Microsoft Surface has already been transformed from its original tabletop multitouch interface to a spherical computer, and this week's PDC added even more excitement with the introduction of SecondLight, the next phase in Surface's development.

As the UK's PC Pro website puts it, SecondLight is like "Surface on steroids." A product of Microsoft's Cambridge, England research labs, SecondLight projects an image through the table, enabling a translucent surface placed on top of the Surface tabletop to display additional information, such as place names, an interior view of an object, and much more.

How does SecondLight work? According to PC Magazine:

The key technology, however, is a switchable diffuser, the same technology that is sometimes used in office buildings or in nightclubs as partitions. Specifically, SecondLight uses polymer stabilized cholesteric textured liquid crystal (PSCT-LC), tied to an optical switch.

When diffuse, the glass is frosted. But when a voltage is applied via the switch, the liquid crystal molecules align and allow light to pass through, becoming clear.

Normally, the Surface display itself serves as a projection screen. But SecondLight's optical switch rapidly flips the display between translucent and clear at 60 hertz (the same refresh rate as a PC's monitor), fooling the eye into creating both the traditional Surface display as well as secondary images projected onto the "magic lenses," which themselves serve as projection screens.

The secondary display can also be used as a multitouch surface.

See a video demonstration of SecondLight (WMV format for Windows Media Player) at the Microsoft Research website. Prefer pictures? Visit Daniel Melanchthon's TechNet blog (but keep a window open for Babelfish or other translation software, as the site's mostly in German). You can also download a PDF copy of the paper presented at PDC from the Microsoft PressPass website.

Have you seen Surface yet? What do you think about the possibilities in what some are dubbing "Surface 2.0?" Hit Comment and tell us what you think about letting your fingers do the walking through the data.

Photos courtesy of Daniel Melachthon and Microsoft Research.