A small inexpensive polarizer fits into trinocular head dovetail bottom

[Hobbyst46]

In the absence of dedicated polarizer/analyzer accessories for the microscope, some folks have considered placing a polarizer inside the trino head. It sits inside the bottom of the trino head, inside the receptacle in the arm.
So far, I did so with piece of a polymer polarizing film, that I cut with scissors.
Recently I found on eBay an inexpensive ready-made glass polarizer in a metal sleeve. It is called a "SVBONY 1.25inch polarizing filter". The outside diameter of the sleeve is 31.7mm and the thickness is 7mm. It has a male thread that I ignore. Due to the small profile, it easily fits (not snugly, needs a few wraps of tape to fit) even into the narrow dovetail bottom of ye olde Zeiss. And the trino head goes back into the receptacle in the arm, and turns around by 360 without problem.
Disclosure: I do not have any bussiness connection of any kind with suppliers/makers of these things. Just a small finding.

[Sauerkraut]

Sounds like we took a similar path. I started out with the plastic polarizing film but felt it slightly distorted the image so found the same (or something similar - can't recall) glass filter on eBay. Since my scope has a slot for a polarizer, I simply unscrewed the glass from the metal housing and made a slider for it.

It seems to create less distortion than the plastic version. Has that been your observation also, Hobbyst46?

[Hobbyst46]

Yes, the glass polarizers convey a true polarization effect; namely, when rotated unto full light exctinction, the background is black.
The thin plastic film works similarly when flat. But, pieces of it in holders, or inside the trino head, often bend somewhat. And produce artifacts, such as dark blue background instead of black.
So, the answer to your question is Yes.