Transmission electron microscope (TEM)

Function: Lets users look at a very thin cross-section of an object (such as a cell).

Maximum magnification: Approximately 5,000,000x.

Best for:

Looking at internal structure of objects.

Looking at objects at very high resolution.

Looking at relationships between structures at high resolution.

Disadvantages:

Can’t be used to look at living things (samples need to be prepared extensively before visualising).

Costly to run.

Video: The transmission electron microscope shoots a beam of electrons at a thin slice of sample. Allan Mitchell points out the components of the transmission electron microscope. Learn about why you would use this microscope over others in Why use the transmission electron microscope?

Transcript

Allan Mitchell

The layout of the TEM is very similar to the compound light microscope. We have an illumination source at the top, which provides us our illumination. In our case, it’s electrons that come from an electron generator, which forms a small cloud of electrons about 50 micrometres in diameter – that’s 50 thousandths of a millimetre.

Below the electron gun, we have a series of lenses called the condenser lenses, and they converge that 50 micrometre spot of electrons down to a 1 micrometre spot, which strikes a sample at this level. The sample is inside the microscope at the end of this rod. Electrons pass through the sample, and some are deflected and some pass right through, and that forms our image, and they are focused by the objective lens which is underneath the sample itself.

Acknowledgements Allan Mitchell, University of Otago