For NRC researchers turning on the lights is never a simple task. They inevitably ask what kind of light and how much? Which is why they're so excited about a new tool that will soon be Canada's ultimate light ruler.

Called an ultra high-temperature blackbody, this rare physics tool now being readied at the NRC Institute for National Measurement Standards (NRC-INMS) in Ottawa will soon be one of the world's most accurate ways to measure ultraviolet, or UV, light. These UV measurements are critical for a wide range of environmental and health issues, emerging industrial technologies, and regulatory requirements pertaining to global trade.

While it's called a high-temperature blackbody, it's all about measuring light. All objects emit some form of electromagnetic radiation. The electromagnetic radiation of a high-temperature blackbody is predominantly in the optical radiation region. This region ranges from the infrared through the visible spectrum to the UV. While you're reading this at room temperature your body is emitting invisible infrared radiation that would be visible with infrared, or "night", goggles. What's special about a blackbody is that it's a perfect emitter. When it's heated, at any particular temperature it emits a distinct amount of energy at each wavelength of light. Thus if you know the blackbody's temperature you can use a physics calculation to determine the amount of light being emitted at any wavelength.

"We now have a light source whose absolute output I can calculate. In the measurement business you need a ruler against which you can measure things. The high-temperature blackbody will become our ruler in light measurement," says Arnold Gaertner, the NRC-INMS research officer leading the blackbody project.

The state-of-the-art equipment, built in Russia and installed in part by two technicians from Russia's National Metrology Institute in Moscow, addresses a growing Canadian demand for more accurate UV measurements. In order to deliver these measurements, UV lamps must be calibrated against a known source. This is where the high-temperature blackbody comes in. Its known UV radiation will be used to calibrate NRC UV standards, which will then be used by NRC-INMS staff to calibrate commercial UV equipment.



Source: National Research Council of Canada

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