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| projects:optics:log [2026/08/29 22:03] – [Day 2026-08-29 (leah, rahix)] rahix | projects:optics:log [2026/10/03 23:41] (current) – [Day 2026-10-03 (rahix, guest)] rahix | ||
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| > //This page is a lab notebook. It documents the work done in the lab and our thoughts, theories, and findings related to it. Everything you read here is work in progress and not final results. We believe it is best to have our lab notes out in the open, because it gives more detailed insight into what worked for us and what didn' | > //This page is a lab notebook. It documents the work done in the lab and our thoughts, theories, and findings related to it. Everything you read here is work in progress and not final results. We believe it is best to have our lab notes out in the open, because it gives more detailed insight into what worked for us and what didn' | ||
| + | ==== Day 2026-10-03 (rahix, guest) ==== | ||
| + | More attempts at alignment with the Open Micro-Manipulator. Managed to get quite consistent coupling efficiency again. Working towards automatic alignment optimization. | ||
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| + | For this, we pointed the collimated fiber output at the camera-branded camera. After quite a bit of fiddling with the camera, managed to get it to fixed exposure at an acceptable level (Something about using the '' | ||
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| + | Truly an experiment setup: | ||
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| + | On the camera, we never see a stable beam, it always looks extremely wobbly: | ||
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| + | We placed the fiber output and camera on the vibration-isolated optics breadboard. A bit better, but still significant (pictures above were afterwards). We are very certain the remaining wobbles is vibration in the fiber alignment part, as you can excite it easily by hand. The missing vibration isolation is very noticeable, even floor vibrations have a visible effect. By eye, you cannot see these fast intensity fluctuations in the output intensity. | ||
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| + | Built a proxy server for allowing network-access to the motion controller and the measured intensity. See [[https:// | ||
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| + | Started working on a tool to sweep areas around the focus region to automatically improve alignment. In a dry run, we already see the expected intensity profiles along the sweep. | ||
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| + | With how things are aligned in the diode case right now, we are always very close to hitting the fiber on the casing/ | ||
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| + | ==== Day 2026-09-27 (anuejn, rahix) ==== | ||
| + | Now using the [[..: | ||
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| + | Once the setup is done: Works amazingly well! The speed and large range of motion of the micro-manipulator make the process much faster. So far, best case light output was compareable to the openflexure. But we still lack a good way to quantify it... | ||
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| + | Tried setting up a camera with a microscope objective for getting a better look at the fiber end. Unfortunately that didn't work out with the hardware we have in the lab. Switched back to the original setup with the soldering microscope. | ||
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| + | The fiber end was re-cleaved for todays alignment. Unfortunately ran out of time before we could do another attempt at glueing the fiber... | ||
| + | ==== Day 2026-09-14 (rahix, guest) ==== | ||
| + | Installed the commercial ND filter in front of the microscope. It does, in fact, not fit the thread. But nothing that some adhesive tape can't fix... With the ND filter, we can dim the picture enough to see some more structure on the fiber end, without overexposing everything. | ||
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| + | Managed to use this to quickly get alignment much better and significant light output. | ||
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| + | Re-installed the brass rod in preparation for gluing the fiber. We filed down the end of the brass rod because it gets too close to the focus of the laser. | ||
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| + | Final alignment using microscope and visual intensity estimate. | ||
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| + | First attempt at glueing but we just made a big mess. Also no good coupling with wet glue applied, maybe we dirtied the fiber end... Will try again next time. | ||
| + | ==== Day 2026-09-05 (rahix, guest) ==== | ||
| + | Re-did alignment without vibration isolation but without great results. Started thinking about instrumenting the openflexure with more software to automate large parts of the alignment sweep. | ||
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| + | Tried swapping the microscope for a camera with macro-lens but this didn't get us enough magnification. Maybe we can adapt proper microscope optics to a camera instead... | ||
| ==== Day 2026-08-29 (leah, rahix) ==== | ==== Day 2026-08-29 (leah, rahix) ==== | ||
| Investigating whether we can just buy an ND filter for our specific microscope. There is a small cover glass on the front with ø=36mm. Seems to have a M34x0.5 thread? There seem to be some " | Investigating whether we can just buy an ND filter for our specific microscope. There is a small cover glass on the front with ø=36mm. Seems to have a M34x0.5 thread? There seem to be some " | ||
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| After lots of trial and error, we achieved //some// coupling again. But we never got it really good and unfortunately the magnification of our microscope is just not good enough to see the focus spot on the end of the fiber. | After lots of trial and error, we achieved //some// coupling again. But we never got it really good and unfortunately the magnification of our microscope is just not good enough to see the focus spot on the end of the fiber. | ||
| - | Clamped the fiber with a protective sleeve now so we don't damage it again. | + | Clamped the fiber with a protective sleeve now so we don't damage it again. |
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| With the light output we got, coupled it into the interferometer setup. We get really nice fringes, though unfortunately hard to take a picture of... | With the light output we got, coupled it into the interferometer setup. We get really nice fringes, though unfortunately hard to take a picture of... | ||
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| Going back to the topic at hand: | Going back to the topic at hand: | ||
| - | The assembly is probably not stiff enough as it stands to meaningfully perform alignment. We removed the vibration isolation again to get some more stiffness from resting directly on the table surface and this helps quite a bit... Achieved better coupling than before | + | The assembly is probably not stiff enough as it stands to meaningfully perform alignment. We removed the vibration isolation again to get some more stiffness from resting directly on the table surface and this helps quite a bit... Achieved better coupling than in the earlier attempts |
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| + | Also we need to investigate what we can use to better check focal plane alignment of the fiber end, with the microscope not working out. | ||
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| + | Considering to just automate the focus search entirely instead of manual stepping. But backlash of the openflexure is considerable which may make this rather difficult. | ||
| ==== Day 2026-08-07 (rahix, guest) ==== | ==== Day 2026-08-07 (rahix, guest) ==== | ||
| Remounted the microscope to get a better view of the fiber end. It still overexposes which currently makes it impossible to see where the beam waist is. Thinking about strapping an ND filter to the microscope objective... | Remounted the microscope to get a better view of the fiber end. It still overexposes which currently makes it impossible to see where the beam waist is. Thinking about strapping an ND filter to the microscope objective... | ||