AO Objective Identification

[mnmyco]

Hi,

I have a set of AO objectives that I am working on getting scope for (maybe), but so far I have not been able to match what I believe are the catalog numbers on the objectives to online resources. I started at PS Neeley's website all abount AO and had no luck, and I had no luck with internet searches. Below is all the text that appears on them. The AO is in the shield design and commas represent new lines, semi-colons represent new text columns. Also, all of these have the 7 lines at the bottom of the objective, and all the lines are the same thickness.

The following are the medium dark phase contrast objectives
AO, Spencer; 10x, N.A. .25; 2114, Made in USA, B56847, Dark M (everything but AO [blue ink] is in green ink) lines green
AO, Spencer; 20x, N.A. .50; 2821, Made in USA, B44055, Dark M (All blue ink) lines blue
AO, Spencer; 43x, N.A. .66; 4834, Made in USA, B32814, Dark M (AO blue, everything else no ink) lines yellow
AO, Spencer; 97x, N.A. 1.25, Oil Imm.; 8058, Made in USA, B54651, Dark-Medium (AO blue, no ink) lines red

The following are the medium bright phase contrast objectives
AO, Spencer; 10x, N.A. .25; 2114, Made in USA, B573570, Bright M (ink as above) lines as above
AO, Spencer; 20x, N.A. .50; 2821, Made in USA, A24914, Bright M (AO blue, no ink) lines as above
AO, Spencer; 43x, N.A. .66; 4834, Made in USA, A62722, Bright M (AO blue, no ink) lines as above
AO, Spencer; 97x, N.A. 1.25, Oi Imm.; 8058, Made in USA, B45790, Bright M (AO blue, no ink) lines as above

I assume these are not infinity corrected and are simple achromats with phase contrast. I would like to know for sure. Also, can anyone answer what "advanced plan achromats" means to AO? I see it in their literature but they do not describe the differences in the catalogs.

Thanks,

mnmyco

[einman]

I would suggest asking Apochronaut. He is the resident AO expert.

[apochronaut]

affordable and excellent. how can one go wrong. the objectives are for the 160 tube length AO microscopes. AO had several different phase annuli in the early phase condenser turrets and the later ones for the series 4 were numbered . The objectives you have ,were engineered to match those annuli numbers, 2114, 2821,4834 and 8058.

it seems you have a nice dark and bright medium 8 piece set. although with the right condenser, they will work well on a series 15, 35, 2 or 4; i would be inclined to put them on a nicely outfitted 4 , with built in bertrand lens. i have a condenser for the 2/4 available, if you are interested.

regarding the designation "advanced plan achro". there are no guidelines for this, that i know of but having run most AO objectives through their courses there is one performance parameter that the objectives noted as advanced seem to collectively have: colour correction. the objectives designated advanced, all seem to have slightly or more than slightly better freedom from c.a. than other achromats or planachromats not designated as such.....not up to contemporary fluorite standards but getting close. this also occurs better at the periphery of w.f. , so the effect is of superior planarity as well.

[mnmyco]

Ah, what I thought were most likely catalog numbers were the phase annulus number. Kind of annoying that I searched the AO catalogs for those series and could not find matching catalog numbers.

Thanks for the info. I will hold on to them for now, but I am more likely to sell them than anything else. Especially since I am looking into a AO scope with infinity objectives.

mnmyco

[apochronaut]

AO did not stamp catalogue #'s on the 160mm objectives, just a serial # about the time they adopted practice of applying the i.d. rings.

The cat. #'s were in a catalogue though and had to be found by comparing a units design parameters to those for the catalogue #. However, if there was a slight modification in the design of a particular component the cat. # might or might not change. An example is the #152 20X .60 apochromat, It was also produced as a 20X .58 apochromat, or more likely, they decided to round it off to .60. If there is a C preceeding the # as many of the cat.#'s on P.S. Neeley's site have , it is the code for coated. In the 50's there was an option.

Unfortunately, with the 160mm phase objectives, the cat.# is keyed to the magnification and the type of phase and does not reference a change in the type of annulus in the condenser or the location and size of the objective's annulus. There is a considerable difference in those two features when comparing a 43X dark M objective without and without the 4834 designation but the cat. # remains the same. This usually happens when there is a substitution.
Generally, using the coded dark M objectives with unmarked condenser annuli causes a shift towards a bright phase type of image, although it is somewhat intermediate . Personally, I have found that mix and match possibility , increases the usefulness of the series 4 as a phase instrument. With those extra elements included, it extends the possible phase combinations from 26 to over 30 in 4 magnifications and allows for some possible combinations with Lomo phase optics, of which there is a range of apochromats and w.i. lenses available.

With the introduction of the first infinity phase system the number of phase options was reduced to 13: 8 dark( probably M) as both achromat and plan achromat so there is not much in the way of difference there, 4 bright( probably M) as achromat and 1 B-Minus ( probably M). There are also a few dark phase objectives in L.W.D.

With the introduction of the second infinity phase system, the range was further reduced to 4 dark. However, Reichert made a broader range of phase objectives for their medium range lab instruments, using the same infinity system, principally as planfluorite and planapo versions of a dark phase. Some of these are applicable to the series 400 instruments.

[mnmyco]

Anyone happen to know if these would work on an Ortholux with a Heine condenser? Hopefully I can get a hold of a Heine some time. I know the 160 length is compatible.

Thanks MNMyco