MicrobeHunter.com Microscopy Forum

Added this one to the collection a few weeks ago, then had some real-life fall on me, so I wasn’t able to really poke around with it until now.

It’s a 1902 B&L scope, and in the case was a set of crystal polarizer and analyzer parts for it.


Imbedded in the parts are two crystals through which the light path passes length-wise.




The polarizer fits into a swing-out condenser housing that has an iris just under the stage, and can be rotated to cross the polls.


The analyzer crystal screws in between the tube and the objective and is threaded to the Royal Society standard. I had to adjust the slide tube to get an image without spherical aberration.
Also, the added length at the objective turns the scope into a potential slide-crusher if the operator is careless.



Time seems to have taken a toll on the crystals but turning the bottom crystal alternates between predominantly red/orange and predominantly green/blue. I had to capture these with my phone, the occuler diameter is ~ 27 mm so I couldn’t adapt the cc camera.

Tylenol 10x? Objective crystal polarizers AO 735 Illuminator




I recall seeing mention of this technique in one of the B&L or Spencer histories on line, but never thought I’d see one much less have one in my collection.

I wasn’t really sure whether to put this post here or in illumination techniques, but I think it fits better here.

Please enjoy,
Jim / Radazz

That is a great find Radazz. Works too. B & L were late to switch their system over to metric. They conformed with regards to the RMS threads on their objectives but maintained inch measurements for the focal length. You can find virtually identical objectives marked in inches 2/3,1/3,1/5,1/6, 1/12 etc. and as 16mm, 8mm, 4mm, 1.8mm, manufactured only shortly after. They also were somewhat persistent in continuing to use the inch sized oculars( 1 1/32") and for good reason. They offered a considerably better field of view. I have no idea why 1 1/32" but had everyone else conformed to that standard for oculars, the fields of view for 50 years, until it was generally possible with better glass formulations to attain W.F. , would have been 50% bigger. It is somewhat similar to the .965 telescope eyepieces compared to 1/1/4".

Very nice microscope.

Thanks, Apo,
And thanks for the info!

Now that's cool! I've been eyeballing polarizing microscopes for years but have yet to snag one (because?) I really don't know much about 'em. So yes, there is interest in this thread, please do keep posting your adventures with it. Love the images.

Thanks KurtM

A 100+ year old working microscope is pretty cool. Congratulations!

Thanks 75
I’m compulsive. If they are not functional I must make them so.

KurtM wrote:Now that's cool! I've been eyeballing polarizing microscopes for years but have yet to snag one (because?) I really don't know much about 'em. So yes, there is interest in this thread, please do keep posting your adventures with it. Love the images.

This one seems to be similarly equipped.
At least it looks like the accessories in the box have crystals in them.
https://www.ebay.com/itm/19th-century-b ... SwW8RbAfn8

Very nice, my B&L is from 1903!

My one has the 3 objective tri-lobe furret and a spencer mechanical stage, but looks like the exact frame, including the odd 27mm occular size.

Can I borrow an idea from this polarizing microscope? it is difficult to find pol accessories for my microscope. Optovars and similar gadgets are rare and expensive, at least for hobby use with only occasional interest in POL microscopy. But I found a thin 10x10 polarizing plastic material (presumably polaroid like) on bay. It is easy to cut circles of it. So, I can place a circle on top of the field diagram, and rotate it at will. I cut another circle, a small one, and insert it into the objective barrel. Will not be exactly perpendicular to the optical axis, but nevertheless.
What do you think? will it work or will there be artifacts?

Hobbyst46 wrote:Can I borrow an idea from this polarizing microscope? it is difficult to find pol accessories for my microscope. Optovars and similar gadgets are rare and expensive, at least for hobby use with only occasional interest in POL microscopy. But I found a thin 10x10 polarizing plastic material (presumably polaroid like) on bay. It is easy to cut circles of it. So, I can place a circle on top of the field diagram, and rotate it at will. I cut another circle, a small one, and insert it into the objective barrel. Will not be exactly perpendicular to the optical axis, but nevertheless.
What do you think? will it work or will there be artifacts?

I’ve played with several different kits and found 2 32mm polarizer disks for around $40 usd.
One of these sits just under the head where it attaches to the limb. Only problem is, while I can easily remove the polarizer from the field lens, I need to disassemble the scope to remove the analyzer disk. So I leave it in all the time. I get good phase contrast with the polarizers in place and uncrossed. Just eats a little light but with a bright scope like the BX40, works just fine.
the stage rotates 200 deg as well, but has no angle reference. I’m doing photography, not chemical analysis, so that’s not a problem either.
Radazz

@Raddaz
Thanks a lot! so "my" idea might work. I would like it for fun, not analysis either. I have a spare 10X objective, inner diameter of about 15mm. To take it of I will just screw the objective out. Worth a try...

There is a kit for Nikon, with a polarizer in a mount that sits on the field lens that comes with an analyzer in a little frame that hangs above the nose piece internally. The actual pol filter fits into a 23mm eyepiece if you pop it out. Easy to scratch it though. If you want to go that route for a monocular microscope, it would be easier to take off for high magnification work.

Thanks Radazz.

Here is a first attempt - a crumpled piece of polarizer in side the 10x objective barrel and another piece from the same $10 sheet on the field aperture. The sample is sand. The eyeview was superb - my photography is not, my apology.
Poor man's Pol?

KurtM wrote:Now that's cool! I've been eyeballing polarizing microscopes for years but have yet to snag one (because?) I really don't know much about 'em. So yes, there is interest in this thread, please do keep posting your adventures with it. Love the images.

I was able to get one like this for less than $200... it works great..

BillT

Hobbyst46 wrote:Thanks Radazz.

Here is a first attempt - a crumpled piece of polarizer in side the 10x objective barrel and another piece from the same $10 sheet on the field aperture. The sample is sand. The eyeview was superb - my photography is not, my apology.
Poor man's Pol?

Any man’s Pol, I’d say. Nice shot!
Are you using a cell phone?
This is exactly how I got started with Pol, and darkfield and Reinberg and GUF, “I wonder if I can...”
Having instant access to the sum total of human knowledge helps a lot.
Radazz

I was able to get one like this for less than $200... it works great..

BillT[/quote]
Beautiful scope, BillT, excellent find!

Radazz wrote:Any man’s Pol, I’d say. Nice shot!
Are you using a cell phone?

Thanks Radazz, Any man's Pol sounds better indeed. Not a cell phone, I am using afocal Canon EOS mirrorless camera, but am trying to improve my
photography.

I am sorry!.. I posted the wrong photo.. I noticed this unit has a turret.. The one I have does not... Here is the correct one...