LOGITECH'S DARKFIELD MOUSE WORKS ON GLASS SURFACES

The computer mouse has come a long way since I first put my hand on one. It was a friction mouse that had a little rubber ball underneath which rolled along the table surface. As you moved the mouse, the rubber ball would spin and that motion was translated into the mouse pointer moving on the screen.

As technology advanced, we saw the introduction of the scroll wheel, the cordless mouse and a variety of user-definable function buttons. But the most significant advancement to the mouse I believe was in the tracking technology. The little ball was replaced with optical technology that uses light to track the table surface to move the pointer on the screen. As time passed, optical refinements continued with infrared and blue LEDs to improve accuracy and responsiveness. Some even replaced the LEDs with lasers for even better tracking results. But with all that, there remained an optical obstacle that has persisted over the years. You couldn't use an optical mouse on a glass surface. To developers, finding a solution to that problem became tantamount to optical technology's holy grail. But now it looks like Logitech has finally broken the glass barrier and they're calling the technology "DarkField Laser Tracking."

Actually optical mice have trouble tracking not only on glass but on most any surface that's extremely smooth or highly glossy such as lacquered surfaces. Optical mice track on normal surfaces by seeing the tiny imperfections found there. As you move the mouse over a surface, the light identifies those imperfections, locks onto them and tracks their movement which are then translated into corresponding cursor movement.

But with clear glass, there are virtually no imperfections to track. Logitech's DarkField technology overcomes this by using a technique used by scientists using a microscope. Dark field illumination blocks out the central source of light and only allows light to enter from an angle. This results in a dark background with bright objects on it, similar to a starry night sky which is where the method gets its name.

Logitech uses two lasers to accomplish the same results, allowing the mouse to see microscopic details in or on the glass surface. Even microscopic bits of dust on the glass can be used by DarkField to achieve extremely accurate results. The mouse now sees the entire surface as black with even the tiniest imperfections or dust particles on it as bright spots.

To activate the DarkField technology, the Logitech mouse sports a little slide switch that uncovers and activates the dual lasers. Logitech does warn that although DarkField works on most glass surfaces found in offices, homes and other public locations, it may not work on glass surfaces that are optically pure or that are kept in a dust-free environment. Typically you only find glass like that in scientific laboratories and clean-rooms. Other than those unusual locations, you should have no problems using a DarkField mouse.

Currently Logitech has built DarkField technology into only two of its most popular mouse models. They are the Performance Mouse MX ($99.99) which is designed primarily for use with a desktop computer and the Anywhere Mouse MX ($79.99) which is their notebook model. Both of these models offer the same features found in their non DarkField counterparts. The DarkField models however also come with Logitech's brand new Unifying receiver. This is the little USB transceiver plug that now supports a variety of other cordless offerings from Logitech such as their cordless keyboards, number pads and even other mice. The Unifying receiver lets you avoid the problem of needing multiple receivers for numerous cordless devices. Now they all work with just one. Kudos to Logitech on finally coming up with a solution to this problem.

The DarkField models work with Windows and Macintosh computers and can be purchased at the Logitech website or most anywhere that sells computer products.

www.logitech.com

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