Patent ID: 7065240

Claim:
A reticle inspection apparatus comprising: an inspection laser light source for emitting an inspection laser light; an objective lens for condensing the inspection laser light and irradiating a reticle with the condensed inspection laser light; image generating means for generating an image of said reticle on the basis of the inspection laser light reflected by said reticle and the inspection laser light transmitted through said reticle and detecting said image of said reticle on defect therein; an auto-focusing laser light source for irradiating said reticle with an auto-focusing laser light in a direction obligue to an optical axis of said objective lens through said objective lens; a position sensor for detecting an incident position of the auto-focusing laser light reflected by said reticle and incident on said position sensor through said objective lens; lens position regulating means for calculating a distance between said objective lens and said reticle on the basis of an output signal of said position sensor and making a focal position of the inspection laser light coincident with an inspection position of said reticle by regulating a position of said objective lens according to the calculated distance; and definition judging means for analyzing definition of the image of said reticle and judging whether or not the definition is within a tolerable range, wherein said definition judging means judges whether or not the position of said position sensor is within a tolerable range by comparing a result of definition judgment performed by said definition judging means with a preliminarily set reference data.