AO 1245 Repair and Trinocular Reassembly

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mnmyco
Posts: 144
Joined: Tue Aug 28, 2018 11:03 pm

AO 1245 Repair and Trinocular Reassembly

#1 Post by mnmyco » Tue Sep 24, 2019 5:01 am

I recently obtained an AO 1245 aperture viewing unit for my series 20 phase system. Sadly, one of the small mirror is loose and another broken. I don’t think the broken one will be too much of an issue as this is just for aligning the phase annuli. I am not sure what is the best method to glue the other mirror back in place. From what I’ve found it seems like RTV silicone is used a lot. Anyone have any suggestions? I will add some photos when I get a chance. I also assume that I am SOL on replacing the broken mirror if I need to and will have to make my own somehow. I will post photos of all of this tomorrow morning, with some sort of scale so you can see the size.

Also, I took the trinocular apart to check the mirror, but I cannot seem to get it back in place so that the lens in the bottom of the head moves up and down. I get the mirror to move with the lever, but the lens will not. Any suggestions. I am looking at you Apo...

MNMyco

apochronaut
Posts: 3637
Joined: Fri May 15, 2015 12:15 am

Re: AO 1245 Repair and Trinocular Reassembly

#2 Post by apochronaut » Tue Sep 24, 2019 1:07 pm

I use epoxy but only a tiny amount for those mirrors. The original glue joints are vulnerable to vibration, like the set screw and or clamp technology that would have been the option . Sitting on a bench in a lab with a centrifuge or homogenizer nearby , is boneshaking. I have seen this in vet labs. Even in surface or air transit , a microscope shipping box can be in the wrong place at the wrong time and standing waves occurring while in transit can reek havoc on what was once a complete functional scope reducing it to a microscope shaped parts bin . In one particular case, a stand was shipped partially disassembled and two cast parts managed to find each other during transit , spending the bulk of the trip in some form of metallic mixed martial arts marathon. The degree of abrasion and gouging of the parts was quite educational. Based on the small size and great number of actual hacks in the aluminum , the strength of the vibration must have been very high with a very high frequency too. I imagined a great bag of packages, all just gently resting in their places , with one or two of them, vibrating and dancing around like Tom Cruise jumping on a sofa.

Those bertrand lens units are extra sensitive to vibration, since the joining surface is quite small. Hopefully there is enough evidence of the original alignment , that you can use that as an alignment guide. They are nestled into a corner, so if the other mirror is tight( check them all carefully), it may serve as a solid guide for the positioning of the other one. They are backed into a corner so to speak, so the alignment should be fairly easy.

The prospect of making a small first surface mirror like that is a bit daunting. There are lots of inexpensive blanks on ebay but cutting one to size( maybe grinding?) will be a touchy project. Since it is a relay optic, primarily for alignment only, you might try getting one of those cheap sets of polished stainless, dental photography mirrors. They are as low as 10.00 with free shipping and claim close to 100% reflectivity. I directed someone on the forum about a year ago to go that route for an illuminator relay mirror and apparently it worked well. They are easy to cut and there are is lots of spare, if you make a mistake. The only tricky part would be alignment because they are thinner than the original glass block and they would have to span the long parallel side of the trapezoid, at the correct angle. The two acute angles on the sides of the mirror would be very short too and would need to be pretty close to equal :.... or if it was cut slightly small, then no angles on the side would need be fashioned. It would rest against the casting on the short side of the parallels and epoxy would fill in the space to make up the required angled mounting surface. You would just then need orient the mirror accurately, tack it with a semi-adhesive , then finish the job with epoxy.


Oh yes, I forgot , that travelling lens. It's actuated by a loose link to the interpupillary adjustment. The interpupillary slider has an arm attached that carries a pin at it's end, which raises and lowers as the slider is adjusted. The travelling telan lens has a short arm with a claw at the end, which engages with the pin. When you install the deviating prism carrier/dovetail plate into the bottom of the head, you must make sure that the claw grasps that pin as the plate is set in and aligned , as well as making sure the correct gear aligment takes place for the trinocular in/out prism. It's a bit tricky. You have to have the interpupillary slider set at it's narrowest so the link arm is at it's lowest point.
Last edited by apochronaut on Tue Sep 24, 2019 6:04 pm, edited 1 time in total.

Hobbyst46
Posts: 3033
Joined: Mon Aug 21, 2017 9:02 pm

Re: AO 1245 Repair and Trinocular Reassembly

#3 Post by Hobbyst46 » Tue Sep 24, 2019 1:51 pm

apochronaut wrote:
Tue Sep 24, 2019 1:07 pm
... The prospect of making a small first surface mirror like that is a bit daunting. There are lots of inexpensive blanks on ebay but cutting one to size( maybe grinding?) will be a touchy project. Since it is a relay optic, primarily for alignment only, you might try getting one of those cheap sets of polished stainless, dental photography mirrors. They are as low as 10.00 with free shipping and claim close to 100% reflectivity. I directed someone on the forum about a year ago to go that route for an illuminator relay mirror and apparently it worked well...
Yes, thanks again Apochronaut for that advice, I followed it and it worked extremely well. I stabilized the mirror in place with a double-sided adhesive tape. I do not quite understand what size is needed in the current post, but I was astonished to find that when I cut the mirror plate, even near the hacksaw cut, the reflective mirror coating was not damaged. I used a 24 tpi saw, yet a 30-32 tpi might be even better. Or perhaps a Dremel tool :idea:
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

apochronaut
Posts: 3637
Joined: Fri May 15, 2015 12:15 am

Re: AO 1245 Repair and Trinocular Reassembly

#4 Post by apochronaut » Tue Sep 24, 2019 6:14 pm

Hobbyst46 wrote:
Tue Sep 24, 2019 1:51 pm
apochronaut wrote:
Tue Sep 24, 2019 1:07 pm
... The prospect of making a small first surface mirror like that is a bit daunting. There are lots of inexpensive blanks on ebay but cutting one to size( maybe grinding?) will be a touchy project. Since it is a relay optic, primarily for alignment only, you might try getting one of those cheap sets of polished stainless, dental photography mirrors. They are as low as 10.00 with free shipping and claim close to 100% reflectivity. I directed someone on the forum about a year ago to go that route for an illuminator relay mirror and apparently it worked well...
Yes, thanks again Apochronaut for that advice, I followed it and it worked extremely well. I stabilized the mirror in place with a double-sided adhesive tape. I do not quite understand what size is needed in the current post, but I was astonished to find that when I cut the mirror plate, even near the hacksaw cut, the reflective mirror coating was not damaged. I used a 24 tpi saw, yet a 30-32 tpi might be even better. Or perhaps a Dremel tool :idea:
Sorry, I couldn't just then remember who it was. The mirrors in question are about 1 cm. x 1/2+cm. x 1/4 cm. thick. That's a guess , since I haven't had one of those apart in several years. I sounds like in your experience, the cut line is pretty clean, so making a small piece like that wouldn't be as hard as it sounds.

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