Scientech S310 Vector - Manual (Page 35)

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Operation of Astral  and Large Aperture Calorimeters with a Digital Volt Meter:
Note: Whenever a large aperture calorimeter is used without an indicator the interface module is not
used .
The calorimeters may be used with any digital volt meter (DVM) capable of reading 5 volts full scale.
Connect the output of the calorimeter to the DVM.
A. Select the DC volts mode.
B. Direct the laser beam on to the absorbing surface of the calorimeter.
C. When the display of the DVM has stabilized (about 2 minutes), calculate the laser power using the formula:
W = V/S where: W = Laser power in watts
V = Voltage reading of the DVM in volts
S = Sensitivity of the calorimeter from page 2.
Operation of Astral  Calorimeters with an Analog Chart Recorder:
Note: Whenever a large aperture calorimeter is used without an indicator the interface module is not
used.
Calorimeter Response:
The response of a calorimeter to a single pulse input as displayed by a chart recorder appears below.
The output voltage from a chart recorder can be converted to wattage at any time by:
W = V/S, W
i
= V
i
/S
V = Chart recorder voltage level in mV
S = Calorimeter sensitivity in mV/W
The total energy (E) in the pulse can be found by integrating the instantaneous wattage over time:
∞
E = ∫ W(t) dt
0
The following methods may be used to compute the total integrated energy:
Numerical Integration:
Finding the area under the curve in figure 7 is the equivalent procedure for determining pulse energy. Choose an
appropriate time interval, dt, and perform the summation:
N N
E = ∑ W
i
xdt = (dt/S) ∑ V
i
I=1 i=1
The error caused by this procedure is:
N
dE = (dt/S) Σ dV
i
i=1