New LEDs for your microscope - tardigrade friendly cold light! (I)
From 230V tardigrade barbecue to clever LED microscope illumination
All of us do know that most technical innovations take their time and that
their step-wise development will be financed partially by the consumer.
Just think about those bizarre mercury loaded energy saving lamps (cf. spectrum in fig. 1) and the "halogen" bulbs
which were recommended to museums, churches and private consumers a few decades ago. Nowadays,
everybody is trying to replace those intermediate products by state of the art LEDs
or even going back to old fashioned, classical filament bulbs.
The spectrum of a typical old-fashioned "energy saving" lamp ("energy saving",
before the LEDs came up finally). It goes without saying
that the distribution of wavelengths is discontinuous, resulting
in very "special" colors. As can be seen in the figure, many intermediate wavelengths
have actually intensity zero and therefore cannot interact with the illuminated objects.
When comparing the above spectrum with the spectrum of natural daylight (see below)
it becomes clear that the light of the energy saving lamp is very artificial
and that its color rendering ability must be miles away from natural daylight:
Fig. 2: The spectrum
of natural daylight has its energy distributed rather smothly over a large range of wavelengths.
Besides, you might note those interesting small "shark tooth" indents called
Fraunhofer lines which were reporting the sun's chemistry to our scientists almost
two centuries ago.
The color rendering is not so much a problem for the microscopist.
Nevertheless modern LEDs can combine perfect color rendering with low heat diffusion,
the latter being very much important for tardigrades studies. Please remember
that we do not want to boil our live tardigrades under the microscope!
But there is even more: LEDs are small, so they can be easily fitted
in old-fashioned housings, like those of high voltage E14 (14 mm thread) bulbs.
As a consequence some microscope LED adapations can be performed by
simply replacing E14 filament bulbs with E14 LED bulbs. No soldering, no
additional wiring, reversible changes to (some, not all - sorry) historical
microscopes. Let's have a look at the respective technical development:
Fig. 3: The metamorphosis
of ancient high voltage bulbs to high performance LED lights
(1) Classical E14 thread 230 V bulb with a power of 25 W. Be warned: this is a tardigrade (heat) killer! (109)
(2) An early E14 LED lamp, unluckily with the light radiating to all sides (10 ... 20)
(3) A more modern, matte LED light with a little bit more power (30)
(4) Our present favorite - a LED lamp with 24 tiny LEDs. It directs most
of its light into the microscope optics - perfect! (112)
The red numbers in brackets are indicating the approximate light output of the respective products.
We will demonstrate the practical usability of those E14 replacements in
the next issue of our magazine.
© Text, images and video clips by
Martin Mach (firstname.lastname@example.org).
The Water Bear web base is a licensed and revised version of
the German language monthly magazine
Style and grammar amendments by native speakers are warmly welcomed.