Simple Measuring Method of Pulse Ruby Laser Output Density

Abstract

Pulse ruby laser is presently used in the treatment of superficial pigmented lesions such as nevus spilus and senile lentigo. However, irradiation of a laser beam with the appropriate output density is required for such treatment. It is difficult to accurately measure the laser output under the treatment. Futhermore, it is much more difficult to measure the laser output density, because the measurement of irradiation area is involved in the measurement of output density. In the treatment of nevus, the laser beam providing uniform intensity output distribution of approximately 20 Joules/ is used. However, it is also difficult to simply measure this output density. In order to solve these problems, we have devised the method to determine the laser output density from the degree of discoloration caused by irradiation of the laser beam onto the color paper with a fixed reflectivity. We measured the reflectivity of many color papers by a photospectrometer, arranged them in order of reflectivity with wavelength of 694nm, and irradiated a ruby laser beam onto them. As a result, we confirmed that the laser output density could be determined by the degree of discoloration of these color papers. Now, we are effectively using this paper for checking the output density before operating equipment in practical use.