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Automated Inspection of components using
The Infrared radiation has been studied for well over a century. It has only been the last fifty years since the science has lead to the development of sensors that are economical enough for use in industrial applications. Today infrared sensors are used as the tool of choice for the detection of over heated circuit, mechanical wear, voids or leaks in roofs, poor barrier seals, and many more applications. Phoenix Imaging's Infraredia group is dedicated to the advancement of automated inspection systems using infrared sensor technology. The Infraredia group has been implementing infrared (IR) inspection systems for over twenty years in a wide range of applications from simple automotive backlight inspection of defroster circuits to advanced vibro-thermography applications to identify cracks in die-cast or powder metal components. Among the many industrial uses of infrared sensors the most popular for our customers include:
There are several different techniques that are applicable to infrared inspection. The most common is passive infrared inspection in which the component being examined is observed in a natural state during the production cycle. Examples of this type of inspection would be components of different temperatures, thermal energy added during the manufacturing process, thermal energy added during the washing or drying process. Active infrared inspection requires that thermal, electrical or magnetic energy is added to the components in order to perform the testing procedure. Active infrared inspection examples would include supplying current to an electrical circuit, adding thermal energy to castings to highlight surface voids, or to excite a laminate with a heat pulse. There is one additional Active technique that converts mechanical energy to thermal energy called Vibro-Thermography, more on this topic later.
A few examples of how infrared technology can be applied are show below:
The electromagnetic spectrum (Background Information)
The electromagnetic spectrum is divided arbitrarily into a number of wavelength regions, called bands, distinguished by the methods used to produce and detect the radiation. There is no fundamental difference between radiation in the different bands of the electromagnetic spectrum. They are all governed by the same laws and the only differences are those due to differences in wavelength. Thermography makes use of the infrared spectral band. At the short-wavelength end the boundary lies at the limit of visual perception, in the deep red. At the long-wavelength end it merges with the microwave radio wavelengths, in the millimeter range.
The name means below red, the Latin infra meaning "below". Red is the color of the longest wavelengths of visible light. Infrared light has a longer wavelength (and so a lower frequency) than that of red light visible to humans, hence the literal meaning of below red.
The infrared band is often further subdivided into four smaller bands, the boundaries of which are also arbitrarily chosen. They include: the near infrared (0.75–3 µm), the middle infrared (3–6 µm), the far infrared (6–15 µm) and the extreme infrared (15–100 µm). Although the wavelengths are given in µm (micrometers), other units are often still used to measure wavelength in this spectral region, e.g. nanometer (nm) and Ångström (Å).
The relationships between the different wavelength measurements is:
10,000 Å = 1,000 nm = 1 µm
In addition, the International Commission on Illumination (CIE) recommended the division of optical radiation into the following three bands:
The Electro-magnetic Spectrum
Although the automated inspection industry and quality control departments consider the visible spectrum as the primary inspection tool, the infrared spectrum offer many opportunities. Consider the EM spectrum illustrated above, notice that the IR spectrum is much larger than the visible spectrum. When using automated inspection equipment the sensor acquires data, not the human eye. There are a range of IR sensors available for each the IR divisions listed above. The task of selecting the proper IR sensor for the application should be left to the expects that implement the technology on a regular basis. Infraredia has the experience to insure that your infrared application is engineered and implemented correctly.