New LEDs for your microscope - tardigrade friendly cold light! (III)
From 230V tardigrade barbecue to clever LED microscope illumination

The tiny social world of microscopists has its trends and fashions, too. Apparently LED conversion is part of them. Nevertheless most of those forum microscope illumination threads will help to come closer to a thorough understanding of the respective light alternatives.

First of all, there are some basics which must be understood: high voltage classical light bulb illumination, no matter whether 110 or 230 V, is evil for tardigrade work, simply because it is generating much heat and little light. The heat will reach your slide and roast your tardigrades. On the other hand we do think that there is little need to replace classical low voltage bulbs by LEDs as the low voltage bulbs do not generate that much heat. And they are definitely benevolent, with a service life time matching the lifetime of the microscopist. They are not flickering and their brightness can easily be adjusted. Please keep in mind that unprofessional illumination conversions from classical low voltage to LED might ruin the iconic character of some classical microscopes and therefore cause a financial loss when trying to resell the converted instrument on Ebay. This is why we gave some technical hints towards reversible LED conversion in the most recent issues of our magazine (cf. our October and November issues.)

A further argument for reversibility is that we can more easily experiment with different light sources. Some of us will like warm colors, whereas others might prefer more neutral, even slightly bluish tinges. Furthermore, there are some specialities which you should keep in mind when looking out for tardigrades. The following video clip is illustrating the advantage of a rather old-fashioned blueish LED when looking for tardigrades in dry moss. Just have a look:

Video: The reddish Echiniscus "tuns" will light up in blue color like saphire when illuminated by an old "blue-tooth" LED.

When looking at the spectra of those old-fashioned LEDs is will become clear that their assumed flaw (the blue tooth in the blue region of the spectrum) is working as a perfect tardigrade indicator - simply by rendering the tuns in intense blue color:

Fig. 1: Spectrum of an old, blueish LED with a strong band in the blue region of the spectrum (around 460 nm) - ideal for finding dry state tardigrade tuns without wetting the moss.

Fig. 2: Spectrum of the more neutral Ikea "Jansjö" LED lamp. This is a perfectly neutral white light illumination for normal microscopic routine. Please note that there is only a neglegibly small 450 nm blue tooth in the spectrum.

Fig 3: Spectrum of an E14 LED as shown in the most recent issues of our magazine. Please note that this is a perfectly smooth spectral curve. But, as explained, you should better use a blueish LED for tardigrade search in dry moss.

© 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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