A stimulation probe system includes a light integrating chamber with a reflecting inner surface. A plurality of LEDs is mounted to introduce emitted light into the light integrating chamber. Each LED produces a different wavelength of light with the plurality of LEDs producing a range of light wavelengths. A hand-held probe includes a circular opening in communication with the chamber positioned to supply light from the chamber to the surface of a body. Electrical circuitry is programmable to activate one or more of the LEDs to produce substantially any light wavelength in the range of light.