Various characteristics measured of copying fluorescent lamps, which are used as radiant source of diazo printings, are described.
In these lamps, the peak of spectral radiant energy is located near ultra violet region in order to respond to maximum sensitivity region of diazo papers. The perk wavelength of radiation is determined by the species of phosphor, and typical phosphors for copying fluorescent lamps on sale today are lead-activated Magnesium Calcuim arsenate, Strontium Barium Magnesium silicate (ternary silicate), Barium disilicate, and Calcium tungstate with no activator.
Essential factors for copying fluorescent lamps are spectral distri-bution of radiant energy, radiant distribution along lamp length, and radiant energy in maintenance.
Results are summarized as below:
(1) The actual diazo sensitivity region is shifted to longer wavelength side through the effect of original papers and printing contact glasses combination, so the spectral distribution of energy in lamps should be in accordance with this sctual diazo sensitivity region which is on the longer wavelength side of sy ensitivit for diazo material itself.
(2) Radiance of lamp decreases remarkably at the end of a tube, and printing width in general use (even 90% of tube center radiance) is expressed by the following formula, experimentally:
Printing width (length) Lp=Lt-4-s4.8d
Lt: lamp overall length
d: lamp tube diameter
(3) Generally these lamps are operated at overload ourrent in order to make printing speedy, but the alectrical characteristics are almost the same as those of general fluorescent lamp.
(4) Lamp life under overloading is 1, 000 hours or more and the remaining radiant flux at life end is sapproximately 80% of the initial flux. Endblacking has little influence on flux maintenance.

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