Introduction of Apochromat

[apochromat]

Hello my name is Michael and I work for the oldest existing microscope maker in the world as a scientist. I am a trained biologist (protozoologist) and I started with microscopy 45 years ago as a hobby. I still love my Photomicroscope III but for my actual investigations of protists I use a JENAVAL which I also adore and think the JENA- 250 CF optics are still among the best ever devised until now.
Thanks
Michael

[apochronaut]

Welcome from Carl Zeiss. Something to ponder. Charles Spencer published his first catalogue in 1838. Spencer became part of American Optiical in 1931. Spencer/AO began priducing infinity corrected optical microscopes in 1961. In 1962, Spencer/AO purchased Carl Reichert and by 1971 Reichert too were mfg. infinity corrected microscopes. In 1985 Spencer/AO/Reichert became part of Cambridge Instruments. In 1991 Cambridge Instruments merged with Wild-Leitz to form the new entity, Leica Microsystems. Leica's Delta infinity corrected optical system used between 1991 and 1997 is a slightly tweaked version of the Spencer/AO/Reichert infinity system. The subsequent HCX and HC systems are further refinements which can trace their heritage back to Charles Spencer's 1838 optician work using the white sand and eventually fluorspar found in the lower Great Lakes basin.

[Wes]

Hello Michael and welcome to the forum. It would be of great interest to me as Phomi III user (and others I am sure) if you show us your scopes and I am looking forward to seeing the protists that you have and will document in the future.

Best regards
Wes

[apochromat]

Dear Apochronaut,
the infinity optical concept was already described by Ernst Abbe in 1873 as "Zerlegung des Mikroskopobjectivs in Fernrohr und Lupe". The first infinity corrected microscope objectives have been in use since the early 1930ies, merely for metallography. Prof. Hans Boegehold at Carl Zeiss (who is also the father of the flat- field correction and plan- apochromats) and Ernst Lihotzky from E. LEITZ, Wetzlar almost simultaneously devised the first infinity corrected objectives for reflected light brightfield (1931/ 1932) and both companies since then make "Epi"- objectives with an infinity correction. The ULTRAPHOT M with a full set of infinity corrected objectives for reflected light brightfield and darkfield was introduced in 1938. Another often used option was to create infinity "spaces" in the beam path with "Korrektionsgliedern", as done in transmitted light polarizing microscopes by R. WINKEL since the early 1920ies. Later such approaches where called "Telan"- lens systems by Kurt Michel at CARL ZEISS, Göttingen.

The first biological infinity corrected microscope was a photomicroscope developed by Kurt Michel in Jena in 1938, that never came to market. Only one picture is existing and a letter of August Köhler from 3rd of april 1947 discussing this matter. Its shape was later copied by Otto Ursinus and made as MIKROPHOT by ROW (Rathenower Optische Werke). The first commercially available high- end microscopes for transmitted light (brightfield, phase contrast and DIC, epi-fluorescence) where the UNIVAR (C. Reichert, Wien, 1972) and the AXIOMAT from CARL ZEISS, Oberkochen following 6 months later in 1973. The first infinity corrected system with an accessible intermediate image of the back focal plane (to add Ph- rings etc.) also having full preservation of the vibration direction of the polarized light was the PERAVAL interphako from VEB Carl Zeiss, JENA in 1967 (Hermann Beyer, Günther Schöppe, Rainer Danz, Horst Riesenberg). The same technology was also used later in the JENAVAL contrast (introduced in spring 1982).

The apochromatic colour correction was invented by Ernst Abbe in 1886 using natural calcium fluoride and new glass types from Otto Schott. Abbe himself learned to mountain climb and from this large calcium fluoride finding in the suisse Oltschi Alp mountains all apochromats from ZEISS where made until the 1920ies. The first microscope objective with only one fluoride lens element within the optical design was invented in 1893 by Rudolf Winkel in Göttingen (which is still the ZEISS- factory for the high-end microscope objectives). Rudolf Winkel called it "Fluorite" objective and it became enormously popular fast. The first anti-stray-light coated fluorite objectives where made after WW II by R. WINKEL GmbH (fully owned by ZEISS since 1911) in 1953 and called the NEOFLUAR since then.

[apochromat]

I depict the microscope here. Nobody knows where it is gone (maybe taken by the American troops or later the Russians after the almost complete dismantling of Carl Zeiss, Jena in 1945). Source: Kurt Michel: Die Mikrophotographie, Berlin und Wien 1962. It has the pancratic condenser from the LUMIPAN (patented in 1933). Due to its beampath, infinity correction was beneficial here. The objectives where calculated by Hans Boegehold. According to Dr. Michel this prototype was larger compared to the LUMIPAN stand. It also had an interchangeable nosepiece. The objective threads where also not RMS but M25.

Maybe this post should be in a different category, but I am new here. So I apologize for posting it in the wrong place.

Thanks
Michael

[apochronaut]

Dear Apochronaut,
the infinity optical concept was already described by Ernst Abbe in 1873 as "Zerlegung des Mikroskopobjectivs in Fernrohr und Lupe". The first infinity corrected microscope objectives have been in use since the early 1930ies, merely for metallography. Prof. Hans Boegehold at Carl Zeiss (who is also the father of the flat- field correction and plan- apochromats) and Ernst Lihotzky from E. LEITZ, Wetzlar almost simultaneously devised the first infinity corrected objectives for reflected light brightfield (1931/ 1932) and both companies since then make "Epi"- objectives with an infinity correction. The ULTRAPHOT M with a full set of infinity corrected objectives for reflected light brightfield and darkfield was introduced in 1938. Another often used option was to create infinity "spaces" in the beam path with "Korrektionsgliedern", as done in transmitted light polarizing microscopes by R. WINKEL since the early 1920ies. Later such approaches where called "Telan"- lens systems by Kurt Michel at CARL ZEISS, Göttingen.

The first biological infinity corrected microscope was a photomicroscope developed by Kurt Michel in Jena in 1938, that never came to market. Only one picture is existing and a letter of August Köhler from 3rd of april 1947 discussing this matter. Its shape was later copied by Otto Ursinus and made as MIKROPHOT by ROW (Rathenower Optische Werke). The first commercially available high- end microscopes for transmitted light (brightfield, phase contrast and DIC, epi-fluorescence) where the UNIVAR (C. Reichert, Wien, 1972) and the AXIOMAT from CARL ZEISS, Oberkochen following 6 months later in 1973. The first infinity corrected system with full preservation of the vibration direction of the polarized light was the PERAVAL interphako from VEB Carl Zeiss, JENA in 1967 (Hermann Beyer, Günther Schöppe, Rainer Danz, Horst Riesenberg). The same technology was also used later in the JENAVAL contrast (introduced in spring 1982).

The apochromatic colour correction was invented by Ernst Abbe in 1886 using natural calcium fluoride and new glass types from Otto Schott. Abbe himself learned to mountain climb and from this large calcium fluoride finding in the suisse Oltschi Alp mountains all apochromats from ZEISS where made until the 1920ies. The first microscope objective with only one fluoride lens element within the optical design was invented in 1893 by Rudolf Winkel in Göttingen (which is still the ZEISS- factory for the high-end microscope objectives). Rudolf Winkel called it "Fluorite" objective and it became enormously popular fast. The first anti-stray-light coated fluorite objectives where made after WW II by R. WINKEL GmbH (fully owned by ZEISS since 1911) in 1953 and called the NEOFLUAR since then.

My apologies for offending you.

[apochromat]

Hello Apochronaut,

I was not offended by you at all and everything is fine. Anyhow, if my writing was a bit without "any circles" I apologize here also.

I just wrote a detailed answer. Here in Europe the history of "AO"/ American Optical is not so prominent. Even that they bought the CARL REICHERT, Wien company in the nineteenfifties from I think the daughters of Otto Reichert is not a well known thing. The original building of the C. REICHERT company in the Hernalser Hauptstrasse is now a grocery and some parts of the old factory are still operated by LEICA Microsystems where the ultra microtomes are made until now. The funny thing is, that this building looks almost similar to the older parts of the ZEISS factory in Göttingen. Buildings with large windows and very thick floors, supported by massive concrete columns for the heavy machines etc.

I have included an image showing the old entrance of the R. WINKEL GmbH (since long part of CARL ZEISS) with its famous logo depicting the fact that Rudolf Winkel was a world known optician specialized in crystal optics of all kinds. The crystallographic product range was quite impressive, going from metal polishing machine, and crystal splitting instruments to world-leading polarizing microscopes and polarimeters.


So if you can share details here it would be most welcome. I only knew that AO also invented the first greenough stereo microscope with a zoom and that these instruments sold in very large numbers. In general the history of the American microscope makers would be very interesting for me.

Take care
Michael

[Sabatini]

Fantastic!!
Thank you and welcome

[apochronaut]

Hello Apochronaut,

I was not offended by you at all and everything is fine. Anyhow, if my writing was a bit without "any circles" I apologize here also.

I just wrote a detailed answer. Here in Europe the history of "AO"/ American Optical is not so prominent. Even that they bought the CARL REICHERT, Wien company in the nineteenfifties from I think the daughters of Otto Reichert is not a well known thing. The original building of the C. REICHERT company in the Hernalser Hauptstrasse is now a grocery and some parts of the old factory are still operated by LEICA Microsystems where the ultra microtomes are made until now. The funny thing is, that this building looks almost similar to the older parts of the ZEISS factory in Göttingen. Large windows with thick ceilings for the heavy machines etc.

I have included an image showing the old entrance of the R. WINKEL GmbH with its famous logo depicting the fact that Rudolf Winkel was a world known optician specialized in crystal optics of all kinds.


So if you can share details here it would be most welcome. I only knew that AO also invented the first greenough stereo microscope with a zoom and that these instruments sold in very large numbers. In general the history of the American microscope makers would be very interesting for me.

Take care
Michael

AO bought Reichert in 1962. They , like a few other companies had been commercially manufacturing. infinity corrected metallographs and vertically illuminated microscopes since the 1940's but also introduced infinity corrected diascopic microscopes in 1961, bringing the concept to Reichert, where they influenced the development of the Univar and Poly series of microscopes. AO already had an 18 watt infinity corrected lab microscope with phase, transmitted fluorescence and photo capability by the mid- 60's, assing a 100 watt infinity corrected model 20 stand with fuller features, including dark, bright and B-Minus phase contrast, high resolution DF, epi fluorescence, transmitted fluorescence and photo capability, with a 19mm plan f.o.v. by 1967 . D.I.C. was added in the 70's, as well as the unique Polanret system. The first generation AO infinity corrected microscopes, unlike the Univar and the Axiomat were affordable. Axiomats were discontinued in 1985 because no one could afford the 6 figure price tag. By then, the much cheaper but equally capable AO/Reichert Polyvar commanded the market.

Regarding Abbe's innovative use of Calcium Fluoride in 1886.
https://books.google.ca/books?id=AfMVAA ... te&f=false

[apochromat]

Hello apochronaut,
very interesting. At least that explains one or two things to me: I have seen one phase contrast image of living rat carcinoma cells from that period taken with an AO phase contrast microscope, that was really far better than most other images taken at that time. Did they also have apochromatic Ph objectives in the earlier days?

Regarding the apochromats, another interesting booklet that is still fairly easy to get, was published in 1936 by ZEISS to commemorate the 50th anniversary of the apochromats. This puplication was written by Moritz von Rohr (the head of the optical design department of ZEISS) in German and English. Moritz von Rohr was married to an American lady. The little book was issued in very large numbers I depict it below.



Thanks
Michael

[MicroBob]

Hi Michael,
welcome to the forum! Your Zeiss know how will for sure be valued here and a lot of interesting topics are discussed here too.

The rounded nose piece of the 1938 Photomicroscope look similar to the later Zeiss Jena NU nose piece.

BTW: Do you happen to have information on the buyer of the first Zeiss Microscope and later the first compound microscope from Zeiss, Hermann Schacht?

Bob

[apochromat]

Hi Michael,
welcome to the forum! Your Zeiss know how will for sure be valued here and a lot of interesting topics are discussed here too.

The rounded nose piece of the 1938 Photomicroscope look similar to the later Zeiss Jena NU nose piece.

BTW: Do you happen to have information on the buyer of the first Zeiss Microscope and later the first compound microscope from Zeiss, Hermann Schacht?

Bob

I have send you a PM on that.

[apochronaut]

Charles Spencer using fluorite lenses twenty years prior to Abbe , achieved numerical aperture angles that won the 1878 Paris Exposition. By this time , Zeiss had finaly realized the value of a condenser giving forth the humble Abbe condenser, one forever beloved by every Chinese microscope purveyor. Ross had produced an achromat condenser 21 years prior.
Yes. I have seen early Zeiss apochromats. There is a thread regarding them on this forum. Was it lousy cement or just lousy fluorite? It was such a challenge producing fluorite influenced lenses in the early days because you had to be sure that you weren't putting the cart before the horse. You had to have excellent pure fluorite and had to be able to discern that, otherwise the advertising was mute.
I have a Spencer apochromat from about 1895, still performing to it's peak. Do you have any old Zeiss apochromats that still work?

[apochromat]

Hello Apochronaut,
interesting what you wrote about Spencer. It is well known that earlier opticians practically figured out that the use of a certain material, be it special glasses or natural crystals, e.g. CaF2, would improve the image quality. Famous Joseph Fraunhofer worked here very early. Also it was not Abbe who practically figured out that front lenses with a certain dimension (later defined by Abbe as numerical aperture) would improve the detecteability of finer structures. That discovery happened several times in England, France and Italy and it is yet not known who was the first. But at that time nobody knew why such front lenses would result in what later was called a better resolution nor where makers able to make such objectives in a repoduceable way. And here it is where Abbe comes into play. Because he was the first to develop the theoretical tools for analysing and describing the image aberrations properly and explaining them and concluding from that what had to be improved by inventing the needed technologies. That is why the making of the first scientifically fully calculated microscope objectives (an achromat series) by Ernst Abbe at Carl Zeiss, Jena in 1868 is regarded as the birth of the scientific microscope making. That already happened only two years after Abbe joined the ZEISS company.
And in 1873 Ernst Abbe was able to explain the image formation in the microscope.
Yes, I have access to old apochromats, also the ones used by Robert Koch. But I do not own nor collect such things. I must say that they all still work flawless and I am surprised of the very high contour contrast in the image center. In the early days it was nevertheless happening that some of the glass materials became hygroscopic. And such objectives will become milky. That was changed in the production process. The CaF2 used by Abbe was natural and it was also mentioned in the old price lists that a certain amount of inclusions is nothing to bother about. Abbe always said "optics is to look through it not at it". The optical cement of that times was canada balsam and aside from getting yellowish it is still a very stable and favourable optical matter, that does not tend to cause delamination.
BTW what is lousy fluoride?
The usefulness of better corrected condensers for a straylight- free imaging of aperture stop became important when Abbe devised his large illumination apparatus with oblique illumination. Also with the advent of a field stop the condenser aberrations became more important. Especially with the invention of August Köhler´s famous illumination in 1893. August Köhler was our scientific head for more than 50 years until his death in 1948. It´s a shame that his highly ditactically and beautifully illustrated book contributions to microscopy are not well known as during WW II whole editions from the publishing houses got lost in the bombings of the German cities.

All the best
Michael

[Scarodactyl]

Woe, what a fascinating thread!

I only knew that AO also invented the first greenough stereo microscope with a zoom and that these instruments sold in very large numbers. In general the history of the American microscope makers would be very interesting for me.

I'm past my depth on the other stuff, but as a minor point it was the other american microscope maker, bausch and lomb, who did the stereozoom series. AO did have a lot of success with the cycloptic shortly before then (I have heard it referred to as the first truly commercially successful stereo) but that's a stepmag CMO system. B&L and AO are easy to mix up on the stereo side, especially since they got mashed into one compaby later on.

I am also very interested in the cf250 system. The other day on eBay I saw objectives thst I think were cf250 labelled dik but don't think I've ever seen a Jena epi DIC system. The west zeiss epi DIC is great but the common delam is a bit of a bummer.

[apochronaut]

Did they also have apochromatic Ph objectives in the earlier days?
Thanks
Michael

No, not catalogued anyway but I have at least one uncatalogued phase objective from the 50's. A dark H, which produces a kind of DF/Phase hybrid. AO, like many other companies, did produce custom items sometimes, so the possibility exists that there were U.S.made ph apochromats. In the achromats there was a wide range of phase types, Dark, Bright, B-Minus and very early on A +Plus.
Production costs in the U.S. were very high compared to Japan and even Germany, right up to the time of reunification, with the differential being much greater the farther one goes back. U.S. products were also locked out of many markets due to trade barriers. Japan is notorious in that regard.
Austria had one of the most depressed economies in Western Europe after the war and did not have the conditions to grow early on , due 10 years of milking by the U.S.S.R. A.O.'s acquisition of Reichert, a skilled but antiquated company by 1962, allowed them to turn over certain expensive projeçts to a qualified sister company with much cheaper labour costs, so the higher end systems and optical components were produced there, when possible. Fluorite and apochromat phase contrast systems were part of that plan. 10 years after the acquisition , Reichert was fully on it's way to being a modern factory producing an ever developing infinity corrected family of microscopes. They used both the AO's original 34mm parfocal infinity corrected optical system from 1961 and the 45mm parfocal infinity optical system launched with the Univar about 10 years later.

Here is a picture of a group of AO apochromats. From the left.
1) made from about 1905 until maybe W.W.I 160mm tube 10X .30
2) made from the early 20's until 1955. 160mm tube 44X .95 with correction collar. These were gold plated for 30 years.
3) c. 1965 made for the series 10/20. infinity corrected. 43X .80 with correction collar
4) c.1985 planapo . made for the series 100/110/120. infinity corrected 40X .80

Throughout most of the history of apochromat mfg., it was always a problem achieving apochromat colour correction through the practice of using correcting oculars, such as were used with achromats. It was impossible to correct for colour, spherical and other aberrations equivalently. This was overcome by overcorrecting in the objective to achieve the minimum corrections required for spherical aberration, while allowing other aberrations such as ca to be overcorrected. By using compensating oculars, the ca overcorrection could be reduced to that required. In otherwords, different eyepieces were required for achromats and apochromats. This is no longer the case. Modern apochromats can be brought to the same level of correction as the achromats, thus they can use the same eyepieces. When did this happen?
Objective #3 from c.1965 is not only probably the first infinity corrected, cover slip corrected apochromat made but also can be used with the same W.F. ( 19mm) correcting eyepieces as is used with the achromats. It is a very early apochromat with that feature.

[apochromat]

Dear apochronaut,

that is really cool stuff and thank You very much for sharing this here. You can be proud of such a heritage of fine microscope optics made in the U.S.A.!

C. REICHERT, Wien always had a very high reputation in the 1980ies in Germany, with prices higher than Carl ZEISS, Oberkochen. They just did not have a strong sales force (W. Pabisch) etc. And sadly so, I think also the relationsship between the US company and the Austrian part was or is not known in Europe.
Apochromats had a non- flattened image. That is why Prof. Hans Boegehold spend a lot of his lifetime to deal with exactly what you mentioned. One result was the development of field- flattening photo projectives together with Prof. August Köhler, called the "Homale" in 1922. He also developed apochromats that had the same CVD (chromatic aberration of the magnification) as the achromat- types. The reference article here is depicted below.

After WW II Ernst LEITZ, Wetzlar was the first to reintroduce apochromats (~ 1955, the fat georgeous objectives for the Heine- Ph) with the same CVD (chromatic aberration of the magnification) as all other objectives. CARL ZEISS did that shortly thereafter with the advent of the W- Stativ (nothing to write home about optically in phase contrast, but an engineering masterpiece; not produced in Göttingen, but Oberkochen), but especially in 1961 with the introduction of their famous three apochromats (5 versions made): Apo 25x/0.65 (soon replaced by the famous Planapo 25x/0.65), Apo 40x/1.0 Oil m. Iris/ Ph3, Apo 100x/1.32 Oil m. Iris/ Ph3. Two of them I still use until today. Carl Zeiss, Jena also continued to produce apochromats directly after the war, but only for brightfield. Some rare and sought after phase contrast apochromats and GF- Planapochromats where available for the MIKROVAL series (1967-1982) but they have been made from "Unobtainium".


Thanks again!

Michael