Scientech S310 Vector - Manual (Page 29)

29
C
ORRECTING
U
LTRA
S
ERIES
HD C
ALORIMETERS
O
PERATING
P
ARAMETERS
FOR
U
SE AT
D
IFFERENT
W
AVELENGTHS
:
NOTE: Due to variability in the manufacturing process the absorption characteristics of the HD and P
model detectors can vary in the UV region (190 to 400nm). Scientech recommends optical
calibration at 266nm if the detector is to be used in the UV region instead of relying on an
absorption rate in the chart at the end of this manual.
Scientech calorimeters in general have a flat response to all wavelengths within their specified spectral
response. HD calorimeters are an exception to that rule and are calibrated at a specific wavelength by adjusting
the calorimeter’s gain circuitry for that wavelength. The calibration wavelength is recorded in the Operating
Parameters section at the front of the manual and on the detector’s serial tag. When a HD calorimeter is used at
a wavelength other than the calibration wavelength, the indicator’s displayed value can be adjusted to
compensate for the absorption rate at the new wavelength by using an attenuation factor. The attenuation factor
is calculated as follows:
1. Find the absorption rate from the chart at the end of this manual for the calibration wavelength of your
calorimeter.
2. Find the absorption rate for the wavelength where you will be working.
3. Determine the attenuation factor using the following formula:
absorption rate of calibration wavelength = attenuation factor
absorption rate of the new wavelength
The attenuation factor can be entered into the S310 as described in the Group Settings section.
A
NALOG
O
UTPUT
:
The analog output is an uncalibrated output accessible via the 50 ohm terminated BNC connector located on the
indicator's rear panel (see Figure 1). Although the analog output voltage level is uncalibrated, it is representative
of the power and energy readings displayed on the S310. The analog output voltage level is approximately 3
volts full scale. For high accuracy, you must determine the relationship between the analog output voltage level
and the power and energy readings on the S310 display.
With a calorimeter connected to the S310 in watts mode, the analog output voltage readings will rise to a steady
level when power is applied to the calorimeter. After the voltage readings become stable, note the analog
output voltage reading and the watt reading on the S310 display. All subsequent voltage readings will have the
same V/W values. In the joules mode, the voltage will rise to a peak value relatively quickly (seconds)
followed by a rapid return to baseline. The peak voltage is representative of the joules value. Again, this can be
determined by noting the peak voltage value on the analog output, and the joules reading on the S310 display.
With a pyroelectric detector connected to the S310, determine the relationship between the peak voltage value
and the energy (joules) or power (watts) reading on the S310 display in the same manner.
The analog output with the various detectors and operating modes should appear as follows: