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nGauge AFM User Manual

 

13

 

 

beyond the range of the Fine Z control, the image will get clipped. To increase or decrease the Fine Z 
scan range, click on the 

Menu

, then under PGAs increase or decrease the Z Fine. For maximum imaging 

resolution, the smallest Fine Z range should be used. It is also possible that the sample topology is not 
centered around the middle of the Fine Z range, which could result in image clipping. The Approach tab 
displays  a  graph  with  the Fine  Z  position.  If  it  appears  that most  of the  image  data  is  at  the  lower  or 
higher  end  of  the  Fine  Z  range,  you  can  click 

Show  Advanced  Controls

  and  increase  or  decrease  the 

Coarse Z to center the data. In some cases, you may even need to 

Disengage

 and then re-

Approach.

 

 

 

There  are  several  parameters  that  you  can  control  to  improve  the  imaging  performance.  The 

Time spent at each point

 is the number of microseconds that the tip will dwell above each data point. 

As you decrease this value, the scan speed will increase and the controller will have less time to track 
the  sample topology, leading to poor image  results. The 

Set Point

  is the  tip oscillation amplitude that 

the controller will try to maintain as the tip scans over the sample surface. It can be thought of as the 
amount of force that the tip exerts as it taps the surface, where a lower setpoint exerts more force. A 
lower  setpoint  can  often  give  better  results,  but  is  also more  likely to  damage the  tip or  sample,  and 
when the setpoint gets too low the imaging performance may suffer. A PI controller is used to maintain 
a constant tip oscillation amplitude throughout the scan by adjusting the Fine Z height. The 

Proportional  

and

 Integral 

control in the advanced controls section are used to adjust the response of the controller, 

and  can  be  tuned  to  give  the  best  sample  tracking  performance.  See  section  6.0  Troubleshooting  for 
more details for PI tuning. 

 

At any time you can click 

Pause

 and 

Resume

 to temporarily halt and then resume the current 

scan, or you can 

Pause

 and then 

Reset

 to re-start the current scan at the beginning. When the scan is 

complete, you will be able to click 

Save

 to save the image as a  .gwy file which is native to Gwyddion (a 

post-processing software), and as a .png image. You can also save the data as a .tsv file where the data 
points are arranged in a 2-d tab and line separated table. The image will be saved in the folder specified 
by 

Path

,  which  you  can  click  on  to  change.  All  6  images  (topo,  phase,  error  forward/reverse)  will  be 

saved, and a Unix timestamp will be appended to the file name. 

 

To zoom into a region of interest, you can drag across the displayed image to select an area to 

zoom in. Click 

Scan

 again after the selection has been made to scan the region of interest. To  reset to 

the original scan area, click 

Reset Zoom

. If 

Reset Zoom

 button is disabled, the AFM will scan the default 

area. 

Summary of Contents for nGauge AFM

Page 1: ...User Manual Version 1 1 Atomic Force Microscope...

Page 2: ...3 1 Where to set it up 6 3 2 How to set it up 7 3 3 Installing the Software 9 4 0 Basic Operation 10 4 1 Software Overview 10 4 2 Preparation and Approach 11 4 3 Imaging 12 4 4 Analyzing Data 14 5 0...

Page 3: ...ollowing warnings and precautions should be observed to ensure the safety of the user and the instrument Use only the power supply provided The driving electronics are designed to accept 7 5Vdc and an...

Page 4: ...ng DOWN in the storage box Use tweezers to pick them up The AFM chip can be placed on a flat surface with the tip facing up The AFM chip can be picked up by hand as long as you don t touch the tip Thi...

Page 5: ...of the cantilever onto a 4 quadrant photodetector that measures any small displacements of the cantilever A piezoelectric Z scanner controls the height of the probe while a piezoelectric XY stage ras...

Page 6: ...mage due to surface charging 3 0 Setup 3 1 Where to set it up The nGauge AFM is small simple and portable and can be set up just about anywhere However for best results it is recommended that you adhe...

Page 7: ...ng it up near sources of electrical noise such as server rooms or rooms operating high power equipment 3 2 How to set it up Setup of the nGauge AFM is very simple 1 Remove the components from the carr...

Page 8: ...nGauge AFM User Manual 8 3 Connect the USB cable to a computer and to the USB connector in the stage 4 Completely unscrew and remove the thumb nut from the stage...

Page 9: ...between the tip and platform 7 Replace the thumb nut and firmly tighten it 3 3 Installing the Software The software required to operate the AFM can be found on the USB stick provided or downloaded fro...

Page 10: ...ftware Overview Launch the software by double clicking on the nGauge program on your desktop or searching for nGauge in the start menu If the AFM is powered up and connected to the computer with the U...

Page 11: ...the platform is low enough Position the sample so that the area to be scanned is directly under the tip Ensure the sample is stable on the sample platform and that it won t tilt roll flutter drift or...

Page 12: ...ls above each point of the scan and ultimately determines the scan speed A smaller number in this field increases the scan speed but if the scan is too fast the resulting image may be blurry or distor...

Page 13: ...s more force A lower setpoint can often give better results but is also more likely to damage the tip or sample and when the setpoint gets too low the imaging performance may suffer A PI controller is...

Page 14: ...want to extract some quantitative data about the sample like the height or width of a specific feature or the RMS roughness of the surface These measurements are best acquired using Gwyddion a powerf...

Page 15: ...ay a 3D view of the image You can rotate or scale this 3D image change the colors and save it Once you are satisfied with the post processed image you can save it as JPG PNG etc using the Save As opti...

Page 16: ...still flat and noisy the AFM chip may be damaged Click on the Menu on the top right of the screen and scroll down and click Read All If any of the values under Resistances is greater than 1000 the AFM...

Page 17: ...The main controls that are visible in each screen should be sufficient for normal imaging conditions However each tab in the navigation contains advanced controls that can extend the functionality or...

Page 18: ...e line is being scanned repeatedly Leveling Direction To correct for the 15 degree tilt of the AFM chip relative to the sample a hardware leveling feature is applied Leveling Direction switches betwee...

Page 19: ...of the Coarse and Fine Z the amplitude of the AC driving signal on the Z actuator and the amount of leveling that is added to each scan PGA values can range from 0 140 ADCs Analog to Digital Converte...

Page 20: ...Port release the USB connection Choose Firmware currently Windows only Opens a window that allows you to locate the firmware update Firmware update files are binary bin files and can be downloaded fro...

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