mechanical and thermal parameters in pulsed laser cutting of tissue 34 ieee journal of quantum electronics vol qe 23 no 10 oct 1987 was used to estimate the heat spread from the hot carbon oil suspension in the duct where u03b4 represents the thickness of a heated zone during a time u03c4 k being the heat of conduction assuming k 1 44 u00d7 10 3 cm 2 sec and using 0 03 sec as the time interval between pulses the heat spreads out an estimated 0 007 cm from the hair duct between each pulse this is about equal to the radius of the hair duct it is assumed therefore that about one half of the temperature rise from each pulse is transferred to the surrounding tissue during the 0 0 3 second following each pulse this means that the net increase in the temperature of the carbon oil suspension from each pulse will be roughly 2 5 u00b0 c thus as depicted in fig4 in about two thirds of a second the temperature of the carbon oil suspension in the hair duct has risen from a normal temperature of 37 u00b0 c to about 90 u00b0 c a temperature high enough to destroy the follicle and the tissue cells immediately surrounding the hair follicle i e within about u00b1 5 hair diameter in a little more than one second the temperature has risen to about 140 u00b0 c which is the upper end of the safe range at this point the patient would begin to feel pain therefore the illumination should be applied so that no spot is illuminated longer than about one or two seconds during one scan fig4 a and 4b show a.