Abstract: A patient interface and method of locating the patient interface for use particularly in spectroscopy applications. The patient interface includes a concave region and first and second convex regions. A wing extends from the concave region to help locate the patient interface properly. The convex regions provide additional adhesion support, particularly when used on the thenar eminence. The patient interface may be placed in a number of locations on a patient to determine an optimum location for measurement prior to affixing the interface to the patient.

Abstract: A spectrophotometric instrument is comprised of a processor, a probe having a tissue engaging surface with an aperture therethrough and a light source producing measurement light signals and optically coupled to the probe via a first optical path. A partially reflective first reflecting member is located in the probe and has a generally elliptical profile positioned to reflect a first portion of the measurement light signals to the tissue aperture and to transmit a second portion of the measurement light signals through the first reflecting member. A second reflecting member is located in the probe and has a generally elliptical profile positioned to reflect the measurement light signals transmitted through the first reflecting member. A second optical path has a distal end positioned to receive the measurement light signals reflected off of the second reflecting member and a proximal end coupled to the processor.