Differences

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--- stm:measurement_procedure [2013/07/10 09:58] – galli
+++ stm:measurement_procedure [2013/07/10 09:58] (current) – galli
@@ Line 9: / Line 9: @@
   - RHK premp: check back side of RHK, switch towards D9.
   - Prepare RHK controller: XYZ offsets in the middle (5.0). Set initially: time constant ~0.2, gain ~0.3. Set appropriate bias and current set points.
-  - In RHK software, set Waveform "Parabola" and "Approach steps = 1". Click "Approach" button.
+  - In RHK software, set Waveform "Parabola" or "Sawtooth" and "Approach steps = 1". Click "Approach" button.
   - Use gain as Z-piezo motor speed control. When the tip and sample gap is very large, set gain ≥ 0.5. Observe if the Z motor moves fast enough. Keep the motor approaching "fast" until the sample gets close enough that the tip-sample gap can't be seen anymore (either via the camera or by eye looking into the view port).
   - When the gap gets small enough (less than 1 mm), slow down the Z motor by decreasing the gain. Decrease the gain till it's very hard to see the motor moving. Now the motor has to move very slowly, or the tip can crash. This is the **fine approach**.