A mysterious field microscope - the Chinese TWX-1 (IV)
In the last issue we demonstrated that the 45x/N.A. 0.63 objective of the TWX-1
is well able to resolve the fine structure ("lines") of the test diatom Pleurosigma angulatum.
This implies that its resolution is roughly comparable to the standard objectives found on larger microscopes.
Furthermore we were able to make plausible by means of a diatom circle specimen
that the overall image quality of the 10x objective will work well for most field applications -
though the field ov view is slightly curved.
As the third remaining objective on the TWX-1 we have a 90x/N.A. 1.25 oil immersion.
For tardigrade viewing we will need this type of objective only rarely. Nevertheless,
for the sake of completeness, we will show here how it is performing on the respective test diatoms.
As has been mentioned already in a former issue the faint dots of the test diatom
Navicula lyra normally cannot be resolved by the 10x objective.
In contrast, this structure is no challenge for oil immersion objectives. As a consequence
also the TWX-1 90x objective reveals impressive resolution down to the dots:
The test diatom Navicula lyra, as seen by means of
the TWX-1 oil immersion objective.
CCD camera: Nikon Coolpix 995, Ebay "CP"-Adapter.
On the other hand those dots of Navicula lyra would
be visible already a resolution class below, with the 45x objective.
Therefore we will turn to a much more difficult candidate, a test diatom called
The test diatom Frustulia rhomboides, as seen by means of the TWX-1 oil immersion objektive.
Camera: Nikon Coolpix 995, Ebay "CP"-Adapter.
Among the most difficult test diatoms are the faint, ghost-like
specimens of Amphipleura pellucida. They are typical objects for oil immersion
and therefore thousands of scientists have the checked their 100x/N.A. 1.40
and 63x/N.A. 1.40 apochromatic objectives by means of Amphipleura pellucida.
Normally one should assume that this test diatom might be at the resolution borderline
of the TWX-1 but due to the possibility to finely adjust the position of
the rotatable mirror we were able to resolve this diatom down to lines as well:
The test diatom Amphipleura pellucida, as seen with the TWX-1 90x oil immersion objective.
Condenser not immersed (i.e. immersion oil only on top of specimen slide), LED light, no special filtering.
Raking light adjusted by tilting of mirror. Camera: Nikon Coolpix 995, Ebay "CP"-Adapter.
As a summary we can conclude that the TXW-1 has to be considered
as a member of the small group of world-class miniature field microscopes.
We have been experimenting recently with other, small electronic
microscopes like those two tiny LCD microscopes shown below:
Tiny LCD microscopes.
Of course, the optical resolution is much lower than with the
TWX-1 field microscopes - but there is an interesting feature which makes us believe
that some of those devices will be helpful for the tardigrade specialist as well.
Just have a glance at the following screenshot:
Detail of the screen of one of the LCD microsopes. The Echiniscus
(i.e. a tardigrade in the desiccated, dry state) definitely looks blue!
We will discuss this strange and helpful effect in the next issue
of our magazine. See you!
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Martin Mach (email@example.com).
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