I decided to share a little about what I've been doing in the lab lately.
Basically, to precisely align the microscope, I first need a collimated laser source.

For more info,
PDF about aligning optics: https://onlinelibrary.wiley.com/doi/10.1002/9783527671595.app1
Videos about aligning optics:
The fiber output is pretty straight forward. It's in a mount where I can adjust the tilt and yaw. And I place the post holder pretty close to a line of holes that will somewhat help me with my alignment later.
The height of the output is close to that of an iris aperture.
The next step is is to add the neutral density filter. Our filter wheel still hasn't arrived yet. So I had to make do with some ND filters that I kindly borrowed from the commercial microscope.
Yes there's tape involved. Just don't bump it! I never said I knew what I was doing.🤣
Now I have to roughly tilt the mount of the optical fiber output such that the laser beam hits roughly at the same height as the iris aperture. And along the row of screw holes on the optical table.
The next step would be to add the first lens (f=30). Basically, the spot has to be in the same place before and after adding the lens.
For the angle of the lens, right now the plane of the mount is pretty close to perpendicular to the optical axis. I guess that's good enough?
The next component to add is the pinhole. This is supposed to help make the beam nice and circular.
But I recently found out that when the pinhole is placed too close to the focal point of the lens, strange things happen...
It's the first time I'm placing a pinhole in a focal plane. So I've no idea what is happening...🤔
So I place the pinhole somewhere slightly further from the focal plane where I get a familiar Airy sort of pattern.
The XY position is adjusted with the micrometers to center the spot in the dot. And the angle of the mount is somewhat perpendicular to the optical axis.
Finally, we have to place the 300 mm lens somewhere.
I use our familiar, friendly neighbourhood shear plate to estimate where is a good position for collimation.
Ok the beam is more or less collimated. But I want a larger beam size. This means I have to put the first lens nearer to the fiber output.
Figure below is beam spot about 7 meters away from the second lens. The adjustable aperture hasn't been added yet.
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