Patent Number: 039393534
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention, will be described by reference to the accompanying drawings. FIG. 1 is a side sectional view of the specimen mounting apparatus for a scanning type electron microscope, and FIG. 2 is a view looking in the direction of the line II--II of FIG. 1. As shown in these drawings, a rotatable cylindrical support member comprising an external shaft 3 fluidtightly inserted, like a round-bar-like plug, into an aperture 2 of a specimen chamber 1 through an O-ring 4. The aperture 2 has a round cross-section and is disposed in a wall 1a of the specimen chamber 1. A rotatable elongated member comprising a round-bar-like internal shaft 6 has one end thereof directly connected to the bottom of a cylindrical specimen stage 5. The shaft 6 is inserted fluidtightly into an aperture in shaft 3 through an O-ring 7. The aperture in shaft 3 is parallel to the axis about which it rotates and is disposed eccentrically thereof. The specimen stage 5 has a flange 5a disposed at the end portion thereof which is connected to the shaft 6. Flange 5a engages with a stepped portion 2a of said aperture 2 in the specimen chamber wall. The stepped portion 2a is in a portion of the specimen chamber which is fixed to a magnetic pole 8 of an electron lens of the electron microscope. When the inside of said specimen chamber 1 is evacuated the flange 5a is forcibly pressed against the stepped portion 2a due to the force on the shaft 6 caused by the pressure differential between the chamber and the atmosphere. A pilot member 9 having a pilot area 9a, approximately as large as the aperture of the specimen stage 5 for holding a specimen, is fixed by a set screw 10 to the external end of the internal shaft 6. Indicating means are provided comprising an indicating member 13 having an indicating part 13a located close to pilot area 9a and in correspondence with a portion 11a, of a specimen 11 mounted on said specimen stage 5, that is irradiated by electron beam 12. The base of the indicating member 13 comprises a shaft 14 fitted in a supporting cylinder 15 which is fixed to the outer surface of the specimen chamber wall 1a. The supporting cylinder 15 also has disposed therein a spring 16 which contacts the base of said indicating member 13 through a die 15a, permitting the indicating member 13 to rotate and move up and down. In FIG. 1 reference numeral 17 denotes a collector mesh, 18 a scintillater, 19 a photo-guide, and 20 a photo-multiplier. The operation of the specimen mounting apparatus will now be described with respect to the structure described above. A desired portion of the specimen 11 is scanned with an electron beam 12, and secondary electrons generated thereby from the surface of the specimen are collected by said collector mesh 17 and fed to the scintillator 18, where they are converted into light which is then converted into electricity in the photomultiplier 20. A enlarged image of the desired portion of said specimen is projected on a Braun tube (not shown) through an amplifier (not shown in the drawings). During the use of the electron microscope when the specimen stage 5 is in a position wherein a portion 11a of specimen 11 is irradiated, an adjustment of the position of the portion 11a may be desired. The adjustment of the portion 11a of specimen 11 which is irradiated by the electron beam 12 is effected by turning the external shaft 3 thereby turning shaft 6 and then turning the internal shaft 6 with respect to shaft 3, which is eccentrically positioned with respect thereto, by holding the upper end of said external shaft 3 and pilot member 9. The relative position of electron beam on the specimen is changed by this operation and is indicated on the pilot area 9a by the indicating part 13a of the indicating member 13. During this adjustment of the portion of the specimen, the flange 5a of the specimen stage 5 is pressed against the stepped portion 2a which is coupled to the magnetic pole 8 of the electron lens to transmit vibratory motion from one to the other. This keeps the irradiated portion of the specimen and the electron beam free from relative movement and thus free from the influence of vibrations from the outside. As a result the image on said Braun tube does not collapse. When a change of the specimen 11 is desired, the inside of the specimen chamber 1 is returned to atmospheric pressure and the indicating member 13 is raised so that the external shaft 3 may be removed together with the specimen stage 5 and the internal shaft 6. When the parts are removed, the specimen 11 in the specimen stage 5 can be changed. The specimen stage 5 can be reinserted into the specimen chamber 1 by simply pushing it into aperture 2 in the specimen chamber wall together with the internal shaft 6 and the external shaft 3, when the inside of the specimen chamber 1 is evacuated, both the internal and external shafts are sucked inward to hermetically seal the aperture 2. The specimen stage 5 is thus maintained at a predetermined position, with the flange 5a thereof forcibly abutting against the stepped portion 2a in the aperture, as described above. The position of the electron beam 12 on the specimen 11 is indicated by the indicating member 13 and adjustment of the position of the specimen by the rotation of the internal and external shafts 6 and 3 of the specimen stage are also performed as described above. As detailed above, the specimen mounting apparatus for an electron microscope according to the present invention has a simple construction and is easy to insert and remove into the electron microscope. The apparatus also makes focusing on a specimen relatively free from vibration. While preferred embodiments of the invention have been shown by way of example in the drawings, it will be understood that the invention is in no way limited to these embodiments.