You are here: Installation and Maintenance Guide > Calibration > Calibration Procedures > Closed Loop XY Calibration

Closed Loop XY Calibration

A separate set of parameters is used to control the scanner XY position when XY Closed Loop is on. These are called the OptoXY Closed Loop Calibration parameters. In addition to the parameter, XY Closed Loop, in the Scan panel, a new panel, OptoXY Closed Loop Calibration, contains scanner calibration parameters associated with the Dimension Icon scanner.

With Scan > XY Closed Loop set to On, click Calibrate > Scanner > X-Y to open the OptoXY Closed Loop Calibration panel:

NOTE: When the Dimension Icon scanner is in open loop mode, a different panel, Scanner Calibration, opens. It shares two of the same parameters as the OptoXY Closed Loop Calibration panel (Rounding Minimum and Minimum Scan Rate), but includes considerably more calibration parameters to compensate for piezo nonlinearity

Closed Loop XY Calibration has four procedural components:

Measure Orthogonality at (0,0) offset
Measure Horizontally at 90 μm Scan Size
Measure Vertically at 90 μm Scan Size
Scan Angle Correction

Other parameters

The remaining parameters in the OptoXY Closed Loop Calibration panel are detailed below.

NOTE: Due to inherent mechanical characteristics of the probe holders used for certain applications (e.g., Fluid Imaging, investigations using the Applications Modules, and Heater Cooler), reduced closed loop X IGain and Y IGain parameters are sometimes necessary. Reduce the closed loop X and Y IGain parameters from their default values when using a probe holder other than the standard air tapping or TR holder. Modified values are given below.

Rounding: Defines the percentage of the fast scan time not captured or shown on the Display Window. A rounding of 0.1 corresponds to 10% longer scan lines than displayed in the image. This function allows mechanical systems to stabilize after the scan direction changes. This function distorts the linearity corrections made on the head or scanner.

NOTE: This parameter should be zero for short, slow scans and increased only for long, fast scans.

Max Scan Size:A software limit on the largest scan along the fast scan axis.

NOTE: Max Scan Size applies only to closed loop operation and is set to 100 μm at the factory. It is not necessary to ever adjust it. Reducing Max Scan Size from its default setting restricts scan size. Increasing Max Scan Size from its default setting cannot damage the scanner and never results in a scan size larger than is obtained in open loop mode with 440 V (the maximum allowed) applied across the piezoelectric scan tube. You might increase Max Scan Size to 110 μm, for instance, if you determine your particular scanner is capable of 110 μm scan size in open loop mode and the extra scan size is valuable to you. The disadvantage of making this too large is that the XY feedback loop may reach the edge of the scan or sensor range. If this occurs, the edge of each line may have several pixels that are all collected at the same point.

Minimum Scan Rate:Sets a lower limit for the Scan Rate parameter on the Scan panel.

X IGain:The integral gain for closed loop scanner control along the X-axis (the fast scan axis if the scan angle is 0°).

Y IGain:The integral gain for closed loop scanner control along the Y-axis (the slow scan axis)

XY Threshold:The RMS amplitude of high pass filtered X- or Y-scan error signal that is interpreted as evidence of control loop oscillation, so triggers reducing X IGain or Y IGain to reachieve control.

PGain/IGain Ratio:Proportional gain as a fraction of integral gain, applied to both X and Y axes.

 

www.bruker.com Bruker Corporation
www.brukerafmprobes.com 112 Robin Hill Rd.
nanoscaleworld.bruker-axs.com/nanoscaleworld/ Santa Barbara, CA 93117
   
  Customer Support: (800) 873-9750
  Copyright 2010, 2011. All Rights Reserved.