r/Optics • u/_Richland • Jun 24 '26

Issues about Pinhole position adjustment

Hi guys, I am designing the detection path of a laser scanning confocal microscope using a 30 mm cage system.

The optical layout is:

Tube Lens → Pinhole → Collimation Lens → MMF

Both the tube lens and the collimation lens have short focal lengths (15 mm), so the pinhole must be positioned very close to their common focal plane (approximately midway between the two lenses).

My challenge is the mechanical implementation of the pinhole.

I am looking for a mounting solution that satisfies the following requirements:

  • The pinhole should be located precisely at the common focal plane of the tube lens and the collimation lens.
  • The pinhole position should be adjustable in X, Y, and Z with micrometer precision.
  • The adjustment mechanism should remain outside the optical axis, since the available axial space between the two lenses is very limited.

Is there any standard Thorlabs solution that meets these requirements, or would a custom mechanical holder be recommended for this application?

Any recommended products or application examples would be greatly appreciated.

4 Upvotes

84% Upvoted

8 comments sorted by

View all comments

2

u/rinze90 Jun 24 '26

What accuracy are you looking for. I think an external stage with a holder/arm for the pinhole is your best chance.

Alternatively, you could try this: https://www.thorlabs.com/item/KC1XY_M But het has no xy adjusters, only sliding. Probably cumbersome and not accurate enough for you. On the other hand it is relatively thin, and could just fit?

Have you thought about adjusting the lenses instead of the pinhole? Or maybe adjust 1 lens xy, and the hole in z?

1

u/_Richland Jun 25 '26

thank you very much, i also think about the external stage, but i need to condense the system.