Bausch + Lomb U.L.W.D. Lens question

[Lothar-Gutjahr]

Hi,

last year i swapped my old Ortholux for a microscope lens i got faszinated for.
My problem now ist, not having any information on how tu use it corect ?

it is a B+L HIGH PERFORMANCE CAT NO 31-13-90 Ultra long working distance 50/0.45 having a adustable iris from 0.15A to 0.45A

Does it need a tube lens ?

for what tubelength is it designed ?

Would it be better to use okularprojektion ?

If yes what kind of okular lens?

Would be nice, if someone has knowledge about, or where to look for data.

Thanks in advance for any help

Lothar

[g4lab]

This lens was probably for a Bausch and Lomb MicroZoom which was one of their last gasps probably in the 1970s or even 80s. They were large stands intended for use by the semiconductor industry which back then was still based here in the USA.

I would expect that these are infinity corrected systems requiring some kind of tube lens. That would be easy enough to figure out by experimentation.
I would expect it to be infinity corrected because that was the way the whole industry was going and many contemporaneous but earlier models from Bausch and Lomb were infinity corrected as well as their big competitor American Optical. Furthermore the MicroZoom did have all kinds of interchangeable modular accessories and this also points to an infinity corrected system.


Another thing you will need to determine is whether additional chromatic aberration correction is expected by this lens. These corrections can either be in the tube lens or in the ocular. I think that in most early infinity systems the corrections were left in the oculars so that they did not have to redesign everything but I don't know for sure on the MicroZoom.

Chromatic aberration can be examined and somewhat corrected in this day and age in PhotoShop and other software which might make your measurements and solutions easier.

Perhaps we have some list members who have specific experience with this system.

http://universalopticservice.com/BLMS.html
http://spectraservices2.com/Merchant2/m ... BJ-BL-0001

[Lothar-Gutjahr]

Hi Gene,

thank you for this interesting explanantion. Today i made a foto from the lens together with a buck to show the dimension. It weights 380 gramm and is not usable on a normal microscope, do to the length plus long working distance. No problem on my homebrew which can displace 360 mm.

Perhaps someone my recognize it by the foto.



Thanks and greetings

Lothar

[g4lab]

Very beautiful and I suspect rare lens. How long is its working distance?

[Lothar-Gutjahr]

it is about 20 mm. Still not having the idea for what tubelenth its designed, thi could slightly vary.

[shrek]

I have the same !

jp

[Lothar-Gutjahr]

Bonsoir Jan Piere,

do you know the data of the lens ? Using normal view to the inscription, it should be a finite korrekted lens. My question is simply: does the U.L.W.D. feature bring loss of resolution ? Actually sharpness? Or is it worth to look for the ideal use of the lens? I fall in love with it for the long working distance.

Greetings

Lothar

[rjlittlefield]

My question is simply: does the U.L.W.D. feature bring loss of resolution ?

Sure -- notice the aperture: NA 0.45 at 20 mm working distance, versus NA 0.55 typical for 50X at shorter working distances.

Wavefront errors scale in proportion to the size of the lens, so it requires very sophisticated lens design and manufacture to get high NA at long working distance.

At any particular price point, this means a tradeoff between aperture and working distance.

There may be other tradeoffs too, for example with chromatic aberration. The Mitutoyo Plan Apo SL at 50X NA 0.42 and WD 20.5 mm is very well color corrected, but it carries a list price of $3,325.

Or is it worth to look for the ideal use of the lens? I fall in love with it for the long working distance.

The difference between NA 0.45 and NA 0.55 is not so huge if you love the long working distance.

You should be able to figure out finite vs infinite pretty easy -- just test it both ways and see which one gives good contrast. An NA 0.45 lens will suffer obvious loss of contrast due to spherical aberration if used in the wrong configuration. See for example http://www.photomacrography.net/forum/v ... 915#103915. For the finite test, use whatever extension gives 50X. If you deviate very far from that, then you will introduce a "tube length error" that will also cause loss of contrast. For the infinite test, just be sure the tube lens really is focused at infinity. Magnification is not so important there, but probably you will get 50X at around 200 mm. (This is true for other brands. I don't know about B&L.)

--Rik

[Lothar-Gutjahr]

Hi Rik,

many thanks, i will follow that road and doe also resolutiontests at different tubelength. My hembrew universal foto microscope alows tubelengthvariations from 140 to 300 mm or even more using a second bellow.And the inscription of 50/0.45 without that x behind the number should normally signalize a finite correction. Checking my eyepiece collection i found two diferent B+L, i can use for tests in okularprojektion also.

I will report about or come with new questions.

Greetings Lothar

[rjlittlefield]

And the inscription of 50/0.45 without that x behind the number should normally signalize a finite correction.

I did not notice the missing X, and I don't know what it means. In my Nikon objectives, some have the X and some do not, apparently at random.

On all the objectives I have, finite vs infinite is indicated by a notation such as 160/0.17 (160mm tube length, 0.17mm cover glass), 210/0 (210 mm tube length, no cover glass), ∞/0 (infinity, no cover glass) and so on.

Be sure to check all over the lens for such notation. Sometimes it is on the back side. Or maybe B&L omitted it entirely.

--Rik

[Lothar-Gutjahr]

Hi Rik,

thats the little problem i am standing in front of. It does´nt show any marks about tubelength. This shows the backside:



but curiosity is big and i think i´ll find out about.

Greetings from freshly snowed South-East-Bavaria

Lothar

[Lothar-Gutjahr]

Hi,

there is also a rising question about corrected for coverglas or not.
Last night i made the experiment, fotografing a probe of diatomeas under coverglas. I used tubellength of 200 mm and a Bausch & Lomb 7.5 x hyperplane okular for projection to tha Canon without lens.

Ilumination was a little bit indirekt led light from the back( white paper below the probe about 30 mm below the objectcarrier). And a direct incident light from my new development "fluoreszenzbeamer". Hence i am still waiting for my 445 nm laser, using the 405 nm brings to much green from the posphormix. For that reason the greenish color. Advantage of that type of ilumination is not to use a diffusor in between and not having added flares at the end of the stack.

So i post this foto only for judging a incident iluminated object with ultra long working distance of 20 mm.
Sorry i know, this is not the right procedure to show this little things.

sized down badly


This is a cut out and a little down sized


The foto originated as a stack of 50 fotos spaced 0,6 µm using latest B-version of Zerene Systems.

I did not remove the black spots in the picture. This is dirt on my sensor and it shows a little pattern which was the real displacement of the objekt during stacking.
Not knowing about cover glas or not i will try to find another target, which is better suited for incident light and run more variations. I have a compens 10x from B+L. Also i could try a 200 mm lens as a tubelens?

Greetings

Lothar

[Chris S.]

This lens was probably for a Bausch and Lomb MicroZoom. . .

I just found a reference that seems to confirm this, with the added wrinkle that at least some of specimens were badged as “Cambridge Instruments,” instead of Bausch and Lomb. (Was Cambridge Instruments a B&L nameplate, spinoff, or integrator?)

Anyway, available here is a pdf instruction manual for a “Cambridge Instruments MicroZoom II Microscope.” At the top right corner of page 12, Lothar’s lens is listed among the available objectives. The manual contains other information about the instrument, though not, so far as I could see, whether it is finite or infinite in design, or requires matched eyepieces.

There is a specimen of this lens currently on eBay, with a “Cambridge Instruments” sticker placed where Lothar’s says “Bausch & Lomb.” It is item #321087876711, offered by vendor “maurym.” This vendor seems to sell a fair number of microscope objectives, and might know something about this one.

--Chris

[Chris S.]

There is also a rising question about corrected for coverglas or not.

I would suspect that the lens is intended to be used without a cover slip, since one of the implementations shown in the manual is wafer inspection. (Concurring with g4lab's observation that they were intended for use by the semiconductor industry.) But given the relatively small NA of this lens, it may not greatly matter whether you use a cover slip or not--and if it does, you could use the iris to stop the lens down slightly, which should make any spherical aberration due to the presence or absence of a cover slip go away. Of course, this would be at the cost of some resolution.

This lens might be especially convenient for the technique of stopping down an iris to make a pleasing blur at the ends of a stack.

--Chris

[Lothar-Gutjahr]

Hi Chris,

thanks for this additional info´s. I tryed to contact "Maurym" via ebay and entered another "ebay-hurdle" This time the entering of U.S. and the zip from Miami did not help me any further. Ebay insists that "Maurym" can not answer my question.(Selling U.S. only )

So i waite hopefully if Jean Piere comes with answers to the subject and its my wish, he has not the same problem than i do.

Best wishes for a nice sunday all !

Lothar