Measurement of Total Radiant Flux (2537 A) from Germicidal Lamps, and of Total Radiant Flux from Black-light Lamps

The following means of detection has been tried for measuring the 2537 Å radiation from the germicidal lamp: (1) In order to establish the standard of 2537 Å radiation, a high sensible thermopile with a 2537 Å transmitting filter or a 2537 Å cutting off filter is used. (2) Photo-cell is used for practical measurements of 2537 Å by means of wavelength conversion device such as a fluorescent material. A conversion filter which is excited by 2537 Å radiation and emits visible radiation consists of a thin layer of willemite sandwiched between a glass and a quartz plate. (3) Some ultraviolet-sensitive photo-tube on the other hand can be used by itself or with a sharp-cut filter. The 2537 Å radiant flux density distribution from the germicidal lamp has more diffused character than that of fluorescent lamp, and the radiance along the lamp bulb is down on both sides. The total radiant flux of the germicidal lamp has been measured by the following methods. (1) The zonal factor method by making use of radiant flux density distribution. (2) The three directed radiant intensity measuring method. (3) The horizontal radiant intensity measuring method. The ratio of total radiant flux to horizontal radiant intensity is shown in the following table. Some measurements of black-light radiation have been made by the same technics.