0
$\begingroup$

I have sourced two parabolic mirrors and am planning to set up a Schlieren for ultrasonic visualization and future fluids projects.

A very common dual parabolic mirror configuration is the Z-type, where the light source is on the opposite side from the camera.

enter image description here
Image Source

I am a mechanical engineer and not a physics optics expert, so I know just enough to be dangerous. Is there any reason why a same side configuration will not work? Does this introduce any optical distortion that is not present in the Z-type configuration. Has anyone seen a parabolic mirror configuration like this before in a Schlieren or other device? See my photo-shopped image:

enter image description here

$\endgroup$

1 Answer 1

1
$\begingroup$

It might be that aberrations cancel better with the top one, but that is only a guess. You could buy an optical design package if you want to see. Or you could try it out.

See this for a Veritasium video on a single mirror Schleren system. How To See Air Currents

$\endgroup$
3
  • 1
    $\begingroup$ I agree, this most likely has to do with minimizing aberrations. However, the smaller the pinhole is compared to the mirror diameter, the more ideally the system behaves, and the less it matters. If there is a reason for the U configuration rather than Z, then go for it; it’ll probably be fine. $\endgroup$
    – Gilbert
    Jan 5, 2022 at 19:02
  • $\begingroup$ @Gilbert - Not necessarily. Abberations have to do with the mirror shape not being exactly what is needed to focus all rays to a point. A better pinhole makes a better point, but not a better mirror. In this case, coma could bite you. $\endgroup$
    – mmesser314
    Jan 5, 2022 at 19:40
  • 1
    $\begingroup$ Well it's a matter of semantics, but as far as I know "coma" is short for "comatic aberration," which is indeed what I was referring to. So I agree: there's nothing necessarily wrong with the mirrors. I discovered a parabolic mirror's propensity for coma the hard way when I tried to use a 2"-focal-length, 90-degree-off-axis parabolic mirror as an imaging objective. Bad idea! Everything but the very center of the image was completely aberred. $\endgroup$
    – Gilbert
    Jan 5, 2022 at 20:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.