MIT, Siggraph MIT's GelSight enhances 3-D imaging

MANHASSET, NY -- Researchers have created a simple, portable imaging system that combines a slab of transparent, synthetic rubber, a coat of paint containing tiny flecks of metal, and clever algorithms to achieve resolutions previously possible only with large and expensive lab equipment.

The device could enable a way to inspect products too large to fit under a microscope and could also have applications in medicine, forensics and biometrics.

GelSight  is a slab of transparent, synthetic rubber, one of whose sides is coated with a paint containing tiny flecks of metal. When pressed against the surface of an object, the paint-coated side of the slab deforms. Cameras mounted on the other side of the slab photograph the results, and computer-vision algorithms analyze the images.

A new, higher-resolution version of GelSight can register physical features less than a micrometer in depth and about two micrometers across. This compares to an earlier version presented in a 2009 paper at Siggraph which was sensitive enough to detect the raised ink patterns on a $20 bill.

GelSight grew out of a project to create tactile sensors for robots for giving them a sense of touch. But researchers realized that their system provided much higher resolution than tactile sensing required.

The researchers shrunk the flecks of metal in the paint and used  a different lighting scheme than before which in turn needed a redesign of the computer-vision algorithm that measures surface features.

Traditionally, generating micrometer-scale images has required a large, expensive piece of equipment such as a confocal microscope or a white-light interferometer, which might take minutes or even hours to produce a 3-D image. Often, such a device has to be mounted on a vibration isolation table, which might consist of a granite slab held steady by shock absorbers.

In contrast, researchers Edward Adelson and Micah Kimo Johnson built a prototype sensor, about the size of a soda can, which produces 3-D images almost instantly.

With multiple cameras measuring the rubber’s deformation, the system can produce 3-D models of an object, which can be manipulated on a computer screen for examination from multiple angles.

Adelson and Johnson are in discussion with a major aerospace company and several manufacturers of industrial equipment, all of whom are interested in using GelSight to check the integrity of their products.

The technology has also drawn the interest of experts in criminal forensics, who think that it could provide a cheap, efficient way to identify the impressions that particular guns leave on the casings of spent shells.

The researchers work in MIT’s Department of Brain and Cognitive Sciences.

Papers delivered at Siggraph 2011 in Vancouver this week can be viewed here.
MIT, Siggraph MIT's GelSight enhances 3-D imaging