The determination of sensation thresholds has applications ranging from uses in the medical community such as
neural pathway mapping and for the diagnosis of diabetic neuropathy, to potential uses in determining safety standards.
This study sought to determine the sensation threshold, and the distribution of sensation probabilities, for pulse trains
ranging from two 10 ms pulses to nine 10 ms pulses from 2.01 μm laser light incident on a human forearm and chest.
Threshold was defined as the energy density that would elicit sensation 50% of the time (ED50). A method of levels
approach was used in conjunction with a monovariate binary response model to determine the ED50. We determined the
ED50 and also a distribution of threshold probabilities. Threshold was found to be largely dependant on total energy
deposited for smaller pulse trains, and thus independent of the number of pulses. Total energy becomes less important as
the number of pulses increases however, and a decrease in threshold was measured for a nine pulse train as compared to
one through four pulse trains. Thus we have demonstrated that this method is a useful and easy way for determining
sensation thresholds from a 2.01 μm laser for possible clinical use. We have also demonstrated that lower power lasers
when pulsed can elicit sensation at comparable levels to higher power single pulse lasers.