Infrared (IR) Radiation
Electromagnetic radiation is all around us. The frequency of an electromagnetic wave is determined by its wavelength. Different ranges (or bands) of wavelength have different properties and different uses.
Our eyes see frequencies in the visible light band. The colors we see are determined by the wavelength of the electromagnetic waves that enter our eyes. Infrared radiation consists of waves with frequencies in a band immediately below visible light. An important property of infrared waves is that they are emitted by all matter, travel through space, and then transmit their energy to the objects they strike where its energy is either absorbed, reflected or transmitted. For example a black rock absorbs most of the infrared energy; a mirror reflects most of the IR energy; and gasses transmit nearly all of the IR energy.
The intensity of the infrared radiation that objects give off is known as the radiance. The higher the temperature of a surface, the higher the surface radiance.
An infrared camera measures the radiance of the waves in the infrared spectrum which come from the surfaces of objects. The camera then converts the radiance it measures into a picture in the visible spectrum. The infrared picture is presented either as shades of gray or some color palette. The most common color pallet is the “Iron Palette” which displays temperatures from cold to hot as the colors black, blue, red, orange, yellow and white.
Infrared (IR) thermography uses infrared pictures to provide insights that you cannot get from a visual inspection. IR Thermography is non-destructive and can usually take place without interrupting the operation of equipment. IR thermography can often save considerable money by indicating the need for corrective maintenance which avoids costly and disruptive failures and secondary damage.
The images below show a simple example:
Both pictures were taken at the same time. Nothing unusual is shown in the visible light image. But in the infrared image we can see that the stove was turned on recently, and that a person’s palm was placed on the stove. Now this is not a very valuable insight, but other insights provided by infrared cameras can be very valuable.
Infrared images can identify:
- overheated parts of machinery so they can be replaced adjusted or lubricated before they fail.
- corroded or loose connections in electrical equipment in buildings, factories and electrical utility facilities that can identify dangerous conditions and help diagnose performance problems
- areas of water penetration in flat building roofs This can identify a small, local repairs which eliminate the need to replace the whole roof.
- moisture in ceilings, walls or floors which can indicate problems requiring repair before they do extensive damage or cause mold.
- and many more.