Jeol Ltd.

Other

Katsushige Tsuno

Toshikazu Honda

Masami Terauchi

Michiyoshi Tanaka

G Martinez Lopez

Masao Inoue

Eric Munro

Kenji Tsuda

John Andrew Rouse

Katsuyoshi Ueno

Martinez G Lopez

An energy filter with reduced aberration. The energy filter has a first stage of filter for receiving an electron beam entering along the optical axis and for focusing the beam in one direction vertical to the optical axis and a second stage of filter positioned along the optical axis behind the first stage of filter. The beam once focused by the first stage of filter is made to enter the second stage of filter. In the second stage of filter, the orbit of the electron beam is inverted with respect to the focal point. The two stages of filters are identical in length taken along the optical axis. The first and second stages of filters have electric and magnetic quadrupole fields, respectively, along the optical axis. These quadrupole fields make an angle of 45 degrees to the optical axis to achieve astigmatic focusing.

Energy filter and electron microscope

A Wien filter is provided in which a less amount of secondary aberration is produced than conventional. This filter has 12 poles. These poles have front ends facing the optical axis. These front ends have a 12-fold rotational symmetry about the optical axis within the XY-plane perpendicular to the optical axis.

Wien filter and electron microscope using same

An omega energy filter capable of increasing energy dispersion while canceling out second-order aberrations. The energy filter is mirror-symmetric with respect to the center plane C. A beam enters a first nonuniform magnetic field produced by a first magnet, then enters a second nonuniform magnetic field region produced by a second magnet. The trajectory of the beam is curved by the field produced by the second magnet. Finally, the beam enters a third magnetic field region produced by the first magnet. The beam is deflected in this region and reaches an exit slit.

Energy filter

A monochrometer mounted with the electron gun of an electron microscope or the like. This monochrometer does not need movement of a slit. An electron source consisting of any one of a thermal emission-type electron source (such as an LaB electron source or a tungsten hairpin), a Schottky emission-type electron source, and a tunneling field emission-type electron source is used. The slit is made of a single metal plate and mounted in position fixedly. Electrons are emitted from the electron source and dispersed within a plane including the slit according to energies. The slit is so positioned that it passes only those of the dispersed electrons which have energies close to the peak energy and blocks electrons having energies higher or lower than the peak energy.

Monochrometer for electron beam

A compact magnetic energy filter having at least four magnetic fields to deflect the trajectory of an electron beam from the entrance window to the exit slit. A rotational symmetry axis is located midway between the second and third magnetic fields. The magnetic fields on the opposite sides of the rotational symmetry axis are opposite in polarity.

Magnetic energy filter

There is disclosed an energy filter capable of reducing the Boersch effect. Also, an electron microscope using this energy filter is disclosed. This energy filter is composed of a first-stage energy filter and a second-stage energy filter arranged along the optical axis of an electron beam. The length L of the first-stage filter is selected to be greater than the length L of the second-stage filter. An energy-selecting slit is positioned in the electron beam path within the free space between the first- and second-stage filters. Each of these two stages of filters is a Wien filter having mutually perpendicular electric and magnetic fields.

Energy filter and electron microscope using same

There is disclosed an electron microscope equipped with an &OHgr;-filter and having an improved energy resolution. An objective lens and an intermediate lens system are mounted upstream of the filter. A projector lens system is mounted downstream of the filter. When a total magnification is entered from an input device, a controller sets the magnification of the projector lens system and the magnification of the lens system upstream of the filter so as to make the energy resolution highest. The exciting portion of the microscope is excited accordingly. Exciting currents for accomplishing a desired magnification are supplied from the exciting portion to the lenses. This optimizes the magnification of the projector lens system and the magnification of the lens system upstream of the &OHgr;-filter, thus achieving higher-energy resolution.

Electron microscope equipped with energy filter

There is disclosed an OMEGA energy filter comprising three magnetic field regions and producing small aberrations. The electron beam trajectory from the entrance window plane to the slit plane is continuously deflected into an omega-shaped form. Three magnetic field regions M,, M,, and M,having deflection angles &PHgr;, 2&PHgr;, and &PHgr;, respectively, are arranged in turn from the incident side. The deflection angle &PHgr; is set such that 102&deg;_. . . &PHgr;_. . . 115&deg;. The radius of curvature R,of the beam in the magnetic field region having the deflection angle 2&PHgr; is set less than the radius of curvature R,of the beam in the magnetic field regions having the deflection angle &PHgr;.

Omega energy filter

There is disclosed a small-sized and inexpensive electron spectroscopic imaging (ESI) system using an .OMEGA.-filter. The amounts of currents supplied to the lenses located before and after the .OMEGA.-filter need not be varied, whether the .OMEGA.-filter is used or not. The .OMEGA.-filter has an entrance window and an exit window. A straight path is formed between these two windows. A coil in an objective lens is located above a specimen. An entrance aperture is positioned close to the back focal plane of the objective lens. The objective lens is so energized that an electron microscope image is focused at the center of the filter on the straight path. The first stage of imaging lens is so energized that an image at the position P is an object plane. This image is magnified and focused onto a fluorescent screen by the following stages of imaging lenses.

Transmission electron microscope having energy filter

A transmission electron microscope that produces a monochromated electron beam and thus has improved spatial resolution. This microscope has a retarding monochromator mounted between the first anode (extraction electrode) of a field emission gun (FEG) and the second anode. The monochromator includes a decelerating portion, a Wien filter and an accelerating portion. An exit slit is so positioned that this exit slit and the object plane of the monochromator are symmetrical with respect to the center of the Wien filter. The beam extracted by the cathode of the gun is monochromated by the monochromator and so the chromatic aberrations can be improved. Consequently, the spatial resolution can be improved.

Transmission electron microscope

There is disclosed a highly isochromatic electron spectroscopic imaging filter providing good energy resolution even in a microscope image having a wide field of view. To reduce the difference in energy between the vicinity of the center of the image on the pupil plane and peripheral portions, the relation LL/L.sub.5 &gt; is satisfied, where LL is the distance from the pupil plane to the slit plane S and L.sub.5 is the distance from the exit end surface of the filter to the slit plane S.

There is disclosed a small-sized omega-type energy filter having reduced drift lengths and an increased merit function. Four magnetic fields M.sub.1, M.sub.2, M.sub.3, and M.sub.4 deflect the electron beam into an .OMEGA.-shaped orbit from the entrance window plane to the slit plane. The distance L.sub.4 from the exit end surface of the third field M.sub.3 to the entrance end surface of the fourth field M.sub.4 is set no greater than 50 .sqroot.U*/.sqroot.U*(200) mm. The deflection angle .PHI. is set to a range of from 120.degree.-50.degree. to 120.degree.+5.degree.. The distance L.sub.3 from the central plane between the second field M.sub.2 and the third field M.sub.3 to the entrance end surface of the third field M.sub.3 is set such that 20 .sqroot.U*/.sqroot.U*(200) mm .gtoreq.10.sqroot.U*/.sqroot.U*(200) mm. The distance L.sub.5 from the exit end surface of the fourth field M.sub.4 to the slit plane is set such that 30 .sqroot.U*/.sqroot.U*(200) mm.ltoreq.L.sub.5 .ltoreq.50 .sqroot.U*/.sqroot.U*(200) mm.

Omega-type energy filter

An omega-type energy filter of the B-type in which a beam of charged-particles is focused three times in a direction perpendicular to the direction of magnetic fields and twice in the direction of the magnetic fields. The geometry is so designed that this B-type produces smaller aberrations and larger energy dispersion than the A-type. The filter has four sector magnets M.sub.1, M.sub.2, M.sub.3, and M.sub.4 for successively deflecting the charged-particle beam passed through an entrance aperture and for directing the beam toward an exit slit. The entrance aperture and the exit slit are arranged symmetrically with respect to a central, symmetrical plane. The sector magnets M.sub.1 and M.sub.4 are arranged symmetrically with respect to the symmetrical plane. The sector magnets M.sub.2 and M.sub.3 are arranged symmetrically with respect to the symmetrical plane. The entrance aperture and the entrance face of the sector magnet M.sub.1 are separated by a distance of L.sub.5. The exit face of the sector magnet M.sub.4 and the exit slit are separated by the same distance of L.sub.5. Relations given by ##EQU1## are satisfied.

A differential phase contrast scanning transmission electron microscope capable of obtaining a clear differential phase contrast image. This microscope includes a charge-coupled image sensor on which a diffraction image is projected. The region covered by the image sensor is divided into two parts by a straight line. The difference between the amounts of electrons impinging on these two parts is calculated, and the resulting differential signal is supplied to a display unit to display an image of the specimen.

Differential phase contrast scanning transmission electron microscope

A transmission electron microscope having objective lens comprising upper, middle and lower magnetic pole pieces installed inside a yoke enveloping the first and second excitation coils. The polarity of the first magnetic field between the upper and middle magnetic pole piece is changed according to the selection of the two observation modes for an electron microscope image and for a converged beam diffraction pattern. However, the position of a specimen located at the midst of the second magnetic field between the middle and lower magnetic pole pieces is fixed during said two operation modes, so that analysis for a crystalline material of a very small area in the specimen is carried out by easy operation.

Growing community of inventors

Tokyo, Japan

Katsushige Tsuno