Re: Alignment of a beam expander

verm25@xxxxxxxxxxx writes:

> The Sam FAQ Goldwasser? [bows].

:)

> 840 nm. Yep, my camera can see it. But my camera is too big for a back
> reflection test. I guess if I could get the first lens on axis with the
> laser, then I could check the centration of the second lens by rotating
> it and watching the motion of the beam on camera.

Perhaps something like:

Project the laser onto a white card and have the camera look at that.
(Could even be from behind.)

Identify optical axis without lenses and mark.
Install first lens and make sure blob is also centered.
Install second lens and adjust.

> My plan then would be to precision machine a tube holder for both
> lenses (them being plano-something means that in principle a holder
> should be simple to make on a precision lathe, since plano sides
> face each other), see if the beam still hits the same spot as
> without the beam expander (that should assure lenses being on axis
> IF centration is fine) and then rotate the second lens to check
> centration. Adjust centration and fix alignment again until all is
> good.
>
> Would I miss anything with this method?

Try it!

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Relevant Pages

  • Re: Alignment of a beam expander
    ... my camera can see it. ... motion of the beam on camera. ... (that should assure lenses being on axis IF centration is fine) ... rotate the second lens to check centration. ...
    (sci.optics)
  • Re: Bronica Medium format
    ... possibly because the camera body was so light and flimsy. ... If I could choose only one camera and lens I think it would have to be ... a Nikon F4 and the 20-35mm f/2.8 AF Nikkor. ... If allowed a second lens ...
    (uk.rec.photo.misc)
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