Olympus SPlan Apo 40 / fungus within lens-doublet - REPAIR

Boni · Post by **Boni** » Wed Jun 10, 2020 2:34 am

Hello to the community

I have one Olympus SPlan Apo 40x 0.95NA, 160/0.11-0.23 cover slip - correction collar objective, but within the double-lens system (on lens diagram designated as ZJ 258000) is present fungus or some kind of dirt.

Does somebody now is it possible to repair this lens doublet and how to do this?

I have also put a announcement in Equipment Exchange category
so, if somebody have one broken (or correct one) objective S Plan Apo 40, i am interested in trade, maybe i can simply change lenses in it.

Many thanks and regards,
Boni

Macro_Cosmos · Post by **Macro_Cosmos** » Wed Jun 10, 2020 5:11 am

No kind of repair is impossible, the question is whether it's worth it or not. In this case, I don't really think so.

So there's fungus in the cemented doublet? That's a bit odd, I usually assume there'd be fogging, ie balsam separation.

It would be hard to put the objective back together and have everything calibrated to a factory standard. My honest opinion would be to either get a good copy or live with it. Another broken copy of the exact same objective would be difficult to come by, but the chances aren't zero, right? Put the objective on your ebay watch list, you might be lucky.

Bakwetu · Post by **Bakwetu** » Wed Jun 10, 2020 5:24 am

If it is fungus and if it is on available pieces of glass, it migth be worth to try and clean it with hydrogen peroxide (3-6%) or that + ammonia. There is a lot of information on the net and youtube videos you can search for, like https://petapixel.com/2016/09/29/remove-fungus-lens/

Boni · Post by **Boni** » Wed Jun 10, 2020 5:27 am

Tnx for reply,

So there's fungus in the cemented doublet? That's a bit odd, I usually assume there'd be fogging, ie balsam separation.

I am not quit sure what this within lenses actually is?

Unfortunately, objective gives a very dull pictures, so is almost unusable.

Ichthyophthirius · Post by **Ichthyophthirius** » Wed Jun 10, 2020 5:44 am

The problems don't end at the lens doublet. Even if you had a replacement lens, it's usually not possible to restore the calibration of the lens elements within the assembly.

Here is a description of objective assembly:

"During assembly of the objective, lenses are first strategically spaced, lap-seated into cell mounts, and then packaged into a central sleeve cylinder that is mounted internally within the objective barrel. Individual lenses are seated against a brass shoulder mount with the lens spinning in a precise lathe chuck, followed by burnishing with a thin rim of metal that locks the lens (or lens group) into place. Spherical aberration is corrected by selecting the optimum set of spacers to fit between the lower two lens mounts (the hemispherical and meniscus lens). The objective is made parfocal by translating the entire lens cluster upward or downward within the sleeve with locking nuts so that objectives housed on a multiple nosepiece can be interchanged without losing focus. Adjustment
for coma is accomplished with three centering screws that can optimize the position of internal lens groups with respect to the optical axis of the objective."
https://www.future-science.com/doi/pdf/ ... /02334bi01

The objective then goes into a final quality control, where those objectives that don't meet the quality criteria are selected out and discarded (!). So even under factory conditions, assembly isn't always successful.

Opening objectives completely should be avoided if the objective is still usable. It almost always ends in a loss, except for very simple designs.

Boni · Post by **Boni** » Wed Jun 10, 2020 5:50 am

Yes, the whole process is complex, but at least it's worth a try, much worse cannot happen.

Macro_Cosmos · Post by **Macro_Cosmos** » Wed Jun 10, 2020 8:34 am

This honestly depends. If you're able to get another broken unit for like $25, then it's worth a go. Chances are, you'd be spending $100+ for a broken unit, so you might as well wait for the $250 good condition ones to show up and instead sell this lens as parts.

Boni · Post by **Boni** » Wed Jun 10, 2020 9:34 am

This honestly depends. If you're able to get another broken unit for like $25, then it's worth a go. Chances are, you'd be spending $100+ for a broken unit, so you might as well wait for the $250 good condition ones to show up and instead sell this lens as parts.

Probably you have right.

Anyway, it would be interesting to hear if someone has similar repair attend?
I am willing to pay more than 250 for good-one.

RobertOToole · Post by **RobertOToole** » Wed Jun 10, 2020 1:00 pm

Ichthyophthirius wrote:The problems don't end at the lens doublet. Even if you had a replacement lens, it's usually not possible to restore the calibration of the lens elements within the assembly.

Here is a description of objective assembly:

"During assembly of the objective, lenses are first strategically spaced, lap-seated into cell mounts, and then packaged into a central sleeve cylinder that is mounted internally within the objective barrel. Individual lenses are seated against a brass shoulder mount with the lens spinning in a precise lathe chuck, followed by burnishing with a thin rim of metal that locks the lens (or lens group) into place. Spherical aberration is corrected by selecting the optimum set of spacers to fit between the lower two lens mounts (the hemispherical and meniscus lens). The objective is made parfocal by translating the entire lens cluster upward or downward within the sleeve with locking nuts so that objectives housed on a multiple nosepiece can be interchanged without losing focus. Adjustment
for coma is accomplished with three centering screws that can optimize the position of internal lens groups with respect to the optical axis of the objective."
https://www.future-science.com/doi/pdf/ ... /02334bi01

The objective then goes into a final quality control, where those objectives that don't meet the quality criteria are selected out and discarded (!). So even under factory conditions, assembly isn't always successful.

Opening objectives completely should be avoided if the objective is still usable. It almost always ends in a loss, except for very simple designs.

Nice illustration of element placement errors manufactures are working with.

Have an even better one about scanner/microlithography lenses but I can't find that one now.

Perl · Post by **Perl** » Thu Jun 11, 2020 1:14 am

go for it it fungus are at surface
but this objective do not cost much on ebay i think
Regards
pär

Boni · Post by **Boni** » Thu Jun 11, 2020 1:28 am

Hi Pearl,

i try to find one very intensive over a past month, unfortunately till now no luck. It exist one in GB but way overpriced (over 1000E)!

Regards

Scarodactyl · Post by **Scarodactyl** » Thu Jun 11, 2020 2:05 am

Macro_Cosmos wrote: So there's fungus in the cemented doublet? That's a bit odd, I usually assume there'd be fogging, ie balsam separation.

Sadly not too uncommon. I've seen it a number of times in old b&l stereozooms that were not stored well.

grgh · Post by **grgh** » Thu Jun 11, 2020 6:00 am

just a query? the exploded parts diagram, have you a full repair manual or technical sheets for these and other parts.

I am sure these would be of interest to a few other members.

Macro_Cosmos · Post by **Macro_Cosmos** » Thu Jun 11, 2020 6:08 am

Scarodactyl wrote:
Macro_Cosmos wrote: So there's fungus in the cemented doublet? That's a bit odd, I usually assume there'd be fogging, ie balsam separation.
Sadly not too uncommon. I've seen it a number of times in old b&l stereozooms that were not stored well.

These spores are sure scary, even creeping into a cemented doublet. Better ziplock these objectives up...

Boni · Post by **Boni** » Thu Jun 11, 2020 7:45 am

just a query? the exploded parts diagram, have you a full repair manual or technical sheets for these and other parts.

No, only diagram, nothing else.