Cover glass thicknes

[Glot]

Leitze Labourlux 11 Pol. Bought second hand.
Used for petrology thin sections.
The X4 objective does not have a cover glass thickness on it. Would that mean it's zero or at that power it doesn't matter?
What effect would cover glass have in this situation on any power? Would using them or not using them create any issues?
I have attached photos.

[Scarodactyl]

The '-' means it doesn't matter if it is there or not, which is true in general for low mag (or rather low NA) objectives. At higher NA the image quality will suffer if the wrong thickness of cover glass is used, and it will suffer a lot at highest NAs.

[BramHuntingNematodes]

Yeah so the function depends greatly on NA in a nonlinear fashion. You might not even notice with or without a slip with a 20x but on the 40x apo dry even a little bit off will ruin the image

[MichaelG.]

Your ‘Figure 3’ is interesting, Bram

Could you please give a reference to the source

Thanks
MichaelG.

[BramHuntingNematodes]

It is this article from the Olympus microscopeU

https://www.olympus-lifescience.com/en/ ... orrection/

Also is an interesting note about using oil immersion lens to look at temporary wet mounts

[MichaelG.]

Thanks for that, Bram

MichaelG.

[deBult]

The pictures show a weird mix of objectives, aimed at different tube lengths 170mm, 160 mm and “infinity”.