Yes, I'm using a photomask vendor to fabricate the objective. It's in the low hundreds of dollar to get 7um features, a bit more expensive to reach 4um and bloody murder to get 1um (~thousands).
Currently we have some tiny photon sieves, around 1.5mm aperture ~f/14. The next step is going up to 60mm @ f/6.5. The end goal, and I don't know how achievable this is, will be a very large aperture panelized scope. We've discussed making something unsteerably large, sticking it in a field and using the Earth's rotation to sweep the sky.
There's a little bit of trickery to reduce harmonics, though I'm not sure how it'll perform in practice. Please get in touch if you have experience doing diffraction simulation. After first light I plan to write everything up.
That sounds about in line with a microlithography vendor (UK) I ordered zoneplates from. 7-10µm features were accessible and going to 0.7µm was an order of magnitude higher (and went from film to chrome on glass IIRC). File size was also a factor for more complex patterns.
Do not hesitate to post results on cloudynights or your club's website, I'll refresh it from time to time ! I do not think I have enough diffraction experience to help though.
Do you have any photomask vendors that you recommend. I am trying to do some homebrew lithography and the photomask is not coming out as crisp as I want.
I haven't used them yet, but the University of Louisville's Micro/Nano Technology Center has competitive pricing. They guarantee down to 6um and depending on the design can hit 4um. It's $375 for a 6x6 and $225 for 4x4. 1um is billed at $100/HR and was told that a 4in plate would take several days.
We use Compugraphics in UK at work for DUV masks (fused quartz 6inch) , base price for 700nm CD is much better than what the sibling comment predicts (sorry but I can't disclose).
