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hardware:troubleshooting [2024/01/19 14:24]
Jon Daniels eliminated table at top and rearranged |
hardware:troubleshooting [2024/01/19 15:30] (current)
Jon Daniels |
| ===== Light Sheet Scanner ===== | ===== Light Sheet Scanner ===== |
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| There are two occasional problems people encounter with the scanner, one hardware-related and the second software-related. | There are two occasional problems people encounter with the scanner, one software-related and the second hardware-related. |
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| If the light sheet scan range 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 then it is likely the below "beam displaced" software bug. |
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| 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. | |
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| ==== Damaged MEMS mirror ==== | |
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| 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". | |
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| 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. | |
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| 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. | |
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| | If the light sheet scan range 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. |
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| ==== Beam displaced ==== | ==== Beam displaced ==== |
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| On rare occasion the beam seems to disappear when it shouldn't because it gets moved to the edge of its range. This is a software-related glitch with a straightforward fix. | On rare occasion the beam disappears because it gets stuck at the edge of its range. This is a software glitch with a straightforward fix. |
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| Go to the Navigation panel. The "scanner sheet" axis should be at the following places depending on the state: | Go to the Navigation panel. Depending on the state of the beam/sheet controls the "scanner sheet" axis position should be: |
| - 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 sheet is disabled: at 0 degrees (if you haven't explicitly changed it) |
| - beam and sheet both enabled: changing | - beam and sheet both enabled: changing |
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| In the "beam displaced" situation, the middle of these cases will show 4 degrees instead of ~0 degrees. It is resolved by hitting the "go to zero" button in the plugin which moves it back to the normal operation. | In the "beam displaced" situation, when the beam is enabled but the sheet is disabled (middle case0 the "scanner sheet" position will be 4 degrees instead of ~0 degrees. It is resolved by hitting the "go to zero" button in the plugin which moves it back to the normal position, and things should proceed as expected from there. |
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| If you find a way to reproduce this "beam displaced" situation please contact ASI. We have spent hours in vain trying to figure out what causes this occasional glitch. | If you find a way to reproduce this "beam displaced" situation please contact ASI. We have spent hours in vain trying to figure out what causes this occasional glitch. |
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| | ==== Damaged MEMS mirror ==== |
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| | 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. |
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