Abstract: A non-invasive blood constituent measuring device and method are disclosed for measuring changes in blood thickness of predetermined blood constituents relative to total change in blood thickness at a test area to thereby determine the concentration of such constituents in the blood in a living body, which measured constituents may be, for example, hemoglobin and oxyhemoglobin to enable determination of oxygen saturation of blood. The device includes a plurality of light emitting diodes operationally controlled by timing circuitry for sequentially emitting light at different predetermined wavelengths toward a blood containing tissue sample, such as an ear lobe.

Abstract: A photodetector including a photosensitive material which changes its electrical properties in response to radiation striking the material, and particularly radiation of a wavelength at or near that of light, positioned within an electrically conductive enclosure and having a window transparent to the desired light and near light wavelengths positioned in an opening in such enclosure, the window being electrically conductive to protect the light sensitive material from various electromagnetic, radio frequency and similar interference.