Tardigrades, carrot carotenoids and the DIY Raman spectrometer (IV)

Now, what's all this about? And where are the tardigrades? Well, the answer is quite easy: the Water Bear web base is delivering images and entertainment. But at the same time we intend to demonstrate to a broader audience that scientific DIY and own initiative can be more fun than just a passive consumption of YouTube videos. And, as has been shown in our March issue we can use the Raman spectrometer for some tardigrade related questions as well.

Fig. 1: The DIY Raman microscope spectrometer might help with many analytical tasks. As already illustrated you can use it for the investigation of tardigrade 'tuns' (i.e. tardigrades in the dry state). But you might make use of it as well in order to identify synthetic resins and pain reliver pills, check jewelry or to study minerals like the ones shown in the image above.

Agreed, at first glance it sounds crazy to build this kind of analytical equipment at home. Raman spectroscopy appears to be terribly complicated and chained to expensive instrumention. But the DIY has become feasible because we can take profit from a combination of three modern technical innovations: the solid state laser, interference filters and CCD imaging chips.

Fig. 2: For our DIY Raman we can use a green 532 nm laser which is merely thumb-sized. Our laser is passively cooled, just by air. It came with its own current supply which delivers 5 volts and 0,5 A. The output power is 50 mW. Be warned that this is the 50fold light intensity of a common laser pointer. So please take care that it is not accessible to children, that it is bearing a warning sign at that you do not direct its beam towards your eyes!

The microscope type which is most suitable for our experiment was already discussed in the previous issue of our magazine (cf. our discussion of potential Raman microscopes).

A Nikon Optiphot (or similar microscopes from other brands) might be used as it can be converted into a Raman microscope in a reversible manner. In case you should have finished with your experiments you will be able to turn everything back into a quite normal no-Raman instrument. That's what our instrument looked like before the experiment:

Fig. 3: A Nikon Optiphot microscope, built about 1986, in incident light configuration, with LED illumination and trinocular camera head.

The laser can simply be placed in the position of the LED light. As it has to be focused sharply on the sample under investigation any obstruction, in particular the matte filter, has to be removed. In order to fit the laser into the lamp thread we simply built a mechanical adapter with a thread and some fittings from Ebay - plus some glue:

Fig. 4: This self-built mechanical adapter keeps the laser in a fixed position. The laser just slides neatly into the fitting.

From this point onward you are working at your own risk. High energy lasers are dangerous and can harm your eyesight. Furthermore you should know that many lasers send infrared radiation (invisible radiation) as well which might be even more dangerous. So proceed slowly and carefully!

Fig. 5: The laser is wired and the laser power supply in place, ready for use ...

The eye-pieces should be turned away from the operator, e.g. towards a wall, or be fully closed. In the next issue we will provide some practical hints concerning laser power use, filter choice and the consequences for spectrum quality.

© Text, images and video clips by  Martin Mach  (webmaster@baertierchen.de).
The Water Bear web base is a licensed and revised version of the German language monthly magazine  Bärtierchen-Journal . Style and grammar amendments by native speakers are warmly welcomed.

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