LI-COR LI-191R Line Quantum Sensor

Used to measure sunlight under a plant canopy where the light field is non-uniform, the LI-191R Line Quantum Sensor measures PAR with a single detector integrating measurements over its 1-meter length. The LI-191R makes it easy to measure under-canopy light in many plots quickly and consistently. It measures light in units of Photosynthetic Photon Flux Density (PPFD), which is expressed as μmol s-1 m-2.

Why choose the LI-191R PAR Light Sensor?

• Improved water resistance for long-term outdoor deployment
• Integrated measurements using a single detector prevents variance found in sensors that use multiple detectors
• Selected by the National Ecological Observatory Network (NEON®) for integrated PAR measurements
• Compatible with the HOBOnet Analog Mote that transmits data automatically to cellular RX stations and LI-COR Cloud remote monitoring platform.

How does the line quantum sensor work?

The LI-191R uses a 1-meter long quartz rod under a diffuser to direct light to a single filtered silicon photodiode. The entire LI-191R diffuser is sensitive to light over its 1-meter length. Since the diffuser is one continuous piece, the LI-191R essentially integrates an infinite number of points over its surface into a single value that represents light from the entire 1-meter length. Optical filters block radiation with wavelengths beyond 700 nm, which is critical for under-canopy measurements, where the ratio of infrared to visible light may be high. The unique design of the LI-191R provides an excellent quantum response that is close to the ideal quantum response.