Quantum Sensor—LI-COR LI-190R

The LI-190R quantum sensor measures photosynthetically active radiation and provides analog data to the Sutron 9210B datalogger. Here we provide basic installation and operation instructions for using the LI-190R-SMV or LI-190SL in a LI-COR eddy covariance system with a biomet system running Biomet_100, Biomet_101, Biomet_102, and Biomet_103 programs.

LI-190R Specifications:
Spectral Response: 400 to 700 nm
Energy Range: 0 to 2000 µmol/m2/s
Absolute Calibration: ±5%
Output Signal: 0 to 10 mV
Linearity: Max. deviation of 1% up to 10,000 μmol s-1 m-2
Cosine Correction: Up to 80° angle of incidence
Azimuth Error: <1% over 360° at a 45° elevation angle

Installing the LI-190R

  1. Siting the Quantum Sensor.
    • Position the LI-190R so it will never be under a shadow, either from the surrounding landscape elements or from the tower itself.
    • Mount the sensor on the tower to minimize reflected radiation that is visible to the sensor.
  2. Mount the Quantum Sensor.
    • Mount the LI-190R in the mounting and leveling fixture (2003S).
    • Attach the 2003S to the 7900-350 radiation sensor bracket and level the 2003S.
    • Secure the cable to the tower using zip-ties.
  3. Wire the Quantum Sensor.
  4. The LI-190R Quantum Sensor is supported by datalogger programs Biomet_100, Biomet_101, Biomet_102, and Biomet_103. For custom datalogger programs, use the SolRad block and configure it as described in PAR Sensor (LI-190R or LI-190SL).
  5. Route cables through an opening in the bottom of the enclosure.Note: Route the sensor cable(s) through an opening in the enclosure prior to installing the leads in the terminal strip.

Description Color Terminal
Positive Red A19 (AGND)
Negative Black A18 (CH10)

Since the datalogger reads ± signals, connect the positive (red) lead to the common (low) terminal, and connect the negative (black) lead to signal (high) input.

Important: The millivolt adapter is not weatherproof. Keep it inside the enclosure for protection from the elements.

Retrieving Data

If the system is configured to log biomet data in .ghg files for processing in EddyPro software or the SmartFlux System, data are stored on the removable USB storage device. Refer to the Biomet Instruction Manual for details.


  • Keep the surface and vertical edge of the acrylic diffuser clean.
  • As needed, clean the diffuser sensor with water, mild detergent, or vinegar dilute using a soft, lint-free cloth.
  • Do not use alcohol, organic solvents, strong detergents, abrasive solvents, or abrasive cloth on the diffuser.
  • Return the sensor to LI-COR for factory recalibration every two years. Contact technical support for more information.