www.photomacrography.net :: View topic - Polarizing objectives on an ordinary bright field microscope
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 
Polarizing objectives on an ordinary bright field microscope

 
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Beginners Micro
View previous topic :: View next topic  
Author Message
papaki72



Joined: 10 Jan 2017
Posts: 6

PostPosted: Mon Jan 16, 2017 9:59 pm    Post subject: Polarizing objectives on an ordinary bright field microscope Reply with quote

Is it possible to use such objectives under an ordinary biological microscope? If not is it possible to adapt a bright field microscope to act as a polarizing microscope?
Back to top
View user's profile Send private message
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4007
Location: Valencia, Spain

PostPosted: Tue Jan 17, 2017 8:55 am    Post subject: Reply with quote

Yes it is for sure if the specifications (tube correction, parfocal distance and thread) match your microscope.

For most amateur pol work you don't need dedicated pol objectives, in my experience almost any good objective (and most not so good ones) work very well for pol. In most cases pol objectives are just normal objectives certified to be strain free.

You can adapt almost any BF microscope for pol, you just need to place a polarizer under the condenser (at the filter try or over the light source and and another one, called analyzer, over the objective, usually into the microscope head. You need at least one of them to be rotatable to regulate polarization.
A circular rotating stage is convenient to orientate the specimen but not absolutely required.
You want linear polarizers, although if you already have circular ones putting them with the "front side" facing to the specimen they just work as linear.

For the substage polarizer you can use even film sheets of good quality, as analyzer you need a good flat glass filter. Camera polarizers can do but often do not full extinct light providing a nice but in principle undesirable blue cast and background although some good expensive ones like the B+W usually work well.
_________________
Pau
Back to top
View user's profile Send private message
papaki72



Joined: 10 Jan 2017
Posts: 6

PostPosted: Mon Jan 23, 2017 3:32 am    Post subject: Reply with quote

Would the insertion of a filter in the microscope head affect the tube length and hence deteriorate the quality of the image?
Back to top
View user's profile Send private message
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4007
Location: Valencia, Spain

PostPosted: Mon Jan 23, 2017 11:22 am    Post subject: Reply with quote

With an infinite corrected microscope it will not (in fact inserting optical elements between the objective and the head with no image degradation is in the origin of the infinite design).

With finite corrected microscopes in principle it will do although in practical terms it will be irrelevant except for critical work with high NA objectives. I've done it for many years for low magnification petrography with no issues.

Many finite corrected microscopes place that intermediate optics between two lenses (telan lenses) that create an infinite space between them in an intermediate piece between the microscope nose and head.

What is your intended application? What magnification and equipment do you plan to use?
_________________
Pau
Back to top
View user's profile Send private message
papaki72



Joined: 10 Jan 2017
Posts: 6

PostPosted: Tue Jan 24, 2017 1:52 am    Post subject: Reply with quote

I am a hobbyist and I am using a Biolam R5 microscope that uses compensating eyepieces. I have a pair of 10x infinity corrected and I am looking for objectives of 20x and 10x.
In no case can it be said that I am doing critical work.
Back to top
View user's profile Send private message
Olympusman



Joined: 15 Jan 2012
Posts: 3425

PostPosted: Tue Jan 24, 2017 10:12 am    Post subject: Hybrid polarizing microscopes Reply with quote

Here is an article I wrote on hybrid pooarizing microscopes:

http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artmar08/mm-polar.html

Mike
_________________
Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA
Back to top
View user's profile Send private message
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4007
Location: Valencia, Spain

PostPosted: Tue Jan 24, 2017 10:58 am    Post subject: Reply with quote

After a quick search I can't find info about "R5" but AFAIK the Biolam is a finite (160mm) corrected microscope, so infinite objectives will not work well.
Infinite corrected microscopes do have an adequate tube lens generally placed at the base of the head to converge the parallel rays exiting from the objective to focus them inside the eyepieces/camera. In many cases you can focus a finite scope with infinite objectives but this will degrade the image, especially with high NA objectives, and you will lose parfocality

As I formerly proposed, just dropping a good polarizer inside the microscope over the objective and another one rotatable over the light source will work well and it's very simple.
_________________
Pau
Back to top
View user's profile Send private message
johan



Joined: 06 Sep 2011
Posts: 964

PostPosted: Tue Jan 24, 2017 11:45 am    Post subject: Reply with quote

I've done what you'd like to do on a different brand of microscope. I bought an item like this but for my brand (Nikon labophot): http://www.ebay.co.uk/itm/Polarizing-Assembly-For-AmScope-Microscope-or-Equivalent/272394519036

My scope is also a finite so it works on finites. This comes with 2 components, one part that you open up the scope for to drop into the space between the eyepiece and the nosepiece, and another part that just sits on top of the bottom illumination source. Dropping the part in means you're not adding any distance. It all works very well together indeed.

My advice would be to contact the seller who makes these things and see if they can make or have such a set for your brand and model of scope. The seller goes by the name of optitec2020 - http://www.ebay.co.uk/usr/optitec2020?_trksid=p2047675.l2559 - I am not affiliated in any way.

Good luck
_________________
My extreme-macro.co.uk site, a learning site. Your comments and input there would be gratefully appreciated.
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 -> Beginners Micro All times are GMT - 7 Hours
Page 1 of 1

 
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