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Physicists in the US have made the first ultrathin flat lens. Thanks to its flatness, the device eliminates optical aberrations that occur in conventional lenses with spherical surfaces. As a result, the focusing power of the lens also approaches the ultimate physical limit set by the laws of diffraction.

Really nice indeed! The new flat ultrathin lens is different in that it is a nanostructured "metasurface" made of optically thin beam-shaping elements called optical antennas, which are separated by distances shorter than the wavelength of the light they are designed to focus. These antennas are wavelength-scale metallic elements that introduce a slight phase delay in a light ray that scatters off them. The metasurface can be tuned for specific wavelengths of light by simply changing the size, angle and spacing between the nanoantennas. "The antenna is nothing more than a resonator that stores light and then releases it after a short time delay," Capasso says. "This delay changes the direction of the light in the same way that a thick glass lens would." The lens surface is patterned with antennas of different shapes and sizes that are oriented in different directions. This causes the phase delays to be radially distributed around the lens so that light rays are increasingly refracted further away from the centre, something that has the effect of focusing the incident light to a precise point.

Great engineering feat from Capasso's idea - an integrated flat lens electrically controlled enabling dynamic beam steering. Reconfigurabilility is the aim. The lens can be used microscope systems, holographic and projection imaging, LIDAR and laser printing. Besides working now on the mid-IR, visible light is the target.

Einstein's theory of gravity, General Relativity (GR), has been tested precisely within the Solar System. However, it has been difficult to test GR on the scale of an individual galaxy. Collett et al. exploited a nearby gravitational lens system, in which light from a distant galaxy (the source) is bent by a foreground galaxy (the lens). Mass distribution in the lens was compared with the curvature of space-time around the lens, independently determined from the distorted image of the source. The result supports GR and eliminates some alternative theories of gravity.

Put together two ACT topics and see what happens.

I remember discussing this briefly and then discarding the idea - but don't remember why any more; duncan?

Well, I think that although the antenna is small, you counteract this with a much large metameterial lens. Probably if you design an antenna of a similar size to the 'lens' you can couple power equally well over the same distance. Then again, further optimization might help improve the size. Maybe in the end you want to combine both together, optimization of the antenna, including a metamaterials lens.

A model is provided for the image formation by a three-dimensional lens with negative index of refraction (n) and compared with results for an array of split-ring resonators (SRRs) and wires. For n=−1, a linear decrease in image distance r is expected w

Now we just need an x-ray mode and we are done.

High energy gamma rays are shown to be bent slightly by specialized lenses. The effect is likely due to pair-creation close to the atomic nuclei in the material.

very nice! "For a start, the wires operate well as switches that by some measures compare well to field effect transistors. For example they allow a million times more current to flow when they are on compared with off when operating at a voltage of about 1.5 V. "[A light effect transistor] can replicate the basic switching function of the modern field effect transistor with competitive (and potentially improved) characteristics," say Marmon and co. But they wires also have entirely new capabilities. The device works as an optical amplifier and can also perform basic logic operations by using two or more laser beams rather than one. That's something a single field effect transistor cannot do."

any idea how the shine the light selectively to such small surfaces?

"Illumination sources consisted of halogen light, 532.016, 441.6, and 325 nm lasers ported through a Horiba LabRAM HR800 confocal Raman system with an internal 632.8 nm laser. Due to limited probe spacing for electrical measurements, all illumination sources were focused through a 50x long working distance (LWD) objective lens (N.A. = 0.50), except 325 nm, which went through a 10x MPLAN objective lens (N.A. = 0.25)." Laser spot size calculated from optical diffraction formula 1.22*lambda/NA

Cheap and scalable invisibility cloaks being developed. The setup is so trivial that I would almost call it a "trick" (as in "Magicians trick"): 6 prisms of n=1.78 glass. Nontheless, it does the job of cloaking an object at visible wavelengths and from several directions.

Is this really new? I don't know, but I know that the original idea of cloaking was pretty different. When cloaking as an application of transformation optics became popular people tried to make devices that work for any incidence angle, any polarization and in full wave optics (not just ray approximation). This is really hard to achieve and I guess that the people that tried to make such devices knew exactly that the task becomes almost trivial by dropping at least two of the three conditions above.

I think it is very easy to call something trivial when you're not the one who invested considerable time (5 min in my case) to design a cloaking device and fill the coffee mugs with water... Also, I did not really violate that many conditions: true I reduced the number of dimensions in which the device works to 1 (as opposed to the 2 dimensions of many metamaterial cloaks). However the polarization should not be affected in my setup as well as the wave phase and wave vector (so it works in full wave optics) - apart maybe from the imperfect lens distortion, but hey I was improvising.

Google Glass 2.0 aka Google Contacts

I'll just leave this here :) They only cut corners on the lens - which allegedly should be a Nikkor 8mm F8.0, but the latter is rare and much more expensive than the final product itself (if you manage to find one used, that is)

Waves of electrons have been bent backward in a sheet of graphene, allowing physicists to focus electrons the way a lens focuses light. Electrons coursing through a sheet of carbon atoms exhibited negative refraction, bending at angles not seen in nature. By exploiting this unusual bending, the researchers created a lenslike device to focus the electrons to a tiny point. The new technique could help physicists learn how to manipulate electrons in the tight confines of miniaturized electronic devices, where the particles often behave like waves.

"With a resolution of 297.500 x 87.500 pixel (26 gigapixel) the picture is the largest in the world. (stand December 2009)" Daring statement... I'm not quite sure, but I'd quess microscopic images used in medicine can easily reach terapixels... What a waste of pixels anyway... they weren't able to find a bit more interesing city?

yeah... like Leiden !

Very famous name in IT (know RSA? He's the 'A'...) He does not go into any technological details - so I encourage you to watch it in spare time [MaRu]

Here, we show that quasar microlensing provides a means to probe extragalactic planets in the lens galaxy, by studying the microlensing properties of emission close to the event horizon of the supermassive black hole of the background quasar, using the current generation telescopes

Paper at http://www.nature.com/nature/journal/v548/n7669/full/nature23463.html?foxtrotcallback=true

Thoughts? :)