Bausch & Lomb 4mm 1.00 water immersion objective

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hans
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Bausch & Lomb 4mm 1.00 water immersion objective

#1 Post by hans » Wed Aug 04, 2021 4:53 am

I haven't been able to find any info on this except the attached ad from:
Transactions of the American Microscopical Society, Vol. 44, No. 4 (Oct., 1925), pp. i-viii

And brief mention here:
Molecular Expressions Microscopy Primer: Museum of Microscopy - Bausch & Lomb Slit Ultramicroscope No. 22

The patent date matches 1,557,503 - Optical instrument which covers a general method of parfocalizing objectives (earlier than this one), nothing specific.

Has anyone seen this objective mentioned for general use outside the slit ultramicroscope? Any idea whether it would be corrected for dipping vs. some cover glass thickness?

The glass looks clean focusing through with a stereo microscope except a few scratches and small chips on the front surface. Anything I should look out for as far as determining whether the seals are intact? Would it be a good idea to add some modern sealant before trying it in water?
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apochronaut
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#2 Post by apochronaut » Wed Aug 04, 2021 11:57 am

You see these floating around from time to time. More often, the 26X. There was also one of a higher magnification , 75X or something like that but it was a cover slip corrected w.i. objective, included in their listing of objectives for their research stands. Probably the sealant, if there was any at all would have been a kind of tarry caulking sort of substance. A couple I looked into which were not dipping objectives, Spencer not B & L, seemed to have a metal to metal seal. They hadn't leaked, just had cloudy cement.
If it hasn't leaked by now, I doubt if it will. If it ain't broke, why..... There will be a bit of a build up of some precipitates in the seams , which will probably contribute to sealing. lf it does leak? Those are pretty simple objectives and breaking them down for a cleaning and resealing isn't that difficult. Just observe the alignment marks.
That one looks to be in nice shape.

apochronaut
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#3 Post by apochronaut » Wed Aug 04, 2021 11:58 am

It's interesting that they got 44X out of a 4mm objective with a 160mm tube, exactly the same as Spencer used for about 25 years or so. 44X , then towards the end of the 160mm era, 43X. The same for Spencer's apochromats.
Bausch & Lomb's apochromats however were 4.2mm and varied from 45X to 47.5X

hans
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#4 Post by hans » Wed Aug 04, 2021 5:05 pm

Thanks, I will give it a shot, have you tried one? I was not sure how generally useful it might be since I had only found it mentioned in the context of the slit ultramicroscope. Did some more searching, the 1929 catalog referenced by the Molecular Expressions page on the slit ultramicroscope can be viewed online at https://catalog.hathitrust.org/Record/006148919, table listing the water immersion objectives atttached. Catalog says:
In the Water Immersion Series of objectives for the examination of objects under water, the longest practical working distance and the highest practical numerical aperture have been carefully balanced. They are supplied in three powers 26X (E.F. 7 mm) 44X (E.F. 4 mm) and 81X (E.F. 2.2 mm). Nos. 1036 and 1038 are fitted to mountings for the Slit Ultramicroscope only, being the same in optical properties as Nos. 1037 and 1039 respectively.
That B&L ad is from 1925, same year Richard Zsigmondy received the Nobel Prize in chemistry for study of colloids using slit ultramicroscopes developed with Heinrich Siedentopf of Zeiss. B&L hoping to sell picks and shovels during a gold rush?
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Scarodactyl
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#5 Post by Scarodactyl » Wed Aug 04, 2021 7:38 pm

I have a modern 40x/1.0 water immersion objective and it is great. Water immersion is awfully nice overall.

apochronaut
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#6 Post by apochronaut » Wed Aug 04, 2021 8:44 pm

A couple of things about your objective.
Clearly, there were two versions of it. One specific to the Ultra Microscope, the other corrected for .18 coverslips. B & L didn't have a habit of designating the coverslip correction on the older objectives. You kind of had to look in a manual. Do you know which one you have?
The second thing about B & L is that they had an alliance with Zeiss and a company by the name of Saegmuller , prior to W.W.I . Each company was licensed to sell certain of the others products in their marketplace. B & L had porro prusm binoculars from Zeiss and some microscope stuff. That all went to ratshit during the war but it is possible that it picked up again after. Maybe that microscope design was in fact based on some Zeiss patents.

hans
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#7 Post by hans » Wed Aug 04, 2021 9:13 pm

Not sure which version, this ones looks like a normal objective as far as I can tell but not clear to me what "fitted to mountings for the Slit Ultramicroscope only" from that blurb I quoted would involve. I guess this is probably the normal version, assuming those were more common, slit ultramicroscope is just the first place I found mention of an objective matching the specs. I messaged the seller asking if it was with a microscope and they said no, just in a box of random parts. (It came in the original canister.)

I assume "same in optical properties" would include whether or not they have cover glass correction but didn't see it mentioned for the water immersion objectives. Maybe it is somewhere else in the catalog. I only did a quick search of the to find where the objective was mentioned, haven't read carefully yet.

hans
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#8 Post by hans » Thu Aug 05, 2021 1:08 am

Scarodactyl wrote:
Wed Aug 04, 2021 7:38 pm
I have a modern 40x/1.0 water immersion objective and it is great. Water immersion is awfully nice overall.
Oh yeah I think I just remembered... this monstrosity?

Scarodactyl
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#9 Post by Scarodactyl » Thu Aug 05, 2021 1:12 am

That's the one. Newer design but same mag and na.

hans
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#10 Post by hans » Thu Aug 05, 2021 9:15 am

That 1929 catalog says 0.18 mm cover glass for dry objectives and not critical for homogeneous immersion but nothing about water immersion that I saw. Gave it a quick try with and without cover glass. Not a huge difference but I think no cover is looking a little better. Need to do a more careful comparison -- illumination did not appear to be filling full NA of the objective and camera was awkwardly handheld. Image seems ok, no really obvious problems, but not amazing either. Not sure what to expect from a high-NA non-plan achromat like this. There is some lateral CA, maybe needs the compensating eyepieces which I don't have. Photos are through 10X hyperplane eyepiece with identical processing applied:
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apochronaut
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#11 Post by apochronaut » Thu Aug 05, 2021 1:26 pm

I would give a nod to the dipped image. There is some extra lateral ca and a bit of extra fuzz, even on axis with the cover slip. The ca is magenta outside and sort of a cyan inside, rather than yellow/red that would be more typical with something like an achromat used with a Huygen's eyepiece. It is always possible that the ultramicroscope objective is corrected at different wavelenths for some reason but I guess that the Hyperplane eyepiece has modified corrections over a wider field than a Huygen's, as a result of the effort to flatten the field. They are still correcting eyepieces though.
Typically with achromats of that era, the compensating eyepieces work better than a Huygen's over a fairly narrow diameter off axis but are under corrected outside of that, so have poorer performance at the same field diameter as a Huygens. That's why compens eyepieces are recommended up until roughly the 60's for photography but not visual use with achromats. The photographic field was a narrow rectangle in the middle of the field, so excluded the really poorly undercorrected parts, wheras the eye would see the whole field.

hans
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Re: Bausch & Lomb 4mm 1.00 water immersion objective

#12 Post by hans » Thu Aug 05, 2021 5:23 pm

Yeah after looking at some more stuff, definitely corrected for dipping I think. Changing illumination to get closer to filling the objective aperture and using a test subject that is darker overall with some bright spots (black permanent marker on the frosted end of a slide) makes the spherical aberration haze more obvious. These are somewhat more cropped than the previous ones, a little less than half the FOV diagonally. Same exposure settings and processing, first photo is dipping:
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