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The Golay cell is a type of opto-acoustic detector mainly used for
The Golay cell is a type of opto-acoustic detector mainly used for infrared spectroscopy
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functio ...
. It consists of a gas-filled enclosure with an infrared
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
absorbing material and a flexible diaphragm or membrane. When infrared radiation is absorbed, it heats the gas, causing it to expand. The resulting increase in pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...
deforms the membrane. Light reflected off the membrane is detected by a photodiode
A photodiode is a semiconductor diode sensitive to photon radiation, such as visible light, infrared or ultraviolet radiation, X-rays and gamma rays. It produces an electrical current when it absorbs photons. This can be used for detection and me ...
, and motion of the membrane produces a change in the signal on the photodiode. The concept was originally described in 1947 by Marcel J. E. Golay, after whom it came to be named.
The Golay cell has high sensitivity and a flat response over a very broad range of frequencies. The response time is modest, of order 10 ms. The detector performance is degraded in the presence of mechanical vibrations.
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