dIY DIC

Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
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Sauerkraut
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dIY DIC

#1 Post by Sauerkraut » Sat Jun 08, 2019 5:12 pm

Has anyone had any luck with diy DIC? I found this link and tried out this method but it didn't really work as of yet:

http://www.microscopy-uk.org.uk/mag/ind ... iydic.html

I had fleeting 'just ok/kinda looked like DIC' results with a wedge shaped filter but could not repeat them with other pond water samples. I've also had difficulty getting reliable darkfield with black dots (tried lots of sizes) and am guessing that for some microscopes, it's better to just buy the corresponding darkfield condenser.

Heather

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Re: dIY DIC

#2 Post by PeteM » Sat Jun 08, 2019 7:21 pm

I've been experimenting, sometimes with pretty good results. My ultimate goal is to be able to take amazing pictures for the "single image science lessons" being developed for a kids' program. Too much else going on to adequately document progress so far, but I can make some comments.

1) If it's just reflected DIC you want, it's pretty easy and relatively affordable to buy used gear. And the prisms in an epi unit can provide a basis for further experimentation.

2) My take is that there are three limitations to achieving somewhat decent and affordable transmitted DIC results. First, is finding affordable DIC prisms. Even used, a complete set of prisms top (above the objective) and bottom (in the condenser) runs near $2000 for older gear (e.g. PZO, 1st generation Nikon, older Zeiss), maybe $3000 for slightly more popular gear (e.g. Olympus BH but not BH2), and $4000 up for more modern scopes (BH2, BX series, etc.). The cost is prohibitive for most hobbyists. So, I suspect what most DIY hobbyists have done is buy most any prism that shows up cheap, hoping it can be matched up in a system. Even at this level, you're looking at around $100-150 per prism and might want as many as eight (four top and bottom) prisms.

2) Second problem is that practically no prisms are marked with shear angles or even orientations and few objectives have an indication of where the prism (with some specified shear angle) should be located. So, barring optical testing equipment and greater knowledge of optics than I have, it's a trial and error process. If anyone can point me to a somewhat decipherable optical tract that could help with this, I'd be grateful.

3) Third problem is more mechanical - setting up rigs where one could fairly easily experiment with prism locations. They ideally want three degrees of freedom (rotational, lateral, up and down). That one is a bit easier for me, having been cursed/blessed with the "tool gene."

I've had decent results with these combinations:

1) PZO DIC condenser, re-oriented 45 degrees on a Leica DM series scope, fitted with Nikon 60mm infinity objectives, with Olympus epi prisms fitted to a DIC topside slider. Probably easier, though, to just look for a complete PZO system (though limited a bit by the older PZO objectives). There has been a glut of very cheap 20x infinity Nikon Apo objectives on Ebay -- and DIC results with this objective are very satisfying (at least to me).

2) Various Olympus stands with a proper top slider, with epi prisms removed and re-located as close as possible to the condenser diaphragm. If anyone wants to sell an Olympus condenser populated with Olympus prisms -- for just an arm OR a leg -- please let me know.

3) An actual and complete Nikon v2 DIC condenser and slider (but not holder) fitted to a makeshift holder. This works well with both Nikon top end finite and Olympus top end finite objectives. Olympus SPlan objectives are what they recommend for DIC and they seem to work pretty well. The Nikon and Olympus finite Apos I have also work well.

4) Olympus epi DIC prisms (sometimes affordable) fitted to Olympus SPlan objectives and a makeshift 1.25x polarizer holder up top, and those same type prisms removed and fitted to condenser apertures as close as possible to the iris. I modify condensers to fit a slider holding these prisms.

Sometimes there is banding evident. Sometimes the effect is best with a combination of oblique (prism shifted) and shear angle illumination. And sometimes it's very good. When time permits, I've got a batch of older Leica/Reichert epi prisms to try as well.

In general, my experience is that the cost of experimentation is about the same as biting the bullet and spending the money just once on a proper and complete DIC system. Still, I've enjoyed the experiment and in the end I expect to have half a dozen pretty decent (image-wise) DIC systems.

Someone wanting DIC for a clinical application would likely be crazy to head down this path -- you'd have even less idea of what you were seeing in terms of the false relief. But, someone wanting cool images might actually find greater control with DIC prisms that can be combined with oblique movements.

I realize folks would like photos and better descriptions, but I simply don't have time to make that a priority now. What I can say, is that it's possible -- if time consuming -- to cobble together a pretty decent (image wise) DIC system with just the prisms costing under $1K. But recognize it's also a bit like diving into a black hole :-).

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Re: dIY DIC

#3 Post by viktor j nilsson » Sat Jun 08, 2019 7:55 pm

A while ago I picked up a Nikon optiphot nosepiece that came with 4 epi DIC prisms: 5x, 10/40/100x (2pcs) and 20x prisms. Paid $180 for it. (It also came with 20x and 40x M plan objectives.) I've been experimenting a bit with these prisms on my Wild M20 stand. I still haven't optimized anything: I've simply placed one prism between the nosepiece and binocular head, and held one prism under the condenser (making sure they are aligned and at a 45 degree angle relative to two crossed polarizers. The biggest problem is probably that the top prism is l not at the rear focal plane of the objectives when placed this way, but I've still gotten at least somewhat useful 'true' DIC with 10x,20x and 40x Nikon CF Fluor objectives using some combinations of these prisms (must dig up my notes to remember which ones)..

I plan to post further updates on this whenever I get the time to work on it some more.

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Re: dIY DIC

#4 Post by 75RR » Sat Jun 08, 2019 8:03 pm

What Wim van Egmond refers to as DIY DIC is effectively finely tuned oblique. This takes a little practice but is well worth the extra effort.

Here are a couple of links. The first is to some van Egmond masks in pdf that forum member Rod Nabholz has kindly made avalilable. They are designed to be printed out on acetate film.

viewtopic.php?f=15&t=4499

The other link is to a post on the Gradient Universal Filter (which is also oblique lighting), which shows what can be achieved with it and how the filter is made.

http://www.photomacrography.net/forum/v ... hp?t=15142
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Re: dIY DIC

#5 Post by MicroBob » Sat Jun 08, 2019 8:29 pm

Hi Heather,
these filter tricks work differently well with different microscopes. Also it is always necessary to do some fiddling to get the best image so repeatability or even quick repeatability is not really available. On the other hand side a real DIC setup is also difficult (and expensive!) to assemble and still a bit fiddly.
I think with some experience and a well arranged set of filters very nice results can be obtained.
Dark field can be obtained with dark field stops only for the lower power objectives, in some cases it still works with the 40:1 objective. The whole microscope has to be set up well centered for this to work well.
If it doesn't work right from the beginning I would start to optimize it just for the 10:1 objective. When this is managed I would try it with the other objectives.
There are interesting filter combinations: A light blue background combined with oblique for example. There are filter foil sample kits available for acceptable money. The addition of polarizers can offer interesting effects that can also be varied.

Bob

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Re: dIY DIC

#6 Post by billbillt » Sat Jun 08, 2019 8:49 pm

Sauerkraut wrote:Has anyone had any luck with diy DIC? I found this link and tried out this method but it didn't really work as of yet:

http://www.microscopy-uk.org.uk/mag/ind ... iydic.html

I had fleeting 'just ok/kinda looked like DIC' results with a wedge shaped filter but could not repeat them with other pond water samples. I've also had difficulty getting reliable darkfield with black dots (tried lots of sizes) and am guessing that for some microscopes, it's better to just buy the corresponding darkfield condenser.

Heather
"Hi Heather,

This method is not DIC, but a method of oblique illumination... DIC is much more complex than that...

Regards,
BillT

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Re: dIY DIC

#7 Post by zzffnn » Sat Jun 08, 2019 11:01 pm

DIY oblique gets difficult over 40x NA 0.65 and does not produce the same contrast DIC produces. My own (years of) test results showed that DIY oblique can provide decent visual 3D effects at high power, but such effects cannot be easily captured with camera.

So for me, if I were to pursue DIY DIC like how @PeteM did it, I would want at least 1-2 prism sets for high power objectives. DIY oblique or darkfield did well at equal or under NA 0.65 (so I would save money there, if budget is really tight).

@PeteM and @viktor j nilsson,
You both did great DIY work there. Please update the forum, when you have a chance.

I think when objective NA goes over 0.65, locating objective back focal plane precisely and maintaining tube length gets harder and is much more critical, for finite objectives at least.

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Re: dIY DIC

#8 Post by Sauerkraut » Sun Jun 09, 2019 3:01 am

Thanks to all for the detailed responses. Finely tuned oblique is much more realistic for me than acquiring and experimenting with prisms. At least for now.

I’m going to try those printable filters as a next step. And tinker more with dark field too.

Heather

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Re: dIY DIC

#9 Post by zzffnn » Sun Jun 09, 2019 4:21 am

Here is the gradient oblique template that I made, which may be easier to print than the original: http://www.photomacrography.net/forum/v ... ght#173389

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Re: dIY DIC

#10 Post by MicroBob » Sun Jun 09, 2019 5:22 am

[quote="zzffnn"]DIY oblique gets difficult over 40x NA 0.65 and does not produce the same contrast DIC produces. My own (years of) test results showed that DIY oblique can provide decent visual 3D effects at high power, but such effects cannot be easily captured with camera.

So for me, if I were to pursue DIY DIC like how @PeteM did it, I would want at least 1-2 prism sets for high power objectives. DIY oblique or darkfield did well at equal or under NA 0.65 (so I would save money there, if budget is really tight).

Hi Fan,
thank you for sharing your experiences and an interesting approach! Probably the prices for DIC prisms for 100:1 objectives will skyrocket now! :mrgreen:

I can imagine that these DIY filter contrasting methods have more potential than it appears. When looking at great plancton images they are often taken with DIC. But DIC is commecially availabe (more or less) in a well designed setup. DIY contrast techniques usually consist of a heap of plastic film bits, cardboard and isolation tape of little permanence and appeal. So if one would build a nice set of holders and a box for them they would probably be used more - a nice project for a 3D-printer.

Bob

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Re: dIY DIC

#11 Post by Wes » Sun Jun 09, 2019 6:38 am

zzffnn wrote: So for me, if I were to pursue DIY DIC like how @PeteM did it, I would want at least 1-2 prism sets for high power objectives. DIY oblique or darkfield did well at equal or under NA 0.65 (so I would save money there, if budget is really tight).
I have only two DIC objective prisms, one for 16x/0,35 and one for 63x/1,4 lens. The 16x prism works very well with the 10x/0,32 Planapo (probably the matching NA helps) and reasonably well with 6,3x objectives. The 63x slider I use mostly with a 40x apo lens and while its quite delicate to set it properly it gives satisfactory DIC (but I wouldn't mind getting a dedicated 40x DIC slider in the future).

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Re: dIY DIC

#12 Post by Sauerkraut » Sun Jun 09, 2019 2:17 pm

zzffnn wrote:Here is the gradient oblique template that I made, which may be easier to print than the original: http://www.photomacrography.net/forum/v ... ght#173389
Thank you for this link, zzffnn. I'll play with this idea too. The prism conversations are interesting but admittedly for me as a beginner, are way over my head.

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Re: dIY DIC

#13 Post by zzffnn » Sun Jun 09, 2019 3:15 pm

Wes,

Sorry to be so blunt. Your rotifer image came out great, so I agree that mismatched 16/0.35 slider worked well at 10/0.32.

Have you tested your 63x slider + 40x Apo on a small rotifer or its body part though?

I think paramecium is a comparatively easier subject for DIC, as it would look quite good under oblique (because paramecium are naturally textured, yet those textures are smooth / won't produce too much shadows under oblique; rotifer is a bit more difficult for oblique).

I tested my best oblique under 40/0.95 on a rotifer a few months ago. What I did not like included:

1) oblique produced too much shadows;

2) oblique 's 3D enhancement effect can be seen under visual eyepiece, but contrast is not great and my cameras Olympus E-M10 mk2 and E-M1 mk1 failed to capture such contrast well (lots of software enhancement was needed to even match visual view, camera-captured dynamic range was lacking; I know HDR can be used, but is not appropriate for moving subjects).

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Re: dIY DIC

#14 Post by zzffnn » Sun Jun 09, 2019 3:45 pm

Bob,

Forum member Saul at Photomacrography.net already 3D- printed filters (w/ holder inserted) for Olympus BH(2?) and Nikon Labophot/Optiphot and is probably working on others:
http://www.photomacrography.net/forum/v ... ht=#248468

DIY oblique should not be too difficult, even without 3D printer, for a DIY'er who is willing to try different approaches. Legos, opaque circles, Blutak and glue worked well for me.

I would love a good alternative than buying factory-matched DIC for high NA / high magnification, but I have not found it yet (which is why I am keenly interested in @PeteM 's and @viktor j nilsson's innovative work; I think @apochronaut is doing something related as well).

For me (and maybe some other microscopy enthusiasts), at NA 0.85 and above, oblique's potential is limited by its (sometimes excessive) shadow effects and lack of dynamic contrast, even though it does produce good textural (3D) enhancement. Such shadow effect also limits potential of high magnification darkfield. DIC can produce darkfield effect without much shadow or aperture reduction.

I came to this conclusion, for my own use, after years of experimenting with Leitz Heine, various DIY oblique set ups and oil darkfield condensers.

So I would like to obtain versatile DIC (probably PZO) for NA 0.85 and up for my short LOMO apos. I have not tried Reichert Polyphos or Zeiss pancratic condenser for oblique and darkfield, but I doubt they would produce qualitatively better imagery than the Leitz Heine that I tried (which is still not ideal for high magnification photography). I may try The Zeiss pancratic condenser if I can find one for cheap, but otherwise I would just save up for DIC. And when I do buy DIC, I will sell my Leitz Heine and most of my darkfield condensers. I may have to change to Olympus BH(2?) stands though (from my Nikon Optiphot teaching rig), as I heard Oly has some head compatibility with PZO, but such a transition + modifications will cost me quite a bit :cry:

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Re: dIY DIC

#15 Post by MicroBob » Sun Jun 09, 2019 7:10 pm

Hi Fan,
I have just assembled a PZO DIC set consisting of revolver condenser and MPI-3 (?) head. For a while now I am working on my office/lab room and work is not yet finished, most things are covered and not available. So I only had a quick try with the set and a 1960s cream white PZO MB 30 with some Vickers Microplan objectives and a half working LED. My first test looked promising so far.
As far as I could read the PZO DIC is comparatively adaptable to different setups. In one forum post I read that the member was not fully convinced of the optical quality of the PZO DIC, but this member got his high level of knowledge by being a Zeiss employee. ;)
My two components were bought separately for together about 380€ which is a lot of money for me, but not much for a working DIC setup (if it works as intended, that is). I'm looking forward to diving into this and ther is just one bay window to finish until I'm ready.

Bob

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Re: dIY DIC

#16 Post by PeteM » Sun Jun 09, 2019 7:59 pm

zzffnn wrote:. . . I may have to change to Olympus BH(2?) stands though (from my Nikon Optiphot teaching rig), as I heard Oly has some head compatibility with PZO, but such a transition + modifications will cost me quite a bit :cry:
Fan,

I've had pretty good luck swapping heads on microscopes, by acquiring and re-machining an intermediate adapter. I've also used epi illumination pieces (cutting off the illumination tube) for this purpose.

For finite scopes like the Nikon and Olympus this will usually be a 1.25x with a lot for a polarizer (and sometimes where I also add a DIC prism). You basically keep the dovetail that matches what you want to do but re-machine or re-make the other dovetail to mate it up.

For infinite scopes, just an open intermediate tube with whatever polarizer and/or DIC unit you want is usually all that's needed.

I've mated BHS stands to BX infinity optics, used an Olympus DIC slider on an Optiphot, put Reichert heads on a mis-matched Leica, have a Nikon DIC slider on a BHS, and so on. The Optiphot is a terrific microscope and I'd think you could adapt it. I will say that the Olympus intermediate optics seem a bit easier to come by and have plenty of room to fit most anything you'd want.

Most any metal lathe will cut these dovetails, but you need a very acute angle in the tool to reach into the dovetail.

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Re: dIY DIC

#17 Post by Hobbyst46 » Sun Jun 09, 2019 8:20 pm

Sauerkraut wrote:Has anyone had any luck with diy DIC? I found this link and tried out this method but it didn't really work as of yet:

http://www.microscopy-uk.org.uk/mag/ind ... iydic.html

I had fleeting 'just ok/kinda looked like DIC' results with a wedge shaped filter but could not repeat them with other pond water samples. I've also had difficulty getting reliable darkfield with black dots (tried lots of sizes) and am guessing that for some microscopes, it's better to just buy the corresponding darkfield condenser.

Heather
I do not know which microscope you have, here is a link to an eBay darkfield condenser. It is Carl Zeiss Jena, but perhaps it will fit ?
https://www.ebay.com/itm/Carl-Zeiss-Kar ... 3733578851
(would have bought it myself but he/she only ships to the USA). Of course, I suggest to inquirie the seller about the condition of the optics, delamination, internal mirrors etc.

Here is another eBay item from a seller "near" you - the price is low, I wonder if it is real...perhaps worthy of checking... I have very little experience with DIC so cannot be specific.
https://www.ebay.com/itm/E-LEITZ-LABORL ... 3806059270
Note: I am not related to the above sellers in any way.
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Re: dIY DIC

#18 Post by 75RR » Mon Jun 10, 2019 3:24 am

Note: I am not related to the above sellers in any way.
It would make more sense if you were! ;) Can't see any component that would indicate it has DIC - on top of which the no return policy is not especially helpful.
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Re: dIY DIC

#19 Post by apochronaut » Mon Jun 10, 2019 10:44 am

Sauerkraut wrote:Has anyone had any luck with diy DIC? I found this link and tried out this method but it didn't really work as of yet:

http://www.microscopy-uk.org.uk/mag/ind ... iydic.html

I had fleeting 'just ok/kinda looked like DIC' results with a wedge shaped filter but could not repeat them with other pond water samples. I've also had difficulty getting reliable darkfield with black dots (tried lots of sizes) and am guessing that for some microscopes, it's better to just buy the corresponding darkfield condenser.

Heather
Heather.
If you start looking for PZO DIC, you will find that there are several parts to the system, some of which don't look like they belong there; at least when you compare PZO to other DIC systems. PZO never referred to their system as DIC. The manual for the system is titled Biolar Interference Microscope. There were other interference microscope systems and condensers in the 50's and the PZO system seems to be a bit of a composite. It includes a rotating condenser housing with 4 individual prisms but nowhere does the manual indicate whether the peisms are Wollaston, Nomarski or other. The manual provides instructions for 5 different methods to accomplish interference microscopy, some qualitative and some quantitative.

Another different condenser component in the PZO kit is a variable slit condenser, that is somewhat similar to using masks of various shapes and yields results not too different from Hoffman Modulation, which is a modified slit condenser system. The PZO slit condenser can sometimes by purchased separately and should easily be adaptable to other microscopes. It has a sleeve type mounting of 40mm and in it's complete form also includes a rotating polarizer below, that slides under on a dovetail. Both it and the above prism type condenser are referred to as interference condensers.

Occasionally on the used market, you also see a similar condenser to the PZO ; the Goerz 3-D condenser. The Goerz condenser also includes the possibility of combining a relief image created through a slit condenser but in this case the original set also included 2 darkfield caps. A few people use one to effect. Here is a forum thread populated with some nice results.
http://www.photomacrography.net/forum/v ... 2646add153
Last edited by apochronaut on Mon Jun 10, 2019 1:53 pm, edited 1 time in total.

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Re: dIY DIC

#20 Post by Wes » Mon Jun 10, 2019 1:43 pm

zzffnn wrote:Wes,

Sorry to be so blunt. Your rotifer image came out great, so I agree that mismatched 16/0.35 slider worked well at 10/0.32.

Have you tested your 63x slider + 40x Apo on a small rotifer or its body part though?

I think paramecium is a comparatively easier subject for DIC, as it would look quite good under oblique (because paramecium are naturally textured, yet those textures are smooth / won't produce too much shadows under oblique; rotifer is a bit more difficult for oblique).

I tested my best oblique under 40/0.95 on a rotifer a few months ago. What I did not like included:

1) oblique produced too much shadows;

2) oblique 's 3D enhancement effect can be seen under visual eyepiece, but contrast is not great and my cameras Olympus E-M10 mk2 and E-M1 mk1 failed to capture such contrast well (lots of software enhancement was needed to even match visual view, camera-captured dynamic range was lacking; I know HDR can be used, but is not appropriate for moving subjects).
While I can't recall how a rotifer looks like I've looked into yeast, nematodes, desmids, diatoms, intracellular movement in algae, squished fruit flies and it looks very nice (you can see fine intracellular details). One problem I see is that unlike matched components you do get a light intensity gradient which could be fixed with an exposure counter gradient later in image processing (works very well I only figured it out yesterday and you need RAW images). Now getting decent contrast requires fiddling with the coverslip correction collar, recombination prism lateral displacement (it works better when flipped upside down), condenser aperture and height. I suspect the dedicated 40x prism would give stronger contrast but this works reasonably well.

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Re: dIY DIC

#21 Post by Sauerkraut » Mon Jun 10, 2019 3:57 pm

apochronaut wrote: If you start looking for PZO DIC, you will find that there are several parts to the system, some of which don't look like they belong there; at least when you compare PZO to other DIC systems. PZO never referred to their system as DIC. The manual for the system is titled Biolar Interference Microscope. There were other interference microscope systems and condensers in the 50's and the PZO system seems to be a bit of a composite. It includes a rotating condenser housing with 4 individual prisms but nowhere does the manual indicate whether the peisms are Wollaston, Nomarski or other. The manual provides instructions for 5 different methods to accomplish interference microscopy, some qualitative and some quantitative.

Another different condenser component in the PZO kit is a variable slit condenser, that is somewhat similar to using masks of various shapes and yields results not too different from Hoffman Modulation, which is a modified slit condenser system. The PZO slit condenser can sometimes by purchased separately and should easily be adaptable to other microscopes. It has a sleeve type mounting of 40mm and in it's complete form also includes a rotating polarizer below, that slides under on a dovetail. Both it and the above prism type condenser are referred to as interference condensers.

Occasionally on the used market, you also see a similar condenser to the PZO ; the Goerz 3-D condenser. The Goerz condenser also includes the possibility of combining a relief image created through a slit condenser but in this case the original set also included 2 darkfield caps. A few people use one to effect. Here is a forum thread populated with some nice results.
http://www.photomacrography.net/forum/v ... 2646add153
Thank you for this information. Very useful.

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Re: dIY DIC

#22 Post by MicroBob » Mon Jun 10, 2019 6:22 pm

Hi together,

concerning PZO DIC: There are upper DIC units named MPI-2, MPI-3 (the one I have) and MPI-5 (looks different than the two before). The revolver condenser seems to be always KPI-2. In the internet I found a description of the newest system for the Biolar, with MPI-5, KPI-2 and additional slit condenser.
Does someone have information what the difference between these three upper DIC units is? Does someone have a manual for the system with my MPI-3 head?

Bob

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Re: dIY DIC

#23 Post by Sauerkraut » Mon Jun 10, 2019 6:32 pm

75RR wrote:
Note: I am not related to the above sellers in any way.
It would make more sense if you were! ;) Can't see any component that would indicate it has DIC - on top of which the no return policy is not especially helpful.
Something like this looks better but I'm not well versed on the used market of older scopes and their technology:

https://www.ebay.com/itm/LEITZ-microsco ... SwvmxbcK2p

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Re: dIY DIC

#24 Post by apochronaut » Mon Jun 10, 2019 11:10 pm

I had a bit of an email conversation with that seller regarding another plasDIC system he was selling. It , like the older Leitz in this link was a retrofit and a kind of crude one at that. There was a sticker that said DIC on the slider and it was cockeyed. There was no polarizer. He didn't answer my last question which was: is there a polarizer under the condenser?

So in this case, questions still stand out, not to mention that if the pictures of images he is showing on the computer screen are representative of the quality that the system can do, then I would have to say the retrofit probably needs several years of further development.

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Re: dIY DIC

#25 Post by zzffnn » Tue Jun 11, 2019 3:01 pm

Thank you very much @PeteM. You made a great point, which would save me (and likely other DIY microscopists) quite a bit of money! Let me know how I can return your favor or buy you some (virtual) beer.

The Nikon epi attachment that I have adds 50mm to optical tube length and does not have a pair of lenses to cancel out added tube length (because some Nikon epi objectives use 210mm tube length, as you know). It does offer space to add a prism and a polarizer, along with possibility of changing dovetail.

I do have a Nikon teaching arm attachment that adds about 40mm tube length, which does seem to have a pair of (tube length) correcting lenses inside.

So for such head swapping (which is the darkest magic in microscopy wizard land, other than DIY DIC :mrgreen: ), I need a pair of correcting lenses from some other cheaper parts (recommendations? Lenses of any brand would work as long as they cancel out the added tube Length). That is because my preferred objectives use 160mm tube length.

I think condenser adaptation may be accomplished without machine work. I have done quite a few before.

I hope this discussion can also help others. Complete Nikon scopes seem cheaper and easier to find than Olympus / Leitz / Zeiss in US nowadays.

abednego1995
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Joined: Thu Dec 15, 2016 6:32 am

Re: dIY DIC

#26 Post by abednego1995 » Wed Jun 12, 2019 6:35 am

apochronaut wrote:I had a bit of an email conversation with that seller regarding another plasDIC system he was selling. It , like the older Leitz in this link was a retrofit and a kind of crude one at that. There was a sticker that said DIC on the slider and it was cockeyed. There was no polarizer. He didn't answer my last question which was: is there a polarizer under the condenser?

So in this case, questions still stand out, not to mention that if the pictures of images he is showing on the computer screen are representative of the quality that the system can do, then I would have to say the retrofit probably needs several years of further development.

The Zeiss plasDIC system is a rather "basic" interference system. It beautifully represents what interference between different wavefronts do in a microscope system.
The only catch with the PlasDIC is that it can't be used with high NA objectives due to the slit mask in the condenser aperture plane.

Since PlasDIC is intended for observing objects in birefringent containers, the polarizer is set after the container.
However, the lower polarizer can be anywhere before the Nomarski prism in the light train as long as you don't use birefringent elements in between.
If you already have a Nomarski DIC system, pseudo-PlasDIC can be demonstrated by setting up DIC normally and removing the condenser prism while closing down the condenser iris or making a slit aperture mask that has its long side perpendicular to the objective prism shear direction.

There's a paper explaining how it works.
https://www.osapublishing.org/oe/abstra ... 6-24-19462
PlasDIC.png
PlasDIC.png (179 KiB) Viewed 2795 times
Theoretically, as long as you stick with low NA, I consider this to be the cheapest DIY DIC option there is.
(I also believe you can obtain DIC in this fashion with metallurgical epi-DIC kits in diascopic mode using a polarizer under the condenser)
Due to the very limited NA, prism shear amount is very forgiving (using too small values would decrease the contrast generated though). Plus the back focal plane of low mag objectives is often outside the objective, which is very helpful when aligning mismatched prisms to it.

However, if you just need to observe transparent objects, phase contrast and Hoffman Modulation Contrast is sufficient (and is great with any NA).

So.... the bottom point I guess, is if you want great DIC images at any NA and with perfect pupil compensation (that's why Nomarski DIC needs 2 prisms), get a complete set in the beginning.
If you're the experimenter who cares more about optics and is curious of the physics, DIY DIC is your path (not always pleasant, but rewarding).

Cheers,
John
Last edited by abednego1995 on Wed Jun 12, 2019 7:01 am, edited 1 time in total.

MichaelG.
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Re: dIY DIC

#27 Post by MichaelG. » Wed Jun 12, 2019 7:01 am

Thanks for that, John ... Very helpful.

MichaelG.
Too many 'projects'

viktor j nilsson
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Re: dIY DIC

#28 Post by viktor j nilsson » Wed Jun 12, 2019 10:21 am

Good point, John. I've been wondering why so few people talk about DIC using a slit condenser. If I've understood it correctly, the plasDIC system is basically a rebranding of the techniques that were already fully described in the very earliest DIY literature. (And implemented, for example, in the. PZO slit condenser).

Making a DIY slit condenser would be super simple - my DIY Hoffmann condenser works great, I just cut a slit in an old credit card that fits under my condenser.

I've only found a few pictures online that have been made with a slit condenser/plasDIC, and most of them are from medical research setups that haven't really been done with the aim of getting 'nice' pictures. I'm keen to experiment to see how good it can get.

abednego1995
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Re: dIY DIC

#29 Post by abednego1995 » Wed Jun 12, 2019 10:43 am

Yup, Viktor, I think your getting that effect in your beforementioned setup.

As you mention, in it's most primitive form DIC employs a pinhole condenser.
PlasDIC improves on it by using a rectangular slit allowing somewhat higher NA information to pass through (though direction limited).
So little information and images from PlasDIC is probably due to it's limited use in in-vitro fertilization and micro-injection techniques where that halo from phase contrast is distracting.
(IMO, HMC is good enough for those techniques sans halo, so PlasDIC is something uber-rich clinics and labs might buy in the first place.)

Cheers,
John

apochronaut
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Re: dIY DIC

#30 Post by apochronaut » Wed Jun 12, 2019 4:15 pm

viktor j nilsson wrote:Good point, John. I've been wondering why so few people talk about DIC using a slit condenser. If I've understood it correctly, the plasDIC system is basically a rebranding of the techniques that were already fully described in the very earliest DIY literature. (And implemented, for example, in the. PZO slit condenser).

Making a DIY slit condenser would be super simple - my DIY Hoffmann condenser works great, I just cut a slit in an old credit card that fits under my condenser.

I've only found a few pictures online that have been made with a slit condenser/plasDIC, and most of them are from medical research setups that haven't really been done with the aim of getting 'nice' pictures. I'm keen to experiment to see how good it can get.
The Goerz condenser is also an implementation of the slit condenser interference system. I have never encountered a manual for the Goerz condenser but it also has DF capability. The manual for the PZO polarizing interference microscope shows 3 separate interference methods incorporating their slit condenser; a differential method, a uniform field method with high image shearing and a fringe method.

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