What is an infrared thermometer (infrared temperature sensor)?
Infrared thermometer is a sensor consisting of a lens to focus infrared (IR) energy onto a detector, which converts the energy into an electrical signal that can be displayed in units of temperature after being compensated for changes in ambient temperature.

HORIBA IT-545N High precision infrared thermometer (-50 ~ 500℃)

How does an infrared thermometer work?

Infrared thermometer is a non-contact temperature sensor. used to measure thermal (infrared) energy emitted from an object.

Capable of detecting and capturing thermal radiation, they generate heat without physical contact or penetration into the product.

Used throughout the food manufacturing industry, Infrared thermometers are commonly used in import/export applications. They are a popular choice for tracking frozen food products.

SATO SK-8700II (Item No. 8261-00) Best-selling handheld infrared thermometer with wide measuring range from −20 to 315°C

Non-contact infrared thermometers allow engineers to obtain accurate temperature measurements in applications where it is impossible or very difficult to use any other type of temperature sensor.
In some cases, this is because the application itself actually destroys the contact type sensor, such as when using a thermocouple or resistance temperature detector to measure molten metal. If electrical interference is strong, such as during induction heating, the electromagnetic field around the object will cause inaccurate readings in conventional sensors. Remote infrared thermometers do not suffer from either of these problems.
For maintenance, no other sensor can provide the remote, non-contact temperature measurements needed to find hot spots or trouble areas in distillation columns, vessels, insulation, tubing, motors, or transformers. As a maintenance and troubleshooting tool, it is hard to beat a handheld laser thermometer.
Infrared temperature sensors come in many varieties, from relatively inexpensive infrared thermocouples to sophisticated computer-based line scanners. In between are a wide variety of handheld and fixed-mount IR measurement systems that cover almost any temperature monitoring need imaginable.

Round Laser Waterproof Infrared Thermometer SATO SK-8950 (−60 to 550°C)

What is the minimum/maximum distance you can keep the thermometer away from the product?

Every Infrared Thermometer has what is called a distance-to-point ratio . This tells you the diameter of the area being measured in relation to the distance from the thermometer to the target.

Assuming your thermometer has a distance-to-spot ratio of 12:1, it will be able to measure (approximately) a 1-inch diameter spot when it is 12 inches from the target. However, if you try to use this thermometer to measure a 2-inch wide area even when it is only 1 meter away, you will not be guaranteed an accurate result because the instrument will also measure the temperature outside the desired area.

What factors affect Infrared Thermometers and how do they work?

There are six main factors that can affect your infrared thermometer readings.

1. Measuring angle: The infrared thermometer is supposed to be held at a 45° angle and aimed properly. Otherwise, the displayed value will be inaccurate. Users should also ensure that the target area is clean and any potential obstacles have been removed.

2. Ambient temperature: If an IR Thermometer is moved rapidly between two environments with very different temperatures, the accuracy of the device will be temporarily affected. Ideally, the IR Thermometer should be introduced into the new environment at least 30 minutes before using it to take a measurement. This will allow enough time for the temperature of the thermometer to match the temperature of the environment.

3. Air quality:  Air pollutants such as smoke and dust will make it difficult for your thermometer to receive enough infrared energy to give an accurate reading. This can also be a problem if the lens of your Infrared Thermometer is not clean.

4. Reflective surface:  The accuracy of infrared thermometers can be affected by reflective surfaces. You should be especially careful when measuring the temperature of shiny metal objects, but even shiny, reflective packaging can affect accuracy. One solution is to tape a piece of non-reflective tape to any shiny object you want to measure.

5. Emissivity setting: The 'emissivity setting' of an IR Thermometer determines how effective it is at measuring the infrared radiation emitted by different materials. Depending on the type of thermometer you choose, the emissivity setting can be adjusted to match the characteristics of the surface being measured – improving the accuracy of the results.

An example of this is SATO SK-8920 Infrared thermometer for measuring food temperature (−40 ~ 250°C)

6. Temperature range: Along with emissivity and distance-to-spot settings, infrared thermometers also have a temperature range within which they provide the highest level of accuracy. If the temperature of the product you are testing falls outside this range, this may affect the accuracy and reliability of the results you receive.

If you need further guidance, SEMIKI is happy to assist you. Our in-house technical team will be happy to assist and provide relevant resources. You can also contact us at 
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SEMIKI Measuring Equipment Company Limited
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