Freeform prism array helps microscopes to image in 3D

March 21, 2011
Engineers at Ohio State University have created a freeform prism array that enables microscopic objects to be seen from nine different angles at once to create a 3D image.
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Columbus, OH--Engineers at Ohio State University have created a diamond-turned and milled freeform prism array that enables microscopic objects to be seen from nine different angles at once to create a 3D image. Other 3D microscopes use multiple lenses or cameras that move around an object; the new device results in the first single, stationary lens to create microscopic 3D images by itself.

Researchers Allen Yi and Lei Li described the prism array in a recent issue of the Journal of the Optical Society of America A.

Molding possible for production
About the size of a fingernail, the prototype freeform array has a flat top surrounded by eight facets. Though the engineers milled the prototype thermoplastic piece on a precision cutting machine with a diamond tool, the same shape could be manufactured less expensively through traditional molding techniques, Yi said.

The device was installed on a microscope with a camera looking down through the faceted side, and specimens centered beneath the flat side. Each facet captures an image of the specimens from a different angle, all of which are then combined by a computer to create a 3D image. The engineers recorded 3D images of the 1 mm tip of a ballpoint pen and a miniature drill bit with a 0.2 mm diameter.

Yi called the device a proof of concept for manufacturers of microelectronics and medical devices (such as lab-on-a-chip devices), who currently use very complex machinery to view the tiny components that they assemble. "Ultimately, we hope to help manufacturers reduce the number and sizes of equipment they need to miniaturize products," he said.

"Using our lens is basically like putting several microscopes into one microscope," said Li. "For us, the most attractive part of this project is we will be able to see the real shape of micro-samples instead of just a two-dimensional projection."

In the future, Yi would like to develop the technology for manufacturers. He pointed to the medical-testing industry, which is working to shrink devices that analyze fluid samples. Computer-numerical-control (CNC) machines do the carving, and Yi says that the new lens can be placed in front of equipment that is already in use. It can also simplify the design of future machine-vision equipment, since multiple lenses or moving cameras would no longer be necessary.

Moore Nanotechnology Systems (Keene, NH) provided the ultraprecision milling machine.

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About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.

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