ABOUT MICROSCOPES

Microscopes are rather outside the experience of most people. Often it is thought that microscopes are just for scientists working in laboratories with very expensive equipment.
That is not true. There are microscopes for everybody’s financial means. And you can’t give your child a better present than a microscope, if only you don’t give a toy that promises 600x magnification. Your child will see nothing, and be so disappointed that it will never look through a microscope again.

 

Some people think that a SEM (Scanning Electron Microscope) is used for microscopic pictures.
Not true either. SEMs are able to magnify thousands of times, and requier specialists to handle them. They are not for private use. SEMs are not optically operating; they are computers.

 

So what kinds of microscopes are there for normal people like you and me?
I ‘ll only explain the two main kinds available to us all.
Below you see a ‘compound microscope’, or ‘light microscope’ with one eyepiece. The illumination comes from a mirror, or from an inbuild lightsource, always from UNDER the object. The monoculair tube is in modern microscopes often replaced by a ‘binoculair’ of two tubes, which fascilitates our two eyes and makes looking for some time more relaxed. The optical system though is the same, looking with two eyes doesn’t mean these microscopes have a stereo view!!!!

Below there’s a binoculair microscope with build in illumination. Both type of scopes have a number of objectives to change the magnification. An objective of 100x is more than one will probably need, unless one wants to see bacteria. Other objectives are 4x, 10x, 20x and 40x, standard. The pictures on this site were made with the 4x and 10x objective, mostly.
 

Then there is the Stereo microscope, which has a very different optical system from the aforementioned ones.
A stereo scope typically doesn’t magnify more than 50x.

As you can see in the picture, a stereo is built differently: it has no ‘revolver’ with several objectives, and there is a large ‘working distance’ between the objective and the stage.
That makes a stereo ideal for bigger objects, like everything you’ll find in nature, stones, sand, insects and your own fingers, for example. And here the system allows for stereo view, contrary to the binocular light microscope. This model is wonderful for curious kids, and it’s also the least expensive!!

Illumination in a stereoscope typically comes from ABOVE, but many models also have a possibility for underneath illumination.
The magnification goes from about 5x tot 45x or 50x.

 

Polarization

As mentioned in the introduction, the pictures of crystals are all made with the help of polarization filters. Polarization is an optical method, used scientifically in crystallography, geology and metallurgy. Any microscope of the optical type can be adapted to polarization.
I used to have two hand cut filters in the past. Now I have a slightly more sophisticated polarization set, but the results are the same: color in colorless objects.
You can find everything on polarization on internet. This image is the clearest explanation of how it works.
One filter above the object table (the analyzer) and one below (the polarizer) does the trick, when the one below can be turned around. With turning different colors light up, or are extinguished. Most crystals are optically active, some more than others.

 

Microscopes can be fitted with a number of other possibilities, like ‘phase contrast’ , ‘dark field’ or ‘Rheinberg illumination’, or even more sophisticated, DIC (Differential Interference Contrast). I am not going into those, because they are not relevant for this site.

There’s a long history in microscopy, starting with Anthoni van Leeuwenhoek (1632-1723), who is mostly known in Holland by the cancer hospital named after him. Centuries of improvement followed Anthoni’s work.
Now, being in the digital age, many microscopes are fitted with a screen instead of oculairs.
Images can be seen directly on the computer, and projected elsewhere.
Mobile telephones can be used for taking pictures. It’s just what you prefer.
I prefer a camera on top of my Olympus scope, but that, of course, is personal.

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