On the theory of the Matthews and the Russell-Léonard photometers for the measurement of mean spherical and mean hemisperhical intensities (1905)
National Bureau of Standards · leaf 19
strument is symmetrical with respect to thehorizontal direction, it would be equally applicable to the alternating-current arc, whose intensity curve is approximately the same as thatof the direct-current lamp, except that the distribution in the lowerhemisphere is repeated in the upper one. Let us… … Fig. 4. The equation, expressed in rectangular coordinates, is HTDE.] INTEGRATING PHOTOMETERS. 271 Now the mean intensity for any zone, ^m-i~^m) is given by eq. (26), 1 r\ -i-cos^^ / ^-=cos^. ^^^^ If we make i^ equal to the radius vector of the ellipse given byeq. (29), we get, on transforming to…
Photometry · Lamps and lighting · Optics
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