A fingerprint sensor uses beams of light to detect a fingerprint as the finger is swiped over a ridged surface. The beams of light are directed toward individual regions of the ridged surface so that the light beams will generally be totally internally reflected when a finger is not touching the ridge. The total internal reflection characteristics of the ridged surface are altered at regions touched by the ridges on the finger as the finger is swiped over the sensor. This alters the amount of light reflected by the ridged surface. These changes in light reflection as the finger is swiped over the ridged surface can be observed simultaneously over multiple channels, preferably disposed laterally with respect to each other, to provide a fingerprint.