Some engineers at Fermilab are having fun!
Prototype 570 Mp camera. Source: Symmetry magazine.
They’re building a super-sized digital camera using CCDs (Charge Coupled Devices) that are particularly sensitive to near-infrared light to measure, among other things, redshifts of remote galaxies. The longer-term aim is to study the dark energy of universe more accurately than has been possible to date.
At a half metre in diameter, it’s a big digital camera!
(We really need an astronomer on these blogs. The technology of the endeavour impresses me and I understand it well enough to “get” it, but the astronomy itself is as new to me as it will be to most of my readers.)
It’s a long-running running project, with roots back at least as far as 2004 and a big, multi-lab, multi-national effort. The telescope is located in northern Chile, on Kitt’s Peak.
Kitt's Peak. Source: CTIO newsletter, Dec. 2009.
Looking at the photographs, if I ever make it to Chile, I’d love to visit this place. All those high-tech labs and buildings perched high up.
You can read the CTIO centre’s excellent newsletter free online (offered as PDF documents). As you might expect from an astronomy centre, they have great photos. For example, some of the backstory of the project can be found in the newsletter (PDF).
A great account of the science (with pictures) can be found in an article at Symmetry magazine by Kristine Crane (published by Fermi National Accelerator Laboratory and SLAC National Accelerator Laboratory). Subscription is free. Kristine’s article is well worth anyone reading. (It’s written for a general readership.)
While you might not make it to Chile, you can take the tours at Mt. John observatory at Lake Tekapo in the heart of the South Island of New Zealand (photo below).
Mt John Observatory, New Zealand. Source: wikipedia
New Zealand has been short-listed as one possible location for the Square kilometre array (Ska) telescope, which is–in a manner of speaking–an even bigger camera. Here’s hoping it comes our way!
As an aside, none of my cameras have 15MP. Albeit a wet scan of a film-negative or slide, in a drum scanner, can produce a mighty-big image. :) Pro cameras like the Nikon D3 are still 12 MP. In photography, size isn’t everything and there’s actually some big costs to squeezing more (and tinier) pixel-sensors on to a CCD/CMOS sensor.
The real photographic trick here is the sheer size of the sensor (half a metre across) combined with the cooling (-10 degrees) to reduce digital noise. The size means that each of the CCD sensors (there are 74 of these silicon wafers) is a mere 7 MP. Bearing in mind, that each of these CCD’s has an area of 18 cm2. In a FF digital SLR, the sensor is about 8.4cm2 and an APS-C DSLR, the sensor is about 4.2 cm2.
What that means- in practical terms- is that the pixel sensors on these CCD’s are much, much larger than on a digital camera, and they are also better spaced. This is going to have a very big effect on the amount of detail the Fermilab camera will record. Most importantly, the image will be extremely free of any digital noise (colour artifacts), which I expect is the whole point.