May 27, 2021
A body that is hit by radiation and absorbes it all, is called a black radiator.
This body has no losses due to reflection or transmission and emits the maximum possible energy in all directions equally.
For a defined waveband, the emitted radiation depends only on the temperature of the black radiator.
In reality one can not find a body that can emit 100% of a radiation.
The best possible reproduction is achieved with a cavity with matte black walls all having the same temperature.
A beam falling through a hole into the cavity is reflected and absorbed several times at the inner wall.
The radiation coming out of the hole corresponds to the temperature of the body.
This effect is used, e.g. in the calibration of IR measuring instruments.
Infrared: Schematic structure of a black radiator
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Jan 5, 2019
The ability of an object to emit infrared radiation is called emission.
In the infrared temperature measurement, the temperature of the object is calculated based on the intensity of the emitted radiation.
The proportion on emission of the radiation collected by a infrared camera is described by the emissivity.
Sep 20, 2019
The radiation detected by a thermal camera in a non-contact temperature measurement consists of the reflection, the transmission and the emission of infrared radiation emanating from objects in the field of view of the camera. The emissivity is a dimensionless measure that indicates the ratio of the emitted radiation of the measurement object in relation to the incident radiation.
Emissivity depends on the material, the surface texture and, in some cases, the temperature of a body. In general, the higher the emissivity of a body, the easier the temperature can be measured with a IR-camera.
The following relationship applies: Emissivity + Reflection + Transmission = 1
Infrared:
Emissivity of different materials (Concret = 0,95, Wood = 0,90, Plastic = 0,97)
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Feb 28, 2023
The thermal radiation of objects is found behind the visible red spectrum of light.
This range is called the infrared wavelength range.
Infrared cameras are used to make the temperatures of the “thermal radiation” (wavelength between 1µm and 20µm) visible.
The camera consists of a lens, a spectral filter, the detector (sensor) and appropriate electronics for amplification, linearization and corresponding signal processing.
Infrared cameras are used in many areas, because they allow the measurement of difficult to access or moving objects with short measurement and response times.
During the measurement there is no influence on the object to be measured.
In the field of plastics technology, infrared cameras are used, for example, for testing and monitoring the injection molding process.
Infrared camera for use in manufacturing
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Jan 10, 2019
The ability of an object to mirror infrared radiation is called reflexion.
The amount of the reflected radiation depends on the surface of a given object.
Plastics have usually a low amount, while shining metals (for example an insert in an injection mold) have a high amount of reflexion.
The higher the proportion of reflexion, the more difficult it is to measure temperature using an infrared camera.
