The LI-193 Spherical Quantum Sensor measures PAR in air or underwater from all directions at depths up to 350 meters. This sensor is useful for studies of phytoplankton, which uses radiation from all directions. The measurement is referred to as Photosynthetic Photon Flux Fluence Rate (PPFFR) or Quantum Scalar Irradiance.
Ideal for oceanography, limnology, turbidity, and vertical profiling
How does it work?
The LI-193 uses a diffusive sphere to direct light through glass optical filters to the silicon photodiode. The filters create uniform sensitivity to light between 400 and 700 nm, which closely corresponds to light used by most terrestrial and aquatic plants and algae. The angular response of a typical LI-193 is slightly lower in the direction of the cable connection. When mounted, the low response is usually not significant due to the small proportion of upwelling radiation compared to the total.
Cables and Accessories
LI-193 cables are available in lengths from 3 meters to 100 meters.
We recommend the 2009S Lowering Frame to lower the sensor into water.
Absolute Calibration: ± 5% in air traceable to NIST
Sensitivity: Typically 7 μA per 1,000 μmol s-1 m-2 in water
Linearity: Maximum deviation of 1% up to 10,000 μmol s-1 m-2
Stability: < ± 2% change over a 1 year period
Response Time: 10 μS
Temperature Dependence: ± 0.15% per °C maximum
Angular Response: < ± 4% error up to ± 90° from normal axis (see Angular Response chart)
Azimuth: < ± 3% error over 360° at 90° from normal axis
Operating Temperature Range: −40 °C to 65 °C
Detector: High stability silicon photovoltaic detector (blue enhanced)
Sensor Housing: Corrosion resistant metal for both saltwater and freshwater applications with an injection molded, impact resistant, acrylic diffuser. Units have been tested to 3,400 kPa, 350 meters (500 psi).
Globe: 6.1 cm diameter (2.4”)
Housing: 3.18 cm diameter (1.25”)
Overall Height: 10.7 cm (4.2”)
Weight: 142 g (0.31 lbs.)
Mounting: Three 6-32 mounting holes are tapped into the base for use with the 2009S Lowering Frame or other mounting devices.
Cable: Requires 2222UWB Underwater Cable (available in 3, 10, 30, 50, 100 meter lengths)