A monocle, in the context of displays, is a type of display that is small and held over one eye. It can be about 1 inch wide.
It can use light field technology, for example by using a microdisplay and a microlens array.
A light field monocle can have the benefit of being used both as a near eye display and a standard display. It can be held close to the eye for a wide field of view, or held far away so multiple people can see through it at the same time, depending on its maximum angle of view.
Doug Lanman made a few monocles as part of his research at NVIDIA (Douglas Lanman's prototype light field viewer).