The phrase "as a second display" is correct and usable in written English.
It can be used when referring to an additional screen or monitor that is used alongside a primary display for extended functionality or multitasking.
Example: "I connected my laptop to a larger monitor to use it as a second display for better productivity."
Alternatives: "as an additional screen" or "as a supplementary monitor".
Qualcomm have announced their own entry into the smartwatch market with the Toq – a wearable device "designed to serve as a second display to your smartphone".
And now, you can also use your iPad Pro as a second display.
Connected to another Mac via Thunderbolt, the iMac can act as a second display.
This guy hardwired a LCD to run as a second display on his MacBook which means the chap can display anything he wants on the Apple – including a iSight feed.
I've long been a user of an iPad as a second display, typically employing the software of Astropad competitor Duet Display and using a wired connection to achieve the results I want.
The keyboard support, which is also very handy (it means you can use an iPad as a second display for an iMac – or as a sole display for a Mac mini without another keyboard, for instance), works across platforms.
It's not quite the Surface Studio, but it's easy to see how the company is essentially using the second display as a surrogate for touchscreens — something it has long refused to include in its line of computers.
A second advantage of this procedure is that we can assess the time course of the attentional switch by looking at the accuracy of the eye movements to the second display as a function of time since display onset.
If you have Mavericks, you can use the second display as an extension of your desktop.
As a second example, liver compartments displayed strong "immune response" GO-terms that may be a part of a host counterattack against the invading tumor.
To prevent the preprogramming of saccades, the two halves of the display were presented sequentially, with the second display appearing as soon as observers looked at the first target.
