OBSERVATION DEVICE AND OPTICAL AXIS ADJUSTMENT METHOD

PROBLEM TO BE SOLVED: To solve such a problem of a conventional charged particle beam device that it is manufactured exclusively for observation under a gas atmosphere of a pressure substantially equivalent to or lower than the atmospheric pressure, and there is no device that allows for convenient observation under a gas atmosphere of a pressure equivalent to or substantially equivalent to the atmospheric pressure, by using a conventional high vacuum charged particle beam microscope, and to solve such a problem of a conventional method that it is impossible to perform simultaneous observation of the same point of a sample under such an atmosphere with a charged particle beam and light.SOLUTION: An observation device includes a charged particle beam optical lens barrel for irradiating a sample with a primary charged particle beam, a vacuum pump for evacuating the interior of the charged particle beam optical lens barrel, a detachable barrier membrane arranged to separate a space where the sample is placed and the charged particle beam optical lens barrel, and capable of transmitting or passing the primary charged particle beam, and an optical microscope disposed on the reverse side of the charged particle beam optical lens barrel for the barrier membrane and sample, and having at least a part of the optical axis on the extension of the optical axis of the charged particle beam optical lens barrel.