Infrared Technology Applied to Portable Infrared Thermometers
Accurate temperature measurement relies on a clear understanding of relevant principles. During measurement with an infrared thermometer, the infrared energy emitted by the measured object is converted into an electrical signal on the detector through the instrument's optical system, and the signal is then processed to display a temperature reading. Several key factors affect precise temperature measurement, among which the most critical are emissivity, field of view, distance-to-spot ratio, and spot positioning.
Emissivity
All objects reflect, transmit and radiate energy; only radiated energy reflects an object's actual temperature. When an infrared thermometer measures surface temperature, it receives all three forms of energy. Therefore, infrared thermometers must be adjusted to detect only radiant energy. Measurement errors are commonly caused by infrared energy reflected from external heat sources.
Some infrared thermometers feature adjustable emissivity, and emissivity values for various materials are available in published emissivity tables. Other devices adopt a fixed preset emissivity of 0.95, which applies to most organic materials, painted surfaces and oxidized surfaces. For surfaces that require correction, attach special measuring tape or apply matte black paint to the target area for compensation. After the tape or paint reaches thermal equilibrium with the base material, measure its surface temperature to obtain the true temperature of the object.
Distance-to-Spot Ratio
The optical system of an infrared thermometer collects energy from a circular measuring spot and focuses it onto the detector. Optical resolution is defined as the ratio of the distance from the thermometer to the target to the diameter of the measuring spot (D:S). A higher ratio means better optical resolution and a smaller measurable spot size.
Laser Aiming
Laser aiming is designed solely for positioning the measuring point. The latest upgrades to infrared optics include close-focus functionality, enabling high-precision measurement of tiny target areas and minimizing interference from ambient background temperatures.
Field of View
The measured target must be larger than the instrument's measuring spot. Smaller targets require a shorter measuring distance. For high-precision measurement scenarios, ensure the target size is at least twice the diameter of the measuring spot.
