High Resolution Side-Entry Goniometer

1980 ◽  
Vol 38 ◽  
pp. 56-57
Author(s):  
T. Honda ◽  
H. Watanabe ◽  
K. Ohi ◽  
E. Watanabe ◽  
Y. Kokubo
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Resolution Limit ◽  
Tilting Angle ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
High Resolution Images

An analytical electron microscope equipped with a side-entry goniometer (SEG) has recently become more widespread than a conventional electron microscope by the following reasons: (1) a variety of specimen holders, (2) large tilting angle with eucentricity. However, the resolution of SEG-system is about 0.4 nm, whereas the resolution of 0.25 nm or less can be obtained by an electron microscope equipped with a top-entry goniometer (TEG)1). Factors determining the resolution of an electron microscope are (1) the aberration coefficients of the objective lens, (2) stability of exciting currents, (3) illumination angle of the electron beam on the specimen, (4) energy spread of the electron beam, and ( 5) vibration and specimen drift. It has been usually difficult to observe high resolution images during use of the SEG system, because of the aberration coefficients of the objective lens, vibration and specimen drift. In order to obtain a resolution of less than 0.3 nm with SEG system at 200 kV, both of spherical and chromatic aberration coefficients should be reduced less than 2 mm. Moreover, relative amplitude of vibration between the specimen and pole pieces should be less than a half value of resolution limit. The image drift should be less than 0.02 nm/sec, because the exposure time usually required for photographing a high resolution image is about 5 second.

Design of a 400KV Ultrahigh-Resolution Analytical TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 134-135
Author(s):  
H. Tsuno ◽  
T. Honda ◽  
Y. Kokubo
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spherical Aberration ◽  
New Technology ◽  
Objective Lens ◽  
Ultrahigh Resolution ◽  
X Ray ◽  
Analytical Tem ◽  
Analytical Electron ◽  
Analytical Electron Microscope

The condenser-objective (C/O) lens proposed by Riecke, which has a very short gap length and small spherical aberration, was utilized for a commercial 200 kV ultrahigh resolution analytical TEM by Yanaka and Kaneyama. Fig. 1 shows the relation between theoretical resolution and objective lens (OL) spherical aberration coefficient (Cs) at accelerating voltages 200-1250 kV. It was reported that the Cs of a 400kV high resolution TEM is 1.0 mm and its resolution is 0.167 nm. The Cs of 400kV analytical TEM is 1.8 mm and the pre-field spherical aberration coefficient (Csp) is 1.8 mm. Fig. 2 (A), (B) show beam broading in specimens against the thickness when a 200kV and a 400kV electron beam transmit the specimen (C-Au), respectively. The broading of 400kV electron beam is about half of 200kV one. Then it is expected that spacial resolution of x-ray analysis improve. The above-captioned 400kV ultrahigh resolution analytical TEM is designed by applying a new technology which is adopted for a 200kV ultrahigh resolution analytical electron microscope, JEM-2010.Its fundamental construction is the same as the 400kV analytical electron microscope JEM-4000FX, except the 0L. The goniometer is a modified JEM-2010 goniometer, because it is too small for 400kV EM. Although it was expected that the focus ampere turn increases because of its short gap length, the objective lens coil used by JEM-4000EX/FX is adopted, because it has enough capacity. The shapes of the upper yoke and objective polepiece were calculated by the finite element method (55×110 Meshes) under the following condition: (1) maximum tilting-angle 10° (2) x-ray take-off angle 17.5° and solid angle 0.068 strad (3) minimized Cs.

Development of ultra high resolution analytical electron microscope ISI-EM-002A

1983 ◽  
Vol 41 ◽  
pp. 312-313 ◽  
Author(s):  
T. Yanaka ◽  
A. Yonezawa ◽  
K. Oosawa ◽  
T. Iwaki ◽  
S. Suzuki ◽  
...  
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Voltage ◽  
Electron Gun ◽  
Objective Lens ◽  
Magnetic Circuits ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Mode 3 ◽  
High Voltage Generator

Total design concept of EM-002A is to realize the following essential performance, that is, 1) attainment to ultimate high resolution as the conventional electron microscope, 2) complete compatibility of the high resolution mode and the analytical mode, 3) identification of the analyzed region and the observed image with atomic-level resolution, 4) observation of ultra fine structure of the biological specimen with maximum high contrast and so on.[Electron source] Accelerating voltage ranges from 20kV to 120kV in 6 steps Double Cockroft-Walton circuit is used as the high voltage generator and the high frequency ripple voltage is reduced to 0.1V. Electron gun assembly is composed of high voltage alumina insulator, whose shape is so well designed as to suppress micro-discharge to the negligible order.[Objective lens and specimen chamber] The objective lens is a strong symmetrical lens where the specimen chamber is located between the symmetrical upper and lower objective lens magnetic circuits. The objective lens has two powerful pole pieces, one being used for the ultra high resolution mode and the other for the standard mode.

Development of 200kV ultrahigh-resolution analytical electron microscope

1989 ◽  
Vol 47 ◽  
pp. 108-109
Author(s):  
T. Kaneyama ◽  
M. Naruse ◽  
Y. Ishida ◽  
M. Kersker
Keyword(s):  
Electron Microscope ◽  
Optical Constants ◽  
Materials Science ◽  
Objective Lens ◽  
The Finite Element Method ◽  
Ultrahigh Resolution ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Characteristic Features ◽  
Better Than

In the field of materials science, the importance of the ultrahigh resolution analytical electron microscope (UHRAEM) is increasing. A new UHRAEM which provides a resolution of better than 0.2 nm and allows analysis of a few nm areas has been developed. [Fig. 1 shows the external view] The followings are some characteristic features of the UHRAEM.Objective lens (OL)Two types of OL polepieces (URP for ±10' specimen tilt and ARP for ±30' tilt) have been developed. The optical constants shown in the table on the next page are figures calculated by the finite element method. However, Cs was experimentally confirmed by two methods (namely, Beam Tilt method and Krivanek method) as 0.45 ∼ 0.50 mm for URP and as 0.9 ∼ 1.0 mm for ARP, respectively. Fig. 2 shows an optical diffractogram obtained from a micrograph of amorphous carbon with URP under the Scherzer defocus condition. It demonstrates a resolution of 0.19 nm and a Cs smaller than 0.5 mm.

Development of high-performance objective lens polepiece for ultrahigh resolution Analytical Electron Microscope

1993 ◽  
Vol 51 ◽  
pp. 254-255
Author(s):  
K. Fukushima ◽  
T. Kaneyama ◽  
F. Hosokawa ◽  
H. Tsuno ◽  
T. Honda ◽  
...  
Keyword(s):  
Electron Microscope ◽  
High Performance ◽  
Open Space ◽  
Materials Science ◽  
Objective Lens ◽  
Ultrahigh Resolution ◽  
Science Field ◽  
Specimen Holder ◽  
Analytical Electron ◽  
Analytical Electron Microscope

Recently, in the materials science field, the ultrahigh resolution analytical electron microscope (UHRAEM) has become a very important instrument to study extremely fine areas of the specimen. The requirements related to the performance of the UHRAEM are becoming gradually severer. Some basic characteristic features required of an objective lens are as follows, and the practical performance of the UHRAEM should be judged by totally evaluating them.1) Ultrahigh resolution to resolve ultrafine structure by atomic-level observation.2) Nanometer probe analysis to analyse the constituent elements in nm-areas of the specimen.3) Better performance of x-ray detection for EDS analysis, that is, higher take-off angle and larger detection solid angle.4) Higher specimen tilting angle to adjust the specimen orientation.To attain these requirements simultaneously, the objective lens polepiece must have smaller spherical and chromatic aberration coefficients and must keep enough open space around the specimen holder in it.

Ultra-high resolution SEMI-in-lens type FE-SEM, JSM-6320F, with strong magnetic-field lens with built-in secondary-electron detector

1994 ◽  
Vol 52 ◽  
pp. 484-485
Author(s):  
T. Miyokawa ◽  
H. Kazumori ◽  
S. Nakagawa ◽  
C. Nielsen
Keyword(s):  
High Resolution ◽  
Secondary Electron ◽  
Spherical Aberration ◽  
Incident Beam ◽  
Chromatic Aberration ◽  
Magnetic Flux Density ◽  
Objective Lens ◽  
Electron Detector ◽  
High Resolution Images ◽  
Working Distance

We have developed a strongly excited objective lens with a built-in secondary electron detector to provide ultra-high resolution images with high quality at low to medium accelerating voltages. The JSM-6320F is a scanning electron microscope (FE-SEM) equipped with this lens and an incident beam divergence angle control lens (ACL).The objective lens is so strongly excited as to have peak axial Magnetic flux density near the specimen surface (Fig. 1). Since the speciien is located below the objective lens, a large speciien can be accomodated. The working distance (WD) with respect to the accelerating voltage is limited due to the magnetic saturation of the lens (Fig.2). The aberrations of this lens are much smaller than those of a conventional one. The spherical aberration coefficient (Cs) is approximately 1/20 and the chromatic aberration coefficient (Cc) is 1/10. for accelerating voltages below 5kV. At the medium range of accelerating voltages (5∼15kV). Cs is 1/10 and Cc is 1/7. Typical values are Cs-1.lmm. Cc=l. 5mm at WD=2mm. and Cs=3.lmm. Cc=2.9 mm at WD=5mm. This makes the lens ideal for taking ultra-high resolution images at low to medium accelerating voltages.

Optimizing Spatial Resolution for X-ray Microanalysis

2001 ◽  
Vol 7 (S2) ◽  
pp. 694-695
Author(s):  
Eric Lifshin ◽  
Raynald Gauvin ◽  
Di Wu
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spatial Resolution ◽  
Maximum Diameter ◽  
Thin Sections ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Limiting Value ◽  
Made In

In Castaing’s classic Ph.D. dissertation he described how the limiting value of x-ray spatial resolution for x-ray microanalysis, of about 1 μm, was not imposed by the diameter of the electron beam, but by the size of the region excited inside the specimen. Fifty years later this limit still applies to the majority of measurement made in EMAs and SEMs, even though there is often a need to analyze much finer structures. When high resolution chemical analysis is required, it is generally necessary to prepare thin sections and examine them in an analytical electron microscope where the maximum diameter of the excited volume may be as small as a few nanometers. Since it is not always possible or practical, it is important to determine just what is the best spatial resolution attainable for the examination of polished or “as received” samples with an EMA or SEM and how to achieve it experimentally.

Combined Use of Structure Imaging and Microanalysis in Structure-Composition Analysis By A 400-KV High-Resolution Analytical Electron Microscope

1985 ◽  
Vol 43 ◽  
pp. 228-229
Author(s):  
Yoshio Bando ◽  
Yoshizo Kitami ◽  
Mamoru Mitcmo
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Image Resolution ◽  
Composition Analysis ◽  
Transmission Electron ◽  
Resolution Observation ◽  
Composition Determination ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Normal Transmission

One of the limitations in the use of the conventional analytical electron microscope (AEM) with lower voltages of 100 to 200 kV is based on its poor image resolution compared to normal transmission electron microscope. Because of this, it is difficult to carry out structure determination by directly observing individual atom arrangements in crystals. However, a new AEM with an intermediate voltage of 400 kV (JEM-4000EX, TEMSCAN) is fully capable of high resolution observation under equipment of an energy dispersive x-ray spectrometer (EDS) and an electron energy loss spectrometer (EELS). The present paper shows crystal structure images of sialon polytypes and corresponding EDS and EELS spectra, and describes the usefullness of combined techniques of structure imaging and microanalysis in structure-composition determination.

Development of an Ultra - High - Resolution Low Voltage(LV) SEM with an Optimized “in-lens” Design

1990 ◽  
Vol 48 (1) ◽  
pp. 388-389
Author(s):  
Takashi Nagatani ◽  
Mitsugu Sato ◽  
Masako OSUMI
Keyword(s):  
High Resolution ◽  
Low Voltage ◽  
Collection Efficiency ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Spot Size ◽  
Objective Lens ◽  
Tilting Angle ◽  
Working Distance ◽  
Better Than

An “in-lens” type FESEM, Hitachi S-900, developed as an ultra high resolution SEM having 0.7nm resolution at 30kV(Nagatani et al 1986), was modified for better performance at low beam energy(about 5kV or below) with small aberrations of ths objective lens and dual specimen position design. This is in responce to the recent upsurge of interest in using the LVSEM, which enables us hopefully to observe the surface topography of uncoated samples directly with maximum fidelity(Pawley 1987).The actual visibility of the minute topographical details depends upon not anly the spot size of the scanning beam but also physics of interaction between impinging electrons and solid sample(Joy 1989). However, the resolution can never be better than the spot size. Then, it would seem logical to specify the spot size first when designing a high resolution SEM. As discussed earlier(Crewe 1985; Nagatani et al 1987), the spot size of the beam is mainly limited by spherical aberration of the objective lens and diffraction at high voltage(about 10 kV and above). On the other hand, chromatic aberration and diffraction are the dominant factors at low voltages(about 5kV or below). Source size of a cold field emission is so small that we could neglect it for simplicity.In general, chromatic aberration can be smaller at higher excitation of a narrow gap objective pole-piece, which also made the working distance short. Therefore, some compromise is necessary among minimized aberrations, required specimen size, stage traverse and tilting angle etc. In practice, tolerable distortion of the image at low magnification and collection efficiency of the secondary electrons are another factors to be considered in designing the instrument. By taking these factors in simulation, an optimized objective lens was designed as shown in Table 1.

Application of hollow-cone illumination to High-resolution electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 692-693
Author(s):  
R.A. Herring
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Objective Lens ◽  
Hollow Cone ◽  
Lattice Image ◽  
Resolution Electron ◽  
High Resolution Images ◽  
Z Contrast

TEM hollow cone illumination can produce high resolution images having atomic number (Z) contrast within a lattice image. Inorder to produce these images, the contribution of four sources of electrons should be considered. These are the main, inelastically scattered, elastically scattered, and diffracted beams. This abstract discusses these sources of electrons to the hollow cone (HC) image, and then goes further to propose a possible method of extending the resolution of the electron microscope by using diffracted HC beams to form holograms which should remove the limitation on resolution imposed by the objective lens and inelastically scattered electrons. A Philips EM 430T was used to take the electron micrographs.

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