Patent ID: 6965112

Claim:
An observation system having a source of a beam of charged particles, holder support means for supporting a specimen holder that holds a specimen, an illumination lens for controlling the beam of charged particles emitted by the source and for directing the beam at the specimen, image pickup means for taking a transmission image of the specimen, and a focusing lens for controlling the beam of charged particles transmitted through the specimen and projecting the beam onto the image pickup means, wherein (A) the specimen holder supported by the holder support means has a holder body provided with a hole having a step surface therein and a specimen-holding member having an opening for holding the specimen inside, the specimen-holding member being supported on the step surface in the hole of the holder body and placed within the hole, (B) the step surface in the hole of the holder body is provided with at least one slot, (C) the specimen-holding member has a surface to be supported, and (D) the supported surface has at least one first convex portion inserted in the slot.