New camera may capture distant images without long lens

April 17, 2017

Houston, Apr 17: Scientists, including one of Indian origin, have developed a unique camera that can capture detailed images of distant objects without using a long lens, an advance that could lead to telescopes that are less bulky. The system known as SAVI – for “Synthetic Apertures for long-range, subdiffraction-limited Visible Imaging” – does not need a long lens to take a picture of a faraway object, researchers said.The prototype built by researchers reads a spot illuminated by a laser and captures the “speckle” pattern with a camera sensor.

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The prototype built by researchers reads a spot illuminated by a laser and captures the “speckle” pattern with a camera sensor.

Raw data from dozens of camera positions is fed to a computer programme that interprets it and constructs a high-resolution image.Researchers including those from Rice University in the US, built and tested the device that compares interference pat terns between multiple speckled images. Like the technique used to achieve the “Matrix” special effect, the images are taken from slightly different angles, but with one camera that is moved between shots instead of many fired in sequence. The prototype only works with coherent illumination sources such as lasers.

However, it is a step toward a SAVI camera array for use in visible light, researchers said. The speckles serve as reference beams and essentially replace one of the two beams used to create holograms, researchers said. When a laser illuminates a rough surface, the viewer sees grain-like speckles in the dot, as some of the returning light scattered from points on the surface has to go farther and throws the collective wave out of phase. The texture of a piece of paper – or even a fingerprint -is enough to cause the effect.

“Today, the technology can be applied only to coherent (laser) light,” said Ashok Veeraraghavan of Rice University.”That means you cannot apply these techniques to take pictures outdoors and improve resolution for sunlit images -as yet,” Veeraraghavan said.”With a traditional camera, the larger the physical size of the aperture, the better the resolution,” he said.

“If you want an aperture that is half a foot, you may need 30 glass surfaces to remove aberrations and create a focused spot.
This makes your lens very big and bulky,” he added. SAVI"s “synthetic aperture” sidesteps the problem by replacing a long lens with a computer programme the resolves the speckle data into an image, researchers said.

“You can capture interference patterns from a fair distance,” Veeraraghavan said. The research was published in the journal Science Advances.

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Agencies
June 8,2020

Washington DC, Jun 8: Astronomers acting on a hunch have likely resolved a mystery about young, still-forming stars and regions rich in organic molecules closely surrounding some of them.

They used the National Science Foundation's Karl G Jansky Very Large Array (VLA) to reveal one such region that previously had eluded detection and that revelation answered a longstanding question.

The regions around the young protostars contain complex organic molecules which can further combine into prebiotic molecules that are the first steps on the road to life.

The regions, dubbed "hot corinos" by astronomers, are typically about the size of our solar system and are much warmer than their surroundings, though still quite cold by terrestrial standards.

The first hot corino was discovered in 2003 and only about a dozen have been found so far. Most of these are in binary systems, with two protostars forming simultaneously.

Astronomers have been puzzled by the fact that, in some of these binary systems, they found evidence for a hot corino around one of the protostars but not the other.

"Since the two stars are forming from the same molecular cloud and at the same time, it seemed strange that one would be surrounded by a dense region of complex organic molecules and the other wouldn't," said Cecilia Ceccarelli, of the Institute for Planetary Sciences and Astrophysics at the University of Grenoble (IPAG) in France.

The complex organic molecules were found by detecting specific radio frequencies, called spectral lines, emitted by the molecules. Those characteristic radio frequencies serve as "fingerprints" to identify the chemicals.

The astronomers noted that all the chemicals found in hot corinos had been found by detecting these "fingerprints" at radio frequencies corresponding to wavelengths of only a few millimetres.

"We know that dust blocks those wavelengths, so we decided to look for evidence of these chemicals at longer wavelengths that can easily pass through dust," said Claire Chandler of the National Radio Astronomy Observatory, and principal investigator on the project.

"It struck us that dust might be what was preventing us from detecting the molecules in one of the twin protostars," added Chandler.

The astronomers used the VLA to observe a pair of protostars called IRAS 4A, in a star-forming region about 1,000 light-years from Earth. They observed the pair at wavelengths of centimetres.

At those wavelengths, they sought radio emissions from methanol, CH3OH (wood alcohol, not for drinking). This was a pair in which one protostar clearly had a hot corino and the other did not, as seen using the much shorter wavelengths.

The result confirmed their hunch. "With the VLA, both protostars showed strong evidence of methanol surrounding them. This means that both protostars have hot corinos. The reason we did not see the one at shorter wavelengths was because of dust," said Marta de Simone, a graduate student at IPAG who led the data analysis for this object.

The astronomers cautioned that while both hot corinos now are known to contain methanol, there still may be some chemical differences between them. That, they said, can be settled by looking for other molecules at wavelengths not obscured by dust.

"This result tells us that using centimetre radio wavelengths is necessary to properly study hot corinos," Claudio Codella of Arcetri Astrophysical Observatory in Florence, Italy, said.

"In the future, planned new telescopes such as the next-generation VLA and SKA, will be very important to understanding these objects," added Codella.

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Agencies
March 12,2020

Thiruvananthapuram, Mar 12: In the wake of COVID-19 outbreak, Internet service providers in Kerala have agreed to step up the network capacity by 30 to 40 per cent of the present capacity to meet the demand, especially in view of the spurt in work-at-home mode.

"The decision was made at a meeting of representatives of various telecom service providers in Kerala circle and officials of the Telecommunication Department convened by the Secretary, Electronics and IT, following a direction by Chief Minister Pinarayi Vijayan to look into the issue," said a press release by the IT Department.

The decision will be beneficial for those working in IT institutions. The government has come out with a set of suggestions to avoid social gatherings at public places in view of coronavirus spread. Telecom service providers have assured the government that they are well equipped to face the current situation.

The major part of Internet consumption in Kerala is made available through local servers. Moreover, global Internet traffic is very low as compared to the overall consumption. So, increasing the capacity won't be difficult, service providers informed.

"Complaints regarding the low availability of the Internet due to the spurt in consumption of the Internet can be made to the service providers to their complaint redressal number or inform state government call centre (155300). But complaints regarding the insufficiency in the current network infrastructure should be strictly avoided," said the release.

The IT Department will also demand daily reports from various telecom service providers. By analysing these reports, steps for remedies will be taken after bringing the sudden increase in consumption to the service providers.

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Agencies
June 24,2020

New Delhi, Jun 24: The Centre has made it mandatory for sellers to enter the 'Country of Origin' while registering all new products on government e-marketplace (GeM).

The e-marketplace is a special purpose vehicle (SPV) under the Ministry of Commerce and Industry which facilitates the entry of small local sellers in public procurement, while implementing 'Make in India' and MSE Purchase Preference Policies of the Centre.

Accordingly, the ministry said the move has been made to promote 'Make in India' and 'Atma Nirbhar Bharat'.

The provision has been enabled via the introduction of new features on GeM.

Besides the registration process, the new feature also reminds sellers who have already uploaded their products, to disclose their products' 'Country of Origin' details.

The ministry further said that failing to disclose the detail will lead to removal of the products from the e-marketplace.

"GeM has taken this significant step to promote 'Make in India' and 'Aatmanirbhar Bharat'," the ministry said in a statement.

"GeM has also enabled a provision for indication of the percentage of local content in products. With this new feature, now, the 'Country of Origin' as well as the local content percentage are visible in the marketplace for all items. More importantly, the 'Make in India' filter has now been enabled on the portal. Buyers can choose to buy only those products that meet the minimum 50 per cent local content criteria."

In case of bids, the ministry said that buyers can now reserve any bid for a "Class I Local suppliers. For those bids below Rs 200 crore, only Class I and Class II Local Suppliers are eligible to bid, with Class I supplier getting purchase preference".

In addition to this, the Department for Promotion of Industry and Internal Trade (DPIIT) has reportedly called for a meeting with all e-commerce companies such as Amazon and Flipkart to display the country of origin on the products sold on their platform, as well as the extent of value added in India.

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