Submission + - 'Darkness Ray' Beams Invisibility From A Distance (medium.com)
KentuckyFC writes: Optical engineers generally build imaging systems with the best possible resolving power. The basic idea is that an imaging system focuses light into a pattern known as a point spreading function. This consists of a central region of high intensity surrounded by a concentric lobe of lower intensity light. The trick to improving resolution is narrowing and intensifying this central region while suppressing the outer lobe. Now optical engineers have turned this approach on its head by suppressing the central region so that the field intensity here is zero while intensifying the lobe. The result is a three-dimensional beam of darkness that hides any object inside it. The engineers say this region can be huge--up to 8 orders of magnitude bigger than the wavelength of the imaging light. What's more, that the optics required to create it are simple and cheap: a lens consisting of concentric dielectric grooves. The team has even tested a prototype capable of hiding a 40-micrometre object in visible laser light.
