Microsoft SecondLight Adds Extra Layers to Surface

[Bartek Sikorski]

Take Microsoft Surface, sprinkle it with fairy dust, and you might have something close to Microsoft's SecondLight, a new technology in the works from Microsoft Research.

The experimental SecondLight technology adds a second dimension to Surface, allowing users to slide "magic lenses" over the display to provide a second surface that can be linked to the first. In one example, Microsoft researchers projected a picture of a car on the Surface display. But add separate, portable pieces of glass that can be moved across the display, and presto! the glasses are transformed into "X-ray specs" allowing a wireframe model to be viewed.
It's all sleight of hand, of course. But if history is any guide, SecondLight will eventually be part of future Surface displays.
The research is being presented as part of the User Interface Software and Technology conference this week. In addition to SecondLight, Microsoft's touchless SideSight "touchscreen" for PDAs was presented, as well as "tap" and "caress" movements for cell phones, plus a a new way to interact with images.

How does SecondLight work? As a trick of the light.
Surface projects images onto a display, and Microsoft hasn't abandoned that with SecondLight; the display still detects and interacts with objects or fingers that touch it.
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. Two off-the-shelf Hitachi CPX1 60-Hz projectors in combination with fast optical shutters create the two interleaved 60-Hz images, one on the Surface display, and one on the secondary display objects. The cycle can also favor a display that's left diffuse for longer periods of time, to improve the brightness of the Surface display, while dimming the secondary "magic lenses".

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