Unidirectional imaging forms images solely from one field of view (FOV A) to another (FOV B) while preventing reverse visibility from B to A. According to findings published in *Advanced Photonics Nexus*, this selective capability is achieved using specially engineered asymmetric linear diffractive layers, optimized for partially coherent illumination, which allows image formation to proceed efficiently in one direction.
The UCLA team demonstrated that these imagers perform well under partially coherent light - a light with a certain degree of phase correlation. In testing, the forward imaging direction (A to B) yielded high-quality images with strong power efficiency, while the reverse direction (B to A) showed significantly lower image quality and power efficiency, effectively blocking backward image formation.
Their study showed that the imagers maintain unidirectional transmission particularly well when illuminated by a partially coherent beam with a phase correlation length of at least 1.5 times the wavelength of light (?). Even under reduced correlation lengths, the imagers continue to support unidirectional imaging, though with minor performance impacts.
Compact and versatile, these imagers are less than 75 times the wavelength of light in thickness and work independently of light polarization. They are compatible with various light sources, including broadband radiation, making them adaptable across numerous applications. This directional control over image formation represents a major advancement in visual information processing, particularly for scientific and practical uses in fields like optical communication.
Research Report:Unidirectional imaging with partially coherent light
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International Society for Optics and Photonics
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