Patent Number: 039393534
Section: summary

BACKGROUND OF THE INVENTION The present invention relates to an apparatus for mounting a specimen in an electron microscope. Generally, with known specimen mounting apparatus of this type, a specimen chamber is evacuated while the electron microscope is in use, and is returned to atmospheric pressure when the specimen is changed. This necessitates that the position of the specimen be adjusted from outside the chamber. This has resulted in apparatus that is complicated in construction, troublesome to handle, and sensitive to vibrations which cause a focusing problem. In addition conventional specimen mounting apparatus need complicated structure to indicate the position of the electron beam of an electron microscope on a specimen during use of the electron microscope. SUMMARY OF THE INVENTION The object of the present invention is to solve the aforementioned problems in conventional specimen mounting apparatus by providing a specimen mounting apparatus capable of simple construction and ease of handling. Another object of the present invention is to provide a specimen mounting apparatus which is releasably coupled to the electron lens of an electron microscope to prevent the relative movement of one with respect to the other to ensure proper focusing when the specimen mounting apparatus is induced to vibrate. A further object of the present invention is to provide a specimen mounting apparatus which can easily adjustably position a specimen to be irradiated by an electron beam to select a portion of the specimen to be irradiated. A still further object of the present invention is to provide a specimen mounting apparatus which is capable of indicating the relative position of the specimen to be irradiated to thereby indicate the portion of the specimen that has been selected to be irradiated. Still another object of the present invention is to provide a specimen mounting apparatus which can be easily inserted and removed to change the specimen. These and the other objects of the present invention are carried out by the specimen mounting apparatus of the present invention which comprises specimen-holding means positionable into an irradiating position wherein a portion of the specimen is exposed to the electron beam. The specimen-holding means includes means for adjustably positioning the specimen, when the specimen-holding means is in the irradiating position, to variably select the portion of the specimen exposed to the electron beam. The apparatus also includes means for releasably mounting the specimen-holding means in the irradiating position and for releasably coupling the specimen-holding means to the electron lens, when the specimen-holding means is in the irradiating position, to transmit vibratory motion from the specimen-holding means to the lens to substantially prevent the relative movement of one with respect to the other whenever the specimen-holding means is induced to vibrate, thus maintaining the focus of the electron beam on the selected portion of the specimen. The specimen-holding means comprises a rotatable, elongated, cylindrical member having means disposed at one end portion thereof for mounting the specimen. The elongated member is fluidtightly mounted for rotation about its longitudional axis in a rotatable cylindrical support member which has a main axis about which it is mounted to rotate. The elongated member is inserted in the support member in a throughbore that has an axis parallel to the main axis of the support member and disposed eccentrically thereof. The means for coupling the specimen-holding means to the electron lens comprises means for forcibly abutting a portion of the specimen-holding means on the electron lens. In addition, an intermediate member which contacts the electron lens may be provided and in this case means are provided for forcibly abutting a portion of the specimen-holding means on the intermediate member. The means for releasably mounting the specimen-holding means comprises an evacuatable specimen chamber that is receptive of a negative pressure applied thereto and has means therein defining a throughbore for fluidtightly receiving the specimen-holding means. Thus the specimen-holding means is forcibly held in the wall of the specimen chamber when a pressure differential is developed between the chamber and the atmosphere by evacuating the specimen chamber. The apparatus further comprises indicating means for indicating the relative position of the specimen thereby indicating the portion of the specimen exposed to the electron beam. The indicating means comprises a pilot member with a pilot area approximately as large as the means for mounting the specimen that is disposed at the one end portion of the elongated member. The pilot member is attached to the other end portion of the elongated member. An indicating member is provided with an indicating part that moves in correspondence with the portion of the specimen relative to the electron beam. The indicating part is located close to the surface of the pilot area. Having in mind the above and other objects that will be obvious from an understanding of the disclosure, the present invention comprises the combinations and arrangements of parts illustrated in the presently preferred embodiments of the present invention which is here and after set forth in sufficient detail to enable those persons skilled in the art to clearly understand the function, operation, construction, and advantages of it when read in conjunction with the accompanying drawings.