One of the most common uses of infrared rays is for wireless communication, such as with garage door openers, car-locking systems and handheld remote controls for televisions and other appliances. Since all objects emit some degree of infrared radiation, night-vision devices make use of their sensitivity to infrared rays to capture and transmit images when there is no visible light source. Heat-seeking missiles also rely upon infrared technology to track their targets in passive missile-guidance systems.
Infrared rays are used in some saunas and have been found to provide certain health benefits. Weather forecasting makes use of the infrared radiation emitted by cloud formations, which can be captured and transmitted by weather satellites as images to meteorologists. Astronomers also make use of infrared rays and are able to study the otherwise visibly obscured cores of galaxies cloaked in dust and gas.
The art world found a use for infrared technology in the process known as infrared reflectography. This enables art historians to study the underdrawings, or outlines, used by the artist as a guide before paint was applied to the canvas. A similar infrared-based process has been used by historians to study ancient documents such as the Dead Sea Scrolls.
Technologies based on infrared offer several advantages, one of which is cost. The circuitry required for many commercial wireless transmitter devices can cost less than $5. Power consumption is also low, and the components are small and easily integrated.