Products & Services > Electron Microscopy
Low Voltage Electron Microscope LVEM
Low Voltage Electron Microscope LVEM
Electron microscopes are indispensable tools for the investigation of objects at the micro and nano scale. The LVEM can help you get the information you need. The LVEM is designed to excel across a broad range of applications such as biology, medical diagnosis, and materials science (macromolecular chemistry). Using unstained samples you are able to observe the objects close to their native state with ultra high contrast and nanometer resolutions.
Small installation space
The LVEM is a compact bench top instrument that combines high-resolution imaging with the small footprint of an optical microscope. It consists of four separate parts; the microscope, the electronics unit, the vacuum system, and the PC. Small footprint, no need for a dark room, no cooling water, easy service…all this makes the instrument a multi-purpose personal or in-group electron microscope.
High contrast
The LVEM is a unique investigation tool that allows observation of objects composed of light elements (H, C, N, O, S, P) with high contrast without using heavy metal staining and shadowing. Samples composed of heavier elements can also be observed either in nanometer scale outline detail or in aggregation (lower magnification) when placed in an appropriate embedding matrix or directly on a carbon coated grid. Thus both stained and unstained samples can be observed. High contrast of light elements is achieved through a substantial decrease of electron energy (see the comparison images below). An acceleration voltage decrease from 100 kV to 5 kV significantly increases electron scattering and enhances the contrast of standard test samples (20 nm thin carbon film) by more than 10 times. The spatial resolution of the LVEM is about 2 nm in all modes.
Field emission gun (FEG) and advanced electron optics
The electron gun uses a Schottky field emitter which provides high brightness and coherence with a lifetime of several thousand hours. The high brightness and small virtual source of the electron gun allows transmission and scanning modes. Permanent magnet lenses, an electrostatic lens and electrostatic stigmators and deflectors are used in the electron optics. Permanent magnet lenses are very stable and do not need any cooling.
Two-stage magnification
The design of the LVEM differs considerably from that of standard TEM. The miniaturized electron optics column is oriented upside down with the electron gun at the bottom side. Low voltage electron optics projects enlarged image on an electron-sensitive YAG screen; this image – which contains details at the nanometer scale – is further magnified by optical objective of a light microscope. The YAG scintillator serves as an image converter between the electron and light optics. The maximum magnification is approx. 200,000 in TEM mode. The overall dimensions of the LVEM are comparable with those of conventional light microscopes. Observation of the results is made through binoculars or on a screen via digital camera image capture.
Image capture
A Retiga 4000R progressive-scan CCD camera is attached to the LVEM (2048×2048 pixels). The Qcapture PRO Image Processing Software is used for acquisition, documentation, and archiving, as well as measurement and analysis of high performance image data. Various image processing procedures for pre- and post-processing, such as arithmetic operations, baseline image subtraction, filtering and smoothing procedures. Scanning images can be saved in three resolution levels – 512×512, 1024×1024 and 2048×2048 pixels. Scanning images can be formed by detecting transmitted electrons (STEM – scanning transmission electron microscopy), or backscattered electrons (BSE). IN BSE mode the combination of image signals from two detector segments enables both material and topographic contrast images.
Wide choice of imaging modes
Even though the LVEM is the smallest commercial transmission electron microscope in the world, it features all the standard imaging modes that can be found in conventional TEMs and more. The LVEM can work in transmission (TEM – Transmission Electron Microscope) or diffraction (SAED – Selected Area Electron Diffraction) modes as well as in scanning modes (STEM – Scanning Transmission Electron Microscope and SEM – Scanning Electron Microscope with BSE – Backscattered Electrons) with nanometer spatial resolution.
The following combinations are available:
TEM (with SAED)
TEM (with SAED) + STEM
TEM (with SAED) + SEM
TEM (with SAED) + STEM + SEM
Applications
LVEM is a novel solution for imaging in life sciences and materials science (macromolecular chemistry).
You can read more about LVEM applications on this page.
Easier sample preparation techniques
Conventional preparation techniques are simplified because staining and shadowing may be avoided. The observed image is the real structure without any artifacts stemming from staining or shadowing, closer to the native state of your samples. The sample thickness should be up to 50 nm in TEM mode, up to 70 nm in STEM mode, depending on the sample material. The samples are placed on standard 3 mm discs or grids.
Technical parameters
|
Accelerating voltage
(nominal) 5 kV | |
|
Specimen |
Ø 3 mm TEM grids |
|
specimen exchange time |
approx. 3 min |
|
Electron
optics | |
|
Condenser lens |
permanent magnet |
|
focal length* |
4.30 mm |
|
the smallest illuminated area |
100 nm |
|
condenser apertures |
Ø 50, 30 µm |
|
* calculated for 5 kV | |
|
Objective lens |
permanent magnet |
|
focal length* |
1.26 mm |
|
CS |
0.64 mm |
|
CC |
0.89 mm |
|
dtheoretical |
1.1 nm |
|
atheoretical |
10-2 rad |
|
objective aperture |
Ø 50, 30 µm |
|
* calculated for 5 kV | |
|
Projection lens
(TEM) |
electrostatic |
|
magnification on the YAG screen |
36 to 470× |
|
Electron gun |
Shottky cathode ZrO/W[100] current density |
0.2 mA sr-1 |
|
lifetime |
> 2,000 hours |
|
Light
optics | |
|
objective Olympus M40x |
NA 0.90 |
|
objective Olympus M4x |
NA 0.13 |
|
binocular M10x |
|
|
Olympus U-TR30-2 widefield trinocular
observation tube | |
|
TEM image
capture | |
|
camera |
Retiga 4000R CCD |
|
2,048×2,048 pixels | |
|
digitalization |
12 bits |
|
pixel size |
7.4×7.4 µm |
|
cooling |
optional Peltier cooling available |
|
SCAN modes image
capture | |
|
monitor |
512×512 pixels |
|
saving image |
up to 2,048×2,048 pixels |
|
digitalization |
8 bits |
|
Imaging
modes | |
|
TEM | |
|
resolving power |
2.5 nm |
|
total magnification |
1,500 to 195,000× |
|
ED (electron
diffraction) | |
|
minimum probe size |
100 nm |
|
diffraction lens |
magnification 3.5× |
|
STEM | |
|
resolving power |
2.0 nm |
|
minimum magnification |
(25×25 µm) 6,000× |
|
SEM (BSE
detector) | |
|
resolving power |
4 nm |
|
minimum magnification |
(200×200 µm) 800× |
|
Vacuum | |
|
Airlock system (for sample
exchange) | |
|
diaphragmal pump and turbomolecular
pump |
10-5 mbar |
|
Object
space | |
|
ion getter pump (10
lsec-1) |
10-8 mbar |
|
Electron
gun | |
|
ion getter pump (7
lsec-1) |
10-9 mbar |
|
Weights and
dimensions | |
|
Electron and light optic
system | |
|
weight |
25 kg |
|
dimensions (w×d×h) without
camera |
290×450×455/510 mm |
|
Airlock pumping system Pfeiffer
Vacuum TSH 071E | |
|
weight |
15 kg |
|
dimensions |
300×300×340 mm |
|
Control
electronics | |
|
weight |
19 kg |
|
dimensions (w×d×h) |
470×270×290 mm |
|
Consumption | |
|
Control electronics in stand by (ion
getter pumps only) |
20 VA |
|
Control electronics |
160 VA |
|
Including airlock pumping
system |
300 VA |
|
Camera |
20 VA |
|
PC and monitors |
approx. 450 VA |
|
No cooling water is
required. | |
Electron Diffraction mode
SEM mode
| TEM mode | STEM mode | ||||||||
|
|
Read more about LVEM applications on this page.