ABSTRACT
The Siriraj Phototherapy Lamp (SPL) was invented by the investigator to compensate for a similar, but expensive imported device and h low-efficiency locally-made device. The SPL irradiance and effect on environmental temperature were measured in this study. The device used six fluorescent bulbs of which zero to three were blue. The distance between the bulbs and the mattress was fully adjustable. The blue fluorescent bulb emitted a higher light intensity than the white. In both kinds of bulbs the intensity of light was higher in the center of the bulbs than at the periphery. The light intensity varied proportionately with the number of blue fluorescent bulbs, but inversely with the distance between the bulbs and the mattress. Lining the SPL with a white cloth increased the light intensity. This inverse relationship was also found between the environmental temperature near the mattress and the distance. Placing a plastic shield under the SPL reduced the radiant heat emitted by the bulbs to the mattress which resulted in a decrease of environmental temperatures by 2.3oC and 3.0oC at the distances of 45 and 30 cm, respectively.