What is infrared measurement? A clear explanation of how it measures temperature, moisture, constituent, and thickness.

Infrared radiation is a type of electromagnetic wave.

Infrared radiation is a type of electromagnetic wave, with wavelengths longer than visible light. Electromagnetic waves exist in various wavelengths, and the way they interact with matter and the measurement methods used differ depending on the wavelength.

The "wavelength" of infrared light becomes important in measurements.

Infrared light is not a single type of light, but rather encompasses a variety of wavelengths. Since the information obtained from the object being measured changes depending on which wavelength is used, wavelength selection is crucial in infrared measurements.

The relationship between infrared radiation and an object is used for measurement.

In infrared measurement, infrared radiation emitted from an object is captured, or changes such as absorption and reflection are detected by irradiating an object with infrared radiation. This information is then used to determine the state and quantity of objects that cannot be directly seen.

Infrared radiation is emitted from the object.

Objects with temperature emit electromagnetic waves, including wavelengths known as infrared radiation. Since the state of the emitted electromagnetic waves is related to the object's temperature, this can be used for temperature measurement.

Infrared rays are absorption by matter.

Some materials have the property of absorption infrared light of specific wavelengths. The amount and type of wavelength absorption varies from material to material, and this difference can be used to obtain information about the material's moisture and other constituent.

Infrared rays can both be reflected and transmitted.

When infrared light strikes an object, it may not only be partially absorption, but also reflected or transmitted. Which phenomenon is utilized depends on the object being measured and the measurement method.

Objects that have a temperature emit infrared radiation.

The state of electromagnetic waves emitted from an object is related to the object's temperature. radiation thermometer uses this relationship to determine the object's temperature.

radiation thermometer determine temperature from infrared radiation.

radiation thermometer detect infrared radiation emitted from an object and calculate its temperature from that information. Because they can measure temperature without the sensor touching the object, they are used for high-temperature objects and moving objects.

We need to consider emissivity and measurement conditions.

radiation thermometer require consideration of factors such as the radiation characteristic of the object being measured, the measurement distance, the size of the object, and ambient influences. Therefore, simply detecting infrared radiation does not guarantee an accurate temperature.

The key points for correctly using radiation thermometer, such as emissivity, measurement distance, D:S ratio, and the object being measured, are explained in detail in a separate article.

• A Guide to Avoiding radiation thermometer | Principles, emissivity, D:S Ratio, and Selection Methods for Non-Contact Temperature Measurement
• Is your radiation thermometer reading inaccurate? What causes errors, and how can you correct them and check your readings?

Different substances absorption different wavelengths.

Substances do not treat all wavelengths of infrared radiation the same way. Because absorption different wavelengths more easily, utilizing these characteristics can provide information about specific substances or constituent.

We can determine the relationship between optical changes and the quantity we want to measure.

Infrared measurement detects optical information such as light intensity and absorption. Instead of directly treating this as moisture content or constituent amount, the desired quantity is determined by checking its relationship to a reference value.

Some measurements utilize calibration curve.

One method involves expressing the relationship between optical measurements and actual moisture content or constituent amounts using mathematical formulas or graphs, and then determining the value of an unknown target from that relationship. This relationship is called calibration curve.

Measurement can be taken without the object and sensor coming into contact.

Methods that utilize light or electromagnetic waves can sometimes measure without requiring contact with the object being measured. This allows for avoiding the impact on the object caused by contact, and can be used in process where it is difficult to place sensors close to the object.

It can measure moving objects.

When measuring materials or products that are moving along a manufacturing line, it can be difficult to bring sensors into contact with the object. Non-contact measurement methods can be used for continuous measurement of such objects.

It can also be used for objects that are difficult to contact, such as those at high temperatures.

For materials that are hot, or other objects where direct sensor contact is difficult, non-contact measurement can be a viable option.

Just because it's non-contact doesn't mean it's easy to measure.

Even with non-contact measurement, it's necessary to consider the condition of the object being measured, the distance, the surrounding environment, and the measurement method. It's important to distinguish between "being non-contact" and "being able to measure accurately."

An optical change related to the quantity to be measured is required.

To determine temperature, moisture, constituent, thickness, etc., from information obtained via infrared radiation, a usable relationship is required between the two.

You need to choose the appropriate wavelength.

Because different substances have different absorption characteristic, it is necessary to select a wavelength and measurement method that is appropriate for the substance being measured.

The material and surface condition have an influence.

The infrared information obtained may vary depending on the material, surface condition, composition, and temperature of the object.

The measurement distance and surrounding environment also need to be considered.

For non-contact measurements, it is necessary to check the distance to the object, the measurement range, and the influence of radiation and reflection from the surroundings.

If you want to measure the temperature

This method measures temperature using infrared radiation emitted from an object. Conditions such as emissivity and measurement distance will be checked.

If you want to measure moisture

By utilizing the infrared absorption of water, the measured value is determined in relation to a reference moisture content.

If you want to measure constituent and their content

By utilizing the infrared absorption characteristic related to the target constituent, the amount constituent is determined from its relationship to a reference analytical value.

If you want to measure the thickness or amount of coating

The thickness and coating amount are determined by utilizing the relationship between the amount of the target substance and its optical response to infrared light.