Design of a near infrared reflectometer

A two channel near infrared reflectometer was designed and fabricated using laser (814 nm and 751 nm) diodes and separate photodiode detector circuits. Because the isosbestic point of HbO/sub 2/ and Hb is approximately 814 nm, the gains of each channel were equated at this wavelength. The device is designed to measure relative change of local cerebral blood volume, HbO/sub 2/ and Hb concentration in an unknown sample volume.