Differences

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--- afm [2025/04/30 17:32] – ethanminot
+++ afm [2025/05/01 19:33] (current) – ethanminot
@@ Line 67: / Line 67: @@
   - Start your RELMS reservation on the [[https://relms.oregonstate.edu/facilities|RELMS website]].
   - Turn on the laser - Key switch on the AFM computer
-  - Open version 19 of the AFM software (latest stable version as of April 2025).
+  - Open version 19 of the realtime AFM software (latest stable version as of April 2025).
   - Click the first option, "Template"
   - Once software loads, set AC mode in master panel
@@ Line 113: / Line 113: @@
   - Leave controller and PC running unless expecting a power outage
 ===== Imaging rules of thumb =====
-It is easiest to get a good image on a small scan area (~ 1 micron). Starting from the default settings you can fine tune the image and then start increasing the scan size. Good settings will minimize ringing and reduce shadows while keeping the scan rate reasonably fast.
+It is easiest to get a good image on a small scan area (~ 2 micron). Starting from the default settings you can fine tune the image and then start increasing the scan size. Good settings will minimize ringing and reduce shadows while keeping the scan rate reasonably fast.
 **Beginner settings**
-  *Scan size 1 micron
+  *Scan size 2 micron (look at a random small feature on a flat background to verify the sharpness of the tip)
   *Scan rate < 15 micron / s
   *Integral gain 10
-  *Free amplitude 1 V (~ 100 nm)
+  *Free amplitude 1 V (corresponds to a cantilever motion of ~ 100 nm)
-  *Set point amplitude 0.65 V
+  *Set-point amplitude 0.75 V
-**Rule of thumb: "One high quality slow scan is worth ~5 low quality fast scans."**
+Sometimes the image is improved by lowering the set-point amplitude a few clicks. For example, this might fix parachuting.
-It is tempting to be impatient and try to 'tune' the imaging parameters to get the data you want from a 2 - 5 minute scan. This strategy often backfires though, if you need to return to old AFM images and find they are junk aside from the information you 'tuned' the parameters for. Also, 'tuning' these parameters in the first place probably takes ~10 minutes so you're not really saving time anyway. The best fix for many imaging problems is simply to lower the 'rate'. The price you pay is scan time. However, I've found that you actually save time (and headache) by taking a single high quality slow scan rather than a bunch of quick ones with little parameter adjustments in between. I find that adjusting the rate so that the scan speed is <10 micron/sec works well in nearly all cases.
+Sometimes the image is improved by withdrawing and re-running the autotune procedure (the resonant frequency might have changed).
+When you withdraw from the surface, check the free air amplitude is the same as you when you first tuned the tip.
+Another thing to try is a slower scan rate. The price you pay is scan time. However, I've found that you actually save time (and headache) by taking a single high quality slow scan rather than a bunch of quick ones with little parameter adjustments in between. I find that adjusting the rate so that the scan speed is <10 micron/sec works well in nearly all cases.
 **Using nanotubes as a diagnostic tool**