FAQs

Infrared thermometers can measure surface temperature from a distance, but the measuring distance must match the instrument’s D:S ratio and the size of the target. This guide explains the relationship between distance and spot size and shows how to select an appropriate working distance for different applications while minimizing errors caused by oversized measurement areas and background interference.

D:S is one of the key optical specifications to consider when selecting an infrared thermometer. A higher D:S ratio generally produces a smaller measurement spot at the same distance, making it more suitable for distant or small targets. This guide explains D:S principles, common ratios, target size, working distance, safety considerations, and practical selection methods.

An infrared thermometer is a non-contact temperature measurement instrument that detects infrared radiation emitted from objects. It is widely used in industrial maintenance, electrical inspection, HVAC systems, equipment servicing, and quality control. Choosing the right infrared thermometer requires careful consideration of measurement range, distance-to-spot ratio, accuracy, emissivity adjustment, operating environment, and application requirements.