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hardware:troubleshooting [2022/04/05 11:54]
Jon Daniels [Vibration] 		hardware:troubleshooting [2022/06/10 21:06]
Jon Daniels Scanner troubles new section
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 The procedure for the side with the OBLPA is similar but a bit easier.  The dovetail is integrated into the OBLPA so it's just a matter of loosening the two bolts that connect it to the piezo, pushing them relative to each other so that its lowest edge will be as close to the XY stage and far from the centerline of the microscope as possible when remounted. Retighten the bolts and reassemble. The procedure for the side with the OBLPA is similar but a bit easier.  The dovetail is integrated into the OBLPA so it's just a matter of loosening the two bolts that connect it to the piezo, pushing them relative to each other so that its lowest edge will be as close to the XY stage and far from the centerline of the microscope as possible when remounted. Retighten the bolts and reassemble.
 +
 +
 +==== Troubles with scanner ====
 +
 +There are two occasional problems people encounter with the scanner, one hardware-related and the second software-related.
 +
 +If the light sheet scan is asymmetric or the piezo/slice correspondence is good over part of the scan but not the remainder there may be a damaged MEMS mirror.
 +
 +If the beam/sheet seems to disappear or is wildly offset while using the Micro-Manager plugin then it could be the below software bug.
 +
 +=== Damaged MEMS mirror ===
 +
 +It seems that occasionally a bit of dust shorts out one of the corners of the MEMS mirror, which limits its travel in part of its normal range.  It is often manifest by an asymmetry.  This failure mode seems to be stochastic and requires the MEMS mirror to be replaced by ASI.
 +
 +A good test is to observe the output position optically as it is moved around the center of its travel.  If one side moves more than the other then it is almost certainly a damaged MEMS.  This can be done by e.g. using the sheet in the Micro-Manager plugin if it's along the sheet axis.  In external mode you can move move in equal voltage steps and see whether the resulting optical response is very different on the two sides of center.  Observe optically nearly conjugate to the sample/C-mount, either at the sample with a microscope, with the scanner off the microscope and a witness target cut to C-mount size and dropped into the scanner, or else with the scanner connected to a tube lens and then point the beam at a wall many focal lengths away to simulate the far field.  At either of these places the MEMS deflection should give a linear displacement but if one region is strongly attenuated then the MEMS mirror is damaged.
 +
 +
 +=== Plugin confusion ===
 + 
 +Go to the Navigation panel.  The "scanner sheet" axis should be at the following places depending on the state:
 +- beam disabled: at 4 degrees (to deflect the beam completely)
 +- beam is enabled but not the sheet: at 0 degrees (if you haven't explicitly changed it)
 +- beam and sheet both enabled: changing 
 + 
 +In the "plugin confused" situation, the middle of these cases will show 4 degrees instead of ~0 degrees.  Normally you can fix by hitting the "go to zero" button in the plugin and then moving on.

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