Bertrand Lens

Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
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microb
Posts: 154
Joined: Wed Mar 27, 2019 6:39 am

Bertrand Lens

#1 Post by microb » Sat Sep 14, 2019 3:47 am

Hi,

I would like to find easy to follow procedures with the simplest slides for example, and/or calibration targets to test a Bertrand lens set up for petrographic usage.

I have a granite thin section slide, polarizers, DIC, but none of the well known compensators. What do people in the field use as the simplest set up? What would be a good test? Could one for example focus on a polarized optic filter set up in some particular way and get some interesting Fourier patterns? What's a good reproducible test?

Any other usages for the same set up, please let me know.

Thanks in advance.

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RobBerdan
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Re: Bertrand Lens

#2 Post by RobBerdan » Mon Jan 20, 2020 5:56 am

I have a Bertrand lens in my Unitron Polarizing microscope. To use it I need to use the 40X objective- doesn't work with the other powers. The easiest sample for testing is to put a thin slice of mica where the slide would go. You may have to remove the eye piece to see the interference pattern and be sure the bertrand lens is inserted, on my scope I turn a knob.

To read more see my article: https://www.canadiannaturephotographer. ... light.html
Aslo get a hold of some minerolgy books on polarizing microscopy I have several references at the end of my article. Your interefence pattern for mica should look like the picture I embedded below. It will produce a biaxial interference pattern

The best book on the subject of Polarizing microscopy I have in my library is "Essentials of Polarized Light Microscopy and Ancillary Techniques by John Gustav Delly" - unfortunately the book costs about $300 US. I have asked McCrone if they would consider selling an ebook or PDF version, but they never replied. I purchased the book, don't regret it, but I do wish the cost would be significantly lower. One Amazon https://www.amazon.ca/Essentials-Polari ... 0692979476 it costs $400 Canadian, on the Mccrone site it cost about $300 US though they offered me a small educational discount - but I think it is the most expensive book I have ever purchased. If you do a lot of polarizing microscopy it might be worth the investment - it was for me.
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interference_pattern_DSC7184.jpg
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