| 摘要 |
<p>A single laser system utilizes a grating (12) to provide a shifted beam and a nonshifted beam which are directed through a polarized beamsplitter (14) in the nonsplitting direction. The beams are directed through a 1/4 wave plate (24) by means of a folding mirror (22). The beams (34) from the 1/4 wave plate (24) are focused onto the recording surface of a disk (28) to generate a write spot (30) and a DRAW (direct read after write) spot (32). The DRAW spot (32) is positioned behind the write spot (30) at a distance ot n+1/2 bits. Reflections from the DRAW spot (32) are collimated back through the 1/4 wave plate (24) onto the folding mirror (22). The folding mirror (22) directs the collimated DRAW verify spot to the polarized beamsplitter (14) where it is reflected through a lens (16) to a DRAW spot photodetector (20) for detection. In a like manner, read reflections are directed back to be focused on a read photodetector (18).</p> |
