| 摘要 |
The present invention provides for very rapid autofocusing of optical scanning systems. If a sample is sufficiently out of focus, the focal error signal used to focus a conventional half-blocked system can become saturated. Multiple steps toward the focus position then typically are required to bring the system into the operational range. To minimize this, a light adjustment system is provided to reduce the amount of light impinging on the half-blocked system when the focal error signal is at or near saturation. The half-blocked system then becomes primary controller again, and can move the system into a position generally close to the correct focal point. The light adjustment system then can be deactivated, but since the system now is much closer to focus, the half-blocked system can quickly bring the system into final focus. Alternatively, the photodetectors used to generate the focal error signal are segmented. The approximate distance to the correct focal point then is determined by comparing the amount of light detected by segments at different radial positions.
|
