| 摘要 |
<p>The disclosed apparatus comprises a charged particle beam system and method including a particle beam generator (12) for forming a beam of electrons, ions or other charged particles and for directing the beam along a predetermined axis (16) to a focal point. Object support means (24,26) support an object on the particle beam axis with the focal point on a surface of the object. There is provided an optical beam system forming part of an autofocusing system for maintaining the relative positions of the beam generating means and the object support means along the particle beam axis. The optical beam system comprises means for developing an optical beam (52), and means (56,58) for directing the optical beam transversely to the particle beam axis and at an acute angle to the object surface. Means are provided for forming an optical beam first focus on a surface of the object. Optical image forming mirror (62) means collects radiation from the optical beam first focus and forms a beam second focus in the vicinity of the beam first focus such that a change in the height or vertical position of the object surface along the particle beam axis produces a change in the position of the second focus indicative of the object surface height or position change. <IMAGE></p> |
