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How The Non-Contact Infrared Thermometer Works?


Non-contact infrared thermometers, also known as IR thermometers, utilize the principle of infrared radiation to measure the surface temperature of objects without the need for physical contact. They are commonly used for various applications, including medical diagnosis, industrial monitoring, and household temperature measurements.

Forehead & Ear lnfrared Thermometer YI-100C
Forehead & Ear lnfrared Thermometer YI-100

How Does a Non-Contact Infrared Thermometer Work?

IR thermometers measure temperature from a distance without touching the object being measured, making them useful in situations where other thermometers cannot provide accurate results.

IR thermometers differ from probe-style thermometers or contact infrared Thermometer in that they do not require touching the item being measured; rather, IR thermometers focus infrared radiation onto a detector through a lens, converting it into an electrical signal that can be displayed in temperature units after compensating for ambient temperature variations.

To guarantee accurate readings, it’s essential to select an IR thermometer with a high D:S ratio and emissivity functionality. Emissivity is a measurement of how efficiently an object emits infrared radiation.

What is the Range of a Non-Contact Infrared Thermometer?

An infrared thermometer measures the amount of radiation emitted by objects, which it then collects and converts to electricity.

Forehead thermometers are non-contact, meaning they can measure temperatures safely at a distance. They’re ideal for situations where other types of thermometers might not be feasible, such as when an object is too delicate or hazardous to be near.

Most no-touch thermometers are calibrated to measure a specific range of temperatures. This ensures they will only be accurate if you use them on items within that temperature range.

An IR thermometer’s accuracy is determined by two factors: distance-to-spot ratio and surface emissivity. A thermometer with an emissivity of 0.95 will be more precise than one with a value of 1.04.

What is the Field of View of an Infrared Thermometer?

When selecting an infrared thermometer, the field of view (spot size) should be taken into account. IR thermometer’s spot size varies depending on its orientation to the surface being measured and the distance between it and the object being measured.

For accurate readings, ensure the object being measured completely fills the field of view of the IR device. This is because IR devices measure the average temperature across all surfaces within their viewing angle.

What is the Emissivity of an Infrared Thermometer?

Emissivity is a measure of how much thermal radiation an object emits. All objects emit infrared radiation at different rates depending on their properties, which can be determined using a thermometer.

Emissions (below 0.2) make it difficult to measure temperature accurately with an infrared thermometer. Shiny metallic surfaces, such as aluminum, may give false temperature readings due to their high reflectiveness in the infrared.

This issue can often be solved by painting or coating a non-reflective area of the surface you measure with spray oil, flat black paint, or masking tape. Doing this creates an accurate target from which to measure temperature accurately and consistently.


The Caretek Non-Contact Infrared Thermometer is a versatile and rugged thermometer that features both a probe and an infrared sensor in one unit. It’s ideal for checking the temperature, giving an accurate read.

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