Differential Interference Contrast Microscopy (DIC) - Biomedical Optical Phase Microscopy and Nanoscopy - page 36

Computed phase
(dry mass) image

Color combination of phase (red)
and retardance (green) images

Computed retardance image

Figure 2.9
Metaphase of meiosis I in a crane fly spermatocyte. Color combination of phase (red) and
retardance (green) images. (For interpretation of the references to color in this figure legend, the
reader is referred to the web version of this topic.)

distribution of birefringence due to structural or internal anisotropy of the cell structure. For
instance, in a live dividing cell, the OI-DIC image clearly shows detailed shape of the
chromosomes while the polarization image quantitatively depicts the distribution of the
birefringent microtubules in the spindle, both without any need for staining or other
modifications of the cell.

Figure 2.9 presents combined pseudo-color OI-DIC and OI-Pol image of spermatocytes
from the crane fly, Nephrotoma suturalis , during metaphase of meiosis I. The experiment
was done together with LaFountain. The phase image was computed by Biggs. The set-up
was a Nikon Microphot-SA microscope equipped 60 3 /1.4NA oil immersion at wavelength
546 nm [45] . The changing of bias and rotating the shear direction during DIC image
acquisition were done manually. Also, in order to switch between polarization and DIC
imaging modes, the pair of liquid crystal waveplates was replaced with DIC prisms. At
present, these mechanical manipulations take significant time relative to the temporal
resolution of the test. A microscope which rapidly switches between the OI-DIC and the
OI-Pol modes without any mechanical movement is theoretically possible and a prototype is
in development.

The figure shows a group of 4 conventional DIC images (left top) and a group of 4
conventional polarization images (left bottom). These raw images were employed for