Microsoft IntelliEye optical technology changes the way people use a mouse by removing the ball, thereby providing more control and accuracy and eliminating the need for mouse pads and cleaning. IntelliEye technology provides accuracy and durability by replacing the mouse ball with an optical sensor and digital signal processor (DSP). The sensor captures snapshots of the work surface at a rate of 1,500 images per second, and the DSP translates changes of the images into onscreen movements. The Microsoft IntelliMouse Optical works with both Macs and PCs!!

• Microsoft IntelliMouse Optical USB w/PS/2 Adapter OEM
• IntelliEye Technology - provides unsurpassed accuracy over time by replacing mouse-ball technology with an optical sensor and digital signal processor (DSP). The sensor snaps pictures of the work surface at a rate of 1,500 images per second and then translates changes between the images into onscreen movements. This technique, called image correlation processing, results in smooth, precise pointer movement.
• Ambidextrous Design for Comfort - Whether you are left-or right-handed, or have a large or small hand, the design of IntelliMouse Optical feels comfortable. The shape supports your hand and encourages natural posture.
• The scrolling and zooming wheel lets users enjoy universal scrolling in their favorite applications directly from their mouse without having to use scrollbars. Users can zoom without using toolbars or menus.
• Two new customizable function buttons Browse the Web without using toolbars or the keyboard. Simply use either side button to go forward or backward on the Internet. Or, you can program the buttons to execute routine actions in many of your favorite programs.
• Precision over time - With the new IntelliEye technology, there are no more mechanical parts to become worn or dirty!
• A proven ergonomic design allows users to align their hand and forearm in a natural, relaxed position on the mouse. The shape of the IntelliMouse Explorer supports the entire hand and fingers, while the slope helps keep the hand and forearm aligned naturally.

• PC system requirements: PC running Windows 95, 98, 2000, or NT 4.0 with Service Pack 3 or later; 29 MB available hard disk space; round mouse port (PS/2 compatible) or USB port (USB requires Windows 98 or 2000); CD-ROM drive
• Macintosh system requirements: IntelliPoint software for Macintosh (included), computer running Macintosh OS 8.5.1 or later operating system (iMac also requires iMac update 1.1), 15 MB available hard disk space, USB port

• http://www.pccritix.com/hardware/optical/
• http://www.activewin.com/reviews/hardware/mice/optical/
• http://www.dansdata.com/imopt.htm