31
NOTE
When using the digital filter in SNGL acquisition mode , each measurement is
the average of the last 10 acquisitions independent of how old any of the
measurements are.
Gain
Gain processing accounts for the signal gain of the input amplifiers. The
output is the product of the digitized value and the amplifier gain.
Zero Offset
Zero offset is active whenever the ZERO annunciator is lit, Section 2.3.5. The
zero offset output is equal to the input value less the zero reference value,
S-S
0
.
Responsivity Map(s)
This process scales the input value in accordance with current calibration
wavelength and the responsivity map downloaded from the detector calibration
module. The output of this process, i.e. the measurement value, is the digitized
input value divided by the responsivity associated with the current calibration
wavelength or the user defined calibration value. Different responsivities are
used depending upon if the attenuator, ATTN, annunciator is lit, Section 2.4.5.
Units Correction
Units correction adjusts a measurement value to account for the display units
selected. When the display units are equal to the detector signal units, i.e.
equal to the numerator of the responsivity units, Table 22, the measurement
value is not adjusted. Otherwise the digitized value is adjusted to account for
detector responsivity and/or additional unit conversions such as Joules-to-
Ergs or W-to-W/cm
2
.
NOTE
Per area unit conversions such as W-to-W/cm
2
divide the measurement value
by the active area of the detector. This calculation assumes that the entire
active area of the detector is uniformly illuminated. Per area measurements
where the entire detector active area is not uniformly lit are not accurate. The
user must insure that these conditions are met before utilizing per area units.
3.4
Typical Detector Signals
The flexibility of the Model 2835-C analog signal flow is required in order that
it may properly measure the signals that various types of detectors make.
Basic optical power or energy measurements are related to a measured
detector signal,
S
, in the following way:
P
or
E
=
S
R
λ
Where:
R
λ
= Detector responsivity at
λ
.
S
= Detector signal
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