Making my own Leitz Heine oil cap - questions about adhesives and optics

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viktor j nilsson
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Making my own Leitz Heine oil cap - questions about adhesives and optics

#1 Post by viktor j nilsson » Sun Feb 02, 2020 12:44 am

I have a Leitz Heine, but no oil cap. After looking in vain for an affordable oil cap, I've started thinking about making my own.

I've studied the patent a bit, and the oil cap simply looks like a hemispheric (half ball) lens that fits into the concave surface of the upper lens:

Image
Image

Is it typical for high NA oil condensers to use half ball lenses as top lens? I checked a Zeiss Jena 1.2 cap that I have lying around. It also seemed to hold a simple half ball lens, but with a larger diameter (around 15mm if I remember correctly). I know that the focal length FL of a half ball lens is simply dictated by the diameter of the lens (FL ~ R/n-1, where n is the refractive index). But what is the relationship between FL/diameter and NA? I can't find it now, but I remember reading a thread where Apochronaut mixed and matched top lenses between condensers, and found some very good combinations. Is it just a matter of finding a half ball lens with the right diameter? If that is the case - why aren't more people making their own top lenses? Of course, this assumes that the cheap chinese ball lenses are of good enough quality - but they seem like a fairly easy thing to produce?


Back to the Leitz Heine.
I've measured the diameter of the concave surface of the top lens (by testing paper disks of varying diameter) and found that a ~12mm hemisphreric lens seems to be a good fit.

I have ordered two cheap half-ball lenses (N-BK7 glass) from China; one 12mm diameter, and one 11.12mm diameter. I think that at least one of them should be a very close match.

I've drawn up a sketch in Fusion 360, that I plan to print using the Selective Laser Sintering printer we have at work.

Image

Here' are my final questions:

What adhesive should I use to fix the half ball lens to the cap? I definitely do not want immersion oil in the Heine. I was thinking of using silicone. Or are there better alternatives?

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#2 Post by PeteM » Sun Feb 02, 2020 5:46 pm

Don't know what's best. My experience with silicon adhesives, though, is that they don't adhere well to anything with any sort of contamination. And the porosity of an SLS part might be a problem unless you find a way of sealing it. You'd likely want to test the SLS material and your adhesive first.

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#3 Post by viktor j nilsson » Tue Feb 04, 2020 6:00 am

Thanks, PeteM. I'm thinking it might be wise to use one adhesive to keep the glass in place, and another to seal the gap. Maybe enamel paint for the seal. Or Shellac? I don't plan to clean it with Xylene so that should be OK.

I had a little closer look at the patent, and in Figure 1A the top lens looks like a regular half-ball lens. But in Figure 3 it looks like a little material has been removed from the flat, upper part. I guess patents aren't always accurate. I am not sure if, or how much, this might matter.

If anyone would be willing to try to estimate the diameter and height of their Heine oil cap lenses that would be highly appreciated!

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#4 Post by MicroBob » Tue Feb 04, 2020 7:35 am

Hi Victor,
that is an interesting project!
Pete's hint with the porosity is good, you should fill the pores before use. Epoxy glue becomes failry fluid when warmed a bit an woulp probably soak into the pores well.
Silicone doesn't have much glueing force so I would choose something else to take up the mechanical stresses that can occur in practical use. Would Epoxy do well with your immersion oil and solvents? Can you make the part so the lens is held against downward forces just by the form of the lens seat?

Bob

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#5 Post by viktor j nilsson » Tue Feb 04, 2020 7:49 am

MicroBob wrote:
Tue Feb 04, 2020 7:35 am
Hi Victor,
that is an interesting project!
Pete's hint with the porosity is good, you should fill the pores before use. Epoxy glue becomes failry fluid when warmed a bit an woulp probably soak into the pores well.
Silicone doesn't have much glueing force so I would choose something else to take up the mechanical stresses that can occur in practical use. Would Epoxy do well with your immersion oil and solvents? Can you make the part so the lens is held against downward forces just by the form of the lens seat?

Bob
Thanks for your input, and yes! The form of the hole follows the spherical shape of the lens. This is hard to see on the sketch, but easier here:

Image.

Thus I expect the lens to be well seated on its own, but I still want to make sure it doesn't fall out. I also think I might need to adjust the model a bit after printing (sanding it down, or printing a new one with greater tolerances) as I'm not sure how precise the print will be.

I like working with epoxies, that is a good suggestions. The reason I considered silicone is that it is fairly easy to remove if the lens turn out to be mounted slightly at an angle. If I use epoxy, I definately want to make sure I get everything properly lined up on the first try.

Need to read up and see how epoxy stands up to the substances it would encounter.

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#6 Post by MichaelG. » Tue Feb 04, 2020 8:26 am

Lakeside No. 70C is a remarkable [and ‘reassuringly expensive’] cement, widely used when preparing thin petrographic sections. ... It may be very suitable for this job.
http://www.lakeside-products.com/html/cement.html

Regrettably; although its properties are well described, I have never found its recipe !!

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#7 Post by viktor j nilsson » Tue Feb 04, 2020 8:42 am

MichaelG. wrote:
Tue Feb 04, 2020 8:26 am
Lakeside No. 70C is a remarkable [and ‘reassuringly expensive’] cement, widely used when preparing thin petrographic sections. ... It may be very suitable for this job.
http://www.lakeside-products.com/html/cement.html

Regrettably; although its properties are well described, I have never found its recipe !!

MichaelG.
Thanks, Michael! As I have no idea if this will even work, I'd like to keep the costs down to a minimum. But it does seem like a very very good product!

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#8 Post by MicroBob » Tue Feb 04, 2020 9:22 am

viktor j nilsson wrote:
Tue Feb 04, 2020 7:49 am
if the lens turn out to be mounted slightly at an angle.
Perhaps you can assemble it upside down so the barrel front and the lens rest on a piece of plastic foil on a piece of flat glass.
When your lens is held mechanically silicone will do as a sealant and is easy to repair.

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#9 Post by MichaelG. » Tue Feb 04, 2020 10:30 am

MicroBob wrote:
Tue Feb 04, 2020 9:22 am
viktor j nilsson wrote:
Tue Feb 04, 2020 7:49 am
if the lens turn out to be mounted slightly at an angle.
Perhaps you can assemble it upside down so the barrel front and the lens rest on a piece of plastic foil on a piece of flat glass.
I suspect that the original centring/levelling method might have been to spin the assembly in the lathe, and use a ‘pusher’ ... This was common practice for both optical assemblies and horological jewels.

MichaelG.
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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#10 Post by viktor j nilsson » Tue Feb 04, 2020 10:35 am

MichaelG. wrote:
Tue Feb 04, 2020 10:30 am
MicroBob wrote:
Tue Feb 04, 2020 9:22 am
viktor j nilsson wrote:
Tue Feb 04, 2020 7:49 am
if the lens turn out to be mounted slightly at an angle.
Perhaps you can assemble it upside down so the barrel front and the lens rest on a piece of plastic foil on a piece of flat glass.
I suspect that the original centring/levelling method might have been to spin the assembly in the lathe, and use a ‘pusher’ ... This was common practice for both optical assemblies and horological jewels.

MichaelG.
Interesting, I did not know that but it makes a lot of sense.

Because the rear surface should be more or less perfectly spherical, and hence rather unaffected by rotation, and the top (flat) surface sealed to the cover slip with immersion oil with a similar refractive index, my intuition tells me that the levelling is not as critical in this case as it would be in an objective intended to be used dry. Still, I will consider my options to make sure it is as flat as possible. I might, of course, also want to use it dry in some cases.

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#11 Post by MichaelG. » Tue Feb 04, 2020 4:10 pm

This is an interesting document, Viktor
https://wp.optics.arizona.edu/optomech/ ... nses-1.pdf
You might find some useful ideas in there.

MichaelG.
.

P.S. I have just downloaded the Patent, and I’m almost certain that your copy of Fig.3 is a little distorted
... The one I have seems to show the lens [as we would expect] hemispherical.
https://patentimages.storage.googleapis ... 674157.pdf
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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#12 Post by viktor j nilsson » Wed Feb 05, 2020 7:04 am

Very interesting document, I'll have closer read when I find time.

I think we have the same version of the patent.
There is clearly a slight discrepancy between Fig. 1a and Fig. 3. The lens in 3a looks very much like a half sphere, whereas the one in Figure 3 has been ground down ~0.5 mm or so. Its rear surface still looks perfectly round, though.
Image

Will it matter? Probably not much, I think.

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#13 Post by MichaelG. » Wed Feb 05, 2020 8:27 am

Yes, I agree with your geometry, Viktor

I therefore suspect that Fig.3 is simply a case of ‘artistic license’ being used for the sake of visual clarity.

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#14 Post by abednego1995 » Wed Feb 05, 2020 8:44 am

With these kind of hemispheric top lenses, you have to consider "how thick" your slide glass will be. Note the tight tolerances for oil DF condensers.

BR,
John

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#15 Post by viktor j nilsson » Wed Feb 05, 2020 9:17 am

abednego1995 wrote:
Wed Feb 05, 2020 8:44 am
With these kind of hemispheric top lenses, you have to consider "how thick" your slide glass will be. Note the tight tolerances for oil DF condensers.

BR,
John
Thanks for the input, John. Do you have a grasp of what aspects of the hemispheric lens that will determine if the top lens will fit a standard (1.2mm?) slide? Is it mainly the curvature of the back surface (diameter), or is the height of the lens also important? My intuition is that slight mismatches in the height can be somewhat compensated by moving the condenser up and down (and thus altering the thickness of the immersion oil layer).

I assume that Leitz chose their top lens to fit this standard, and I am trying to replicate it by choosing a half ball lens with the same curvature (diameter) as the original lens. However, as I explained above, the patent gives slightly conflicting information about the height of the lens. Do you know how getting this wrong might impact the results?

I mainly plan to use the top lens to get DF with a Nikon CF Fluor 40x 1.30 with iris. As I can vary the NA of both the condenser and objective, I think that the tolerances might be a little greater than if I were trying to get a fixed-NA DF oil condenser to work with a fixed-NA objective (but I may not be able to get as close to maximum NA as with a perfect top lens).

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#16 Post by Sabatini » Wed Feb 05, 2020 4:49 pm

Thank you very much for the documents related to the Heine

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#17 Post by apochronaut » Thu Feb 06, 2020 3:22 pm

viktor j nilsson wrote:
Wed Feb 05, 2020 7:04 am
Very interesting document, I'll have closer read when I find time.

I think we have the same version of the patent.
There is clearly a slight discrepancy between Fig. 1a and Fig. 3. The lens in 3a looks very much like a half sphere, whereas the one in Figure 3 has been ground down ~0.5 mm or so. Its rear surface still looks perfectly round, though.
Image

Will it matter? Probably not much, I think.
The left hand image is only a partial representation.
If a close look is taken, the the upper plano/convex lens is only allowed to settle into the well below, as far as the lower surface of the lens mount will allow it. That is it's precision shim, so to speak. Since the top surface sits the thickness of upper lens mount above the top edge of the condenser refracting glass, the depiction of it sitting higher in the left hand image is accurate. They have just not included the thickness of the upper lens mounting in that image.

There is a slight discrepancy however in the curvature of the convex portion of the top plano/convex lens and the curvature of the bowl that it rests into. There must be a high degree of precision there, in order to space it ,otherwise damage could occur when the top is threaded on. I have never had a Heine condenser, nor have I had one apart just to look at it but I am reasonably familiar with it's function. However, in the case of it's cap. Is the gap between the upper refracting glass of the condenser and the top lens an air gap, or is it to be filled with oil?

The reason I ask that is , if it is filled with oil; then the top glass section of the condenser becomes homogeneous. That would mean that the two glass components should be of the same n. The same in fact as the immersion oil used. If it is an air gap, then it should mean that the upper lens would have a higher n than the lower refracting glass. I am assuming that the N.A. of the oiled condenser needs to be 1.4? Typically, the curvature of the bottom surface of the top plano/convex lens in a 1.4 N.A. condenser has a rather strong curvature, followed by a large meniscus lens of an even greater curvature. The exit diameter of 1.4 N.A. top lenses are narrower than that of a 1.25 for instance due to the more severe curvature of the convex portion.
In the drawn image ,the curvature of the upper refracting glass is drawn as more severe than the curvature of the top lens, which makes sense , since aside from the DF stop, that glass functions as the meniscus lens.
My impression is that the n of the upper lens might need to be from a fairly high n glass. BK7 is around 1.51, light crown 1.54 lower N.A. flint 1.57. It will make a difference to the N.A. of your condenser. BK7 might not be enough.
I had a look at a patent for an AO 1.3 N.A. achromat/aplanat filed in 1973. This would be the condenser used in the AO 21 DIC microscope and the fluorescence scopes, some others. The n of the top lens is 1.521. That condenser is almost identical to the later condenser used in the series 400 scopes where the 1.30 planfluorite objective was fitted, only it was upgraded to a 1.4 N.A. and likely a higher n front lens. The diameter of the upper plane surface on those is 9mm , the extension from the plane surface to the bottom of the hemisphere is about 8mm, fitted into a brass housing of 28mm o.d., with an internal thread of just over 25mm( probably a 1" thread). I have a spare one of those, if it is of interest to you. It is a brand new 1.4 N.A. top lens fitted into a housing. Cost would be my cost( around 20.00, I believe it was) plus shipping., which would be about 12.00, I am guessing.

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#18 Post by viktor j nilsson » Fri Feb 07, 2020 10:51 pm

Thanks a ton for your input, Phil! Reading your post and the AO patent has gotten me a lot further to understanding what is going on.

apochronaut wrote:
Thu Feb 06, 2020 3:22 pm
The left hand image is only a partial representation.
If a close look is taken, the the upper plano/convex lens is only allowed to settle into the well below, as far as the lower surface of the lens mount will allow it. That is it's precision shim, so to speak. Since the top surface sits the thickness of upper lens mount above the top edge of the condenser refracting glass, the depiction of it sitting higher in the left hand image is accurate. They have just not included the thickness of the upper lens mounting in that image.
Yes, the left-hand figure omits the top lens mount. But this still does not explain why the lens looks like a full half-sphere in Figure 1A, but somewhat less of a half-sphere in Figure 3. If it were a full half-sphere in Figure 3, the lens would reach up to the bottom of the cover glass. Actually, when I think about it - maybe they drew the edge of the top lens a little below the cover slip simply to illustrate that there is an oil-filled gap between the lens and the cover glass?

apochronaut wrote:
Thu Feb 06, 2020 3:22 pm
There is a slight discrepancy however in the curvature of the convex portion of the top plano/convex lens and the curvature of the bowl that it rests into. There must be a high degree of precision there, in order to space it ,otherwise damage could occur when the top is threaded on.
Yes, the lens 11 does look like it have a slightly smaller diameter than the bowl 11a, which makes sense. That is actually why I bought one 12mm lens and a 11.12mm lens. I measured the curvature of the bowl to around 12mm diameter spherical, but figured it would be best to also try a hemispherical lens with a slightly smaller diameter (and hence more severe curvature).

The unit 11 can slide up and down inside the Heine. Lens 11a remains stationary at the top. Figure 3 shows the condenser with unit 11 at its uppermost position. I agree that I will need to be careful to get the spacing right so as to not damage the lenses when mounting the top lens (or moving unit 11 to its top position).

apochronaut wrote:
Thu Feb 06, 2020 3:22 pm
I have never had a Heine condenser, nor have I had one apart just to look at it but I am reasonably familiar with it's function. However, in the case of it's cap. Is the gap between the upper refracting glass of the condenser and the top lens an air gap, or is it to be filled with oil?
There is an air gap between lens 11a and unit 11.

apochronaut wrote:
Thu Feb 06, 2020 3:22 pm
The reason I ask that is , if it is filled with oil; then the top glass section of the condenser becomes homogeneous. That would mean that the two glass components should be of the same n. The same in fact as the immersion oil used. If it is an air gap, then it should mean that the upper lens would have a higher n than the lower refracting glass. I am assuming that the N.A. of the oiled condenser needs to be 1.4?
Correct, the original top lens is meant to achieve a NA of 1.4. However, it doesn't need to go that high in my DIY setup. I would be more than happy if I was able to get somewhere around 1.25-1.30.

apochronaut wrote:
Thu Feb 06, 2020 3:22 pm
Typically, the curvature of the bottom surface of the top plano/convex lens in a 1.4 N.A. condenser has a rather strong curvature, followed by a large meniscus lens of an even greater curvature. The exit diameter of 1.4 N.A. top lenses are narrower than that of a 1.25 for instance due to the more severe curvature of the convex portion.
In the drawn image ,the curvature of the upper refracting glass is drawn as more severe than the curvature of the top lens, which makes sense , since aside from the DF stop, that glass functions as the meniscus lens.
My impression is that the n of the upper lens might need to be from a fairly high n glass. BK7 is around 1.51, light crown 1.54 lower N.A. flint 1.57. It will make a difference to the N.A. of your condenser. BK7 might not be enough.
I had a look at a patent for an AO 1.3 N.A. achromat/aplanat filed in 1973. This would be the condenser used in the AO 21 DIC microscope and the fluorescence scopes, some others. The n of the top lens is 1.521. That condenser is almost identical to the later condenser used in the series 400 scopes where the 1.30 planfluorite objective was fitted, only it was upgraded to a 1.4 N.A. and likely a higher n front lens. The diameter of the upper plane surface on those is 9mm , the extension from the plane surface to the bottom of the hemisphere is about 8mm, fitted into a brass housing of 28mm o.d., with an internal thread of just over 25mm( probably a 1" thread). I have a spare one of those, if it is of interest to you. It is a brand new 1.4 N.A. top lens fitted into a housing. Cost would be my cost( around 20.00, I believe it was) plus shipping., which would be about 12.00, I am guessing.
Thanks for the offer! I do however think a 9mm lens will be too small.
The rays that bounce around in unit 11 can only "escape" through the narrow gap at the very top, where the rays labelled "24" exits unit 11.
So based on my understanding, a suitable top lens must:

1) Be wide enough to collect the light rays labelled "24"
and
2) Have a strong enough curvature and/or refractive index to refract these rays sufficiently to achieve a high NA.

I think you are right that the original lens probably had a fairly high n in order to reach 1.4. But I don't think that the curvature needed to be as great as that of the 1973 AO condenser, since the light rays "24" already have a rather steep angle when they leave unit 11 (the Heine has a NA of ~.75 or so when used dry without the top lens). Which is why I think the Heine has a relatively large (~12mm) hemispherical top lens compared to other high NA condensers.

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#19 Post by viktor j nilsson » Fri Feb 07, 2020 11:32 pm

I recieved the two BK7 hemispherical lenses yesterday and I've done some quick experiments. They were quite promising!

I first tried to simply place a lens inside the "bowl" of the lower unit and using the condenser dry (didn't want to risk getting oil in the condenser). This, however, resulted in a ton of weird internal reflections. Looking at the rear focal plane (RFP), there was not one hollow cone of light, but two or three concentric cones of light. Presumably the rays that left the lower unit were hitting the flat upper surface of the top lens at such an acute angle that it achieved total reflection, with weird results.

I then tried to create small "lens holders" by cutting 10, 11 and 12mm holes in transparent plastic and using them to hold the lenses slightly above the "bowl". Although fiddly, the lenses worked a lot better when I raised them a bit. I now got a single hollow cone of light at the RFP with both the 12mm and 11.12 mm top lenses. But the light cone was not very clean, with lots of halos and color shifts. This was probably a combination of using these uncoated lenses dry, and the lens being slightly (or grossly) tilted.

It was also quickly obvious that my adapter for mounting the Heine was unsuitable for high NA work, as I was not able to raise the condenser high enough to reach the bottom of the slide. The old adapter can be seen here: viewtopic.php?t=6861. I will need to make a new adapter ASAP. I have some ideas.

After this, I simply held the Heine with one hand under the stage, pressed against - but not attached to - the condenser holder of my Wild M20.

I also realized that I could oil the top lens directly to the slide - it adhered well enough to stay there on its own.

Having oiled the top lens to the slide, things were looking a lot better. I was getting a very narrow, crisp and clear cone of light at the BFP with the 12 mm lens. I could get DF easily with my Nikon CF Fluor 40x 0.85 and CF PlanApo 60x 0.90 dry objectives. This I could not do before without a top lens, so that was already an improvement. But it was clear I could reach quite a lot higher NA. How high, I will have to find out another day. It was too late and I didn't want to oil the objective.

So, the principle is working, but I will need to sort out some mechanic problems before I can really evaluate which lens, and at what distance from the bowl, works best.
Last edited by viktor j nilsson on Fri Feb 07, 2020 11:42 pm, edited 1 time in total.

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#20 Post by viktor j nilsson » Fri Feb 07, 2020 11:36 pm

By the way, here are the two lenses I bought if anyone is interested:
https://www.aliexpress.com/item/32902662159.html
https://www.aliexpress.com/item/32973679058.html

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#21 Post by MichaelG. » Sat Feb 08, 2020 8:19 am

Item 8 in the ‘Directions for Use’ seems quite explicit about usage of the immersion cap:
http://microscope.database.free.fr/Acce ... denser.pdf

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#22 Post by viktor j nilsson » Mon Feb 10, 2020 8:36 am

MichaelG. wrote:
Sat Feb 08, 2020 8:19 am
Item 8 in the ‘Directions for Use’ seems quite explicit about usage of the immersion cap:
http://microscope.database.free.fr/Acce ... denser.pdf

MichaelG.
Thanks, I actually haven't looked at that for a while. What exactly are you referring to regarding the usage of the immersion cap? Do you mean that they are only talking about using it with both the objevtive and condenser oiled? Or that the oil cap is meant to remain stationar just below the slide, adjusting only the mirror part?

I'm wondering if Leitz ever intended the cap to be used dry?

There's an eBay seller who sells adapters to fit the Heine to various microscopes, for example the Nikon Labophot:
https://www.ebay.com/itm/HEINE-to-Nikon ... SwFnFWFT8l

In the description, the seller cites the Better Microscopy blog:
https://bettermicroscopy.blogspot.com/2 ... art-2.html

In the blog post, the author claims that the Heine can be used with the oil cap dry:

Image

It would be great if someone with a Heine+Oil cap could show the quality of the illumination cone at the rear aperture with and without oil, so I know what to strive for!

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#23 Post by viktor j nilsson » Mon Feb 10, 2020 8:43 am

Btw, I just sent the .STL files for a new 39.5mm condenser sleeve adapter + oil caps (11.12mm and 12mm) to the SLS printer at work. They've been rather slow to respond, so I'm not sure how long it'll take.

Image

The "snap-on" fit of the 39.5mm adapter sleeve is a little experimental. I don't know how well it will work or how tight it will fit (I'm very new to 3D printing). I chose this approach as it enabled the adapter to be as low-profile as possible, which will ensure that the Heine can reach the bottom of the slide, in contrast to my earlier attempt.

Kind of wish I had the Heine version with a 39.5mm condenser sleeve. But hey, I got the Leitz Heine for $20 so I can't complain!

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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#24 Post by MichaelG. » Mon Feb 10, 2020 9:41 am

viktor j nilsson wrote:
Mon Feb 10, 2020 8:36 am
MichaelG. wrote:
Sat Feb 08, 2020 8:19 am
Item 8 in the ‘Directions for Use’ seems quite explicit about usage of the immersion cap:
http://microscope.database.free.fr/Acce ... denser.pdf

MichaelG.
... Do you mean that they are only talking about using it with both the objevtive and condenser oiled? Or that the oil cap is meant to remain stationar just below the slide, adjusting only the mirror part?

I'm wondering if Leitz ever intended the cap to be used dry?
.

My reading would be ... Yes, Yes, and No

MichaelG.
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apochronaut
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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#25 Post by apochronaut » Mon Feb 10, 2020 12:49 pm

Whether your condenser performs adequately dry in the .70-1.00 N.A. corridor, should be fairly easy to determine during use. You have the up to .70 version without the immersion cap and the oil immersion version with cap at whatever N.A. it ends up at as comparisons, that is presuming you have an objective in the .70 to 1.0 N.A. band with which to test it.
You could always just try it with an oil immersion objective too, bearing in mind that working dry, it should only detract from the peak performance of your 1.25 objective by about .10 N.A., which with many subjects it would be difficult to see any difference. Without the cap, there would be a considerable reduction, if the condenser works at .70.

viktor j nilsson
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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#26 Post by viktor j nilsson » Mon Feb 10, 2020 12:58 pm

apochronaut wrote:
Mon Feb 10, 2020 12:49 pm
Whether your condenser performs adequately dry in the .70-1.00 N.A. corridor, should be fairly easy to determine during use. You have the up to .70 version without the immersion cap and the oil immersion version with cap at whatever N.A. it ends up at as comparisons, that is presuming you have an objective in the .70 to 1.0 N.A. band with which to test it.
You could always just try it with an oil immersion objective too, bearing in mind that working dry, it should only detract from the peak performance of your 1.25 objective by about .10 N.A., which with many subjects it would be difficult to see any difference. Without the cap, there would be a considerable reduction, if the condenser works at .70.
I will for sure test how it performs and present the results here. I have several objectives in this range - a Nikon CF PlanApo 20x 0.75, a Nikon CF Fluor 40x 0.85 Dry, a Nikon CF PlanApo 60x 0.90 Dry, and a Nikon CF Fluor 40x 1.30 Oil with variable iris - so I should be able to pin down the NA range and performance of each combination with pretty good accuracy.

viktor j nilsson
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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#27 Post by viktor j nilsson » Mon Mar 02, 2020 11:13 am

The condenser caps have been printed, painted flat black with enamel paint, and the half-ball lenses have been glued in place with transparent silicone glue. I will be trying them out soon, but I first need to deal with some other issues. First, I need to clean up a little silicone that ended up on the half ball lens. Second, I think I will add a second layer of defence around the edge of the lens to protect against immersion oil. Maybe nail varnish?

And third, I need to print a new condenser sleeve adapter. Unfortunately, the 39.5mm sleeve of the condenser holder adapter turned out a little too narrow (39.4 rather than 39.5mm) in print and was also too thin and flexible. I did not expect the SLS nylon to be quite so soft. The condernser holder of my M20 also have very tight tolerances, the diameter of the condenser really needs to be 39.5mm+-0.05mm, or it wont grab on. Some other condensers I've tried (Zeiss jena) that were supposed to be 39.5mm have been too wide.

I tried to jerry rig it temporarily by putting electrician's tape around the sleeve. It allowed the Heine to stay in place, but the sleeve flexed so much that it was hard to get the condenser perfectly aligned with the optical axes. I've sent an updated version to the printer. Hope it'll work better.

The snap-on clips worked great, though! Very convenient and firm attachment. And I now get enough vertical movement to reach the bottom of the slide.

Oh, and I might have found a second Leitz Heine with the 39.5mm condenser sleeve AND oil cap for a very affordable price. So in the end I might not need this one at all. If I get it, I will of course try them out against each other to see how the DIY version works out!

viktor j nilsson
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Location: Lund, Sweden

Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#28 Post by viktor j nilsson » Sun Jun 13, 2021 8:03 pm

viktor j nilsson wrote:
Mon Mar 02, 2020 11:13 am
Oh, and I might have found a second Leitz Heine with the 39.5mm condenser sleeve AND oil cap for a very affordable price. So in the end I might not need this one at all. If I get it, I will of course try them out against each other to see how the DIY version works out!
After a long covid-related delay, I have finally managed to purchase the aforementioned Heine with oil cap. I've also made a very nice adapter that let's me mount the Heine on my Vanox AH. I really look forward to comparing my DIY oil cap against the real deal. I'll post the results here at some point.

Hobbyst46
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Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#29 Post by Hobbyst46 » Sun Jun 13, 2021 8:21 pm

viktor j nilsson wrote:
Mon Mar 02, 2020 11:13 am
...First, I need to clean up a little silicone that ended up on the half ball lens. Second, I think I will add a second layer of defence around the edge of the lens to protect against immersion oil. Maybe nail varnish?...
I do not know if that question is still open, but may I note that nail varnish is definitely incompatible with immersion oil.

viktor j nilsson
Posts: 760
Joined: Thu Aug 23, 2018 10:12 pm
Location: Lund, Sweden

Re: Making my own Leitz Heine oil cap - questions about adhesives and optics

#30 Post by viktor j nilsson » Sun Jun 13, 2021 8:35 pm

Hobbyst46 wrote:
Sun Jun 13, 2021 8:21 pm
viktor j nilsson wrote:
Mon Mar 02, 2020 11:13 am
...First, I need to clean up a little silicone that ended up on the half ball lens. Second, I think I will add a second layer of defence around the edge of the lens to protect against immersion oil. Maybe nail varnish?...
I do not know if that question is still open, but may I note that nail varnish is definitely incompatible with immersion oil.
Thanks, that's a good reminder. I've only glued them on with silicone, and have not had any leaks. So no need for adding anything else.

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