C5 PAR SENSOR
The LICOR LI-193SA Underwater Spherical Quantum
Sensor gives an added dimension to underwater PAR
measurements as it measures photon flux from all
directions. This measurement is referred to as
Photosynthetic Photon Flux Flounce Rate (PPFFR) or
Quantum Scalar Irradiance. This is important, for
example, when studying phytoplankton, which utilizes
radiation from all directions for photosynthesis. The LI-
193SA features a high sensitivity optical design and
compact, rugged construction (3400 kPa, 350 meters
depth). The OCEAN SEVEN 310 probe LI-193SA analogue interface transforms, by means of a linear
current to voltage pre-amplifier, the LI-193SA sensor output (current in μA) in ADC counts.
Calculation of the calibration coefficients implies a preliminary calculation that is carried out by
using the LICOR calibration certificate and the probe calibration certificate. By applying the below
calculation, the OCEAN SEVEN 310 transforms the sensor readings in μmol s-1 m-2.
Calibration constants
LI-193SA calibration constant in water = 4.71 μA per 1000 μmol s-1 m-2
OCEAN SEVEN 310 Full Scale current = 9.83 μA equivalent to = 65536 ADC counts
Calculation of the full scale PAR sensor
F.S. (9.83 μA / 4.71) * 1000 = 2087.048832 μmol s-1 m-2
Afterwards, the calibration coefficients (a+bx) can be calculated using the value tabled herewith.
μmol s-1 m-2 ADC counts (bit)
0.0 0.0
2087.048832 65536
From the above table of data, the offset and slope coefficients to be entered during the PAR
calibration procedure must be calculated by the operator. This can be done using the “Interpolate”
tool distributed with the IDRONAUT ITERM program.
C5.1 CONFIGURATION
The following parameters are requested to properly set up the PAR. The sensor setup sequence can
be run using the CNAP command available under the CONF menu
Logical code [0..255]:25
Description :PAR
Significant digits [1..13]:10
Digits after the dot [0..9]:6
Do you want to store it ?:Yes
Do you want to show data ?:Yes
Data processing method
0)Counts,1)mV,2)Custom&UNESCO,3)Polynomial,4)a+bx
Method [0..4]:4
Mux[0..7,240=A.Board,255=NU]:2
Compensate thermal drift ?:No
C5.2 CALIBRATION
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