Add-in spectrograph brings color to linescan applications

Add-in spectrograph brings color to linescan applications

Until recently, high-quality color image processing has been a difficult task for machine-vision-systems integrators. Often, system integrators handle the problem of sorting color objects by adjusting the sensitivity and spectral range of their line- or area-array cameras; however, the work is very application-specific.

An invention by Spectral Imaging (Oulu, Finland) will now make inspecting slight color differences in objects at web rates easier. Spectral Imaging`s ImSpector is an imaging spectrograph that can be fitted to any monochrome charge-coupled-device (CCD) camera to provide spectral diagnosis of color images in machine-vision and industrial inspection applications.

In operation, the spectrograph fits between the C-mount lens and the housing of a 1/3-, 2/3- or 1-inch monochrome CCD camera. By capturing a line image through lenses and a prism-grating-prism component, the instrument splits the received light into a spectrum from ultraviolet (UV) to near-infrared (IR). Because the light falls on the camera`s area array, each frame contains the line pixels along the spatial axis and spectral data for each of those pixels along the spectral axis. In this manner, the imaging spectrograph optically changes monochrome CCD cameras into spectrophotometers.

Already two companies have endorsed the ImSpector matching cameras, frame grabbers, and software for systems integrators to rapidly develop on-line color web-inspection systems. One company, PixelVision (Beaverton, OR), the US distributor of the ImSpector, has coupled the device to its SpectraVideo CCD camera--an 1100 ¥ 330 ¥ 16-bit digital camera. The combination transforms the camera into an 1100-line linear imager with 330 bits of spectral information. "The spectral range of the back-illuminated CCDs [UV through near IR] used in the SpectraVideo camera is especially useful in imaging the UV spectrum, where traditional [cable-TV] cameras have little response," says George Williams of PixelVision.

To interface the system to personal computers, systems integrators also can use the company`s Lynx PCI-based frame grabber and spectral classification software to display both color and intensity plots of linescan signals.

The other company endorsing Spectral Imaging`s ImSpector is Orbis Oy in Finland. It has bolted the device to TM-6 CCD matrix cameras from Pulnix (Sunnyvale, CA) and uses a 5200/5400 PC add-in image processor from Cognex (Natick, MA) for image processing. The image-inspection system created by Orbis is currently being used for semiconductor inspection and sorting.

For more information, contact George Williams at GeorgeW@ pv-inc.com.