QuickLook-Fullscreen-Gallery

QuickLook Fullscreen Gallery is a free and open source QuickLook plug-in that enables you to access QuickLook in full-screen mode.
Once the program is installed in Finder's toolbar, you can simply click it when viewing a folder which you would like to QuickLook.

Once clicked, you can use the LEFT or RIGHT keys to navigate, or you can click the button called Index Sheet.