US 5,500,527 AGranted

Electron/ion microscope with improved resolution

OwnerAlexander Zarubininventor

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Abstract

A new type of electron microscope comprises a charged particle source and a condensor that form a dark-field illumination system with an incident beam of a small spatial coherence width compared to the transverse dimensions of the specimen. An interferometer is positioned along a direction of scattering to produce the superposition of two lateral areas of the scattered beam to form interference and to vary the amount of shear. The microscope includes a rotation means for turning the direction of shearing relative to the scattered beam around the scattering direction. The interference fringes are recorded by a detector at different directions of shear with variable amount of shear within each shear direction. A data processor (digital computer) evaluates the visibility and the phase shift of the interference fringes to obtain Fourier components of an image of the specimen and to synthesize the image from those components. Aberrations of this microscope can be substantially reduced and its numerical aperture increased, resulting in a higher resolving power.

Claims18

Dependent claims

A microscope having a source means (10) for producing charged particles and a condenser means (20) to form an electron or ion particle beam incident on a specimen (30) thereby forming a scattered particle beam having an optical axis (14) and comprising a specimen holder (31) and a detector (50), characterized in that:

the source means (10) and the condenser means (20) form a dark-field illumination system with an incident beam whose spatial coherence radius is less than the transverse dimensions of the specimen (30), and in that the microscope comprises
an interferometer means (40) positioned along the optical axis for forming interference fringes by superposing two lateral areas of the scattered particle beam which are separated by a variable shear distance;
rotation means for turning the direction of shear, produced by the interferometer, relative to the scattered beam around said optical axis;
the detector (50) being positioned to take recordings of said interference fringes, and
data processor means (60) for evaluating the visibility and the phase shift of said interference fringes from said recordings for obtaining Fourier components of an image of the specimen and to synthesize the specimen image from said Fourier components.

2 more elements

Dependencies are inferred from the claim text.