Closterium with Plan Apo 10x/0.45 and Euglena with Plan Apo 20x/0.75.
I like the 3D view that gives polarized light on the Closterium, check the flat that the DIC looks.
Closterium DIC stack:

Closterium by Rogelio Moreno G., on Flickr
Closterium polarized light stack:

Closterium by Rogelio Moreno G., on Flickr
Euglena DIC:

Euglena by Rogelio Moreno G., on Flickr
Euglena polarized light + lambda plate:

Euglena by Rogelio Moreno G., on Flickr
Rogelio