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The materials used for the LED have a direct band gap with energies corresponding to near-infrared, visible, or near-ultraviolet light. LED development began with infrared and red devices made with gallium arsenide. Advances in materials science have enabled making devices with ever-shorter wavelengths, emitting light in a variety of colors.
The forward voltage drop (about 1.7 V for a red LED or 1.2V for an infrared) can be used instead of a Zener diode in low-voltage regulators. Red LEDs have the flattest I/V curve above the knee. Nitride-based LEDs have a fairly steep I/V curve and are useless for this purpose.
This principle can be used also for non-contact [1] infrared non-destructive testing (IRNDT) of materials. [2] The IRNDT method is based on an excitation of a tested material by an external source, which brings some energy to the material. Halogen lamps, flash-lamps, ultrasonic horn or other sources can be used as the excitation source for the ...
Infrared heating uses infrared lamps, commonly called heat lamps, to transmit infrared radiation to the body that is being heated. When a body with a large surface area needs to be heated, an array of infrared lamps is often used. The lamp commonly contains an incandescent bulb that produces infrared radiation.
Inset shows false color infrared thermograph of a roof on a sunny day; the white surfaces (colored blue in the thermograph) have been coated with an elastomer to reduce solar loading and have a surface temperature of approximately 60 °F (16 °C); the gray surfaces (colored red/white in the thermogram) are a standard asphalt (bitumen) coating and have a surface temperature of approximately 160 ...
Unlike an infrared thermometer, these can be used orally, rectally, or under the arm. Temperature readings may take a little longer (about 8 seconds), but are highly accurate, testers say.
A manual subjective test is implemented to determine the MRTD. An operator uses a series of 4-bar targets of different spatial frequencies. For each target he/she adjusts the blackbody, (source of Infrared radiation), temperature up and down until the pattern is "just resolvable."
The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) which produces an infrared spectrum. An IR spectrum can be visualized in a graph of infrared light absorbance (or transmittance ) on the vertical axis vs. frequency , wavenumber or wavelength on the horizontal ...