Diatom Test Slide of Micromanipulated Pinnularia dactylus var. dariana

DIATOM TEST SLIDE of Micromanipulated Pinnularia dactylus var. dariana (A.Schmidt) Cleve

Details to detect: poroids

The theoretical limit of resolution of most light microscopes is ∼ 0.2 μm, but these poroids can be detected by the techniques below, thanks to Diatom Cubed high refractive index mountant!

Viewed with SEM, QUANTITATIVE FEATURES in Diatom Lab's sample are:

Poroids inside the striae: 44 - 45 in 10 µm

Average distance between poroids: 0,072 - 0,089 µm. See SEM image from the same sample!

(While In Amphipleura pellucida striae number 37-45 in 10 µm and pores are spaced 0,16 - 0,19 µm apart)

Recommended microscope objectives: Oil-immersion 63 or 100x objectives having a very good or excellent numerical aperture (1,3 or 1,4);

Suggested techniques to detect the poroids: Double immersion (= Oil immersion objective and Oil immersion condenser) with Polarized light (the polarizers should be oriented perpendicular to each other = maximum level of extinction) and possibly oblique illumination; or Immersion dark field condenser (better 1,2/1,4) with Polarized light (the polarizers should be oriented perpendicular to each other = maximum level of extinction)

In Diatom Cubed mountant (refractive index > 1,7)