Omega Engineering OS531, OS530HR Thermal Radiation, Appendix How Infrared Thermometry Works a

Appendix: How Infrared Thermometry Works A

Thermal Radiation

Heat is transferred from all objects via radiation in the form of electromagnetic waves or by conduction or convection. All objects having a temperature greater than absolute zero (-459°F, -273°C, 0 K) radiate energy. The thermal energy radiated by an object increases as the object gets hotter. Measurement of this thermal energy allows an infrared thermometer to calculate the object’s temperature if the emissivity (blackness) is known. Generally, it is convenient to measure the amount of radiated energy in the infrared part of an object’s radiation spectrum.

Figure A-1 shows a block diagram of an infrared radiation thermometer. Energy from the object is focused by the lens onto the detector. As the detector heats up, it sends out an electrical signal, which in turn is amplified and sent to the circuitry of the thermometer. The thermometer software then calculates the temperature of the object.

LENS

OBJECT

AMPLIFIER

DETECTOR

THERMOMETER CIRCUITRY AND DISPLAY

OR

SIGNAL OUTPUT TO SERIAL PRINTER

OR PERSONAL COMPUTER

Figure A-1. Infrared Thermometer Block Diagram

A-1