What even is this: Plan Apo 40x/1.0 W infinity f=180 unbranded m25 75mm long

[Scarodactyl]

So I recently won an eBay auction on this bad boy:





It just came in and it's just baffling. As the title of the thread says it's a Plan Apo 40x/1.0 infinity water immersion 0.17 f=180 75mmish long (excluding the threads) beast of an objective. It's gigantic, 38mm around on the objective alone and weighs a ton too. It has a 75mm parfocal distance (like Nikon Engineering objectives, I guess?) and an M25 thread, but the focal length is Olympus standard. It's unbranded but has a serial number of 00002 on it. It has some sort of electrical thing clamped around the top, and some other sort of thing clamped around the bottom with what look like tiny metal tubes sort of crudely added going down to the front lens element.

What the heck is this thing? Who made it, and how much did someone pay to have it made?? How did it end up in the inventory of some pawn shop/lost freight broker in Utah???

Anyway, it was the sort of thing I couldn't not buy at the price it went for, but I am not 100% sure what I'll do with it either.

[mrsonchus]

Cripes - it's gigantic! It looks as though it may be heated in some way?

[Plasmid]

Mi guess that being water immersion, the tip is some sort of cathode -55mv range to probably play around with action potentials on cell walls.. I've always thought about making something of the sort, but Im just guessing. .........

[Hobbyst46]

Heated by two gadgets. The top one - the brown tape - is a heating tape for use. Electrical. The collar with inlet and outlet tubing is likely a water circulation collar, to heat the nose of the objective. Was possibly used for the study of live cells at 37C; the cells were sitting in a petri dish on an inverted microscope, and the petri dish was possibly inserted in a stage incubator, so they wished to prevent heat conduction through the objective nose. All my wild conjectures of course.

Even a wilder guess - the bottom is a sort of a heated chamber for cells. and the whole think sits on the stage...

[apochronaut]

It looks more than a little like a Chinese industrial objective. The resason I say this is that I have been looking at a lot of Chinese objectives lately. First there are those water immersion objectives and then I have been putting together a set of planfluors. During the process I came across some L.W.D. highly corrrcted no cover objectives that had an almost identical paint scheme as that , also marked with F = 180mm. Is it marked with capitol W after the N.A.?
The Chinese industrial and research microscope development is a lot different than the Amscope scene.

Here is a thought. That blue colour code band with the distinct segmentation shows up on a series of 180mm infinity corrected objectives that are 100% perfect in both the 34mm and Reichert Austria 45mm systems. They all have the same corrections. Sharp as a tack and with perfect ca regularity, axis to edge. Some Chinese infinity corrected objectives exist that are 40X .66. Not .65 but .66. Aside from those, AO is the only company that ever produced that N.A.
Leica for sure sold some of their unwanted older or non-essential designs to some Chinese microscope concerns.

That objective may be a Reichert Austria design . They definitely produced higher end no cover water immersion stuff and infinity corrected designs are not that hard to fiddle with in terms of parfocality. Whoever bought it, probably didn't pay what one would think, especially if the design came cheap and the labour to make it even cheaper.

[Scarodactyl]

Thanks Apo, I appreciate your insight on that. You're probably the only one here who's gottena closer look behind the curtain so to speak. It is marked with a capital W right after the 1.0 as you say.
I'll need to get some adapters together and see if I can get a sense of the image it produces. I don't have a Reichert system to try it on but heck, I might get one of it looks promising.

[MicroBob]

Interesting catch!
With all the heating it would make sense to measure the temperature. Is it possible that the tiny elements next to the front lens are a thermocouple? They put out a tiny voltage, perhaps you can measure it.

Bob

[Hobbyst46]

Interesting catch!
With all the heating it would make sense to measure the temperature. Is it possible that the tiny elements next to the front lens are a thermocouple? They put out a tiny voltage, perhaps you can measure it.

Bob

Bob, indeed, that wiring in the plane of the front lens very likely lead to a sensor. However can you see their other end ? if they are directly connected to the 4-prong black power connector, these will not be thermocouple wires but just ordinary copper leads. So the sensor could be a two-wire PT-100 sensor or some other sensor. On the sleeve of the objective, 3 wires are visible: two to the heater tape and a third one - probably to the sensor. Maybe there is a fourth wire that is hidden by the power block.

The 4-prong connector should be fed from a controller unit, so 2 pins for power and 2 pins for the sensor, for the control.

[MicroBob]

Hi Doron,
I thought of a thermocouple as they are small. The more common PT or NTC sensors would be too big to fit next to the front lens. I don't know the electrical resistance of thermocouples, but a resistance measurement might help to narrow down the selection of opportunities.
These could also electrodes to measure conductivity.

Bob

[Hobbyst46]

Hi Doron,
I thought of a thermocouple as they are small. The more common PT or NTC sensors would be too big to fit next to the front lens. I don't know the electrical resistance of thermocouples, but a resistance measurement might help to narrow down the selection of opportunities.
These could also electrodes to measure conductivity.
Bob

Yes, thermocouples star as tiny sensors.
A conductivity cell so near the highly-conducting objective front - hmmm... What possible purpose for conductivity data ?

Another point: there seem to be three liquid connections a;together. For connecting flexible tubing. Two inlets and one outlet ? was it for carrying out some sort of chemical reaction under the objective ? or one was for cold water and the other for hot water, and they are mixed within (I know, it sounds stupid to control temperature like that). Or feeding growing cells from two sources of liquid nutrients ?

[wabutter]

Keep in mind that Nikon and Leica are the two companies that offer M25 standard thread size for their life science microscopes. I agree with Hobbvst46 that these are heating elements for working in the 37C range for live cell work. Maintaining water contact on an invert platform is challenging as it quickly evaporates due to the added heat. Although it is not unheard of.
I think the Mitutoyo Finescope also used A M25 thread. The Finescope was used in semiconductor work and water immersion would be the preferred immersion method in that discipline. It also had longer barrel objectives. But I have not seen a 40x in their program.
It could also be from a confocal OEM supplier for use with specialized application such as TIRF.

[apochronaut]

They are also being used by some Chinese mfg., particularly those ones that build equipment for Nikon and Leica.

[Scarodactyl]

The finescope line is still around, but Mitutoyo objectives are m26 with a 95mm parfocal distance. I don't think they make any immersion objectives, just metallurgical objectives for various wavelengths and a couple of subseries corrected for thick cover glass.
It's definitely a weird mix of different companies' proprietary features, with the Nikon/Leica M25 thread, the weird 75mm(ish?) parfocal distance (which I think Zeiss uses or used on some metallurgical objectives?) and then also the Olympus reference focal length. And of course unknown corrections which I'll need to see if I can figure out.
It pretty much must be a custom job made in China--it's kind of hard to imagine any of the big dogs making anything with this mix of features, especially unbranded. I guess in theory there are other companies like Navitar who make custom optics, but they'd probably have some branding on it (Navitar in specific would, not sure if that's standard across other places). There are always those lesser-known optics companies in Japan as well I suppose but China seems most likely.

[Scarodactyl]

So, I just learned about the Olympus XLUM series of objectives. They are water dipping, m25 thread having, 180mm reference focal length 75mm parfocal distance objectives. So that explains where the specs came from anyway.

[Scarodactyl]

I've used this objective a few times now for looking at very small gem inclusions and really liked it--the water immersion is just wonderful for cutting down reflections from the stone surface in coaxial illumination and I can see details I've never seen before. But that isn't a very formal test, and while I like the photos I've taken I'm still getting used to the very shallow DoF and high NA and the stacks are a bit messy. I wanted to take some more controlled photos to get a sense of how good it actually is, so I put a cover slip on top of a nice, detailed wafer, put a drop of water on top and took a few pictures. This is with my Nikon scope, so it has a 200mm tube lens pushing it up to 44x.
The wafer was a little angled, and it also has a fair amount of depth to it when viewed with this objective so there are some stacking errors in the photos I took, but I have to say I'm extremely happy with this one.
For CA, a look at this area:


center^

corner^
If it weren't for the corner shading (still not sure what's causing that, it's not the objective my microscope just does that) I think I'd have trouble telling which one was the center and which was the corner. I can see a very minor hint of red/green axial CA when focusing in and out on bright white details but it's awfully faint, within what I'd expect for an apo objective.
Here are a few crops from a single shot.

center

bottom edge
Again, if not for the slight change in focus (because the wafer wasn't level, planarity doesn't seem to be an issue) I don't know if I'd be able to tell which is which.
The original Olympus XLUM fluorite 20x is only specced for a 22mm FoV, though with the same resolution. This one's coverage impressed me a lot.
All I can think it someone must have paid a lot of dollars for this lens: custom made, properly apo, nice big FoV and matching many of the specs of a 9 thousand dollar Olympus original--I really didn't realize there was any whitebox company that could produce this kind of lens, even with some of the advanced stuff coming out of China.

[apochronaut]

That's a pretty impressive objective. Probably a rival for best second hand deal of the year. The fact that the objective performs well with a Nikon telan lens is somewhat telling. Certainly Bestscope International could make it. They are making NIS 60 planapos but for 200mm. Probably Motic too.

I have seen some anomalies. 45mm parfocal infinity sets that work perfectly in AO 34mm parfocal microscopes. 45mm parfocal infinity corrected 40X objectives with a .66 N.A.
Leica may have sold or dealt some older not needed designs to India. The ATC 2000 was made there, later , in the same facility that produces some Labomed stuff, which subsequently showed up infinity corrected. Reichert made some infinity water immersion met objectives with larger diameters and threads and could have been part of that. Many designs would be in the files that never went to production. Leica has let a great many older AO and B & L patents lapse. Probably Reichert too.

The Reichert and Nikon compatibility is high.