Fiber optic ear thermometer

An ear thermometer for measuring body core temperature through infrared radiation from the tympanic membrane which comprises:

• a probe adapted to be inserted into the ear canal;
• said probe containing an infrared transmitting optical fiber assembly having a first end positioned adjacent to the tympanic membrane when said probe is located in an ear canal;
• a disposable sheath surrounding the probe and isolating said probe from contact with the ear canal;
• said sheath including a thin infrared transmitting window formed as part of said sheath and positioned over said first optical fiber end;
• a housing adjacent to said probe and receiving the second end of said optical fiber;
• a thermopile detector adjacent to said second end of said optical fiber and positioned to receive radiation emitted by said second end and for generating an electrical signal corresponding to said radiation;
• electrical circuit means for calibrating said signal and compensating for ambient temperature and detector temperature fluctuations and producing an output electrical signal accurately indicative of tympanic membrane temperature;
• said electrical circuit means for calibrating said signal including means for measuring the resistance of said thermopile detector to determine the precise present temperature of said detector and means to compensate for variations in said temperature to provide an accurate, drift free, detector output voltage;
• said electrical circuit means for calibrating said signal being capable of calibrating said thermopile detector immediately after taking a temperature measurement to assure an accurate temperature measurement;
• said electrical circuit means for calibrating said signal comprising:
• said thermopile detector;
• thermally stable amplifier means for amplifying the output signal from said thermopile detector;
• an analog to digital converter for receiving a signal from said amplifier means and for producing a corresponding digital signal;
• and
• a microprocessor for receiving said digital signal and controlling calibration of the system and production of an accurate signal corresponding to the temperature measured and for sending said digital signal to said display means;
• said microprocessor controlling a plurality of switches for selectively measuring an input signal, measuring the signal from said thermopile detector, correcting for system errors including thermodrift of the input voltage and current, errors generated by contact thermopotentials and electro-magnetic fields, measuring resistance of the thermopile detector and correcting for thermopile temperature errors, measuring ambient temperature and correcting for errors caused by variations thereof, and measuring voltage from the power supply and indicating insufficiency thereof;
• and
• display means for displaying indicia representing the output signal according to a selected temperature scale.