• Be sure to select the camera icon within the Asylum software to bring up camera window
• (If camera closed without closing “camera panel” camera icon will not work, close camera panel)
• Check that light source (next to computer tower is on) and brightness knob turned up (in front of controller)
• Check to be sure camera mount is aligned with mirror (mounted behind AFM head

Check controller to be sure laser (key) is on

When aligning laser please use centering method:

1. Turn Y-laser wheel (PDY) one direction, all the way until it stops
2. Count turns (PDY) while turning all the way the other direction = total working length
3. Turn Y-laser wheel (PDY) until 1/2 total working length
4. Repeat steps 1-3 with X-laser wheel (PDX)
5. Laser should be somewhere near edge of probe/cantilever and with slight adjustments of PDX; and can be clearly seen if reflected off larger probe area (+ PDX)
6. Move laser to base of cantilever
7. Position (maximum sum) in Y-direction
8. Then move (X-direction) to end of cantilever

Thermal scan is a survey of cantilever signal at all possible operating frequencies and is important in identifying specific cantilever resonance frequencies for non-contact/tapping modes of use.

Irregularities in Thermal scan can arise from:

• Improper probe mounting (misaligned/loose) –> check probe seating in holder
• Damaged tip/cantilever –> check for visual cracks in probe material
• Fouled tip (excess weight on cantilever) –> clean probe with air/water
• Laser/detector misalignment –> See Laser alignment FAQ

Tuning:

Topographical scanning in non-contact/tapping mode relies on cantilever operation at resonant frequency to maintain regular oscillation of tip in the z-direction. Tip engagement with surface may alter this behavior and require re-tuning of tip.

Set Point:

Often when engaged signal quality may be too low for effective computer generation of topographical image. Lowering set-point allows for harder tip-surface contact and measurement of surface features. Note: set-point is relative to cantilever (sum) signal when not in contact with surface (“free air amplitude”). Low set-point relative to free air amplitude can result in harder contact with surface and blunting/damage to tip.

Gain:

When engaged on surface the z-piezo controls tip approach or withdrawal form surface in order to maintain good contact. The amount/length of adjustment in the direction for tracking up and down vertical features is controlled by the Gain value. A high (>50) versus low (<5) gain value allows for greater step sizes when controller adjust tip in z-direction. This, however, is relative to how fast a scan is being conducted as slower scan speeds (≤5 nm/s) allow for greater time to climb up and down surface features. Hysteresis of drift between trace and retrace curves can be improved by increasing gain. Note: Higher gain results harder contact with surface and blunting/damage of tip.

Sinusoidal “noise”/Gain:

Gain can also result in the creation of additional noise in a scan through over/underestimating of necessary step length and repeated corrections to maintain good contact with surface. This typically results in the appearance of a sinusoidal waveform in image that is not actually there. Reducing gain will reduce or remove waveform all together.

Attractive/Repulsive imaging/Phase:

Tip-surface interaction can also play a critical role in image quality. Specifically phase shifting of tip when in close proximity to surface can effect attractive and repulsive interactions between tip-surface. “Attractive” forces can be observed when Phase is > 90˚, “repulsive” when < 90˚. Tuning typically attempts to center phase @ 90˚, but further adjustments can be made by altering "phase" offset during tuning.