OTHER TECH

Panasonic's laser assembly starts with an infrared semiconductor laser operating at an invisible 820-nanometer (nm) wavelength. Its beam is directed into an "optical waveguide" made of lithium niobate (its chemical formula is LiNbO₃). The wavelength of the emerging light is only half as long, or 410 nm, which is visible as a very deep blue. The crystal distorts the beam so much that its second harmonic (twice the frequency = half the wavelength) is the primary waveguide output. Unfortunately, the physics explaining this phenomenon is far too abstruse for these pages. It's almost as mysterious as Star Trek's dilithium crystals.

Use of SHG with an infrared laser has quite down-to-earth benefits, however. The laser's output power is potentially higher than that of intrinsically blue semiconductor lasers (Panasonic has produced 30-milliwatt prototypes on the way to commercialization, as early as 2003, at 50 mW). Infrared lasers are also longer-lived than blue lasers (10,000 vs. 3,000 hours), and the SHG waveguide, being completely passive, will long outlive the attached infrared laser.

Using the new laser assembly, Panasonic has developed a high-def system that can put up to 50 gigabytes on a dual-layer recordable disc. That's enough space to store 4 hours of HDTV material at a data rate of 25 megabits per second (Mbps) - 25% higher than allowed in broadcast HDTV, which means potentially better picture quality. Broadcasters, look out!

An even higher data rate of 28.2 Mbps is achieved by JVC's HM-DH30000, the D-VHS recorder announced last November. If real, honest-to-god Hollywood studios release high-def movies in the D-Theater format for this machine (see "Hollywood Finally Goes High-Def"), that will be the first packaged medium for high-def video. All videophiles should desire such a development - even if it does use VHS tape.