| 摘要 |
<p>A recording medium has a first fringe pattern which is described by a first spectral bandwidth ( DELTA lambda 1) and a first image blur factor ( DELTA THETA ). The recording medium also has a second fringe pattern which is described by a second spectral bandwidth ( DELTA lambda 2) and a second image blur factor ( DELTA THETA ). The first spectral bandwidth ( DELTA lambda 1) is different from the second spectral bandwidth ( DELTA lambda 2). The first image blur factor ( DELTA THETA ) is substantially equal to the second image blur factor ( DELTA THETA ). By providing multiple holograms in the single recording medium, the spectral bandwidths ( DELTA lambda 1, DELTA lambda 2) of each hologram are combined to provide an overall spectral bandwidth. Since the image blur factors ( DELTA THETA ) of each hologram are substantially the same, i.e. overlap, when the two holograms are combined, the overall image blur factor ( DELTA THETA i min ) is not increased. Indeed, it decreases at the same time the thickness of the recording medium is increased by a factor which is equivalent to the number of exposures in the single recording medium. The result is increased bandwidth without a concomitant increase in image blur.</p> |
