Ch. 19. Air Temperature Controller Sec. 19.1. Overview
Figure 19.1.: Basic Diagram of ATC airflow. Cool lab air enters via a HEPA filter at the bottom of the
Cypher ATC and then passes through fans and heater coils and travels via corrugated hose to the Cypher
enclosure. Temperature signals travel from the Cypher back to the ATC (dotted line). Air exits the Cypher
from the bottom rear.
If the temperature of your laboratory varies by more than a few tenths of a degree over time (almost
all labs do), your SPM images may be suffering from distortion due to differential thermal expansion
and contraction of the entire instrument. The Cypher ATC can improve the situation by gently forcing
filtered temperature controlled air through the AFM enclosure.
The Cypher ATC is a box containing a heater/fan sub-assembly and an electronics board for controlling
the amount of heat generated and the volume of air flowing into the Cypher SPM enclosure. The interior
temperature of the Cypher enclosure is regulated by a software driven feedback loop that controls the
ATC system’s heater to maintain the temperature of a thermal sensor located on the back of the Cypher
SPM chassis.
The temperature in typical labs will vary by a few degrees during the course of the day, often oscillating
due to the turning on and off of air conditioning. The ATC will counter these temperature swings by
adding more of less heat to counteract these temperature swings. Since the ATC can only add heat, the
temperature setpoint must be set above the maximum temperature swing of the laboratory, typically 2-5
BETA
Page 204
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