Compound microscope (light)

Function: Uses visible light to illuminate a thin section of sample.

Maximum magnification: Approximately 2,000x.

School light microscopes that do not use oil immersion have a magnification range of 40–400x.

Best for:

Looking at some living things (for example, a single cell layer).

Looking at cells and tissues (preparation steps are less critical than for electron microscopy).

Getting an overview of a sample.

Disadvantages:

Low resolution compared to electron microscope.

Video: Allan Mitchell, Technical Manager of Otago Micro and Nanoscale Imaging, discusses the benefits and limitations of the compound microscope and the stereomicroscope.

Transcript

Allan Mitchell

There are two types of basic light microscope configuration. There is the compound microscope, which is the microscope that shines light through a slice of a sample, and then there’s the stereomicroscope, which looks at the surface of the sample.

The key advantages of light microscopy is you can look at living material. You can see processes that may be occurring dynamically, whereas in the electron microscope, because we have to do so much preparation to get the sample in there, the sample is essentially dead – we get a moment in time.

When people do light microscopy, they start to run out of resolution at round about 2,000 times magnification, so a lot of assumptions are made about what they’re actually seeing when it comes to fine detail. There are very specialised light microscopes coming on the market now which can resolve this, but essentially, for most microscopy work, anything smaller than 200 nanometres is invisible to a light microscope.

Acknowledgements: Allan Mitchell, University of Otago Ningbo Optical Microscopes Company Dr Bronwyn Lowe, University of Otago Rosa Henderson, Manaaki Whenua – Landcare Research Dr Leon Perrie, Te Papa Dr Jenni Stanley, Leigh Marine Laboratories, University of Auckland