MicrobeHunter.com Microscopy Forum

I played around a bit with the formula in graphing software and it seems like it can produce that kind of surface: Looks like a Mathematica plot? I do have access to Mathematica and was also playing with the parameters a bit yesterday, have you tried plotting the second derivative? My suspicion is ...

The Microstar IV does not have Critical Illumination, it has a modified Koehler Illumination system. Modified by the dispersion filter. The diagram posted at the beginning of the thread shows a Koehler illumination system, with the beam focusing ahead of the object plane and providing a defocused s...

Just occurred to me -- possibly the reason the outer image is hazier with less distinct focus is because my crudely-fractured piece of cover glass is not covering the periphery of the first lens well.

I'm calling the two regions of the aspheric surface "inner" (0-10 mm radially) and "outer" (10-20 mm radially). The inner region actually images the filament just before the collimating lens, 5 mm below the face of the casting where the collimating lens rests. The outer region and collimating lens t...

Same source (optitec2020) might have them? Not really clear to me what they are selling, I guess "lambda" alone should imply full-wave? But some of the "Wave Plate Retarder Lambda" listings say quarter-wave in the actual listing text, others don't specify. Would be interesting to compare a ‘proper’...

PeteM wrote: ↑

Sat Oct 17, 2020 8:17 pm

FWIW, an Ebay seller has recently been offering very affordable quarter wave plates laminated between (usually) acrylic and sometimes glass.

Do you know of any affordable sources for full-wave plates?

With the filament being visible now, it may be possible to find its focal plane by moving a viewing screen (e.g. frosted class or tissue paper) up and down underneath the condenser and see where it lands. I did try this briefly last night but the results were confusing due to the aspheric surface a...

Welcome, I am also in San Diego with some AO/Reichert stuff. You should post some photos of your 120 darkfield setup. Seems like the upgraded illumination stands 20/120/420 are not so common on the used market (eBay at least) these days.

Wes wrote: ↑

Sat Oct 17, 2020 2:26 pm

Cool shots! Third one I like the most, psychedelic zebra pattern.

Yeah the third one looks a lot like one of those sunset-reflected-in-a-breaking-ocean-wave photos.

I have a broken Microstar IV that I have been stripping for parts, and from what I recall that lens did look aspheric. According to the patent it is intended to be, but a lot less dramatically so than the drawing makes it look - according to the text and the lens surface equation they give it's sim...

I popped the second collector lens out of my assembly that was already missing the first one (came out very easily which probably explains why the first one was missing) and got a photo of a reflection of a ruler in the aspheric surface which shows the shape pretty well. The curvature definitely doe...

Adhering a piece of cover glass to the frosted collector lens with Cargille type B worked well and the filament is clearly visible through a phase telescope, so I guess I now have a 410 with a "less-modified" Koehler system. The filament appears pretty close to conjugate with the condenser diaphragm...

These old filaments were wide enough to function as an extended source of light when projected by the condenser onto the specimen. Yes, and as we were just discussing, a pure Koehler system with no diffuser can still be though as critical illumination system behaving as if the opening in field diap...

I guess I am not really following the broader argument... Having the filament focus at the conjugate plane ( field diaphragm, object , visual) is critical illumination. Then my following comment was suggesting that maybe we were talking about different things, since I (and I think Brian) were discus...

...the frosted glass, making an evenly-lit field, is right before the field iris which is to be conjugate with the specimen. Look upon the frosted glass as 'the filament' in this kind of system, slightly defocused from the specimen plane so you don't see the granularity of the actual frosted surfac...

I had in mind, and I think Brian was referring to, the other set of conjugate planes -- filament, condenser aperture diaphragm, objective rear focal plane, exit pupil? The filament is clearly fairly close to being conjugate with the others in both the patent design and the actual 410, but... Is the ...

The way it bends straight lines, looks more extreme than just parabolic to me, but hard to get much of a sense of shape looking at the lens itself. On the other hand, lens II performs differently than expected. It may just be that imaging the filament exactly at the condenser pupil is not hugely cri...

Five is great, I was expecting that you had to order a 1000 of them. Yeah, 5 seems very low even if the design is already complete. Maybe they share many elements with other objectives that are in production, and the differences are mainly in assembly, like the positioning/spacing of the elements?

It may be that subsequent iterations were deemed too derivative to be worthy of their own patent. Could be, I do have a couple beater 110s now that I was going to try to mix-and-match into a good one but have not looked at them closely yet. When I get a chance I will take one apart and see how well...

Thanks, I will continue to keep an eye out for a 50. I don't think I have ever seen one for sale individually on eBay, although there is currently a comically-overpriced set of neoplans including the 50, as well as a couple beat-up 410 stands that have one.

I have also been trying to better understand the 410 illumination system, a few thoughts: As a simple example, this patent seems to closely match the diascopic illuminator in my Microstar IV (the actual spacing/sizes are different in the real thing of course, but the same lens elements in the same a...

Bemoc wrote: ↑

Thu Oct 15, 2020 7:33 pm

Now, since reading your post, I can just say 'trafo', lol. It did take me a minute to figure that word out.

Same, a few weeks ago, while reading some old posts about series 10 illumination. Canadian thing?

Certainly possible there is something wrong with my neoplan 100 and I only have one of them so can't compare. Focus point is close, I went back and checked more carefully after you mentioned it, it is about 5 um off from the planachro I have been comparing it to, does that sound reasonable? And the ...

Plasmid wrote: ↑

Thu Oct 15, 2020 5:21 am

Would you mind recommending the supplier you use?

It was all one-off lots of new surplus slides and cover glass from various eBay sellers. Chemglass, VWR, Thermo, Cardinal Health, Knittel are some brands, for example.

I have not been able to obtain working distance with my 100x Neoplan, at least with a cover glass that is, theres just not enough room for the objective to clear the cover glass, regardless of how thin I prepare the slide sample. Have you encounter the same issue? Working distance is small but I ha...

I have mostly plan achro objectives but have had one neoplan 10X for a while. Viewing through the eyepieces I would say the difference vs. the 10X plan achro is mild -- noticeable if you put them both in the nosepiece and switch back and forth, but not really dramatic. Based on that experience with ...

The markings on the microscope indicate that it can safely accept any line voltage between 100 and 240 volts at either 50 or 60 Hz. So yeah, if the connectors fit, the cable is marked as meeting the relevant safety regulations, and you are buying it from a reputable distributor, there should be no p...

Any cord with the correct connectors should be fine. The line frequency doesn't matter for the cord, and I think it would not be legal to sell a cord with UK plug that was not approved to handle the voltage.

IEC 60320 C13/C14

Power cords are often referred to as "IEC cords" in the US, not sure about elsewhere.

I was looking at the colorful artifacts in this one, particularly around the edge: