Geoffrey Graham Diamond,Tat Hean Gan,David Arthur Hutchins
申请号：
US14677474
公开号：
US09201006B2
申请日:
2015.04.02
申请国别(地区):
US
年份:
2015
代理人:
摘要：
Apparatus for inspecting an article comprising: a controller configured to generate a drive signal having a periodic amplitude variation a source, the source being operable by the controller to emit a source beam thereby to irradiate an article, the source beam comprising a beam of electromagnetic radiation having a periodic amplitude variation corresponding to that of the drive signal and a detector, the detector being configured to detect a portion of the source beam that has been transmitted through at least a portion of the article, and to generate a detector signal having an amplitude variation corresponding to the amplitude variation of said portion of the source beam, the controller being further configured to generate a difference value corresponding to a difference between the amplitude of the detector signal and the amplitude of a reference signal.
