Phased-array optics
Phased array optics (PAO) is the technology of microscopically controlling the phase of light waves reflecting from, or transmitting through, a two-dimensional surface. It is the optical analog of phased array radar. By dynamically controlling the optical properties of a surface on a scale close to the wavelength of light, it is possible to steer the direction of light beams, or the "look" direction of sensors, without any moving parts. Hardware associated with beam steering applications is commonly called an optical phased array (OPA). Phased array beam steering is used for switching and multiplexing in photonic devices, and for aiming laser beams on a macroscopic scale for optical communications systems.
Complicated two-dimensional patterns of phase variation can be used to produce diffractive optical elements, such as dynamic virtual lenses, for focussing or beam splitting in addition to aiming. Dynamic phase variation can also produce real-time holograms. Devices permitting detailed addressable phase control over two dimensions are a type of spatial light modulator (SPM).
In nanotechnology, phased array optics refers to spatial light modulators with addressable phase and amplitude elements with a spacing smaller than a wavelength of light. While still theoretical, such high resolution SPMs would permit extremely realistic three dimensional image display by dynamic holography with no unwanted orders of diffraction.
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