Creative cameras: photography in a new light at the Royal Society Summer Science Exhibition 2014

Creative cameras: photography in a new light at the Royal Society Summer Science Exhibition 2014


How do you take images so fast that you can see light travelling through air? How do you take pictures without using a camera? And how do you use the latest technology to look around corners and see objects hidden from view? These are the questions that researchers from Heriot Watt University and the University of Glasgow, the Creative Cameras team, are looking into. Light is made up of photons travelling at 300 million metres per second, and nothing can travel faster than the speed of light. Photons travel so fast that normal cameras cannot freeze their motion as they move. But the team at Heriot Watt University is using a new type of camera – a camera so sensitive and so fast that we can capture individual photons and take videos of pulses of light as they travel through air. The camera, developed by the University of Edinburgh, is made up of an array of single photon-sensitive pixels and these pixels have two very special properties. The first is their sensitivity to single photons. Each pixel is around ten times more sensitive than a human eye. The second is their speed. Each pixel can be activated for just 67 picoseconds – that’s more than a billion times faster than you or I can blink. These properties allow us to perform light in flight imaging – an approach to imaging where light itself is captured as it travels through air and scatters off objects. The camera works in combination with a pulsed laser source. Photons in the pulse of light travel through air. Here, we see them reflecting off a series of mirrors. The pulses randomly scatter individual photons when colliding with air molecules. Some of these photons are captured by the camera. When the pulse of light leaves the laser, a signal is sent to the camera to start individual timers associated with each of the pixels. Every pixel has its own individual timer. When a photon arrives at a pixel on the camera, the timer for that pixel is stopped, and the time of arrival is recorded. After many pulses from the laser, a video of light travelling through air is recorded. The camera lends itself to applications where precise timing information is needed, and one such application is recording the scattered light from objects hidden from view, enabling us to look around corners. There are a variety of potential applications for this, ranging from search and rescue missions, where faint signals will enable trapped people to be found, to medical imaging inside the body, where new forms of endoscopy are enabled by time-of-flight imaging. The team at Glasgow University is taking a different approach to imaging and looking into taking pictures outside of the visible spectrum, with only single pixels. Normal cameras use a lens to form an image on a rectangular array of light-sensitive detectors. The signal from each individual detector gives the value of the corresponding pixel in the image. An alternative approach called ‘computational ghost imaging’ instead uses a data projector and a single detector to form an image of the object through a process known as data inversion. The data projector illuminates the object with a sequence of patterns that resemble random crossword puzzles, and a single detector collects all the back-scattered light. When more of the white squares of these puzzles overlap with the object, the intensity of the light returning to the single detector is higher. One random pattern and the corresponding detector signal does not give an image of the object, but the object can be deduced from a sequence of different patterns and corresponding detector signals. The number of patterns needed gets higher as the desired resolution increases, but a modern day projector can display the required number of patterns in only a few seconds. Surprisingly, the images produced in this way contain all the information that can be collected by conventional methods. The contours and shading can be recovered perfectly, and even colour information can be gathered with a set of single pixels. Interestingly, the shadows in the image are not determined by the position of the light source, and rather, it is the position of the detector that determines the shadow detail. This ghost imaging technique is certainly strange, but this is more than a clever method for three-dimensional imagery construction. Normal cameras work well with visible light, but getting images in ultraviolet or infrared can be hard. By contrast, data projectors can work over a whole range of wavelengths, even far removed from the visible spectrum. Perhaps we can use this ghost imaging approach to make camera-like systems working over a much wider range of the electromagnetic spectrum.

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    The Royal Society

    Enjoy the video? Listen to Quentin Cooper's interview about cameras that see through walls and round corners : https://soundcloud.com/theroyalsociety/sets/royal-society-summer-science

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    Apiwat Chantawibul

    I really like the video, only the animation at 3.52 is potentially misleading for people who is really trying to understand the technique. Because a 'packet' of information received each time should be 'how much does the image match the mask' but the illustration might wrongly lead viewer to think that a packet has the information of just one 'pixel' of the image.

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    刘宇龙

    夏普,,,点针術,多针而齐発图,但耗电,若掃图慢,,,所以是欲以水内伸缩原理否,,,OK,,,再構思後伝於,,,。

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    刘宇龙

    OK,,,勿施巨型注射针(但可射向日,,,),,,。
    極速圆型电射集,,,可向鋼化透明晶罐制造商,和極电人工研究中心★←加丶加卵加卯众之旧前,,,卞前主公認悉知或电内容,,,才知旧贞众,,,才可至北挪鋼鲸旧申請許可,,,才能研究出,,,。
    而晶罐內以稀气室建(所以窗吸错为仿,,,不同组),而晶罐置中,,,再以極功率高速倍率,射圆至罐(会乱跳不知,,,但可在晶罐外以空气引电流←因为电会受空气吸取有温稀气,←哪,是博士論講的,和仼何人事物无関,若有仿同,必为仿众,,,),而若以温稀气引电圓,←哪,是欲封存晶囗而温稀气←众多博士論講的,和仼何人事物无関,如有仿,必是另另一组众,,,),而图为,,,曰←欲射电集圆極超高倍功率,口←射管囗,一7罐置中,亅←罐底備晶片,>防罐落和推冂←而封,須待罐内气吸无而冂再封包(人员勿在研究室内外,以防商業間諜探知而待價股高颷时,,,),而封包囗須无缝细,以防空气漏入和外空气吸电圓和,,,电圆跑出罐外,,,。
    而晶罐圓电封包後,勿急进入(因为稀气室门一開,会有空气进入,所以須在室外待,,,),等一时期,晶罐无冀狀而再入取出,,,必须保存完備,但怕遺漏,未建保存室,可護送至凡帝殿内存,但,,,須经教皇教主教宗及研究呣師允许,若无,可在殿外交付,,,卞前主而代进入,,,或,,,以高價股賣出,欣赏,但,,,勿锁在保管箱,,,因为种种人因素,,,会,,,?,,,不懂众大人心,難理解,,,?。

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