SpectralEmissivity & Emittance

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Improving Temperature Measurement of Low Emissivity Targets

Helpful Tips for Users From FLIR

fliratspr118-imageMeer, Belgium — FLIR Systems has published a new technical note that investigates and describes how to use low-cost materials to increase target emissivity to enable accurate measurement using a thermal imaging camera.

Clean, unoxidized, bare metal surfaces such as are found in many R&D applications have low emissivity. Consequently they are difficult to analyse with a thermal imaging camera.

To get good accurate temperature measurements there is a consequent need to increase the emissivity of these problematic targets.

The technical note provides an informative introduction to emissivity and how a target’s emissivity, reflectance and thermal conductivity values are highly dependent on material properties.Read More

Ultra-thin perfect absorber employing a tunable phase change material

New device hides, on cue, from infrared cameras

November 26, 2012

Tunable material developed at Harvard boasts nearly 100% absorption on demand

Cambridge, Mass. – November 26, 2012 – Now you see it, now you don’t.

A new device invented at the Harvard School of Engineering and Applied Sciences (SEAS) can absorb 99.75% of infrared light that shines on it. When activated, it appears black to infrared cameras.

Composed of just a 180-nanometer-thick layer of vanadium dioxide (VO2) on top of a sheet of sapphire, the device reacts to temperature changes by reflecting dramatically more or less infrared light.

Announced today in the journal Applied Physics Letters, and featured on its cover, this perfect absorber is ultrathin, tunable, and exceptionally well suited for use in a range of infrared optical devices.

Perfect absorbers have been created many times before, but not with such versatile properties. In a Fabry-Pérot cavity, for instance, two mirrors sandwich an absorbing material, and light simply reflects light back and forth until it’s mostly all gone. Other devices incorporate surfaces with nanoscale metallic patterns that trap and eventually absorb the light.
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Thermal infrared remote sensing of crude oil slicks

In: Remote Sensing of Environment, Volume 45, Issue 2, August 1993, Pages 225-231.

by John W. Salisbury a, Dana M. D’Aria a and Floyd F. Sabins Jr.b
aDepartment of Earth and Planetary Sciences, Johns Hopkins University, Baltimore U.S.A.
bChevron Oil Field Research Company, La Habra, California U.S.A.

(Abstract Online)
With all the interest on the Gulf Oil spill and recent accounts of the use by British Petroleum and others of Infrared Thermal Imaging to search for surface oil slicks, it seemed very timely to be sure we had included some links and summaries of articles dealing with the thermal Infrared optical properties of crude oil on seawater.

Article AbstractRead More