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Some lenses to play with on the cloudy days
Posted: Thu Oct 21, 2021 11:32 am
by j.gardavsky
Hello all,
I have received from Oberkochen some of their "deplorable" lenses from the ongoing projects,
Top, left to right: 235mm dia positive 500/88087, and field booster 211
Bottom, left to right: 100mm dia positive doublet 22107, 88mm plan/plan CaF2 crystal 107929, 152mm dia positive meniscus (no ID)
Still considering to buy more CaF2 crystal blanks,
JG
Re: Some lenses to play with on the cloudy days
Posted: Thu Oct 21, 2021 1:09 pm
by notFritzArgelander
What mischief are you planning?
Re: Some lenses to play with on the cloudy days
Posted: Thu Oct 21, 2021 1:25 pm
by j.gardavsky
There are a few ideas.
One of them is a 200mm
aperture fast refractor for the OIII/H-Beta vision.
Another is to make a CaF2 light path corrector and to use its anomalous dispersion characteristic.
Still condidering to buy more CaF2 crystal blancs,
to play with the anomalous dispersion is more tempting than just the extra low dispersion of the ED glass (not crystal) materials.
Thank you for asking,
JG
Re: Some lenses to play with on the cloudy days
Posted: Thu Oct 21, 2021 1:57 pm
by notFritzArgelander
j.gardavsky wrote: ↑Thu Oct 21, 2021 1:25 pm
There are a few ideas.
One of them is a 200mm
aperture fast refractor for the OIII/H-Beta vision.
Another is to make a CaF2 light path corrector and to use its anomalous dispersion characteristic.
Still condidering to buy more CaF2 crystal blancs,
to play with the anomalous dispersion is more tempting than just the extra low dispersion of the ED glass (not crystal) materials.
Thank you for asking,
JG
Interesting projects to be sure!
Re: Some lenses to play with on the cloudy days
Posted: Sat Oct 30, 2021 2:14 pm
by Makuser
Hi JG. A very interesting set of CaF2 lenses. I was particularly interested in the plan/plan lens in your photo with it's unusual altered convex shape. There a lot of new optic designs being developed now and I call your attention to this one here, at:
https://www.spiedigitallibrary.org/conf ... 9442.short
Thanks for your post and picture JG and the best of wishes with your future optical projects.
Re: Some lenses to play with on the cloudy days
Posted: Sat Oct 30, 2021 8:39 pm
by j.gardavsky
Hello Marshall,
the CaF2 crystal lens has a bright convex rim with a faint bluish coating, otherwise planar. The purpose of the rim is not known to me.
It has been likely manufactured by Corning U.S. for a UV (193nm) research and development project in Oberkochen.
One more lens, a cemented triplet is on the way.
Best,
JG