| abstract |
An oximeter having a single light-emitting diode structure capable of emitting the three wavelengths required for oximetry and dye dilution measurements. A ring counter causes three semiconductor chips in the device to be energized in sequence. Light is directed toward the blood sample and the reflected light is extended to three synchronous detectors. Each detector operates only when a corresponding semiconductor chip in the light-emitting diode is energized; each detector thus responds only to the intensity of light at a respective wavelength. The outputs of two of the detectors are extended to a ratio circuit for deriving a final measurement. The ratio circuit itself has a high accuracy over the relatively low dynamic range of the ratio values. |