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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Scarodactyl
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Re: dIY DIC

#61 Post by Scarodactyl » Tue Nov 08, 2022 10:30 pm

My 20x nikon planapo works fairly well with my nikon epi dic prism.

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essence25
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Re: dIY DIC

#62 Post by essence25 » Wed Nov 09, 2022 12:29 am

Are the Plan Fluor's for EPI? I have the 10x and 20x.

PeteM
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Re: dIY DIC

#63 Post by PeteM » Wed Nov 09, 2022 12:59 am

essence25 wrote:
Wed Nov 09, 2022 12:29 am
Are the Plan Fluor's for EPI? I have the 10x and 20x.
Assuming yours are the plan fluors marked for a .17mm cover slip rather than MPlans, they're meant for transmitted use. The 10x should resolve OK, with the likelihood of some loss of contrast if you're epi illuminating through the lens. Certainly worth a try.

20x normally has enough depth of field to give somewhat decent images without a cover slip (with the same caution that they're usually not optimized to baffle light from the back side). The Nikon plan fluors are high enough numerical aperture (.50), you might begin to see some loss of resolution. Still, epi DIC should sharpen things up a bit and there's some chance the 20x prism will give a somewhat even result (as it does for Stephen with his 20x Plan Apo). Since you have the kit, surely also worth a try.

LouiseScot
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Re: dIY DIC

#64 Post by LouiseScot » Wed Nov 09, 2022 10:14 am

Once I'm happy that my epi/vertical illuminator is behaving, I'll certainly give the two Nikon CFI60 objectives a go with the epi dic. The epi dic nosepiece is obviously intended for finite optics so I'm not sure whether it can still work with even the epi infinity objective anyway? I've previously presumed that the prisms are so close to the rear aperture stop that they wouldn't realise the difference but maybe I'm quite wrong! I forgot to mention before that I have a Zeiss Inko DIC condenser and will try that out (though the iris diaphragms are currently stuck!). I'm not sure whether it's possible to get any of the Zeiss prisms to work with the Nikon reflected light prisms on the nosepiece but it might be worth a try! There's nothing like mix and match!

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

Scarodactyl
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Re: dIY DIC

#65 Post by Scarodactyl » Wed Nov 09, 2022 8:56 pm

Finite vs infinity doesn't matter. You can get away with some mis.atching with epi DIC anyway.
The 20x/0.75 gives surprisingly decent views of wafers in coaxial epi illumination without a coverslip, though of course it's significantly better with one. Oblique seems to be a little less forgiving.

LouiseScot
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Re: dIY DIC

#66 Post by LouiseScot » Wed Nov 09, 2022 9:25 pm

Scarodactyl wrote:
Wed Nov 09, 2022 8:56 pm
Finite vs infinity doesn't matter. You can get away with some mis.atching with epi DIC anyway.
The 20x/0.75 gives surprisingly decent views of wafers in coaxial epi illumination without a coverslip, though of course it's significantly better with one. Oblique seems to be a little less forgiving.
Thanks for the reassurance! Fingers crossed I can get the epi DIC working with the proper 5x Epi, at least. Anything else will be a bonus!
Cheers

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

jmp
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Re: dIY DIC

#67 Post by jmp » Thu Nov 10, 2022 12:59 am

I've had some success using a single Sanderson prism for DYI DIC.

Here´s a diatom lineup, from one of those Victorian slide makers, with a 10x LOMO objective:
DSC_3854_small.JPG
DSC_3854_small.JPG (45.61 KiB) Viewed 2262 times
This is the result of translating the prism along its shorter edge (left to right across the interference pattern, see the last image in this post):
DSC_3856_small.JPG
DSC_3856_small.JPG (39.61 KiB) Viewed 2262 times
There's still an image-doubling-and-shifting artifact, more evident in the top figure that I'm sure has more to do with the narrow prism (about ~1cm wide) and the crude jig that I used for testing:
20220904_175537'_small.jpg
20220904_175537'_small.jpg (56.31 KiB) Viewed 2262 times
I´m testing this in an inverted LOMO microscope that brings the back focal plane of 10x and 20x objectives to locations in the tube that were designed for sliders that hold either phase rings or a Wollaston prism for DIC (which recently surfaced in another forum thread). Easy access to the back focal plane of the objective greatly simplifies the use of Sanderson prisms. Also, instead of a prism before the condenser this system was designed to use a polarizer with a slith in a slider before the condenser (so, plas-DIC really). Again, having to fiddle with just one prism greatly simplifies things.

Initially I tested a 3D printed bending jig, but the bending force needed to generate the desired fringe pattern was more than what the plastic frame would take. I came with the all-metal contraption above to be able to apply more bending force, and still be able to place the prism in the slider slot. I imagine that a machined aluminum block would work wonders for this. Anyway, the crude jig worked better than I expected, but the edge of the prism ends up close or within the light path and my guess is that this might be the cause of the artifacts I´m seeing. Here´s a view of the interference finges at the back focal plane of the 10x objective (Sanderson prism jig inserted, but with the slith slider not inserted):
20220904_170644.jpg
20220904_170644.jpg (45.91 KiB) Viewed 2262 times
The edge of the prism is clearly visible on the right side of the image.

In all it looks feasible to use a Sanderson prism to get DIC in this platform; milage might vary for other platforms. I see two major limitations: easy access to the back focal plane of the objective, and the size of the jig needed to apply the bending force (shorter prisms appear to require more bending force than larger ones).

LouiseScot
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Re: dIY DIC

#68 Post by LouiseScot » Thu Nov 10, 2022 9:15 am

Hi

I thought I was getting somewhere with it (see my long thread from May last year https://www.microbehunter.com/microscop ... 78#p104178) but in the end decided what I was seeing wasn't true DIC. I did find that the amount of screw tension needed to produce the interference fringes towards the centre varied according to the orientation of the polycarbonate sheet when cutting a prism from it. One way needed a lot of tension, but turning the sheet 90 deg before cutting - not much at all. As in the original paper, access to the objective bfp can be obtained via some simple 2f relay optics. Anyway, I've abandoned that project for now. If I can get my epi dic nosepiece working, I might see if a polycarbonate prism can be used at the condenser side for transmitted dic.

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

Sure Squintsalot
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Re: dIY DIC

#69 Post by Sure Squintsalot » Tue Nov 29, 2022 12:20 am

I'm trying to fit a polycarbonate Sanderson Prism to the condenser-side of my Optiphot, which has legitimate Nomarsky prisms on the objective side. So far, my testing has been limited to 5x and 40x objectives and a few pretty crappy DIY slides of diatoms fixed in Permount; still looking for decent deals on DIC objectives! I machined an aluminum holder that can provide a goodly amount of force on two different sized plates:
Screenshot 2022-11-28 165803.jpg
Screenshot 2022-11-28 165803.jpg (111.18 KiB) Viewed 2093 times
Additionally I'm testing different thicknesses of polycarbonae: 1.90mm (pictured), 2.40mm, and 2.87mm, and 10.27mm, among others, with the goal of seeing what thickness polycarbonate and cut orientation works best.
jmp wrote:
Thu Nov 10, 2022 12:59 am
I've had some success using a single Sanderson prism for DYI DIC.
Here´s a diatom lineup, from one of those Victorian slide makers, with a 10x LOMO objective:
These look a little like my results, but without the double-image.
jmp wrote:
Thu Nov 10, 2022 12:59 am
This is the result of translating the prism along its shorter edge (left to right across the interference pattern, see the last image in this post):

There's still an image-doubling-and-shifting artifact, more evident in the top figure that I'm sure has more to do with the narrow prism (about ~1cm wide) and the crude jig that I used for testing:
Yep....looking a lot like my results, too.
jmp wrote:
Thu Nov 10, 2022 12:59 am
I´m testing this in an inverted LOMO microscope that brings the back focal plane of 10x and 20x objectives to locations in the tube that were designed for sliders that hold either phase rings or a Wollaston prism for DIC (which recently surfaced in another forum thread). Easy access to the back focal plane of the objective greatly simplifies the use of Sanderson prisms. Also, instead of a prism before the condenser this system was designed to use a polarizer with a slith in a slider before the condenser (so, plas-DIC really). Again, having to fiddle with just one prism greatly simplifies things.

Initially I tested a 3D printed bending jig, but the bending force needed to generate the desired fringe pattern was more than what the plastic frame would take. I came with the all-metal contraption above to be able to apply more bending force, and still be able to place the prism in the slider slot. I imagine that a machined aluminum block would work wonders for this. Anyway, the crude jig worked better than I expected, but the edge of the prism ends up close or within the light path and my guess is that this might be the cause of the artifacts I´m seeing. Here´s a view of the interference finges at the back focal plane of the 10x objective (Sanderson prism jig inserted, but with the slith slider not inserted):
I've had decent luck with lightly bending a 1.90mm plate. There's no way a 3D printed unit would have survived the strain I put my holder. Different scopes and optics might allow different results, however.
jmp wrote:
Thu Nov 10, 2022 12:59 am
The edge of the prism is clearly visible on the right side of the image.
I see these interference patterns with too much bending of the plate. I also see the edge of the plate, and resultant oblique lighting on the smaller of the two plates I'm testing which is a sorta convenient way to distinguish it from actual DIC.
jmp wrote:
Thu Nov 10, 2022 12:59 am
In all it looks feasible to use a Sanderson prism to get DIC in this platform; milage might vary for other platforms. I see two major limitations: easy access to the back focal plane of the objective, and the size of the jig needed to apply the bending force (shorter prisms appear to require more bending force than larger ones).
I agree. I am, however, struck by how fiddly my system is: the condenser must be just right as must the field and condenser diaphragms. Polarizers too must also be angled just right with respect to the lower Sanderson plate and the upper Nomarsky prism. Once dialed in, the effect is pretty mesmerizing!
Plankton at center, shot through 10x eyepiece and 40x objective: unadorned, regular 'ol brightfield:
Screenshot 2022-11-28 211018.jpg
Screenshot 2022-11-28 211018.jpg (94.24 KiB) Viewed 2072 times
Same, but with crossed pols, Sanderson plate at condenser, Nomarsky prism at back focal plane (objective):
Screenshot 2022-11-28 211113.jpg
Screenshot 2022-11-28 211113.jpg (126.48 KiB) Viewed 2072 times

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