INFICON Cygnus 2 Thin Film Deposition Controller - Manual (Page 113)

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Cygnus 2 Operating Manual
TIME LIMIT . . . . . . . . . . . . . . . . . . . 00:00 to 99:59 min:s
This is the deposition time at which the Time Limit is triggered. This time begins
to accumulate at the start of the Deposit state. The Time Limit, once triggered,
remains active until the start of the IDLE state. The default value is 00:00.
RATE FILTER TIME . . . . . . . . . . . . . One Tenth (0), Four Tenths (1), One (2),
Four (3), Ten (4), Twenty (5), Thirty (6)
seconds
This parameter is used to apply a boxcar filter to the measured raw rate which
is used to produce the Rate DAC output voltage.
The Rate Filter Time may be used for enhanced resolution. If a source has a
long time constant, rate may be taken as constant over longer intervals.
Averaging provides an opportunity to reduce rate noise. Depending on the
source of the noise, averaging can improve rate resolution:
 If the noise is crystal frequency resolution limited—the thickness change
over one second provides ten times the thickness change vs. the thickness
change measured over a tenth of a second. A one second averaging
interval will improve rate resolution by 10 times.
 If the sensor noise is random, then RMS reduction of rate noise is provided
by the square root of the number of point’s averaged (example a 10 point
average provides a factor of 3.1 noise reduction).
The selection of the appropriate Rate Filter Time value will be dependent on the
characteristics of the source. The default value is One Tenth.
TIME POWER AV(ERA)G(ING) TIME0 to 30 min. (default = 0)
This parameter value determines the amount of time used in calculating the
average rate and average power for use in Time Power and for Auto Soak 2.
The Averaging Time parameter is the time interval used to calculate both the
average rate and average power applied, if a crystal fails, for Time-Power and
Non-Deposit Hold states. When the Averaging Time parameter value is 0, then
a 2.5 second average, ignoring the most recent 0.5 second, is the averaging
interval.
The status message ABBR(EVIATED) AVERAGE is generated if the averaging
interval has not been reached, but there was at least a complete whole minute
of data to average.
The status message NO or NEG AVERAGE is generated and Stop is entered
if a crystal fail occurred within the first minute of control with Averaging Time set
>0. This error also occurs if there is a crystal fail during the first 2.5 seconds of
control with the Averaging TIme = 0. (There are also remote communication
commands to get and set the average rate and average power values.)