FIELD: instruments. SUBSTANCE: device has light emitting and light receiving elements placed on film base at given distance from each other. When detector operates, light is transmitted through test object. Light absorption of test object is measured. According to this value information about patient condition is generated. Photodiode is placed near light emitting diodes which belong to light emitting element and it detects intensity change in emitting light. When temperature of light emitting element changes processor corrects light emission by change of current running through light emitting element. According to second invention claim thermal resistor and heater are placed near light emitting diode and provide thermal stability of light emitting or light receiving elements due to measured output parameters of thermal resistor. EFFECT: increased precision. 6 cl, 9 dwg
