American Optical AO Ortho-Illuminator lens

[XrayOptics]

Hello, this is my first post on this forum.

I have an AO/Spencer Ortho-Illuminator that I use with a Series 10 scope. When using the regular condenser (#1088), it is easy to focus the condenser to get crisp images of the field aperture. However, with the aspheric condenser (#1084), no amount of moving the condenser puts the edges of the field aperture in focus — that position seems like it would be with the top surface of the condenser above the slide! This is the case with all the objectives I have tried: 4x, 10x, 20x, 40x, and 100x (dry).

In poking around the internet I have come across a reference to different lens that could be used at the output of the Ortho-Illuminator when using different condensers. Does anyone know if this is true, and if so, what are the lenses?

Many thanks

[apochronaut]

Yes. There were different aux. lenses used for the different focal lengths of certain condensers but I don't know for sure, whether the #1084 abbe aspheric was included in that. There might not have been any point because by the time that abbe aspheric was introduced the concept of the Ortho-illuminator had been integrated into the series 20 with a filtered 100 watt halogen illuminator, so the Ortho- illuminator was becoming obsolete by that time.

The model 600 ortho-illuminator has an aux. lens compatible with the cat.# 1088 abbe condenser and with maybe another aux. lens the # 1241, 1242 and 1243 phase condensers and the 2110 1.3 N.A. achromat aplanat condenser. All of those condensers have long front focal lengths, and also work with the series 20. In order to work with the series 10 the standard #1036 in base illuminator provides the same long front focus through lensing , which is longer than it's physical length, so the compact illuminator design can use all of those series 20 condensers. The model 600 ortho-luuminator is also most likely compatible with earlier abbe and achromat condensers catalogued for the 15/35 and series 2, which were current models when the Ortho-illuminator was being made and sold. I don't know that the model 600 is for those for sure though, there may have been a slightly altered model version for those stands but the catalogue fragment below makes it look that way.
When the # 1084 abbe aspheric condenser arrived on the scene, it was made with a finite focal length dovetailed to the in base # 1031 halogen illuminator's shorter focal length, instead of the longer focal length, such as the #1088 condenser used. The older tungsten illuminator # 1036 with it's altered focal length, compatible with the #1088 abbe condenser's longer front focal length became available in a modified form, the #1036A which looks like the # 1036 but to work with the shorter focal length #1084 abbe aspheric condenser, it must have the shorter front focal length, like the # 1031 halogen illuminator.

The # 1084 abbe aspheric condenser was never catalogued for the series 20 and no modification was made for it to work on the series 20. This might seem odd, that only an abbe was available for the better stand but for applications that required a better condenser, the #1242 was a dry achromat possibility and the #2110 1.3 N.A. achromat aplanat oil immersion condenser was usually trotted out for serious stuff. Perhaps they planned a modification at some time or maybe there was a factory retrofit available to use the #1084 on the series 20 I don't know about but in any catalogues I have seen, only the 1088 and 2110 were catalogued for the 20 as B F. condensers.

One might be able to modify the Ortho's focus with a d.i.y. aux. lens, follwing the 1036A's concept . I don't know of any source for model or part #'s, just this tiny entry in an old partial catalogue.

" Catalog number 600-860. Aux. lens in mount for Abbe condenser N.A. 1.25 , Achromat Aplanat condenser N.A. 1.30 - 1.40 "
That looks like two separate part #s. for the two condenser types and is for the series 2 and earlier.

Maybe Wayne will chime in. He might know something more or different.

[Phill Brown]

I found a bucket load for the orthoro illuminator, is this the same thing?

[apochronaut]

AO called it the Ortho-Illuminator. I have seen a Baker version. Don't know what they called it.

[Phill Brown]

I found it as AO orthoro illuminator in the AO information.
Double checked.
Science -net PDF.
Might just be the same pages anyway.

[apochronaut]

Just a typo.

[XrayOptics]

Many thanks, apochronaut.

Different focal length configurations for the condensers explains what I am seeing; I didn’t know that the 1084 had a different focal length than the 1088. The series 10 scope that started all this came with the Ortho-Illuminator and a 1088. However, in going for a set of better objectives, I got from eBay a series 10 with 5 late model Reichert (series 10) lenses and the 1084 condenser, with what I now imagine is the 1036A illuminator. However, on that stand all the knobs are frozen, so I have been wanting to use my original setup with the nice, bright Ortho-Illuminator with its handy filters.

Looks like I should try to find a 1240/1242 condenser set. What is the difference between the 1241, 1242, and 1243? Working distance to the sample?

Either that, or try to find a 2110 condenser!

[apochronaut]

The #2110 condenser is a hard find. It was used for the DIC ( series 21 ) scope and fluoresence maybe. I use a 10 quite a bit still but mostly for phase, so I use the #1242 condenser for that and it works quite well for BF too. It is a practical dry condenser, giving excellent results with all objectives except perhaps the 1.25 oil immersion for peak resolution . It would outperform the 1088 and the 1084 when all were used dry and likely only be exceeded by the 1084 by a small margin when the latter was oiled.
I have one in the single phase mount available. P.M. me if you are interested. You could pick up a diaphragm for it and objective and add one phase mag. to your scope if desired.
Yes, the difference between 1241,42 and 43 is the w.d. The 1242 is standard w.d..