Differences

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--- afm [2025/10/07 11:51] – [Imaging rules of thumb] ethanminot
+++ afm [2025/10/07 12:02] (current) – [Step-by-step walk through for AC mode imaging] ethanminot
@@ Line 82: / Line 82: @@
     * Move laser toward the tip of the cantilever - the control wheels are labeled LDX and LDY (laser deflection x and y). They are located on the back & right side of the MFP-3D tripod. Use these controls to maximize the 'Sum' signal. If the laser is badly misaligned, it can be hard to locate. If you "loss" the laser spot, ask an experienced user for help.
     * Adjust the photodetector (PD) position. The control wheel for the photodetector is located on the left side of the MFP-3D tripod and is labeled PD. Set the PD 'Deflection' meter to near zero.
-  - X Set AC Mode - In main tab of the master panel select 'AC Mode' in the 'Imaging Mode' pull down menu
   - Tune the AFM
     *  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
     * Set the I gain to 10