| 摘要 |
<p>A diffraction grating head up display which blocks solar radiation from impinging upon and washing out the image of display information on an optical display device. This is accomplished by means of a filter such an optical element (12) made of photochromic material which is positioned between the display information surface (10) and relay optics lenses (14) preferably at the back focal plane thereof, so that focused solar radiation darkens a localized spot in the photochromic material. The darkened spot blocks the solar energy but reversibly lightens after the focused solar energy is removed. This photochromic material allow substantially unimpeded transmittance of the image of the display information except at the darkened spot. Also included in the optical system are a folding reflector (16) and a combiner lens element (18) which combines and superimposes the image of the display information on the scene being viewed when an observer looks through the combiner element (18). This combiner element (18) is a diffraction grating holographic lens which is reflective or diffractive of a narrow bandwidth of light which includes the narrow bandwidth light of the display information. </p> |
