Patent ID: 6429954
Filing Date: 2002-08-06
Classification: G02B

Abstract:
An image display device for displaying a combined image by combining a virtual image with an image of an external object, comprising:an image display for displaying the virtual image, the virtual image comprising light in a selected frequency band; and a combining prism including a material having a refractive index greater than one, and having a holographic reflective surface and a selection surface, wherein the holographic reflective surface is reflective of light in the selected frequency band and the selection surface selectively reflects and transmits the virtual image from the image display, the image display being positioned to direct the image onto the selection surface at an angle of incidence greater than a critical angle, wherein the virtual image is reflected by the selection surface, is reflected by the holographic reflective surface, is transmitted through the selection surface, and is directed to the pupil of an observer, while the image of an external object is transmitted through the holographic reflective surface, transmitted through the selection surface, and directed to the pupil of the observer.