Recent articles

Tuesday, March 20, 2012

Using light echos to see around corners


The ability to see objects hidden behind walls could be invaluable in dangerous or inaccessible locations, such as inside machinery with moving parts, or in highly contaminated areas. Now scientists at the Massachusetts Institute of Technology in Cambridge have found a way to do just that.

They fire a pulse of laser light at a wall on the far side of the hidden scene, and record the time at which the scattered light reaches a camera. Photons bounce off the wall onto the hidden object and back to the wall, scattering each time, before a small fraction eventually reaches the camera, each at a slightly different time. It's this time resolution that provides the key to revealing the hidden geometry. The position of the 50-femtosecond (that’s 50 quadrillionths of a second) laser pulse is also changed 60 times, to gain multiple perspectives on the hidden scene.
"We are all familiar with sound echoes, but we can also exploit echoes of light," says Ramesh Raskar, head of the Camera Culture Research Group at the MIT Media Lab, which carried out the study.
Source: Nature

Tuesday, January 10, 2012

Single image of the night sky


The interactive and zoomable image is available at
http://skysurvey.org

Photographer Nick Risinger traveled 60,000 miles around the globe to piece together a single image of the night sky that contains a staggering 20 million stars. The 5,000 megapixel image of the milky way galaxy is stitched together from over 37,000 digital images taken using a custom mount with standard camera and lenses.

Hardware:
Cameras—Finger Lakes ML-8300
Lenses—Zeiss Sonnar 85mm f2.8
Filters—Astronomik LRGB, Astrodon Ha
Mount—Takahashi EM-11 Temma 2 w/ custom armature
Generator—Yamaha EF1000iS for USA trips
Laptop—Intel Core i7-820QM running Linux Fedora, 8GB RAM w/ 4TB external storage

Software:
MaximDL—mount control, image capture, and creation of calibration frames (dark, bias, flat)
IRAF—many scripted tasks such as up-scaling, registration, saturated pixel replacements with scaled exposures, stacking, and median background modeling
SExtractor—building each frames list of objects
SCAMP—cross referencing to create position and distortion headers
Swarp—reprojection and stitching of frames
PixInsight—generate final LRGBHa color composite, midtones transfer function, noise reduction
GIMP—final assembly, curve & saturation tweaks

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