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hardware:troubleshooting [2022/04/05 11:54]
Jon Daniels [Vibration] 		hardware:troubleshooting [2022/10/26 12:02]
Jon Daniels [Troubles with scanner]
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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 ===
 +
 +The most common hardware failure of the scanner is when a bit of dust shorts out an actuator on one corner of the MEMS mirror, which is manifest by an asymmetry in scanner. This failure mode seems to be stochastic and can happen after months or years of use without any problem.  It requires the MEMS mirror to be replaced by ASI.  The damage can occur with either the "slice axis" or "sheet axis".
 +
 +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. 
 +
 +Observe the beam or sheet optically conjugate to the sample/C-mount.  There are a few ways of doing this.  One is at the sample with a microscope in epi view and a uniform sample.  Another is with the scanner off the microscope and a witness target placed near the C-mount image plane (decent at the outside edge of the scanner, better at the lip at the bottom of the threads, and best 17.5mm inside the outside edge.  Another is with the scanner connected to a tube lens and pointed at a wall several meters away.  Then move the MEMS from the center position.  This can be done either by moving the static position of the beam or else adjusting the amplitude of a continuous movement, either with serial commands or using the plugin.  The displacement of the beam should be linear with commaded MEMS deflection, but if one region is strongly attenuated then the MEMS mirror is damaged.  
 +
 +
 +=== Micro-Manager 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.
 +
 +If you find a way to reproduce this "plugin confused" situation please contact ASI.  We have spent hours in vain trying to figure out what causes this occasional glitch.

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