| 摘要 |
<p>The invention concerns an optical device for a system presenting collimated images through an off-axis spherical concave mirror (1). The invention enables to present to the user (3) an image with correction of the eccentric distortion caused by the off-axis spherical concave mirror (1) without altering the quality of the image. For this purpose, said device comprises a diffractive mirror (21) set in the neighbourhood of an intermediate image (25, 27) of the device, preferably the second intermediate image (27). The extent of the neighbourhood is limited by the image resolution and, in the neighbourhood, the correction by the diffractive mirror (21) does not alter the resolution. The diffractive mirror has a hologram which may be digital or made of a photosensitive material. The hologram substrate is preferably not planar to operate partly upon the correction, the residual correction being carried out by the hologram. The invention is particularly applicable to an aircraft pilot's visor.</p> |
