Observation Modes

Observation Modes on Zeiss Axiophot:

This example shows live cells of the filamentous fungus Neurospora crassa, expressing Green Fluorescen Protein (GFP) fused to Histone H1. The GFP fusion protein is localized in the nucleus.

Nomarski GFP Fluorescence
overlay DIC + fluorescence
Differential Interference Contrast (DIC) The image shows the characteristic '3-D relief' appearance and good resolution of subcellular details Fluorescence
Excitation 488 nm, emission detected through a 520 nm longpass filter. The green signal indicates nuclear localization of the GFP- fusion protein.
Overlay of the DIC and fluorescence images.
brightfield phase contrast

Because the cells are not stained, condensor aperture had to be closed down to increase contrast. This caused dffraction artefacts and loss of resolution
Phase constrast.
This observation mode is very useful for detection and observation of small, colorless objects, such as bacteria or cultured cells. The cells show the typical bright 'halo' around their periphery.

The following pictures show a transversal hand section of a wooded plant stem.

brightfield 1

darkfield 1

Polarization in transmitted light:
Anisotropic structures, such as cellulose cell walls, show birefringence and are visualized in bright tones..

Excitation with UV light, tissue autofluorescence viewed through a 400 nm longpass filter with a 20x objective. Image acquired with Nikon DXM1200 color camera.
fluorescence 1