AO series 10 loose mirror

[apochronaut]

It is not uncommon for the original glue marks on those to be difficult to decifer because the circular expansion relief in the middle of the mirror bracket is circular and symmetrical. The glueing is minimal and leaves a small trace in a circular pattern. It isn't the same as a glued prism where a clear fracture of a thick cement struçture makes the original position more obvious.

[hans]

Yeah that is the situation in the loose one I have, mentioned earlier in the thread, which is why I could not give a definitive answer on the orientation, only speculation based on the shape of the mirror relative to the light beam.

[quantum]

I went through a similar process, including gluing the mirror on incorrectly 90 degrees off. Then I did it again, right this time.

Presently everything works but I am still wondering what the correct way to align the mirror, using those three springs, is? The question was asked in this thread but I did not see the answer.

I figure those spring adjustments are there for a reason. I can eyeball it and things look okay, but I can change the adjustment on the springs quite a lot and things still look "okay". I suspect that there is a right way to do it, and I sure would like to know what it is. (The degradation caused by misaligning might not be completely obvious initially but could still detract.)

All I could figure was this: remove the objective and eyepiece, and project the light out the top of the scope onto the ceiling at night. Adjust until the circle of light seems even. But that is crude at best.

Any other ideas?

[henryr]

I like your thought on the alignment.

[apochronaut]

Here is my method. Put a towel or cloth on a table or bench near to an outlet and flatten it out. The surface must be large enough to also accept the transformer, if it is the 18 watt tungsten model. Turn the microscope gently over on it's side and remove the 4 coverplate screws under the mirror. Adjust the 3 mirror adjustment screws to have equal tension about midway through their range. Then, put the microscope upright and preferably , bring the microscope forward on the bench so that the mirror adjustment screws just clear the edge of the bench. Usually the back of the microscope needs to be secured or weighted with something, because the overhang tips the microscope forward. The idea is to be able to access the mirror adjustment screws while looking through the microscope. Alternately, you can tip the microscope up on it's side to get at the screws. You will find a stubby screwdriver or even just a bit, will do well. You can wrap a bit with masking tape to get more leverage.
Turn on the illuminator. It only needs to be medium bright. Open the field diaphragm all the way and open the condenser iris diaphragm all the way. Bring in the 10X objective, install a slide and focus the 10X objective on any detail of the slide, even the edge of the coverslip will do. Remove the slide. Then close the field diaphragm until you can see it shrinking in the field of view. Adjust the condenser( usually up) until the field diaphragm leaves are sharply focused. Center the field diaphragm. Then focus the 10X objective down, until you have focused on the dispersion filter/ground glass of the illuminator collimating system. It will be a grainy image with a pronounced focused dome , yielding to an unfocused periphery with lots of ca. At this point both the field diaphragm and the condenser diaphragm are in about the same focus. a little blurry but still easily adjusted. By manipulating the field diaphragm centering and the condenser centering, you can now parcenter the two diaphragms. Once they are centered, you can then adjust the mirror to provide the brightest center illumination. The two diaphragms and the mirror need to be aligned. Using the evenness and central brilliance of the collimating ground glass , you will be able to collimate them all, using the dispersion filter ground glass as a screen to monitor the eveness and centering of the illumintor.
Takes a bit of time , sometimes.

[quantum]

Thanks, apochronaut, that is a very interesting & clever technique. I was able to improve the mirror centration using those ideas.

Here are a few notes & questions, for those who may be interested now or later.

1. To be specific, my equipment is as follows. Series 10 with 1036a illuminator, 1084 aspheric condenser, 1019 10x plan objective, binocular head with two 10x #176 WF eyepieces.

2. In the instructions, after the step where I center the field diaphragm, I was initially unable to then focus down into the diffuser, and the reason was simply that my scope was set up with the auto-focus stop set for normal operation. The focus could not go down, because it encountered the stop. So I simply unlocked the stage and moved it down some, locked it up again, and continued.

3. Doing this, I see the grainy image with the domed focus, and also the field diaphragm (at this point a little out of focus). But note that I could not see the *condenser* diaphragm at all. I would not expect to, because it is not ordinarily conjugate to the image plane, and even with this focus setting I would not really expect to see it. And I did not. (If I took off one eyepiece and looked down the tube, there it was. Or if I used a Bertrand lens, there it was.) So I am puzzled about the step that says, as I understand it, that these two apertures should be visible at the same time.

4. On the other hand, the condenser aperture (by which I mean the aperture diaphragm) is not actually adjustable on my condenser. So there is nothing to center.

5. Anyway, I found it rather hard to judge uniformity of brightness when looking at the domed grainy image. But rather easy to notice differences in focus. So what I did was pay attention to the periphery of the field, and adjusted the mirror screws so that, going all the way around the periphery, all parts were in focus at the same time. (And then the middle was blurry.)

I think doing that is a good step in the right direction. I might have something else going on with this scope, because the illumination seems a little odd still. In particular, even at 10x if I look at something in focus through the binocs and then move my head laterally a bit, the image disappears. It is as though it exits the pupil of the eyepiece over a very small angle, or something like that. I have used AO10 scopes that were just lovely to look through, but this is not yet one of those. So I think I have additional issues to work through, probably involving alignment.

Thanks again!