Lake Shore 350, User Manual

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30 c
HAPTER
2: Cooling System Design and Temperature Control
Model 350 Temperature Controller
It is important to look at instrument specifications before ordering calibrated sen-
sors. A calibrated sensor is required when a sensor does not follow a standard curve if
you wish to display in temperature. Otherwise the Model 350 will operate in sensor
units like ohms or volts. The Model 350 may not work over the full temperature range
of some sensors. The standard inputs are limited to operation above 100 mK even
with sensors that can be calibrated to 20 mK.
2.9.2 SoftCal™ SoftCal™ is a good solution for applications that do not require the accuracy of a pre-
cision calibration. The SoftCal™ algorithm uses the well-behaved nature of sensors
that follow a standard curve to improve the accuracy of individual sensors. A few
known temperature points are required to perform SoftCal™. The Model 350 can also
perform a SoftCal™ calibration. You need to provide one, two, or three known tem-
perature reference points. The range and accuracy of the calibration is based on these
points (section 5.10).
Lake Shore offers two or three point SoftCal™ calibrated sensors that include both
the large interpolation table and the smaller breakpoint interpolation table for 400
series diode and Platinum sensors.
2.9.3 Sensors Using
Standard Curves Some types of sensors behave in a very predictable manner and a standard tempera-
ture response curve can be created for them. Standard curves are a convenient and
inexpensive way to get reasonable temperature accuracy. Sensors that have a stan-
dard curve are often used when interchangeability is important. Some individual sen-
sors are selected for their ability to match a published standard curve, but in general
these sensors do not provide the accuracy of a calibrated sensor. For convenience, the
Model 350 has several standard curves included in firmware.
2.9.4 Curve Handler™ Lake Shore provides a software application, called Curve Handler™, which makes
loading temperature curves into the Model 350 a very simple process. The program
can copy curves from properly formatted files into the Model 350 user curve loca-
tions. You can also use it to read curves from the Model 350 and save them to files.
Lake Shore calibrated sensors are provided with a CD containing all the proper for-
mats to load curves using the Curve Handler™ software program.
There are two versions of the Curve Handler™ application. The fully featured version
is a 32-bit Microsoft Windows™ application that must be installed on a Windows™
PC. This version works with the IEEE-488 and USB computer interfaces on the
Model 350, and allows you to manipulate the temperature curves directly in the pro-
gram window. This version will also work with all existing Lake Shore temperature
controller and temperature monitor instruments. The Windows™ version of the

Curve Handler™ application is available, free of charge, from the Lake Shore website
at www.lakeshore.com.
The second version of Curve Handler™ is written in the Java™ programming language
and is available through the Ethernet web interface on the Model 350. This version
allows you to copy curves from files to the Model 350, and vice versa, but it does not
allow manipulation of curve data and only works using the Ethernet interface. Refer
to section 6.4.4 for details on connecting to the web interface and opening the
embedded Curve Handler™ application.
2.10 Sensor
Installation This section highlights some of the important elements of proper sensor installation.
For more detailed information, Lake Shore sensors are shipped with installation
instructions that cover that specific sensor type and package. The Lake Shore Tem-
perature Measurement and Control Catalog includes an installation section as well.
To further help you properly install sensors, Lake Shore offers a line of cryogenic
accessories. Many of the materials discussed are available through Lake Shore and
can be ordered with sensors or instruments.