Differences

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--- afm [2025/10/07 11:56] – ethanminot
+++ afm [2025/10/07 12:02] (current) – [Step-by-step walk through for AC mode imaging] ethanminot
@@ Line 85: / Line 85: @@
     *  Open 'Tune' tab in the master panel
     *  Set 'Target %' to -5.0 %. This setting is a first guess at the ideal drive frequency (setting it slightly less than the resonant frequency). You may have to test different drive frequencies later if you notice "phase jumping" during imaging.
-    * Click the 'Auto Tune' button and wait for tuning to finish. Software will set drive frequency.
+    * Click the 'Auto Tune' button and wait for tuning to finish. Software will set drive frequency and drive amplitude. The graph of amplitude and phase should look like the textbook curves for a driven damped harmonic oscillator.
+    * In the read-out window of the software, you will now see a 1-volt amplitude signal underneath the sum signal. Maximize this amplitude signal by moving the laser along the length of the AFM cantilever. When the amplitude is maximized, the sum signal will be slightly less than its max value.
+    * Click 'Auto Tune' one more time (or manually adjust the drive amplitude).
   - Engage the tip
-    * You will now see an amplitude signal next to the sum signal in the read-out window. Maximize this amplitude signal by moving the laser along the length of the AFM cantilever. The sum signal will be slightly less when the amplitude is maximized.
-    * Click 'Auto Tune' one more time (or manually adjust the drive amplitude).
     * Set the I gain to 10
     * Make the 'Set Point Voltage' about 95% of the measured free-air amplitude signal. (The measured free-air amplitude signal is probably 1 V right now, but you need to watch this, it might be drifting.)