| 摘要 |
<p>An image display apparatus includes an image display device (4) such as, for example, a liquid crystal display panel, having a plurality of dot-shaped picture elements (12) arranged in a two-dimensional pattern, and a diffraction grating (5) disposed on an optical path through which imagewise rays of light emerging from the device (4) travel. To minimize a reduction in quality and contrast of an image displayed by the device (4), the grating(5) has a spatial cut-off frequency (fc) chosen to be of a value lying between the sampling frequency (1/PH), determined by the pitch between picture elements (12) of the image display device (4), and the Nyquist frequency (1/2PH). For the same purpose, the intensity of +/-1st order light relative to the intensity of 0-th order light in the diffraction grating (5) is within the range of 60 to 80% at a center wavelength of the image display device (4), and the sum of the intensity of the 0-th order light and that of the +/-1st order light relative to that of total diffracted light is equal to or higher than 80% at the center wavelength of the device (4). <IMAGE> <IMAGE></p> |
