Session 3H: Optical Transmission Properties of Tissues in the Mid-Infrared

The intensity and spot size of any beam of light delivered to tissue is impacted by scattering, absorption, and reflection. The wavelength of light, the type of tissue, and the tissue thickness determine how much the properties of the light beam change. To successfully construct a cochlear implant that stimulates auditory neurons with light, these characteristics must be investigated, and the stimulation of target neurons must be maximized. In this project, we determine how different types and thicknesses of tissue impact the angle of spread and the radiation energy of light beams. Pig skin, muscle, and fat tissue of different thicknesses were irradiated with infrared, red, and green light. Images of the beam spot were taken after it passed through the tissue. The angle of spread and the fluence rate were calculated by analyzing these images in ImageJ and Igor Pro. Preliminary results reveal that muscle tissue widens the beam much less than skin tissue does. The differences in angle of spread and fluence rate are compared for each type of tissue to determine parameters for the utilization of optical radiation in cochlear implants