MicrobeHunter.com Microscopy Forum

Both of the ones of mine you refer to are images taken with the prism under stress i.e. with a bending moment. Same with jmp's... Yes, quite a large bending moment judging from the fringe density. I was referring to the bias/shift of the fringe pattern away from the center of the beam, which as far...

patta wrote: ↑

Thu Jul 15, 2021 8:36 am

Diffraction grating = phase plate with stripe pattern

Yes, this is a good analogy, I think.

My guess is that UV protection is not the main cause of birefringence with no bending moment applied. But not sure the inherent birefringence, whatever the cause, is a red herring. Many photos posted earlier show quite strong inherent birefringence, maybe not as much as my 1/8" plain TUFFAK bar (whi...

This is what Wiki says: ... McMaster-Carr has three different types advertising resistance to: [impact], [impact, UV], [impact, UV, scratch]. These probably correspond to the three cases mentioned on Wikipedia: UV stabilizer added to the bulk material; additional UV-resistant coating (maybe the 15-...

Agree it is interesting to play around with the optics and attempt to explain the results. I did some simple experiments like this while trying to understand the common formulas related to camera setup. For a change in tube length the resulting change in working distance can be estimated by pretendi...

To make sure I follow: The 10X is normally 4.5 mm from the specimen before you lower it 4.0 mm (5/32 inch) by adding the O-ring. Then to regain focus after adding the O-ring you have to lower the stage by 5.8 mm (1.8 mm more than you lowered the objective) meaning the distance between the objective ...

I would double-check the working distance measurement. Assuming a 160 mm finite microscope (adding a spacer under an infinity-corrected objective shouldn't significantly change the working distance) then I think the 1.8 mm increase is much larger than expected and also going in the wrong direction f...

Cool photo, how long does the process last? You just look around the sample until you find one that happens to be in the middle of it?

It may be worth browsing here: https://www.bulbworks.com/microscope.php Thanks, the advanced search is helpful, this looks like a close match: https://www.bulbworks.com/light-bulbs/MA2201 Unfortunately it seems like 120V bulbs with the double contact bayonet bases are pretty rare, most are 6V or 12...

This thread from a few years ago is why I was thinking the manufacturer might be Kyowa? There is a small made in Japan tag on the back but I couldn't find any info about the model online. The styling on the housings containing the erecting mirrors is identical to a Unitron ZSM I have which is also ...

Why are there no modern systems using this? Is it dimmer than PH masks? From the blog patta linked, sounds like it was just too expensive for not enough practical benefit. I wonder if polymer polarizing filters and waveplates would have helped? I don't know what was available in the ~50s-70s. Then ...

Scarodactyl wrote: ↑

Thu Jul 08, 2021 4:36 am

And impressively neat, too!

Yeah, when I post photos I like to keep them close and narrowly cropped, easier to shuffle all the junk out of the background and maintain an illusion of cleanliness.

What's the wood (?) box in the lower right corner?

perrywespa wrote: ↑

Wed Jul 07, 2021 8:58 pm

I was gifted an old B&L Dynoptic...

Uh oh, more competition for Dynoptic parts... Did yours come with an illuminator? That's the main thing I'm still trying to get set up on mine.

It is kind of a pretty photo with the interference colors. Seller has kindly saved you all the trouble people normally go to crystallizing stuff on slides to get similar photos.

Two patents, overall arrangement doesn't look quite the same as Polanret, but maybe related:

2,516,905 - Microscope with variable polarizing and birefringent means for producing contrast in optical images
2,700,918 - Microscope with variable means for increasing the visibility of optical images

Hm and turning the polarizer would, well that would be a worthwhile experiment. At 45 degrees to the optic axes that is the usual circular polarizer case so I think you end up with left/right-handed circular for direct/diffracted, swapping as you add 90 degree increments to the initial polarization...

That "1/4 wave retarder" part confuses me, since I can't figure out a material for that which is a thin smokey-grey film typically glued into these objectives. I haven't done much searching on how phase objectives are made but seems likely it would need to be a deposition or etching process directl...

If I put a ring of film-1/4-waveplate into the Fourier conjugate plane of an objective, then that just retards the light in that polarized plane. All the other light would basically not be effected. In this case the ring will retard direct-ordinary relative to direct-extraordinary by 1/4 wave. But ...

If one puts two orthogonal quarter waveplates together, would assuming a linear additive effect be valid in making a 1/4 wave retarder regardless of the polarized state of the light? I haven't figured out what the Jones matrices would be. Need to look that up. Have never used Jones calculus and wou...

If one puts two orthogonal quarter waveplates together, would assuming a linear additive effect be valid in making a 1/4 wave retarder regardless of the polarized state of the light? I think no... the 90 degree rotation swaps the fast and slow axes which is equivalent to inverting the sign of the b...

My impression from the fiddling so far is that lateral shifts were not having much effect, while some rotations clearly were. Not sure how plan this really is, it appears to be a simpler design with not as much glass in it compared to the Reichert 1742 10X phase objective for the 400 series, maybe i...

Interesting, would xylene work, or too aggressive? I think 100% ethanol is difficult for private individuals to buy in the US. So is it not possible to actually separate the elements in the cell because of the way they are assembled? Or not possible to correctly realign after?

This book has a lot of interesting stuff in it. The sample is also assumed to rrtard light by about a quarter wave. I haven't yet managed to understand the arguments in Bennett's book for why this is true and the "Molecular Expressions" primer and related manufacturer-specific sites don't really ex...

Thanks for the ID help, while we are on the subject, these were in an AO 10 stand I bought for parts. No markings other than 10X W.F. shown in the photo. I haven't tried them in the Dynoptic, assumed they were for something newer (one of the StereoZooms?) due to the styling, but I see the -22 and -2...

The 3mm 1.40 is bad, internal cloudiness but also sort of a fractured look I have not seen before. Ordinary delamination, or something worse? Seller refunded and didn't want it back so maybe I will try disassembling at some point, my track record with objectives is not good so far, though...

Oops here's the photo:

Since it came from a Dynoptic... Actually no idea what it was on originally. Seller didn't say and was selling a wide variety of surplus, no other B&L stuff. Both the 15x compens and hyperplane eyepieces are very good and will give considerably more relief than the Huygens. ... Some of the Huygens ...

The ATC 2000 production went to India at some point, made in the same facility as some Labomed microscopes. Is the machining a bit coarse? Not like a Microstar objective? The early ones said Made in U.S.A. on the rating plate. The Indian ones say Assembled in U.S.A. The finish on the objectives too...

I believe 1/4 wave is referring to different things in the two contexts. For the phase plates, 1/4 wavelength of optical path difference between direct and diffracted independent of polarization. For example a 250 nm difference in glass thickness of the phase ring would give 125 nm optical path diff...

The parfocality of the two 1.0 N.A. objectives I have is quite different but the w.d. very similar , 250 and 265 microns, measured by bringing the objective in contact with cover slip and then backing off to focus. Yeah seems like parfocality adjustment moving the whole objective together should no...