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 13,2020

The Brazilian government said that the Amazon rainforest witnessed deforestation of a record 829 sq km in May, the highest monthly level since 2015.

On Friday, the National Institute for Space Research (INPE) said that deforestation in the Amazon increased by 91 sq km compared to the same period last year, reports Xinhua news agency.

Between January and April, destruction of the forest by illegal loggers and ranchers rose 55 per cent, or a total of 1,202 sq km was wiped out, it said.

The Real-time Deforestation Detection system, a federal project created to monitor human activity in the Amazon, alerted authorities to the increase in the rate of destruction of the rainforest.

A recent study by the Amazon Environmental Research Institute (IPAM) warned that deforestation in 2020 could reach 11,900 sq km if the pace of May, June, and July follows the historical average.

Deforestation in the region has soared since President Jair Bolsonaro took office last year, according to conservation groups.

He has argued that more farming and mining in protected areas of the forest were the only way to lift the region out of poverty.

Bolsonaro's environmental policies have been widely condemned but he has rejected the criticism, saying Brazil remains an example for conservation.

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News Network
July 24,2020

Melbourne, Jul 24: Home-made cloth face masks may need a minimum of two layers, and preferably three, to prevent the dispersal of viral droplets associated with Covid-19, according to a study.

Researchers, including those from the University of New South Wales in Australia, noted that viral droplets are generated by those infected with the novel coronavirus when they cough, sneeze, or speak.

As face masks have been proven to protect healthy people from inhaling infectious droplets as well as reducing the spread from those who are already infected, several types of material have been suggested for these, but based on little or no evidence of how well they work, the scientists said.

In the current study, published in the journal Thorax, the researchers compared the effectiveness of single and double-layer cloth face coverings with a surgical face mask (Bao Thach) at reducing droplet spread.

They said the single layer covering was made from a folded piece of cotton T shirt and hair ties, and the double layer covering was made using the sew method described by the US Centers for Disease Control and Prevention (CDC).

The scientists used a tailored LED lighting system and a high-speed camera to film the dispersal of airborne droplets produced by a healthy person with no respiratory infection, during speaking, coughing, and sneezing while wearing each type of mask.

Their analysis showed that the surgical face mask was the most effective at reducing airborne droplet dispersal, although even a single layer cloth face covering reduced the droplet spread from speaking.

But the study noted that a double layer covering was better than a single layer in reducing the droplet spread from coughing and sneezing.

According to the researchers, the effectiveness of cloth face masks is dependent on the number of layers of the covering, the type of material used, design, fit as well as the frequency of washing.

Based on their observations, they said a home made cloth mask with at least two layers is preferable to a single layer mask.

"Guidelines on home-made cloth masks should stipulate multiple layers," the scientists said, adding that there is a need for more research to inform safer cloth mask design.

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Agencies
June 16,2020

Paris, Jun 16: Increasing numbers of readers are paying for online news around the world even if the level of trust in the media, in general, remains very low, according to a report published Tuesday.

Around 20 percent of Americans questioned said they subscribed to an online news provider (up to four points over the previous year) and 42 percent of Norwegians (up eight points), along with 13 percent of the Dutch (up to three points), compared with 10 percent in France and Germany.

But between a third and a half of all news subscriptions go to just a few major media organisations, such as the New York Times, according to the annual Digital News Report by the Reuters Institute.

Some readers, however, are also beginning to take out more than one subscription, paying for a local or specialist title in addition to a national news source, the study's authors said.

But a large proportion of internet users say nothing could convince them to pay for online news, around 40 percent in the United States and 50 percent in Britain.

YouGov conducted the online surveys of 40 countries for the Reuters Institute in January, with 2,000 respondents in each.

Further surveys were carried out in six countries in April to analyse the initial effects of COVID-19.

The health crisis brought a revival of interest in television news -- with the audience rising five percent on average -- establishing itself as the main source of information along with online media.

Conversely, newspaper circulation was hard-hit by coronavirus lockdown measures.

The survey found trust in the news had fallen to its lowest level since the first report in 2012, with just 38 percent saying they trusted most news most of the time.

However, confidence in the news media varied considerably by country, ranging from 56 percent in Finland and Portugal to 23 percent in France and 21 percent in South Korea.

In Hong Kong, which has been hit by months of sometimes violent street protests against an extradition law, trust in the news fell 16 points to 30 percent over the year.

Chile, which has had regular demonstrations against inequality, saw trust in the media fall 15 percent while in Britain, where society has been polarised by issues such as Brexit, it was down 12 points.

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