MicrobeHunter.com Microscopy Forum

hello everyone
I was wondering if it was possible to mount objectives of different brands and different types on a microscope.
EX. Leica with 10x Nikon plan infinity objective and 20X Zeiss infinity non-plan objective.

Yes, assuming the thread is the same but varying degrees of distortion or aberrations will likely occur, yielding an image that will not be as good or as or accurate as if the objective were designed for the system. Tube lengths can vary considerably as well altering the magnification from spec.

Generally, Chinese made objectives manufactured to either Olympus or Nikon formats have full compatability with Olympus or Nikon microscopes and at the other end of the continuum Zeiss is sufficiently different to be seemingly incompatible with all else. In between those extremes , a degree of compatability can exist but often requires the use of eyepieces that have either a + or - shift in corrections in order to neutralize those distortions or aberrations.
One odd compatability is that earlier AO and Reichert infinity systems are compatable with later made Nikon infinity system, if you are willing to accept a 10% magnification variance from that marked on the objective.

Thanks a lot

Can I ask another questions? What is the differences and the advantages of INFINITY object?
They are much better than the standard achromat object?

Ange20 wrote: ↑

Thu Jul 13, 2023 2:34 pm

Can I ask another questions? What is the differences and the advantages of INFINITY object?
They are much better than the standard achromat object?

As I understand it, the main advantage of infinity is the ability to add extra equipment between the head and objective without having to add extra optics to correct the focal point; beamsplitters, analyzers, whatever you've got, because the eyepiece doesn't have to be at a set distance from the objective. Also adding extra equipment shouldn't significantly alter the magnification.

Here's an example of what you get on an infinity objective with the head removed and the beam allowed to project onto the ceiling. Due to the beam of light being mostly parallel, it is a usable image at any point along the beam instead of at a specific convergent point as with finite objectives.

Objectives for non-inifinity microscopes are designed to focus the image at one fixed, specified eyepiece distance. Objectives for an infinity system are not designed to bring the image to a focus, but rather to send the light out as parallel rays; an additional lens in the infinity-system microscope focuses this at the eyepiece location. The advantage of an infinity system is that the distance between objective and eyepiece is not critical, so it is easy to add other optical components in the light path.

The presence or lack of the "infinity" marking on an objective does not tell you about the quality of the image, but rather what type of microscope (infinity or fixed tube length) it is designed for.

Thank you so much!!!
The difference of price is justificated?

Ange20 wrote: ↑

Thu Jul 13, 2023 4:27 pm

The difference of price is justificated?

Infinity is not necessarily better than finite. There have been very high end finite optics. Today all high-end microscopes use infinite optics while low end Chinese stuff is frequently finite. That may give the false impression that infinite is always better.

Good discussion!

While it is true that finite optics can perform equally compared to infinity optics theoretically , it must be remembered that since the time when the microscope industry as a whole has switched over to infinity correction beginning in 1961 through to the early 90's, very little innovation has been carried out in fixed tube optics towards the end of the finite tube era in each respective company. Thus , little after about 1991. That which has continued to be manufactured since the majors in the industry switched over, is based on conventional older designs, mostly in China and India.
One of what are called milestones in optical design, is the system standardization designing the rear lens group of all objectives in a series to produce a commonly corrected image which can be equally attenuated in a telecentric lens to form a convergent image at an eyepiece that requires equal corrective properties,
This provides an optical platform that has a higher degree of predictability in the design stage,

So while the industry moved from finite optics to infinity optics, why did finite optics reign supreme in the beginning?

Why didn’t designers use infinity optics in the beginning since it had a clear advantage in system design?

Thoughts?

Scoper wrote: ↑

Fri Jul 14, 2023 3:52 am

So while the industry moved from finite optics to infinity optics, why did finite optics reign supreme in the beginning?

Why didn’t designers use infinity optics in the beginning since it had a clear advantage in system design?

Thoughts?

My speculations, if I'm wrong please inform otherwise....

Simpler design early on most likely, then as time progressed just sticking with the "standard" so as to remain compatible with previous products would be my guess. There were many variations on finite, Leitz's 170mm for example and some metalurgical instruments have other lengths (180, 210)....I think. Leitz eventually switched over to 160mm.

Much like the standardizing on short objectives then, as tech improved that had to be adjusted to 45mm, etc to accommodate more elements.

Scoper wrote: ↑

Fri Jul 14, 2023 3:52 am

So while the industry moved from finite optics to infinity optics, why did finite optics reign supreme in the beginning?

Why didn’t designers use infinity optics in the beginning since it had a clear advantage in system design?

Thoughts?

Another take - "necessity" is supposedly the mother of invention. The primary advantage of infinity designs is allowing the insertion of additional imaging elements (beam splitters, DIC prisms, Bertrand lenses, etc.) between the objective and eyepiece. Prior to the 1930's when Reichert pioneered infinity compound microscopes, there wasn't much call for epi-flluorescence, DIC was decades away, and phase contrast had just been invented.

I think you may have gotten the idea that Reichert pioneered infinity correction in the 1930's from the info. promoted in a molecular expressions article, Pete?

I have communicated with one of the authors some years ago, and he agreed that, that information is an error they were aware of but they have yet to correct it. Those authors are pretty good on theory but not so good on history.

AO was the prime developer of infinity correction. The first commercial use ( aside from in condensers) I know of for microscopes was the Apergon metallurgical system AO used in the 1940's and on for some time. Reichert didn't develop an infinity system until about 8 yesrs after AO had acquired the company from the Reichert family, and about 20 years after AO had first launched the Apergon system and 10 years after they launched their 182mm diascopic infinity system. The timeline roughly goes AO Metallurgical infinity system 1948, AO Diascopic Biological 182mm infinity system 1961 or 2, Reichert Diascopic and Episcopic 182mm infinity system 1971. All +- a year or so.

One major overlooked advantage of infinity correction and aside from the very useful infinity space , is probably the major design principal that elevates infinity correction above finite corrected systems is that the concept forces the objective designers to step up to another level of objective design and equalize the objective corrections across the entire series made for any particular system.
In finite tube systems, it is still possible to design objectives individually and have a somewhat disparate group, with each one requiring slightly different corrections or compensation. Thus certain eyepieces are found to perform better with certain objectives. In practice, one or several eyepiece sets became used for achromats and fluorites and others for apochromats and sometimes fluorites as well as occasionally achromats. Such a condition was a more or less situation depending on the manufacturer but most finite systems had certain objectives that were more finely tuned to the dystem and others, less so.

In infinity systems, the telecentric/telan/tube lens is in many ways the back lens of each objective, installing convergence to the image beam down through the reference length to the eyepiece. Each objective must conform to the requirements of that lens and be optimized to utilize it's optical characteristics in as close to a perfect way as possible. Thus the eyepiece must be brought to a level of correction that harmonizes with the output of the tube lens. It can be anywhere on the continuum of correcting through to compensating , it doesn't matter as long as it matches the needs of the tube lens output and therefore is optimized to work perfectly with all objective magnifications and all levels of colour correction.

It might well have been that article, Phil.

American Optical bought out Reichert around 1935 and also Spencer around the same time. I'd assumed (based on the claim that Reichert invented the infinity approach) that some infinity research and designs came along with the acquisition.

It sounds like the first production of infinity scopes was around 1948. AO did make use of that infinity space, with polarizers, Bertrand lenses, and epi illuminators inserted in some (60's? 70's?) scopes I've had -- and well before Nikon and Olympus caught up.

PeteM wrote: ↑

Sun Jul 16, 2023 8:42 pm

It might well have been that article, Phil.

American Optical bought out Reichert around 1935 and also Spencer around the same time.

American Optical bought Spencer Lens Co. a few years prior to 1935. 1931 or 32.
The year of purchase of C. Reichert is way off. It was 1962, they bought Reichert, about 3 years after the development of their first infinity Diascopic system began.

Austria , after W.W. II was a basket case. Unlike the partition of Germany , the 3 allied nations had a non-functional 4 way partnership with the Soviet Union in occupying and managing Austria until 1955. During that10 years the Soviets milked Austria dry and destroyed what little economy they had. Very low currency value. and labour was somewhere less than 1/2 the cost in N.A. When Austria gained independence, the Soviets insisted that they not be allowed to join Nato and that they must always remain neutral, a condition they maintain today.

Reichert was in rough shape by 1955. Excellent but increasingly outdated designs, probably mainly competetive due to an undervalued currency.. Their flagship Zetopan , persisted into the 70's but AO bought the company in 1962 and by 1970 roughly, they had an infinity system up and running in Austria. The Univar. Labour was about 1/2 that in the U.S., so the company filtered production, producing the labour intensive stuff more in Austria than in the U.S., although items can be found that were made in both cities. AO equipment showed up in Reichert cataogues with Reichert badges on them and sometimes not, still badged AO. The Austrian factory also made smaller desk top small lab infinity microscopes for the European market, using off the shelf 34mm AO infinity objective designs, built into Reichert style shrouds with spring loaded noses, something Reichert refused to give up.

Thanks, Phil.