B&L Phase Contrast Condenser Sliders

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microb
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B&L Phase Contrast Condenser Sliders

#1 Post by microb » Fri Jul 03, 2020 3:38 am

So how does this fit or what condenser is needed?

Thanks.
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BramHuntingNematodes
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Re: B&L Phase Contrast Condenser Sliders

#2 Post by BramHuntingNematodes » Fri Jul 03, 2020 3:45 am

I believe the Balplan, like the earlier B&L phase system with inserts, has a special purpose condenser with a huge slot in it above the iris but below the condenser lens, as well as an additional set of centering screws.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

microb
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Re: B&L Phase Contrast Condenser Sliders

#3 Post by microb » Fri Jul 03, 2020 5:49 am

Anyone have a 31-55-32 or 31-55-31?

What NA condenser could I use in its place if I could get the phase contrast annuli installed?
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apochronaut
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Re: B&L Phase Contrast Condenser Sliders

#4 Post by apochronaut » Fri Jul 03, 2020 12:36 pm

Those insert annuli are for the L.W.D. phase system. It does use the standard phase objectives, so it is probably only medium working distance.

I have the Balplan phase system in it's entirety. It is a good system. I am not sure what other condenser would duplicate the focal point of that phase condenser. They are dsigned to establish the correct conjugate plane for phase. Problem is too, the Balplan has such a unique dovetail, you would need to pilfer that from a derelict condenser.
I have played with phase condensers in the AO system because they use a thread in condenser lens pack in the phase carousel. I tried 7 condensers with a dark phase planachro system and various other phase objectives from either AO or Reichert systems. I couldn't get phase at all with some of them. One of the high N.A. achromat/aplanats gave interesting results when oiled , with a specific objective( kind of a D.I.C. in DF) but mostly it was pretty apparent that to get consistent phase results within the design parameters of the objectives, the condenser needs to be the one engineered for the job, or one very similar. In this regard, AO produced 2 standard working distance phase condensers between 1965 or so and 2002. Both work well with all of the objectives made during that period. There might be a slight difference where the earlier objectives might be better with the earlier condenser but that is hard to tell due to other possible contributing factors.

microb
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Re: B&L Phase Contrast Condenser Sliders

#5 Post by microb » Fri Jul 03, 2020 2:26 pm

apochronaut wrote:
Fri Jul 03, 2020 12:36 pm
Those insert annuli are for the L.W.D. phase system. It does use the standard phase objectives, so it is probably only medium working distance.

I have the Balplan phase system in it's entirety. It is a good system. I am not sure what other condenser would duplicate the focal point of that phase condenser. They are dsigned to establish the correct conjugate plane for phase. Problem is too, the Balplan has such a unique dovetail, you would need to pilfer that from a derelict condenser.
I have played with phase condensers in the AO system because they use a thread in condenser lens pack in the phase carousel. I tried 7 condensers with a dark phase planachro system and various other phase objectives from either AO or Reichert systems. I couldn't get phase at all with some of them. One of the high N.A. achromat/aplanats gave interesting results when oiled , with a specific objective( kind of a D.I.C. in DF) but mostly it was pretty apparent that to get consistent phase results within the design parameters of the objectives, the condenser needs to be the one engineered for the job, or one very similar. In this regard, AO produced 2 standard working distance phase condensers between 1965 or so and 2002. Both work well with all of the objectives made during that period. There might be a slight difference where the earlier objectives might be better with the earlier condenser but that is hard to tell due to other possible contributing factors.
What is the distance the B&L condenser holds from the specimen when getting a phase contrast image? How many lenses or condenser type is the Balpan phase condenser?

From what you are saying, did you get an AO condenser to work with the B&L Balplan phase objectives?

microb
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Re: B&L Phase Contrast Condenser Sliders

#6 Post by microb » Fri Jul 03, 2020 2:42 pm

I'm trying to expand out from the citations and references sections:

https://patents.google.com/patent/US2565419A/en
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apochronaut
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Re: B&L Phase Contrast Condenser Sliders

#7 Post by apochronaut » Fri Jul 03, 2020 10:19 pm

I'll do some checking on Sunday or Monday for you.Thurs through Sat. are always committed tmes for me and except for occasional glances, I'm not really able to do much in the way of hands on assesment or quality referencing for the forum.

microb
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Re: B&L Phase Contrast Condenser Sliders

#8 Post by microb » Sat Jul 04, 2020 7:02 am

apochronaut wrote:
Fri Jul 03, 2020 10:19 pm
I'll do some checking on Sunday or Monday for you.Thurs through Sat. are always committed tmes for me and except for occasional glances, I'm not really able to do much in the way of hands on assesment or quality referencing for the forum.
Awesome. Thanks.

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Re: B&L Phase Contrast Condenser Sliders

#9 Post by apochronaut » Sun Jul 05, 2020 5:54 pm

The Balplan phase condenser is marked abbe 1.25 N.A. Unlike the other Balplan condensers, which require that you remove the dovetail and enter the condenser from below, this one is split and the top lens threads off. The optics are different than the abbe/aplanat 1.25. The top lens is wider; 16mm. There is also a negative lens in the bottom, below the annuli, fitted as part of the dovetail section.

I will measure the focal length a little later.

microb
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Re: B&L Phase Contrast Condenser Sliders

#10 Post by microb » Sun Jul 05, 2020 6:16 pm

apochronaut wrote:
Sun Jul 05, 2020 5:54 pm
The Balplan phase condenser is marked abbe 1.25 N.A. Unlike the other Balplan condensers, which require that you remove the dovetail and enter the condenser from below, this one is split and the top lens threads off. The optics are different than the abbe/aplanat 1.25. The top lens is wider; 16mm. There is also a negative lens in the bottom, below the annuli, fitted as part of the dovetail section.

I will measure the focal length a little later.
Since it is an Abbe condenser, does that mean the top 16mm lens threads off and there is another lens below it. So three lens if that below the annuli lens is counted as well? Or just two lenses, a 16mm half-ball and a negative lens?

Next weekend, I'll set up an optical track and try to get reproduce the lamp conjugate image: https://youtu.be/60_jgZtyR6U?t=2347 (cool reference video mentioned in this thread viewtopic.php?f=25&t=9648&p=83493&hilit ... R6U#p83493)

apochronaut
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Re: B&L Phase Contrast Condenser Sliders

#11 Post by apochronaut » Sun Jul 05, 2020 8:05 pm

The negative lens below the annuli, is not something that would normally be there, if it was not a phase condenser. It is a 2 lens abbe, possibly aspheric, or should I say likely.

The third lens is something I also have seen on the AO series 10 phase set up. The 10 does not have a true Koehler illumination system, although it has a field diaphragm with the better illuminators. It uses an aux. negative lens under the phase condenser to alter the existing illumination sytem to one that can mimic a Koehler system for the purpose of establishing conjugate planes of focus. When the same condenser is used in a series 20, an otherwise identical microscope with only an illuminator difference which does have a Koehler system; that lens is removed.

Likely, the Balplan has a similar illuminator organization. I do not have access to any information about setting up phase on the 100 watt Balplan but it would surprise me if the information did not recommend removal of the negative lens under the condenser.

apochronaut
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Re: B&L Phase Contrast Condenser Sliders

#12 Post by apochronaut » Tue Jul 07, 2020 9:29 pm

microb wrote:
Fri Jul 03, 2020 2:26 pm
apochronaut wrote:
Fri Jul 03, 2020 12:36 pm
Those insert annuli are for the L.W.D. phase system. It does use the standard phase objectives, so it is probably only medium working distance.

I have the Balplan phase system in it's entirety. It is a good system. I am not sure what other condenser would duplicate the focal point of that phase condenser. They are dsigned to establish the correct conjugate plane for phase. Problem is too, the Balplan has such a unique dovetail, you would need to pilfer that from a derelict condenser.
I have played with phase condensers in the AO system because they use a thread in condenser lens pack in the phase carousel. I tried 7 condensers with a dark phase planachro system and various other phase objectives from either AO or Reichert systems. I couldn't get phase at all with some of them. One of the high N.A. achromat/aplanats gave interesting results when oiled , with a specific objective( kind of a D.I.C. in DF) but mostly it was pretty apparent that to get consistent phase results within the design parameters of the objectives, the condenser needs to be the one engineered for the job, or one very similar. In this regard, AO produced 2 standard working distance phase condensers between 1965 or so and 2002. Both work well with all of the objectives made during that period. There might be a slight difference where the earlier objectives might be better with the earlier condenser but that is hard to tell due to other possible contributing factors.
What is the distance the B&L condenser holds from the specimen when getting a phase contrast image? How many lenses or condenser type is the Balpan phase condenser?

From what you are saying, did you get an AO condenser to work with the B&L Balplan phase objectives?
I never tried to use an AO phase condenser with a Balplan. AO produced a lot of different phase systems, so there is an unusual amount of almost modular stuff to work with in the AO stable. The Balplan phase system is plainer and more straightforward. The components are very direct and work well. The condenser nicely made.

I did do some measurements for you. The Balplan Abbe 1.25 N.A. phase condenser has a focal length to achieve Koehler illumination of right around 500um. I got about 28um more but .5 mm plus a bit should do. The only other Balplan BF condensers I have are the flip top 1.25 abbe and the 1.25 3 lens aplanat. I only tested the aplanat but it would be surprising if the abbe 1.25 for BF, which I don't have or the flip top abbe were much different. The aplanat focuses at 300um.
The back focal plane is about 5mm for the phase condenser and that of the aplanat is about 3mm.


The lenses in the phase condenser are very broad. : 15mm for the top lens and 30mm for the bottom. This a technique used also by PZO, where the special purpose condensers had very broad lenses. This provides a greater area of well corrected on axis glass, lessening peripheral aberrations. It is possible that the condenser is aspheric but I have no evidence for that. My guess is that B & L used a broad 2 lens abbe at the start for achromat phase and stuck with what worked. Engineering an aplanat for phase , probably wasn't on their immediate list of to do's.

microb
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Re: B&L Phase Contrast Condenser Sliders

#13 Post by microb » Wed Jul 08, 2020 3:17 am

So I'm going through parts, and I have one of these B&L .7NA condensers. I don't know if that gets me anywhere if I test with a phase annulus.
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apochronaut
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Re: B&L Phase Contrast Condenser Sliders

#14 Post by apochronaut » Wed Jul 08, 2020 12:57 pm

Maybe for the insert you have it might work. That is for the 160mm Dyna series. What are the dimensions of that insert? I have a condenser from a Flat Field Dyna series here that has a slider. The slider has a lens on one side and an open hole on the other. I assume the open hole is for higher power objectives and the lens is an aux. condenser for lower power ones. It's a 1.30 abbe fitted with an integrated blue filter and iris but I also have one without the iris.
The mount was designed to take quick change condensers, that have the correct round dovetail. You loosen two elongated thumbscrews and the condenser and iris pop off. Presumably, there were dovetailed .70 like yours and maybe the 1.4 N.A. achromat/aplanat. All the ones I have seen of those have a sleeve.
Bausch & Lomb was not a condenser focused company, at least not in terms of an array of them. They made only what was required. They never even made an achromat for the Balplan, which probably was an on hold decision pending the sales of the Flat Field Apochromats. As it turned out, those were discontinued sometime after 1977. They were terribly expensive objectives.
The cat. 31-55-13 1.25 abbe aplanat is one hell of a condenser, though. In use, when comparing it to the 1.25 abbe phase condenser for BF, it gives noticeably brighter, more contrasty and even more finely resolved imaging. Obviously that wouldn't be true for phase. It is a very tightly packed 3 element aplanat, with a small diameter top lens and all of the lenses stuffed into about 3/4 inch of depth.

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Re: B&L Phase Contrast Condenser Sliders

#15 Post by microb » Wed Jul 08, 2020 5:30 pm

Wait, am I missing a second interior lens here?

It just has the top one and bunch of unused internal threading for something.
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microb
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Re: B&L Phase Contrast Condenser Sliders

#16 Post by microb » Wed Jul 08, 2020 5:34 pm

apochronaut wrote:
Wed Jul 08, 2020 12:57 pm
Maybe for the insert you have it might work. That is for the 160mm Dyna series. What are the dimensions of that insert?
Below the iris is a 35mm <1.8 mm high filter disc slot.

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Re: B&L Phase Contrast Condenser Sliders

#17 Post by apochronaut » Wed Jul 08, 2020 6:10 pm

microb wrote:
Wed Jul 08, 2020 5:30 pm
Wait, am I missing a second interior lens here?

It just has the top one and bunch of unused internal threading for something.
Yes, there is supposed to be a second lens in there and a retainer. My question was about your 20X annulus slider. I am wondering if it might be the same dimensions as the slider in the 1.30 condenser, I described above. It might work for you, if the dimensions are right.

microb
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Re: B&L Phase Contrast Condenser Sliders

#18 Post by microb » Wed Jul 08, 2020 6:51 pm

apochronaut wrote:
Wed Jul 08, 2020 6:10 pm
microb wrote:
Wed Jul 08, 2020 5:30 pm
Wait, am I missing a second interior lens here?

It just has the top one and bunch of unused internal threading for something.
Yes, there is supposed to be a second lens in there and a retainer. My question was about your 20X annulus slider. I am wondering if it might be the same dimensions as the slider in the 1.30 condenser, I described above. It might work for you, if the dimensions are right.
So it is missing a lens. Getting parts isn't easy. It would be great to have your help on this.

If I know the masking dimensions that work, I could make some new custom annuli if these sliders here are not a fit.
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apochronaut
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Re: B&L Phase Contrast Condenser Sliders

#19 Post by apochronaut » Wed Jul 08, 2020 10:05 pm

The slider on that Dyna condenser mount is 42mm x just a little over 9.5mm deep, so not very far off. The bottom of the channel is actually provided by several cylinder head screws, so they can be backed off to provide more depth.

The open port itself is 33.5mm and it has a lip to receive a filter or perhaps your annulus?

Where a problem might exist is the rear focal length of the condenser. It sits 27mm from the filter bed but that might be o.k. for the L.W.D. condenser.

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