Converting Brightfield Microscope To DIC

[MicroscopyLearning]

Hello. Could someone explain what components are needed to convert a brightfield microscope into a DIC microscope. I have found this article: scientifica.uk.com/learning-zone/differential-interference-contrast, but I did not understand what it meant by an objective specific prism. Is this an additional prism one must add, or is it talking about a prism a brightfield microscope would already have. The microscope I am looking to convert is: Swift SW350T. Could the analyzer be put in the place below the head?

[apochronaut]

The extra components and critical alignments necessary to convert a microscope like yours to DIC are roughly equivalent to converting a basic television set into a 3-D home theater.

[Wes]

The extra components and critical alignments necessary to convert a microscope like yours to DIC are roughly equivalent to converting a basic television set into a 3-D home theater.

I wonder if the promiscuous PZO DIC kit can fit his scope.

[apochronaut]

Putting the PZO interference head on it would be like trying to make a houseboat out of a disused hockey arena. I think it outweighs the microscope.
There is no condenser carrier, the illumination is a 1 watt led, the objectives are not strain free, the PZO dovetail is 43mm. PZO interference kits are north of $1000.00
these days.

[Greg Howald]

I'm pretty sure you are stuck with "poor man's DIC".
You can do some amazing things with oblique filtering which will produce wonderful results even when using phase contrast, but without the items necessary for actual DIC You can not achieve it. DIC is costly. If you try to do it by buying parts to build it, DIC can cost you more in parts than the new scope.
I suppose you could achieve it with lots of patience and lots of time. I tried for a while.
Greg

[BramHuntingNematodes]

Yeah if I ever luck into some nice iceland spar at a swap meet and manage to cobble together a CNC faceting machine I got the barnesite all hooked up and ready to try out I don't know I guess the dozen or so configurations we would need to hone in on the right prism specifications ought to be p. straightforward

[synnus]

Hello. Could someone explain what components are needed to convert a brightfield microscope into a DIC microscope. I have found this article: scientifica.uk.com/learning-zone/differential-interference-contrast, but I did not understand what it meant by an objective specific prism. Is this an additional prism one must add, or is it talking about a prism a brightfield microscope would already have. The microscope I am looking to convert is: Swift SW350T. Could the analyzer be put in the place below the head?

I have a PZO mpi5 for sell. If you are interested. please inform me.

[MicroscopyLearning]

The extra components and critical alignments necessary to convert a microscope like yours to DIC are roughly equivalent to converting a basic television set into a 3-D home theater.

I wonder if the promiscuous PZO DIC kit can fit his scope.

What does this kit contain? I have not been able to find much about it.

[microb]

Swift SW350T

Can the condenser be removed?

Is there a phase contrast option that can be bought for the Swift SW350T?

[DonSchaeffer]

Don't laugh but I think you can get pretty close to a DIC look by closing your condensor iris down in bright field, adjusting the contrast, and focusing carefully.

[MicroBob]

Hi Don,
can you post an image where your method has actually worked?

Bob

[MicroscopyLearning]

Swift SW350T

Can the condenser be removed?

Is there a phase contrast option that can be bought for the Swift SW350T?

It appears that it can. It has screws that look like they can be taken out. I do not think there is an option for phase contrast on this microscope, but I will look.

[MichaelG.]

Don't laugh but I think you can get pretty close to a DIC look by closing your condensor iris down in bright field, adjusting the contrast, and focusing carefully.

I think you will find that approach creates diffraction artefacts, Don
… The ‘look’ may be similar, and quite pleasing, but much of the ‘information’ is fake.

MichaelG.

[DonSchaeffer]

I alsays thought microscope optic relies on diffraction patterns. It's basically all fake.

[BramHuntingNematodes]

But we do want our image to have some sort of correspondence with the observed object in a reliable, consistent fashion. Gray gives a good illustration of the spurious artifacts in his Handbook, showing that non-existent holes can be made to appear in torn foil with a sufficiently tamped-down NA.

The appearance of relief in DIC is also false, but It's false in a different way than oblique or field stop narrowing. There then is at least one difference in the techniques.

[farnsy]

The components in a DIC system, from the bottom (light source) to the top are:

1. A linear polarizer (easy to get)
2. A lower Nomarski prism (has to be the right one for your objective)
3. A fluorite or apochromatic objective (Swift does not sell any of these but you may be able to find them on old microscopes)
4. An upper Nomarski prism (also specific to your objective)
5. An analyzer (that is, another linear polarizer)

To address the original question, the Nomarski prisms are not anything a regular microscope comes with. They are specialized equipment designed for DIC . On my scope, I have a lower prism for 10X, one that works for 20X and 40X, and one that works for 100X. One upper prism (slider) works for 10X-20X, another for 40X-100X. If you buy them direct from the Chinese factory, the kit costs just over $3,000 before shipping and tariffs with a 6 week lead time or so. I'm pretty sure this is rock bottom pricing for this equipment (new). That's why it probably doesn't make much sense to try and adapt it for a $250 microscope.

The lower Normarski prisms can likely be placed in a condenser designed for phase contrast (mine is). The upper prisms and analyzer can be in sliders. Of course, your scope has to have a slider slot and a slider that can accommodate what you need to put in it.

In general, it's not real easy to add DIC to a system that wasn't designed for it.

[viktor j nilsson]

You don't need fluorite or apochromatic objectives for DIC. For best performance, you want the objective the system was designed for. In many cases that will be the better corrected objectives, but sometimes it is not. The BH2 era olympus DIC systems, for example, was designed for the SPlan Achromats. But the more highly corrected objectives also work quite well.

My older Olympus Vanox AH DIC system was designed to use the short-barrel plan Achromats, and don't work as well with the contemporary PlanApo's. So it's not a guarantee that Fluorites and PlanApo's give better DIC, even from the same maker and era.

[farnsy]

You don't need fluorite or apochromatic objectives for DIC.

That is interesting; not what I had heard. The folks who sold me my system said you need fluor or better and the only test I've been able to perform indicates that my 60X achromat doesn't work with my 40X/100X DIC components. There could be other reasons for that, though. I guess I should never say never.

[viktor j nilsson]

You don't need fluorite or apochromatic objectives for DIC.

That is interesting; not what I had heard. The folks who sold me my system said you need fluor or better and the only test I've been able to perform indicates that my 60X achromat doesn't work with my 40X/100X DIC components. There could be other reasons for that, though. I guess I should never say never.

The most likely explanation is that the prisms were designed for those objectives. Like I said, you want the objectives that the system was designed for. For modern systems, it is typically the better ones.

[DonSchaeffer]

Hi Don,
can you post an image where your method has actually worked?

Bob

Watch my videos about microbes.

[DonSchaeffer]

Hi Don,
can you post an image where your method has actually worked?

Bob

These are screen prints of a video. I usually erase the stills after I upload to YouTube.

four.jpg (30.27 KiB) Viewed 7928 times

five.jpg (69.47 KiB) Viewed 7928 times

six.jpg (109.6 KiB) Viewed 7927 times

[PeteM]

For comparison, some actual DIC video images. Go in about 10 seconds to get an idea of the detail and contrast possible with DIC:

https://www.youtube.com/watch?v=UFErSrAr5xM

[PeteM]

Or this:

https://www.youtube.com/watch?v=-6XH4DeQSvw

[DonSchaeffer]

Wow! That's the end of that argument. I think I was confusing phase contrast with DIC. What I was imitating was phase contrast!

[PeteM]

No problem. I just didn't want others to be confused. Closing the condenser iris down does increase contrast and depth of field, but at the expensive of resolution.

[DonSchaeffer]

The thing is, you can sometimes see things that will not be seen when the diaphragm is open.

[MichaelG.]

The thing is, you can sometimes see things that will not be seen when the diaphragm is open.

Some of which don’t actually exist … That was my point at post #13

MichaelG.

[DonSchaeffer]

You mean that some of those entities in my last image, the moving strings of bacteria, don't really exist? Those amoebas don't exist?

[Dubious]

If they are moving around, they probably do exist--for some suspected bacteria and amoeba, that's about the best I can do

The tradeoff between reduced resolution and more contrast as you close the iris down that last bit of range should be noticeable if you focus on a fixed object (ie, not moving) that has tiny detail.

DIC (which I would like to have someday) is impressive for many things but introduces its own artifacts, namely the hills/valleys/contours that don't actually exist, which can leave some waterlife looking like it was sculpted out of mud. I was looking at some traveling rotifers scoot along the other day using Hoffman Modulation Contrast (similar to DIC but probably even worse in this respect) and remember thinking it made them look like they had alligator hide.

[MichaelG.]

You mean that some of those entities in my last image, the moving strings of bacteria, don't really exist? Those amoebas don't exist?

No, I mean some of the ‘detail’ within them doesn’t exist.

MichaelG.
.

Edit: __ Please see p8 of the excellent paper by Michael W. Davidson and Mortimer Abramowitz

Available here: https://cw.fel.cvut.cz/b182/_media/cour ... oscopy.pdf

When the aperture diaphragm is erroneously closed too far, resulting diffraction artifacts cause visible fringes, banding, and/or pattern formation in photomicrographs. Other problems, such as refraction phenomena, can also produce apparent structures in the image that are not real (21).