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--- hardware:troubleshooting [2022/06/10 21:06]
Jon Daniels Scanner troubles new section
+++ hardware:troubleshooting [2022/10/26 12:02]
Jon Daniels [Troubles with scanner]
@@ Line 53: / Line 53: @@
 === 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.
+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.  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.
+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.
-=== Plugin confusion ===
+=== 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 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 is enabled but not the sheet: at 0 degrees (if you haven't explicitly changed it)
-- beam and sheet both enabled: changing
+  - 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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