| 摘要 |
<p>A light source (L) is provided on an optical axis (O-O), and first and second reflectors (M1), (M2) are set firmly in the vicinity of the same optical axis. These reflectors consist, for example, of curved surfaces extending around the optical axis (O-O). The first reflector (M1) has such a three-dimensional shape that it can reflect a beam from the light source (L) so that the distribution of the beam becomes uniform. The second reflector (M2) has such a three-dimensional shape that it can receive and reflect the beam reflected on the first reflector (M1), to focus the resultant beam at a point (13) on the optical axis (O-O). Owing to such an arrangement, the beam leaves one point (13) and has a predetermined directivity. Accordingly, if an original (11) is placed in the path of the beam, a correctly-focused image of the original (11) is formed on a screen (S) no matter what the distance from the original (11) to the beam-focused point (13).</p> |
