Temperature Measurement · Glossary

What is an Infrared Thermometer?

non contact pyrometerTemperature Measurement

An infrared thermometer, or pyrometer, measures surface temperature from the infrared radiation an object emits.

Infrared Thermometer Explained

All objects emit radiation that increases strongly with temperature. The pyrometer focuses it on a detector and converts it to temperature using the set emissivity.

It suits moving, very hot or inaccessible objects. Errors come from wrong emissivity, reflections, dust and a target smaller than the spot size.

Infrared Thermometer Formula

P = ε σ T⁴

P	radiated power per unit area (W/m²)
ε	emissivity
σ	5.670 × 10⁻⁸ W/(m²·K⁴)
T	surface temperature (K)

Calculators for Infrared Thermometer

CalculatorPyrometer Emissivity CalculatorFree online calculator with formula and worked example.CalculatorRadiation Heat Loss CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is an Infrared Thermometer?

An infrared thermometer, or pyrometer, measures surface temperature from the infrared radiation an object emits.

What is distance to spot ratio?

The ratio of distance to the measured spot diameter; the target must fill the spot.

Can a pyrometer measure through glass?

Normally not; glass blocks most long wave infrared. Special wavelengths are needed.

Learn more on the blog

Thermocouple and RTD installation precautions

A practical guide on instrumentationblog.in with more detail on infrared thermometer and how it is applied on real plants.

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