For researchers who make live-action movies of cellular processes, Jena, Germany-based Carl Zeiss' http://www.zeiss.com new LSM 5 LIVE confocal microscope system may be the equivalent of moving from flip books to movie cameras.

The new microscope "lets us quantify a higher order of dynamic processes," says Mary Dickinson, assistant professor of molecular physiology and biophysics at Baylor College of Medicine, who helped Zeiss develop the new system. "You're able to collect images much faster and still maintain a reasonable sensitivity for biological work."

Two improvements give the 5 LIVE those advantages. First, the system captures full 512 × 512-pixel images at 120 frames per second, about 25 times faster than previous models. (In contrast, big-screen movies display 30 frames per second.) Typical confocals illuminate and capture one pixel at a time, scanning a sample point-by-point through a pattern of pinholes, but the 5 LIVE projects light through a confocal slit the full width of the image.

Second, according to Zeiss, the 5 LIVE boasts greater sensitivity than previous Zeiss microscopes, processing more than 90% of the light returning from the sample. The improvement is due in part to Zeiss' new "Achrogate" beam splitter, which Sebastian Tille, product manager with Carl Zeiss MicroImaging in Thornwood, NY, calls "ingenious in its simplicity."

Unlike conventional splitters, the Achrogate can reflect excitation energy of any given wavelength over the entire spectrum of light. The splitter works in tandem with a detector specially designed for line-based imaging, which alone, Zeiss claims, raises the 5 LIVE's quantum efficiency threefold over previous Zeiss systems. According to Karl Garsha, a microscopy specialist at the University of Illinois, initial tests indicate that "signal-to-noise ratios with the 5 LIVE are well beyond anything we have achieved" with point-by-point scanners under similar conditions.

"We were able to improve both speed and sensitivity, two factors that usually are in opposition in fluorescence microscopy," Tille says, "while also introducing more flexibility for fast-scanning systems, such as dual-channel capability, independent variable confocal apertures, and full AOTF [acousto-optic tunable filter] attenuation for all laser lines."

He admits that the new speed and sensitivity rob the resulting images of "a few percentage points of resolution" compared to other Zeiss confocals. But that loss is so slight that the advantages outweigh it, he says. Samples showing greater structural contrast are affected less than the more homogeneous ones.

A one-channel model of the 5 LIVE costs about $250,000 (US), nearly 25 percent more than a standard, real-time confocal system. The higher-contrast two-channel system is priced at about $350,000.

R. Howard Berg, director of the Integrated Microscopy Facility at the Donald Danforth Plant Science Center in St. Louis, says that for studying live samples and biological processes, the 5 LIVE might be worth the extra cost. "Among the current offerings of real-time optical sectioning [instruments]," he says, "it possibly offers the best combination of speed and image quality."