Abstract: A thermopile detector means for a temperature measuring instrument physically and electrically configured to supply an output signal which indicates target temperature substantially independent of the influence of ambient temperature changes. The detector means includes a first thermopile device exposed to radiation from the target and a transducer means, preferably a second thermopile device, shielded from the target and connected in series opposition to the first.

Abstract: A portable, battery operated noncontact temperature measuring device including a lens for collecting infrared radiation and a thermopile for producing a signal indicative of the intensity thereof. The thermopile signal is amplified, linearized and summed with an ambient temperature signal derived from a temperature responsive element, e.g. a diode chip mounted immediately adjacent a cold junction of the thermopile. The resulting composite temperature signal is then processed and displayed. The ambient temperature signal is also utilized to control the impedance of a dual field effect transistor, which in turn controls the gain of the amplifier. Thus, temperature induced variations in the responsivity of the thermopile are compensated by corresponding changes in the gain of the amplifier.

Abstract: A pair of resilient side-by-side elongated coils of different thermocouple material are mounted in a ceramic housing and project forwardly with their forward ends connected to form a thermocouple junction that is adapted to be pressed against a surface of which temperature is to be measured. A retractable protective sleeve is spring-urged to a forward position in which it extends beyond the end of the thermocouple housing and is retractable, when the probe is pressed against the surface, to a limit position in which the end of the ceramic thermocouple housing is maintained just clear of the surface, while the resilience of the thermocouple coils enables good contact of the junction and the surface.

Abstract: The platinum resistive sensor of a temperature measuring surface probe has a resistance greater than the resistance to which the associated meter is calibrated. This provides a compensation that is a function of temperature and decreases errors due to heat loss from the probe. An immersion probe having no heat loss can be used interchangeably with the same meter by adding sufficient fixed resistances in the circuits of the two probes to provide equal resistance outputs to the meter from both the probe that experiences no loss and the one that does, with the meter being calibrated to a standard resistance curve.

Abstract: Temperature dependent and reference time intervals are simultaneously generated and differentially combined to provide a temperature signal that is employed to generate a probe linearization signal for combination with the temperature signal and digital display. A low resistance platinum probe carries a low current in a timing circuit having a small capacitor charging to a relatively high voltage to provide a high gain for temperature to time conversion circuitry. A continuous real time probe linearization signal is computed for large temperature readings by a double integration circuit having an adjustable readout time for determining the magnitude of the twice integrated temperature signal.