www.photomacrography.net :: View topic - Jewel Beetle
www.photomacrography.net Forum Index
An online community dedicated to the practices of photomacrography, close-up and macro photography, and photomicrography.
Photomacrography Front Page Amateurmicrography Front Page
Old Forums/Galleries
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Jewel Beetle
Goto page Previous  1, 2, 3, 4
 
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Technical and Studio Photography -- Macro and Close-up
View previous topic :: View next topic  
Author Message
mjkzz



Joined: 01 Jul 2015
Posts: 965
Location: California/Shenzhen

PostPosted: Sun Sep 16, 2018 7:41 pm    Post subject: Reply with quote

thanks, I think I will get those coaxial stuff when I come back from vacation. I saw one in a machine vision/robotic show last year and it was cheap, maybe I will give them a call.
_________________
https://www.facebook.com/groups/mjkzzfs/
Back to top
View user's profile Send private message Visit poster's website
Lou Jost



Joined: 04 Sep 2015
Posts: 2762
Location: Ecuador

PostPosted: Sun Sep 16, 2018 7:45 pm    Post subject: Reply with quote

Rik, as you said, if you do that with a mirror, you cause aberrations. To avoid that, it should be better to use the method I linked to, a half-silvered front-surface mirror reflecting the subject into the lens. A light behind the mirror fills in the black shadows. The light from the object doesn't pass through the mirror, so there are no aberrations.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
Lou Jost



Joined: 04 Sep 2015
Posts: 2762
Location: Ecuador

PostPosted: Sun Sep 16, 2018 7:55 pm    Post subject: Reply with quote

Quote:
My guess is that those instruments linked by Lou do not have pellicle beamsplitters, but instead just thin glass or maybe even prisms. Placed behind the objective, there is no need for the thinness of a pellicle, and glass would be a lot more robust.



Rik, I can't vouch for all optical comparators, but at least some of them do use pellicle mirrors, according to their specs. See for example:
https://www.mqs.co.uk/nikon-pcb31000-projection-lens-10x-description-projection-lens-10x-with-built-in-half-reflecting-pellicle-mirror-new-code-pcb31001.html

Note that these seem to be finite lenses, so there is a good optical reason for the use of pellicle mirrors instead of thicker glass mirrors.

Edit: I bought several of these comparator lenses to experiment with, and their mirrors are completely invisible.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 19323
Location: Richland, Washington State, USA

PostPosted: Sun Sep 16, 2018 8:43 pm    Post subject: Reply with quote

Lou, thanks for the reference. It seems very clear that the PCB31000 does use a pellicle.

So then, from the standpoint of re-purposing used equipment, the issue would become: what do you do with a microns-thick pellicle that has been integrated by the manufacturer into the innards of a device like those comparators?

I've never had one of these in hand, so I don't know for sure, but I certainly expect that harvesting and reusing the pellicle will not be at all like harvesting the lens from a scanner.

--Rik
Back to top
View user's profile Send private message Visit poster's website
Lou Jost



Joined: 04 Sep 2015
Posts: 2762
Location: Ecuador

PostPosted: Mon Sep 17, 2018 5:11 am    Post subject: Reply with quote

The idea would be to harvest the whole tube segment containing the pellicle. This just involves removing the lens. Whether that is easy or not depends on whether the lens unscrews. If so, you're done! Easier than disassembling a big scanner.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
mjkzz



Joined: 01 Jul 2015
Posts: 965
Location: California/Shenzhen

PostPosted: Tue Sep 18, 2018 2:59 pm    Post subject: Reply with quote

found this little guy (trying to escape hurricane?) in kitchen, never stacked a spider . . . yeah, there is that black hole!


_________________
https://www.facebook.com/groups/mjkzzfs/
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Technical and Studio Photography -- Macro and Close-up All times are GMT - 7 Hours
Goto page Previous  1, 2, 3, 4
Page 4 of 4

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group