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Low Voltage Electron Microscope

High contrast

The LVEM5 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 LVEM5 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 LVEM5 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 LVEM5 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 high-sensitivity IEEE 1394 FireWire^© QImaging^© Retiga-4000R digital camera with 2048×2048 pixels progressive-scan interline CCD sensor is attached to the LVEM5. The image capture software is designed for acquisition, documentation and analysis of high performance image data. Various image processing procedures, such as summing, FFT, histogram, gamma correction and automatic contrast adjustment are available. 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 LVEM5 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 LVEM5 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 5 is a novel solution for imaging in life sciences and materials science (macromolecular chemistry).

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