Light field cameras use something called computational photography to gather addition information to allow for the ability to refocus an image after it has been taken. The problem is that the refocusing reduces image quality substantially. MIT researcher has a solution.
A typical 12 megapixel, light field camera can refocus an image after it has been captured, but a camera with a 20 megapixel sensor will produce a refocused image of only one megapixel. While this may be fine for posting on Facebook, it's not much use for professional photography.
The Researchers' in the Camera Culture Group and MIT's Media Lab have come up with a novel solution that only requires the insertion of a small rectangular piece of plastic film, that has a unique checkerboard pattern printed on it, beneath the lens of an ordinary digital SLR camera and software does the rest.
They are calling the system Focii, and you can read all the technical details by jumping to the source link. Very impressive work.