| 摘要 |
<p>A laser beam position sensing arrangement using two similar sensors where, instead of the first sensor being aligned normal to the beam scan path, the angle which bisects the two sensors is aligned normal to the beam scan path. The average of times T1 and T2 at which the laser beam is incident the respective sensors is used for the horizontal or start of scan value, and the difference (T2-T1) is proportional to the vertical or process direction value. From the difference between the two determined times, the longitudinal beam position may be determined.</p> |
