be regarded, strictly, as the rate of passage of radiant energy as just defined, it can, nevertheless, be accepted as an entity for the purposes of practical photometry, since the velocity may be regarded as being constant under those conditions.
Page 8 - The brightness in a given direction of a surface emitting light is the quotient of the luminous intensity measured in that direction by the area of this surface projected on a plane perpendicular to the direction considered. 8. The unit of brightness is the candle per unit area of surface.
Page 16 - During the period between one hour after sunset and one hour before sunrise...
Page iv - Geometrical Investigation of the Formation of Images in Optical Instruments. Embodying the Results of Scientific Researches conducted in German Optical Workshops. Edited by M. von Rohr (forming Vol. I. of "The Theory of Optical Instruments").