Look at me: Twin cameras hidden beneath the screen of this prototype tracks the user’s gaze.
Tobii
Eye-tracking cameras offer a new way to control your computer.
Tom Simonite
A camera over the screen is a standard feature for laptops. But only Lenovo's new model has a pair of cameras below its display to track the movements of a user's eyes.
The prototype laptop can be controlled with eye motions, reducing the need to use the mouse and making it faster to navigate through information such as maps or menus.
The laptop can notice when its user has read to near the bottom of a page and can automatically scroll down to reveal more text. The same trick also makes it possible to browse through an e-mail in-box without using the mouse at all. When using a map application, the user can zoom in on an area by looking at it and scrolling the mouse wheel. The computer also dims its screen automatically to save power when it detects that the user's gaze has left the screen.
"We're attempting to make the process of interacting with your computer a more natural experience," says Barbara Barclay, who heads North American operations for Tobii, the Swedish company that supplied the eye-tracking hardware and software for the prototype. So far, only 20 of the new computers have been made; Tobii and Lenovo will each have 10 with which to test out new ideas.
The two cameras below the laptop's screen use infrared light to track a user's pupils. An infrared light source located next to the cameras lights up the user's face and creates a "glint" in the eyes that can be accurately tracked. The position of those points is used to create a 3-D model of the eyes that is used to calculate what part of the screen the user is looking at; the information is updated 40 times per second.
The system can accurately track the direction of the user's gaze to about 0.5 degrees, which translates to about half an inch on the screen of the laptop. A user can shift position, says Barclay, but the head must be kept within a volume of roughly two cubic feet. Because the hardware is mounted and moves with the laptop's LCD screen, a user's efforts to accommodate the display's limited viewing angle by adjusting head and monitor position usually ensure that the eyes remain in proper camera range.
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Voltage is the difference of electrical potential between two points of an electrical or electronic circuit, expressed in volts. It measures the potential energy of an electric field to cause an electric current in an electrical conductor.
Most measurement devices can measure voltage. Two common voltage measurements are direct current (DC) and alternating current (AC).
Learn the fundamentals of creating an AC or DC voltage measurement system. See how to properly connect the signals to your data acquisition system for accurate acquisition.
This document is part of the How-To Guide for Most Common Measurements centralized resource portal.
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