Technology Trends: Development system uses CCD cameras, PCs to increase depth of field

In August, CDM Optics (Boulder, CO) signed an agreement with Adaptive Optics Associates (AOA; Cambridge, MA) allowing AOA to license CDM Optics' Wavefront Coding technology.

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In August, CDM Optics (Boulder, CO) signed an agreement with Adaptive Optics Associates (AOA; Cambridge, MA) allowing AOA to license CDM Optics' Wavefront Coding technology. Says Lawrence Schmutz, AOA's president and general manager, "Prototype cameras at AOA have already resulted in a greater than 36-in. depth of field with 250 dpi resolution." This is an increase of more than 10 times the depth of field from a equivalent traditional system.

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At the recent Vision Show (Oct. 1999; San Jose, CA), CDM Optics showed the company's first development system targeted at OEMs wishing to incorporate the technology in their imaging systems. Consisting of a Rodagon lens from Rodenstock Precision Optics (Rockford, IL) equipped with a CDM Wavefront Coded phase mask, a PCI-based Depict camera and controller board from Opteon (Cambridge, MA), and CDM's EDFSoft application software, the system can process full-size images at video rates.

PHOTO. Wavefront Coding techniques can greatly extend the depth of field in many imaging applications, including microscopy. Carol Cogswell of the University of Sidney, demonstrates a Zeiss Axioplan fluorescent microscope used with 100X optical magnification to image dividing Hela cells in a biological research application. The image on the bottom is blurred due to a too small of a depth of field, while the top image uses Wavefront Coding techniques to remain in focus over the entire depth of viewd cells.

To perform Wavefront Coding, the Rodagon lens incorporates CDM Optics' Wavefront Coded phase mask and customized digital filters. The phase mask is placed near the aperture stop of the lens and encodes the images before they are digitized, making them invariant to misfocus. For specific imaging applications, system developers can choose from a range of Rodagon lenses with focal lengths of 35 to 135 mm. Other lenses will be available soon, according to Jeff Nissley, director of marketing.

CDM EDFSoft software digitizes and decodes the images, extending the depth of field and reducing focus-related aberrations. In addition to providing image-acquisition and camera-control features, the MMX-based software allows images to be processed at 30 frames/s. To increase this processing speed, AOA is developing a specialized processor board that will perform the decoding.

One of the target application areas for Wavefront Coding is microscopy. In this application, Wavefront Coding enables light-sensitive applications by providing a larger depth of field without increased illumination, exposure time, or loss of spatial resolution.

The cost of the Wavefront Coded development system is $14,500. Additionally, users can purchase EDFSoft/S C/C++ source code to customize applications of Wavefront Coding algorithms. CDM's Nissley says, "Although initial costs of implementing Wavefront Coding may appear high, customers using it have been able to increase their performance in ways previously unachievable and to reduce system development time and cost.

—Andrew Wilson

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