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| NTU Invention Allows Clear Photos in Dim Light Posted: 23 Jul 2013 08:58 AM PDT Cameras fitted with a new revolutionary sensor will soon be able to take clear and sharp photos in dim conditions, thanks to a new image sensor invented at Nanyang Technological University (NTU). The new sensor made from graphene, is believed to be the first to be able to detect broad spectrum light, from the visible to mid-infrared, with high photoresponse or sensitivity. This means it is suitable for use in all types of cameras, including infrared cameras, traffic speed cameras, satellite imaging and more. Not only is the graphene sensor 1,000 times more sensitive to light than current low-cost imaging sensors found in today's compact cameras, it also uses 10 times less energy as it operates at lower voltages. When mass produced, graphene sensors are estimated to cost at least five times cheaper. Graphene is a million times smaller than the thickest human hair (only one-atom thick) and is made of pure carbon atoms arranged in a honeycomb structure. It is known to have a high electrical conductivity among other properties such as durability and flexibility. The inventor of the graphene sensor, Assistant Professor Wang Qijie, from NTU's School of Electrical & Electronic Engineering, said it is believed to be the first time that a broad-spectrum, high photosensitive sensor has been developed using pure graphene. His breakthrough, made by fabricating a graphene sheet into novel nano structures, was published in Nature Communications, a highly-rated research journal. "We have shown that it is now possible to create cheap, sensitive and flexible photo sensors from graphene alone. We expect our innovation will have great impact not only on the consumer imaging industry, but also in satellite imaging and communication industries, as well as the mid-infrared applications," said Asst Prof Wang, who also holds a joint appointment in NTU's School of Physical and Mathematical Sciences. "While designing this sensor, we have kept current manufacturing practices in mind. This means the industry can in principle continue producing camera sensors using the CMOS (complementary metal-oxide-semiconductor) process, which is the prevailing technology used by the majority of factories in the electronics industry. Therefore manufacturers can easily replace the current base material of photo sensors with our new nano-structured graphene material." If adopted by industry, Asst Prof Wang expects that cost of manufacturing imaging sensors to fall - eventually leading to cheaper cameras with longer battery life. How the Graphene Nanostructure Works Asst Prof Wang came up with an innovative idea to create nanostructures on graphene which will "trap" light-generated electron particles for a much longer time, resulting in a much stronger electric signal. Such electric signals can then be processed into an image, such as a photograph captured by a digital camera. The "trapped electrons" is the key to achieving high photoresponse in graphene, which makes it far more effective than the normal CMOS or CCD (Charge-Coupled Device) image sensors, said Asst Prof Wang. Essentially, the stronger the electric signals generated, the clearer and sharper the photos. "The performance of our graphene sensor can be further improved, such as the response speed, through nanostructure engineering of graphene, and preliminary results already verified the feasibility of our concept," Asst Prof Wang added. This research, costing about $200,000, is funded by the Nanyang Assistant Professorship start-up grant and supported partially by the Ministry of Education Tier 2 and 3 research grants. Development of this sensor took Asst Prof Wang a total of 2 years to complete. His team consisted of two research fellows, Dr Zhang Yongzhe and Dr Li Xiaohui, and four doctoral students Liu Tao, Meng Bo, Liang Guozhen and Hu Xiaonan, from EEE, NTU. Two undergraduate students were also involved in this ground-breaking work. Asst Prof Wang has filed a patent through NTU's Nanyang Innovation and Enterprise Office for his invention. The next step is to work with industry collaborators to develop the graphene sensor into a commercial product. Source: Nanyang Technological University |
| Digital Camera Add-On Means the Light's Fantastic Posted: 23 Jul 2013 08:16 AM PDT KaleidoCamera is developed by Alkhazur Manakov of Saarland University in Saarbrücken, Germany, and his colleagues. It attaches directly to the front of a normal digital SLR camera, and the camera's detachable lens is then fixed to the front of the KaleidoCamera. After light passes through the lens, it enters the KaleidoCamera, which splits it into nine image beams according to the angle at which the light arrives. Each beam is filtered, before mirrors direct them onto the camera's sensor in a grid of separate images, which can be recombined however the photographer wishes. This set-up allows users to have far more control over what type of light reaches the camera's sensor. Each filter could allow a single colour through, for example, then colours can be selected and recombined at will after the shot is taken, using software. Similarly, swapping in filters that mimic different aperture settings allows users to compose other-worldly images with high dynamic range in a single shot. And because light beams are split up by the angle at which they arrive, each one contains information about how far objects in a scene are from the camera. With a slight tweak to its set-up, the prototype KaleidoCamera can capture this information, allowing photographers to refocus images after the photo has been taken. Roarke Horstmeyer at the California Institute of Technology in Pasadena says the device could make digital SLR photos useful for a range of visual tasks that are normally difficult for computers, like distinguishing fresh fruit from rotten, or picking out objects from a similarly coloured background. "These sorts of tasks are essentially impossible when applying computer vision to conventional photos," says Horstmeyer. The ability to focus images after taking them is already commercially available in the Lytro – a camera designed solely for that purpose. But while Lytro is a stand-alone device which costs roughly the same as an entry-level digital SLR, KaleidoCamera's inventors plan to turn their prototype into an add-on for any SLR camera. Manakov will present the paper at the SIGGRAPH conference in Anaheim, California, this month. He says the team is working on miniaturising it, and that much of the prototype's current bulk simply makes it easier for the researchers to tweak it for new experiments. "A considerable engineering effort will be required to downsize the add-on and increase image quality and effective resolution," says Yosuke Bando, a visiting scientist at the MIT Media Lab. "But it has potential to lead to exchangeable SLR lenses and cellphone add-ons." In fact, there are already developments to bring post-snap refocusing to smartphone cameras, with California-based start-up Pelican aiming to release something next year. "Being able to convert a standard digital SLR into a camera that captures multiple optical modes – and back again – could be a real game-changer," says Andrew Lumsdaine of Indiana University in Bloomington. By Hal Hodson, New Scientist |
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