Laser absorption spectroscopy with an ATR prism--noninvasive in vivo determination of glucose.

The use of lasers as light sources in IR spectroscopy allows an improvement in measuring sensitivity by a factor of about 100 as compared with the conventional technique. In addition, the monochromaticity of lasers appreciably improves the resolution. Combining lasers with an ATR plate acting as test prism gets rid of transmission cells without impairing the measuring sensitivity. It also considerably reduces the thermal load on the test sample; in vivo measurements on biological tissue can thus be made simply.