International Precision Incorporated

Akashi Seisakusho Ltd.

Kohei Shirota

Akira Yonezawa

Takashi Yanaka

A method and apparatus for automatically focussing a specimen image in an electron microscope. Excitation currents for an objective lens of the microscope are previously determined in accordance with predetermined magnifications in one-to-one correspondence. When one of the magnifications is selected, the objective lens is automatically excited with the current corresponding to the magnification, whereby the specimen image is automatically properly focussed.

Image focusing method and apparatus for electron microscope

A symmetrical magnetic field type objective lens for an electron microscope comprises an upper magnetic pole piece and a lower magnetic pole piece disposed below the upper pole piece with a predetermined inter-pole distance S. Bores of a same diameter b are formed in the upper and the lower pole pieces, respectively. The distance S and the diameter are selected so that 1.ltoreq.S/b.ltoreq.5. Additionally, excitation J of the objective lens is so selected with respect to a predetermined magnetomotive force Jc.o. of a Riecke-Ruska's condenser objective lens that the condition that 1.4 Jc.o..ltoreq.J.ltoreq.1.7 Jc.o. is fulfilled. The objective lens assures a wide field of view without being accompanied with blurs or distortion of image.

Objective lens for electron microscope

This invention relates to a method and apparatus for obtaining a single photograph of electron microscope images, with low gain in magnification, of relatively thick specimen, which photograph is suitable for direct comparison with a corresponding photograph of the same specimen obtained with an optical microscope: wherein either the specimen or the electron beam is so manipulated that the electron beam passes discretely and stepwisely through sequential portions of the specimen, and prior to impinging on the photographic plate the electron beam is screened to eliminate any portion thereof which would produce aberrations or other distortion and is controllably directed to impinge on a portion of the photographic plate which corresponds to the portion of the specimen through which the beam is passing.

Growing community of inventors

Akikawa, Japan

Kohei Shirota