Linearity And Temperature Effects - Aerotech QNP3 Series Hardware Manual

Overview

1.3. Linearity and Temperature Effects

Linearity is measured and calibrated for every QNP3 stage purchased with the -C feedback configuration.
Unless otherwise specified, it is measured 15 mm above the center of the tabletop with the stage mounted in
a standard horizontal position. The surface that the stage is mounted to must meet or exceed the
requirements in Section 2.3.
Aerotech products are designed for and built in a 20°C (68°F) environment. Extreme temperature changes
could cause a decrease in performance or permanent damage to the QNP3. At a minimum, the
environmental temperature must be controlled to within 0.25ºC per 24 hours to ensure the QNP3
specifications are repeatable over an extended period of time. The severity of temperature effects on all
specifications depends on many different environmental conditions, including how the QNP3 is mounted.
Contact the factory for more details.
The Z-axis of the QNP3 is sensitive to thermal expansion because of its relatively small open loop travel (±1
µm). Therefore, the physical travel range of the stage will shift relative to the sensor feedback range as a
function of stage temperature. If the temperature of the stage changes by more than ±3 °C from the
temperature at which it was configured, the entire configured closed loop travel range will no longer be
achievable.
If the entire closed loop Z-axis travel cannot be achieved, adjust the Absolute Feedback Offset of the Z-Axis
in software to re-center the configured travel in the working range. Refer to Aerotech controller
documentation for more information on how to adjust the Absolute Feedback Offset. The working
temperature of the stage must be controlled to ±3 °C to ensure the entire closed loop range will be available
for the duration of a continuous process.
Configure the Absolute Feedback Offset in software as described in the Aerotech controller documentation
as part of the initial startup procedure for the QNP3 to ensure the working range of the Z-axis is adjusted to
the ambient temperature in its operating environment.
N O T E : QNP3 stages with feedback are paired with their drives and extension cables, if purchased, at
the factory. If a stage with feedback is operated with different drives, amplifier slots, or extension cable
lengths than it was initially paired with, the QNP3 may not maintain its specified linearity. New drive and
stage combinations can be re-qualified at Aerotech to maintain optimum performance.
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to maintain the linearity measured at the factory.
Chapter 1
QNP3 Hardware Manual
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