Stymied on the application of these

Here you can discuss all microscopy-related accessories and equipment (microtomes, filters...)
Post Reply
Message
Author
apochronaut
Posts: 6272
Joined: Fri May 15, 2015 12:15 am

Stymied on the application of these

#1 Post by apochronaut » Mon May 11, 2020 4:16 pm

I bought a small joblot of old AO parts, mostly due to the fact that I had never seen them before and they would also very useful. For older microscopes, 5 place nosepieces are always useful. I'm pretty sure these parts were used together because I can see a purpose for them but just why that purpose was necessary in whatever their application was /is a mystery. Can anyone shed any light ?

Here is what I know. AO switched from black microscopes to grey microscopes with the introduction of the series 4 and the 50 and 60 student scopes, sometime in the late 50's. On the series 4, at the same time, the nosepieces became fitted with a circular 1 7/8" dovetail, rather than an R.M.S. mounting thread. The latter was a historical vestige, where it was possible to screw one objective into the viewing body or put in a nosepiece if preferred. The series 4 continued to have a black nosepiece, as did the previous AO microscopes. With the introduction of the infinity corrected series 10, the nosepiece was similar from the outside but the possibility of 5 places was added to the lineup and the dovetail was reduced in size to 1 1/2". They were grey.

The nosepiece pictured below is a black 5 position with a 1 1/2" dovetail, clearly from a series 10/20. However it is black and mounted in an auxiliary centering mount, which screws into an R.M.S. thread. It dates from the 10/20 era or from 1961 forward but is designed to fit a microscope that takes a single screwed in objective. A black one. The last A.O. black microscope that received a single objective in the viewing body was the series 5 large research stand, discontinued in 1955.
The condenser that came with it is self illuminated. AO made self illuminated cardioid dark field condensers since the 1920's and continued the concept until the series 110/120 was released around 1980. This is not a DF condenser. It is in fact a Reichert Austria BF condenser marked A= 1.25, factory fitted to the body of an AO self illuminated DF housing. AO and Reichert shared components a lot. A perusal of catalogues from both companies show components from the other factory used where it made economic sense. They consolidated effort since both companies were under one ownership. The condenser dovetail ring on AO series 10/20 condensers was designed to fit over the body of Reichert condensers , so they could be used, when it made sense.

Question is. What microscope/application would require a 5 place centering nosepiece and the level of illumination necessary from a self illuminated 1.25 N.A. oil immersion BF condenser? It uses an 18 watt incandescent bulb. The other question is; what microscope was this used on? Could it have been an Austrian Reichert model, since no AO microscope after 1955 had an R.M.S. thread on the optical tube. An early type of transmitted fluorescence scope has crossed my mind.
Attachments
Parts as found.
Parts as found.
DSC03202 (1280x719).jpg (172.23 KiB) Viewed 2254 times
Grey series 10/20 5 place nosepiece and black 5 place nosepiece mounted into centering intermediary mount.
Grey series 10/20 5 place nosepiece and black 5 place nosepiece mounted into centering intermediary mount.
DSC03205 (1280x719).jpg (153.34 KiB) Viewed 2254 times
Grey and black series 10/20 nosepieces flanking black centering intermediary mount with R.M.S. to optical tube coupling.
Grey and black series 10/20 nosepieces flanking black centering intermediary mount with R.M.S. to optical tube coupling.
DSC03206 (1280x719).jpg (176.49 KiB) Viewed 2254 times
Bottom of AO self illuminated DF condenser right and bottom of AO self illuminated BF condenser left.
Bottom of AO self illuminated DF condenser right and bottom of AO self illuminated BF condenser left.
DSC03204 (1280x719).jpg (174.92 KiB) Viewed 2254 times
AO self illuminated DF condenser right and Reichert 1.25 BF condenser on AO DF housing left.
AO self illuminated DF condenser right and Reichert 1.25 BF condenser on AO DF housing left.
DSC03203 (1280x719).jpg (181.68 KiB) Viewed 2254 times

PeteM
Posts: 2989
Joined: Tue Dec 06, 2016 6:22 am
Location: N. California

Re: Stymied on the application of these

#2 Post by PeteM » Mon May 11, 2020 5:52 pm

Phil, could it have been an attempt with a turret-based polarizing microscope? If the earlier pol scopes were one lens at a time, perhaps someone thought that a turret that could quickly be adjusted to center might have some value? Would likely have to be one of the earliest infinity scopes, if so, because of the added tube length.

And since some chemical/geological specimens are less transparent than cells, maybe the desire for a bit brighter lamp?

Hard to know, but the centering adapter looks to be either little used or of a more recent vintage. Do the knobs suggest it was built by A.O. or someone else?

Hobbyst46
Posts: 4277
Joined: Mon Aug 21, 2017 9:02 pm

Re: Stymied on the application of these

#3 Post by Hobbyst46 » Mon May 11, 2020 7:02 pm

apochronaut wrote:
Mon May 11, 2020 4:16 pm
... An early type of transmitted fluorescence scope has crossed my mind.
Transmitted fluorescence is better done with a darkfield condenser, since it can separate the excitation from emission. In principle, this would hardly be possible with a brightfield condenser.

apochronaut
Posts: 6272
Joined: Fri May 15, 2015 12:15 am

Re: Stymied on the application of these

#4 Post by apochronaut » Mon May 11, 2020 9:51 pm

PeteM wrote:
Mon May 11, 2020 5:52 pm
Phil, could it have been an attempt with a turret-based polarizing microscope? If the earlier pol scopes were one lens at a time, perhaps someone thought that a turret that could quickly be adjusted to center might have some value? Would likely have to be one of the earliest infinity scopes, if so, because of the added tube length.

And since some chemical/geological specimens are less transparent than cells, maybe the desire for a bit brighter lamp?

Hard to know, but the centering adapter looks to be either little used or of a more recent vintage. Do the knobs suggest it was built by A.O. or someone else?
I suppose a polarizing scope is possible. There isn't much evidence that the condenser is a pol condenser, though. Due to the location of the lamp, the polarizer must be in the condenser. Spencer/AO was already making binocular pol microscopes and had been making what they called chemical microscopes and then polarizing microscopes as monoculars, for 35 years prior. Probably their first binocular pol microscope was the Polarstar, which was basically a series 4 fitted with all the bell's and whistles that a polarizing scope should have. It did not have a nosepiece with centering adjustments in the fancy incarnation, so they continued to use the stirrup mounted objectives. There was a cheaper model, which used a non-centering nosepiece.
One thing of note is that in photos 4 and 5 above, the dovetail is reversed between the BF condenser and the DF condenser. The DF condenser is designed to fit into the dovetail of a reversed microscope, where the user faces the front of the stage. The BF condenser is designed to be used on a microscope where the user views from the back, as was the case with microscopes in the past. The series 4 was a transitional instrument . Many of the images of them around and in fact many for sale, have the eyepieces facing to the rear, being or having been used in the traditional manner. The phase wrenches face rearward on them and it wouldn't be surprising for the centering wrenches on the condenser to face rearward too. That wasn't the case with the earliest infinity microscopes. There is also the nagging fact that the centering nosepiece unit pictured above, is designed to thread into an R.M.S. port. Neither the 4 or 10 have that facility and the nosepiece itself is from a 1960's era microscope. However, the Polarstar does have an adapter with an R.M.S. port, so you might be on to something. Perhaps that 5 place nosepiece is from a very early production, when the concept of the series 4 was still vivid, a grey scope with a black nosepiece. There was likely some overlap between the last series 4 production and the early series 10.
Regarding the origins of the parts. The only one that I am unsure of is the centering adapter. All of the parts appear unused. The centering adapter does not appear to be of AO manufacture but it fits the dovetail of the nosepiece like a glove. It does look custom made for this applcation, though.The knurled knobs are unlike anything I have ever seen attached to an AO stand.
Hobbyst46 wrote:
Mon May 11, 2020 7:02 pm
apochronaut wrote:
Mon May 11, 2020 4:16 pm
... An early type of transmitted fluorescence scope has crossed my mind.
Transmitted fluorescence is better done with a darkfield condenser, since it can separate the excitation from emission. In principle, this would hardly be possible with a brightfield condenser.
Yes. DF is used for transmitted fluorescence but also is BF. However, you are correct nonetheless because there is no location in the system to place a barrier filter. It is always possible that the items came from an experimental set up and the barrier filter was placed up inside the housing . There is enough room and it would act as a heat filter . Although the 18 watt bulb is in a ventilated tube, it will still get hot in there. It is only about 1 cm. from the lower condenser lens. It is always possible that the condenser lens is heatproof. The lamp used in the DF version is only a 13 watt.

Post Reply