MicrobeHunter.com Microscopy Forum

Jose Antonio Mena: very nice work, and it gets better and better! I don’t have anything to add but would be following and learning from your work.

There is another slit condenser that commonly shows up for sale, again a little different than the PZO or Zeiss. It is the Göerz condenser, produced by the east bloc. Hungarian splinter of the former C.P. Göerz

Thanks Apochronaut:

Can you share any information about the Göerz slit condenser?

The PZO one can be seen in Ebay from one seller from Poland, if somebody wants to know about its construction.

Have you any advice for this work?

Between the Nikon SK condensers, who is better for this aplication, achromat or the aplanat one?
The aplanat-achromat one is difficult to find...


Thanks Zzffnn too...
Best regards

Jose Antonio

Jose Antonio Mena wrote: ↑

Thu Nov 30, 2023 3:16 pm

Thanks Apochronaut:

Can you share any information about the Göerz slit condenser?

The PZO one can be seen in Ebay from one seller from Poland, if somebody wants to know about its construction.

Have you any advice for this work?

Between the Nikon SK condensers, who is better for this aplication, achromat or the aplanat one?
The aplanat-achromat one is difficult to find...


Thanks Zzffnn too...
Best regards

Jose Antonio

It was made by C.P. Göerz in Hungary. I gather that after the war, the German C.P. Göerz wss broken up. Part of it went to Meopta. I also read somewhere that Max Pluta had involvement with people st Göerz.
The only ones I have ever seen are marked Göerz 3-D Condenser on the cardboard outer box but not marked on the well made birch dovetailed 11cm. square box inside it. The original kit contains a condenser, presumably an abbe type, an A.1.2 N.A. obviously oil immersion B.F cap, an A. .08 - 1.2 N.A. D.F. cap and a 0.65 N.A. D.F. cap.
The condenser is solidly made , brushed chrome on brass.
The input end has a plate that has two half moon areas with some degree of light absorption separated by a bright slit of just under 5mm width down the middle. Unlike the PZO slit condenser, the Goerz slit's width and geometry are not adjustable. The lone adjustments are that the slit and reduced transmission zones can be collectively rotated against the iris section of the condenser and it's swinging filter tray. Three filters are provided, blue , green and clear : all frosted.
Further, there is a lateral adjustment that moves the slit and absorption plates along the slit axis, producing an oblique effect. Also unlike the PZO condenser, there is no specific polarization component, although a pol filter could be placed in the filter tray.
The body is a 37mm sleeve type and 38.5 and 39.5 mm spring type adapters are included in the kit as is a centering telescope.

The kits were sold in the U.S. by American Optical Company of New York, which is not the same company as American Optical Corporation.They are frequently listed as an AO item for that reason and not as Goerz because both the maker's and importer's names are on the cardboard box and despite having a very different logo and head office, American Optical Company gets tagged as AO.

I will post pictures in a few days, when I get the time.

Regarding your condenser considerations.. I would be concerned that a strain free condenser might be called for. PZO used a polarizer under the slit diaphragm body and always used the 1.2 N.A. condenser, not the 1.3, which easily could screw in there. I assume that the 1.2 was strain free and the 1.3, not.
One of the things about the PZO condenser is that it has unusually wide optics, so it will have a larger central area well corrected than a standard abbe.

Always an achromat aplanat is a better choice but if it has to be strain free then that would over rule other considerations. For fluorescence , Nikon used a 1.4 aplanat on the SK. They also had a 1.25 achromat and a 1.4 achromat aplanat.

Thanks Apocronaut:

The strain free consideration is very relevant for DIC, and before your advice I didn´t take it in consideration; so, I will check the 3 nikon sk condensers optics that I have for look for the better extintion between crosed polarizer.

I have seen the Göerz 3 D conderser that you described; I see that it isn´t for DIC; it´s something similar to a gradient contrast system, but If I have understand you well, with the frosted filters you will lost the Koeler ilumination; everyday I learn something new.

I will return with the results of strain check of the optics.

I think that the slit condenser results with the Epi-DIC are nice, because it´s a cheap way to access to DIC, despite the disdvantages compared with DIC with prism condenser.

Regards

Pic of cells / bacteria (cocos, bacilo) with cf10X

CF20X pic

cf40X

cf40X

CF20X oblicue darkfield

Hi folks:

Here are some pics that I have taken.

Slide with fresh cheeck cells, cover 0,17mm Zeiss.

SLIT DIC as M. Pluta described (PZO system)

Photo pol filter over field lens.

Condenser before presented with achro 1,25 optics

Slit slides placed in the condenser matched with each objective.

Nikon optiphot I type epi-DIC BD nosepiece, with CF plan 10X, 20X, 40X 160mm/0,17mm objectives, adapters rings from BD female to RMS.

Nikon 1,25X pol analyzer.

Nikon optiphot I type F trinocular head.

Nikon PL 2,5X projection lense.

Home made brass adapter for optical port of trinocular head to Nikon F mount.

Nikon D800 camera.

Some shake in the pictures due to the mirror movement in the camera.

Pics in monorome mode, resized in a smaller size.

I have add a darkfield pic with a oblicue slide in the condenser, adjusted for darkfield.

Best regards

Jose Antonio

Maybe you can find some useful ideas from my design.
The most recent version looks a little bit different, but the main idea is the same.
The design has two perpendicular slots for sliders, a couple of locations for the 32mm filters, and a slot for the rotational filter.

https://www.photomacrography.net/forum/ ... 12#p269212

Nice work Saul, thanks:

I have seen a thing in your condenser that is great: the two orthogonal access to the back focal plane of condenser.

I thougth for a while about how can adjust the position of the slide in the Z (vertical axis), and finally decided put three colums (two of them with treads); now seeing your work, I think that would be better to have four colums, and to access to the back focal plane in two directions. Next proyect will be so...

I want to adjust the receptacle for the slides in the Z axis, because I want to experiment with Nomarsky and Wollaston prisms in the condenser, over and below the back focal plane of the condenser optics. With four colums I will can mantein the Z adjust and have the two orthogonal access to the optical axis.

Thanks again; a improvement will come.

Jose Antonio

PS: I´ve seen too the support over the field lense that you can balance/oscilate; I have the same system that you (only difference: it´s built in brass) with a mica / plastic plate in order to get an adjustable retarder (something like a Bereck compensator)

Jose, is it possible to optically remove the dark grey gradient from your slit DIC (without using software processing)?

Well implemented oblique contrast (in either circular oblique [COL] form or in offset oblique form) can produce smoother background without dark grey gradient.

Have you compared COL or offset oblique with your slit DIC?

Prisms are not cheap and not easy to find. If slit DIC does not produce significantly better 3D image than COL or offset oblique, then I would wonder if slit DIC is worth the extra cost and effort.

And would 100x epi prism produce good transmitted DIC effect for 100x immersion objective?

Thank you.

Hi Zzffnn:

This pics are with the achromat optics and the slits that I made for the Abbe optics. The two have different focal lengt, and I´ve found that the slits that worked with one objective and one objective prism, now doesn´t match with the same... With longer condenser focal, for the same objective NA, It´s needed a thinest slit... so, I´m not sure if this pics have the better result that can be reach, probably no. I want to return to Abbe again, and take pics, and compare. As you can read in the Zeiss paper, there is a optimal width of the slide.
Just now, I can´t say how much can it be improved.
The first test I did with the same preparation with DIC and oblicue ilumination, I think (I did´take pics) I got better contrast with DIC than with oblicue.
Need more time for have a answer.

I haven´t tried the 100X 1,25 inmersion oil objective.

At least, I´m learning a lot.

I have built this condenser for test oblicue too, and other ilumination techniques.

Related to DIC with this home made condenser it must be said that we can´t espect to reach a level of proper trasmited DIC system: I use 160mm optics in a 175mm system; the slit have a low NA in one direction, I use old CF objectives non DIC, my codenser optic mustn´t be strain free.... But the epi-dic nosepiede cost me 200 Euros, and a DIC system for Optiphot must cost about 1500 Euros at least...

Thanks again

PZO were publishing very fine interference contrast images through various systems in their manual in 1975 : in colour and with their planachromats. They used their interference head with the slit condenser. Pluta, knew what he was doing.
I"m curious why not follow their pattern as closely as possible?

Thank you, Jose.

I was going to ask you about tube length error on your DIY system.

15mm tube length error is not too much (may not be obviously visible) for immersion objectives with NAs up to 1.25. For dry objectives though, it does have some negative effect on dry NA 0.65.

Hi Apochronaut:

I´s good to know what kind of results can be achieved with Pluta´s slit DIC system. I haven´t got good references of it. If you say that the results can be good, it must be possible to achieve them. If you have more information about this issue, I will be very glad If yuo can share it with me or with all the comunity.

I don´t know if I´m doing some wrong, apart what I know (160mm versus 175mm, non DIC declared strain free optics, I haven´t adjust the optimal width of the slit, my POL filter could be that isn´t the better one...); but I think that I am doing the Plutta pattern, isn´t so?

I have studied the pics about the PZO Pluta slit condenser; you can adjust freely the position of the four sides of the slit. I had in mind one arragement symilar to install in my condenser, in a way that can be possible a continuous adjustmen of the width of the slit and discrete adjustment of the lengh of the slit, but until now I havent time for do it; For that reason I tried with fixed slits made of cardboard, and after your generous information, I think that with a proper adjust, the gradient of density that Zzffnn said, can be eliminated. The only thing is work more on it. Need time.

The Saul contribution that aid to access to the optical axis of the condenser in two orthogonal directions, aid in the desing of a slide with an adjustable slit.

All your knowelege are wellcome, for me, and for all the comunity.

Thanks

JA

Hi Zzffnn:

Thanks for your contribution.

I think that the ideas from Apochronaut about this issue give us clarity about what can be achieved if the things are well done; I think that the main isse with the gradient is adjust the slit, and other improvements will get with the proper optics (strain free optics).

The objective I use are 160mm, and my real tube span is about 175mm due to the width of the Nomarky arragement over the objective in the nosepiece, and the ring adapptor between BD tread, and RMS tread; The nose-piece wasn´t made for trasmited ligh DID,but for EPI DIC, with another equipment and with a 210mm objectives in use.

I havent tried until now the cf 100X 1.25 due to need of time, i Will do, and i Will return with the results.

I hope that with you ideas and from other people, we can upgrade the proyect and results.

Best regards

JA

Oblicue versus slit DIC

oblicue versus Slit DIC

I think that the gradient could be smoothed, but, at least with this optics and this prisms the results are similar than oblique

The results depend on greatly on the size and position of the slit. And you can choose colour DIC too with the position of slit.

Later, oil inmersion.
Sorry Zzffnn, I have tried the 100X, but my objective, that I bought for this project dosn´t work; the front element has movement, it´s free...

One thing that I´ve found is that the Nikon SK achromat 1,25 and Nikon SK aplanat 1,4 condenser optics doesn´t match very well with the optical trail of the Nikon Optiphot, or at least I think so; If I try to adjust the Z position of the condenser for get a focus image of the slide and the field iris, the upper lens of the condenser touch the slide. I don´t know if I´m wrong in this dignosis; Can Apochronaut confirm this?

Below the slide used for the pictures in oblique illumination.

Thanks

JA

A rude atempt for DIC combinating a PZO 20X condenser prism, Nikon SK Abbe 1.3 condenser optics and the nikon CF plan 40X + BD40X prism...

For Sure Squinsalot.

Hey, that's pretty good!

Jose, I did not understand you there.

It is common for a 100x immersion objective to have spring loaded (free-moving) front element that retracts when touching cover glass.

Are you using oil immersion on condenser top lens? It sounds like you may get a focused image of field iris, if you immerse condenser top lens.

Yes, Zzffnn; I bougth the objective (CF plan 100X 1,25) weeks ago, and it´s broken; the front element is loose from the barel. You can see it only with a binocular loupe.
I have used several times inmersion oil objectves ( 40X, 60X, 100X).
No, the movement isn´t related with the spring; it´s in the X-Y axes, the cement of the lense to the barrel must be loose... I have ask to the seller...

I have a CF plan apo 100X 1,35; other dayy I will check

And, as you said, the oblique is as good as the results of my slit dic system.... bad... or good news...

For all these test I have built this condenser...

That is fascinating. As you say I don't know if it's bad news for the dic or if it's good news for the oblique. Probably the latter, you're getting really good lighting. Probably time to try it on some diatoms or other classic fun subjects.

Except for the odd shading effect. Photos provided by PZO in the 70's had none such. I have avoided asking why such exists but I assume it is an artifact of oblique lighting which essential DIC does not possess. It is a bit of folly to refer to this as DIC , since even PZO did not do. Their nomenclature was Interference Contrast Microscopy and they used it for images produced by the slit condenser ,or prism condenser irregardless ofthe nature of the downstream optics. Pluta wss in some ways a competitor to Nomarski and when he wheedled his way to a Zeiss patent and it was honoured subsequently, Pluta worked through eastern block channels.

Where does this shading come from? Is it simply the obliqueness of the lighting source?

apochronaut wrote: ↑

Fri Dec 08, 2023 3:28 am

Where does this shading come from? Is it simply the obliqueness of the lighting source?

Jose, can you post your DIC images in full color? I'd be curious to see if you have any rainbow artifacts. That might answer apo's question.

I'm taking Jose's claim for DIC at face value given that he's using a PZO prism in its proper position within the condenser. Assuming it's not the correct one for 40x, there should be some interference mismatch and some 1st order colors (as well as some loss of resolution).

Shading like that is common with slightly mismatched DIC prisms, isn't it?