Portable surface-capture tool could find use in forensics

A new portable imaging system capable of capturing 3D, micron-level renderings of surface structures could find use in industry, medicine, forensics and biometrics.

It achieves resolutions previously possible only with large, expensive laboratory equipment and as such could provide manufacturers with a way to inspect products too large to fit under a microscope.

A team led by Edward Adelson of the Massachusetts Institute of Technology (MIT) developed the device, which is based on a technology dubbed ‘GelSight’.

Essentially, what this comprises 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 analyse the images to create 3D renderings.

The latest prototype device incorporating GelSight looks like an elongated drinks can and can be moved across the surface of a structure to register physical features of less than a micrometre in depth and about two micrometres across.

Traditionally, generating micrometre-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 3D 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.

Adelson said the team is already in discussion with one 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. There could also be applications in dermatology, distinguishing moles from cancerous growths, and even biometrics.

GelSight grew out of a project to create tactile sensors for robots, giving them a sense of touch, but Adelson and his team quickly realised that their system provided a much higher resolution than tactile sensing required.