The recording and measurement of wavelengths shorter than about 3300A has generally involved the use of equipment to isolate this region, such as quartz spectrographs and photoelectric meters, The present work has resulted in photosensitive papers that respond only to the shorter wave ultraviolet and thus provide materials for recording and measuring this region with the ease of a photographic printing out process. The basis of the new papers lies in the activation of triphenylmethane dye cyanides so that they will react to ultraviolet with the formation of the associated dyes. Activators have been found that produce photosensitive mixtures suitable for use on paper. The sensitized papers print out fully formed, permanent images. Materials are described that are sensitive to 3250A and shorter and to 3350A and shorter wavelengths but are quite unaffected by sunlight through such a colorless glass as Corning No. 7380. Actinometers may be prepared to measure the short wave ultraviolet output of lamps, the erythemal component of sunlight and dosages of therapeutic ultraviolet. Another use for the papers is in recording instruments where a beam of ultraviolet may be employed to trace a line on the moving paper, which is fully visible behind a window of colorless ultraviolet-absorbing glass.
LYMAN CHALKLEY, "Photometric Papers Sensitive Only to Short Wave Ultraviolet," J. Opt. Soc. Am. 42, 387-392 (1952)