The principle of infrared temperature measurement

    Objects above absolute zero (-273°C) will radiate infrared energy of different wavelengths. Infrared thermometers can capture the infrared energy radiated from all objects. Infrared radiation is part of the electromagnetic spectrum, which also includes radio waves, microwaves, visible light, ultraviolet rays, gamma rays, and X-rays.

    Several important concepts of infrared temperature measurement: wavelength, emissivity and distance coefficient.

    The radiation curves of different temperatures never intersect. As the temperature rises, the radiation energy increases and the peak wavelength decreases. The wavelength is inversely proportional to the temperature.

    The emissivity is the ratio of the radiance of an object to the radiance of a black body with the same temperature as the object. The emissivity determines the infrared radiation characteristics of the object. The main factors affecting emissivity are: material type, surface condition (polishing, roughness, oxidation, sandblasting, etc.), surface geometry, surface physical and chemical structure state (sediment, oxide film, oil film, etc.), transmittance, measurement temperature , Measuring angle, etc.

    The distance coefficient refers to the ratio of the distance from the probe to the target and the diameter of the measuring spot. To ensure that the target is larger than the size of the dot measured by the instrument, the smaller the target, the closer it should be.

    The infrared thermometer is composed of optical system, photodetector, signal amplifier, signal processing, display output and other parts. The optical system condenses the infrared radiation energy of the target in its field of view, and the infrared energy is gathered on the photodetector and converted into a corresponding electrical signal, which is converted into the temperature value of the measured target after conversion.

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