Abstract

Dynamic scattering of coherent light by moving particles causes a Doppler shift of the original frequency, depending on the velocity and the scattering angles. This phenomenon was used for the detection of abnormal spontaneous muscle activity caused by the denervation of muscles. Transmission measurements of low frequency modulated laser irradiation have been made in 110 denervated first dorsal interosseous who had previously been imposed to electromyography which detected abnormal activity. Measurements have also been made in 173 normal muscles. The laser used was a diode laser emitting at 830nm and a pulse generator modulated the laser radiation to a low repetition frequency of 84Hz. While passing through the denervated muscles, the incoming laser beam gets a frequency shift due to the contraction of the denervated muscle fibers and mixes with the ballistic part of the beam. To analyze the inherent information the outcoming laser light was transformed into electric current by a photodiode and the signal after being selected by an A/D card was submitted to the Fast Fourrier transformation. The findings of our suggested method have been compared to those of the normal muscles as well as to the electromyographic findings of each denervated muscle.

© 2003 SPIE