Closed Loop Z Calibration

Several additional parameters are used to calibrate the Z-axis in closed loop operation:

Z Sensor Sens:The sensitivity, in nm/V, of the optical Z-axis sensor when Z Sensor Gain Factor = 1.

• Determine this by measuring a calibration standard with the Z sensor channel. See Z Sensor Sensitivity, page 468.
• Range and Settings: 0–1000 nm/V
• Typical value: 500 nm/V

Z Sensor Gain Factor:During the engage, the Z piezo is ramped to find the Z piezo range. The sensor gain is adjusted to set a Z sensor range that is:

(Z sensor range factor)*(Z piezo range)=gain of the Z sensor

Make this larger than 1 to ensure that the dynamic range is covered. Note that the resolution of the Z sensor ADC is decreased by this amount.

• Range and Settings: 1–2
• Typical value: 1.5

Z CL Range Factor:The range of the Z sensor that is used in Z closed loop mode (ramping). Making this larger increases the chance that part of the ramp may reach the end of the scanner range.

• Range and Settings: 0–1
• Typical value: 0.9

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