Scanning infrared thermometer with DC offset and emissivity correction

In a scanning infrared thermometer having a scanning optical system for collecting light from a target and means including a photoelectrical element for converting the collected light to an analog temperature signal with a magnitude related to temperature, the improvement being a correcting circuit, comprising:

• means for automatically altering the analog temperature signal to correct for DC offset errors from the detector to produce a first order corrected analog temperature signal;
• means including an analog to digital converter for converting the corrected analog temperature signal to a corresponding corrected digital temperature signal representative of magnitude of the corrected analog temperature signal;
• and
• means responsive to the corrected digital temperature signal for displaying the temperature of the target.

In a scanning infrared thermometer having a scanning optical system for collecting light from a target and means including a photoptical detector for converting the collected light to an analog temperature signal with a magnitude related to the temperature of the target, the improvement, comprising:

• a correcting circuit responsive to the analog temperature signal circuitry for producing a corrected analog temperature signal corrected for errors due to at least one of (a) variations in DC offset of the light converting means and (b) errors due to target emissivity, at least once per complete scan of the scanning optical system;
• a linearizing circuit responsive to the corrected analog temperature signal for producing a linearized corrected digital temperature signal;
• a controller responsive to the linearized, corrected temperature signal for controlling the correcting circuit;
• a housing assembly for protectively enclosing together in proximity the correcting circuit linearizing circuit and the controller;
• and
• an output interface including
• an output terminal mounted to and accessibly from the outside of the housing, and
• means for producing a representation of the linearized, corrected temperature signal at said output terminal in digital form.

In a scanning infrared thermometer having a scanning optical system for collecting light from a target and a detector circuit including a photoelectrical device for converting the collected light to an analog temperature signal having a magnitude related to temperature, the improvement being a correcting circuit, comprising:

• means for altering the analog temperature signal to correct for DC offset errors from the detector circuit to produce a corrected analog temperature signal;
• means for altering the magnitude of the analog temperature signal to correct for magnitude errors caused by at least two of emissivity effects, circuit stability and component variations;
• means including an analog to digital converter for converting the corrected analog temperature signal to a corresponding corrected digital temperature signal representative of the magnitude of the corrected analog temperature signal;
• and
• means responsive to the corrected digital temperature signal for outputting the signal in digital format to at least one of a display, a recorder and a process controller.