Difficult perpendicularity measurement on a small part

[JibJabCory]

I was hoping to get some help measuring the perpendicularity of the end faces relative to the OD of a 1 mm rod. The tolerance is 2.0 mrad and I would also like to sort out the ones that are below 1mrad.
The tight tolerance is required for the optical performance of my design.

ROD: 1mm diameter and 2.6 mm length. Material: Glass
Measurement: 2 mrad perpendicularity (~about 2um across the 1 mm surface) and be able to sort out the rods that are 1 mrad or better.

Currently I'm using an optical comparator with a 50x objective and I would say my confidence in the measurement is +/- 1.5 mrad. My limitation is my vision and I think I may be able to fix this if I purchase a 200x objective.

Does anyone have any other suggestion as to how to inspect this tolerance.
Thanks,
-Cory

 

[MintJulep]

Maybe a performance based measurement rather than a physical measurement?

Shoot a laser through and measure the angle of the beam leaving?