Abstract: A non-invasive apparatus and related method for measuring the concentration of glucose or other blood analytes utilizes both diffuse reflected and transmissive infrared absorption measurements and may be applied to either in vitro or in vivo sampling. The apparatus and method utilize non-dispersive correlation spectrometry and apply it to liquid blood serum analysis. Spectrally-modified near infrared light from the sample containing the analyte is split into two beams, one of which is directed through a negative correlation filter which blocks light in the absorption bands for the analyte to be measured, and the other of which is directed through a neutral density filter capable of blocking light equally at all wavelengths in the range of interest. Differencing the light intensity between the two light paths provides a measure proportional to analyte concentration.

Abstract: Conventional omnidirectional lamp light is converted into a narrowly focused, highly intense beam with a power comparable to certain types of lasers. The lamp light is collected and focused with conventional means into an optical coupling cone which condenses the conventionally-focused beam to a very small diameter for launching into a fiber optic cable. An optical terminator at the end of the optical fiber retains collimation of the beam and a power density comparable to certain types of lasers, such as those used in medical applications.