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Recently I am searching for a Shack-Hartmann wavefront sensor for university laboratory usage. I was expecting my target sensor to be cheap, which is:

  • Low spatial wavefront resolution (50 x 50) for beam measurement;

  • Low frame rate;

  • Portable design, and easy to use.

Most quotations are beyond my expectation. On ThorLabs it costs 4k USD (which is, "cheaper" compared to most competitors): https://www.thorlabs.com/thorproduct.cfm?partnumber=WFS30-5C

Following reasons may to blame for this high price:

But I am not convinced by myself.

Any ideas why a Shack-Hartmann sensor is so expensive?

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    $\begingroup$ There are several things that drive the price up higher than you would initially expect. There's quality in workmanship, a warrantee, a guaranteed spec that it will meet, software, support, accessible repair, a large installed base and track record, etc. In the end these add up to the costs that you encounter. Add to that the idea that if they made a low-end sensor, people wouldn't be forced to buy the expensive one! $\endgroup$ – uhoh Jul 8 '19 at 14:16
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    $\begingroup$ You certainly may be able to build your own using a cheap microlens array or even a pinhole array in some specific cases, depending on what you need to resolve and the nature of your incoming wavefront. You'll have to mount the array and the sensor rigidly, take care to manage every bit of stray light (especially any with spatial structure!) think about thermal expansion, write your own analysis software, etc. If you have the time it might be quite fun! $\endgroup$ – uhoh Jul 8 '19 at 14:18
  • $\begingroup$ I'm voting to close this question as off-topic because it's really about business economics, not astronomy. $\endgroup$ – StephenG Jul 8 '19 at 21:39
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    $\begingroup$ @StephenG I'm voting to keep this question open! We talk about the price difference between cheap and expensive telescopes here, and what it is that makes the expensive one expensive, you wouldn't want to close all of those too now would you? A Shack-Hartmann sensor is a standard Optical metrology tool and has application in telescope building and characterization, I don't think this question is off-topic here. $\endgroup$ – uhoh Jul 9 '19 at 6:54
  • $\begingroup$ @uhoh Questions like this are not only time limited in usefulness, but also region limited in usefulness. It's just not a good fit for SE's model. Ultimately something costs what it does because that's what someone decided to charge for it. $\endgroup$ – StephenG Jul 9 '19 at 10:07
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Why are Shack-Hartmann sensors so expensive (4k+ USD)?

I had the same feeling the first time I saw their prices. In principle they are just an array of microlenses one focal length in front of a CCD or CMOS imaging chip. It can even be a pinhole array in some specific cases, depending on what you need to resolve and the nature of your incoming wavefront.

Here are some examples of being used to analyze the optical performance of astronomical telescopes:

If the 4k+ is well outside the range you'd like to spend on this application, then consider building your own for some simple tests. After trying that a while you may discover that your results are off, or non-repeatable, or getting the software to reliably extract a reasonable wavefront shape is harder than you thought.

But yes, in principle it's just a dark box with an array of lenses or holes and a CCD or CMOS imaging array, and a bunch of software that you'd have to write from scratch.

You'll have to mount the array and the sensor rigidly, take care to manage every bit of stray light (especially any with spatial structure!) think about thermal expansion, write the capture, processing, and wavefront-extraction software, etc yourself.

There are several things that drive the price up higher than you would initially expect. There's quality in workmanship, a warrantee, a guaranteed spec that it will meet, software, support, accessible repair, a large installed base and track record, etc. In the end these add up to the costs that you encounter. Add to that the idea that if they made a low-end sensor, people wouldn't be forced to buy the expensive one!

Shack-Hartmann sensor Alcor-Systems Source: Alcor-Systems

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