Fujifilm has patented an EVF with diffractive optics, which should allow for better and more compact EVF design. From the patent description:
“A finder optical system suitable for an electronic viewfinder, etc., capable of widening the viewing angle, correcting various aberrations and downsizing
In recent years, an electronic view finder (Electronic View Finder) is often used as a finder of a digital camera or the like. The electronic viewfinder includes a display element such as a liquid crystal panel for displaying an image of a subject, and an eyepiece optical system for observing the image displayed on the display element.
However, the degree of freedom in the configuration of the display element and the eyepiece optical system in the electronic viewfinder is extremely low. If the specification of the finder magnification is increased, that is, the viewing angle is increased, the number of lenses constituting the eyepiece optical system increases, and it becomes difficult to reduce the size of the finder unit. When it is attempted to improve the specifications without increasing the number of lenses, it is difficult to correct various aberrations of the finder optical system.
In view of the above circumstances, the present invention can be suitably used for an electronic viewfinder and the like, and various aberrations can be corrected well while achieving a wide viewing angle, thereby reducing the size of the finder unit.”
Full patent here.