LI-COR LI-191R Line PAR Sensors
Features
- Spatially averages PPFD over its 1m length
- Uses a 1m quartz rod under a diffuser to conduct light to a single Quantum sensor
- Improved water resistance for long-term outdoor deployment
- Free ground shipping
- Expedited repair and warranty service
- Lifetime technical support
- More
Overview
The LI-191R Line Quantum Sensor measures Photosynthetically Active Radiation (PAR) integrated over its 1-meter length. It is used to measure sunlight under a plant canopy, where the light field is non-uniform. It measures light in units of Photosynthetic Photon Flux Density (PPFD), which is expressed as μmol s-1 m-2.
Mechanics
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. The diffuser and single photodiode in the LI‑191R provide stable, integrated measurements that are superior to averages provided by many linear sensors. 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.
- Absolute Calibration: ± 10% traceable to National Institute of Science and Technology (NIST). The LI-191 is calibrated via transfer calibration
- Sensitivity: Typically 7 μA per 1,000 μmol s-1 m-2
- Linearity: Maximum deviation of 1% up to 10,000 μmol s-1 m-2
- Response Time: 10 μs
- Temperature Dependence: ± 0.15% per °C maximum
- Cosine Correction: Acrylic diffuser
- Azimuth: < ± 2% error over 360° at 45° elevation
- Sensitivity Variation over Length: ± 7% maximum using a 2.54 cm (1”) wide beam from an incandescent light source.
- Sensing Area: 1 m × 12.7 mm (39.4” × 0.50”)
- Detector: High stability silicon photovoltaic detector (blue enhanced)
- Sensor Housing: Weatherproof anodized aluminum housing with acrylic diffuser and stainless steel hardware.
- Size: 121.3 L × 2.54 W × 2.54 cm D (47.7” × 1.0” × 1.0”)
- Weight: 1.4 kg (3.0 lbs.)
- Cable Length: 2 m, 5 m (6.5', 16.4')
- (1) LI-191R Line PAR Sensor
- (1) Bubble level
- (1) Detachable 10 ft. cable
- (1) Hard-sided carrying case
Select Options
In The News
Long-Term Monitoring in the Chautauqua Lake Watershed
With a widely developed shoreline, Chautauqua Lake experiences influxes of non-point source pollution that have historically impacted the health of the lake. The Chautauqua Lake Association (CLA) has been monitoring the lake for over two decades, reporting on changes that have occurred over the years. A pair of local lake advocates, Jane and Doug Conroe, have lived on the lake for over 40 years and have played an important role in establishing monitoring programs and facilitating consistent data collection throughout the watershed. Doug has been involved with the Chautauqua Lake Association (CLA) since the pair moved to the area in 1980, and is currently serving as the Executive Director.
Read More
No Red Herrings: Data Driving the Largest Salt Marsh Restoration in the NE USA
The Herring River system encompasses around 1,000 acres in the Towns of Wellfleet and Truro, Massachusetts. In 1909, the Chequessett Neck Road dike was built at the river’s mouth, drastically limiting tidal flow. Today, it’s one of the most restricted estuaries in the northeastern United States. As a result, the area has suffered environmental decline, including poor water quality, hypoxia, lower pH, and salt marsh degradation. In 2023, the Town of Wellfleet received $14.7 million from NOAA’s Office of Habitat Conservation to fund the Herring River Restoration Project (HRRP). Francesco Peri, President and CEO at Charybdis Group LLC, uses a network of NexSens data loggers to monitor water level and water quality on the Herring River.
Read More
Carbon and Nutrient Monitoring in the Great Lakes Using Satellite Observations
Carbon and nutrients are the foundation of lake food webs and play an important role in the chemical and physical processes that shape aquatic ecosystems and various lake dynamics. Studying these cornerstones can help improve understanding of other lake conditions like harmful algal blooms, hypoxia, and phytoplankton community composition. The way in which these characteristics are monitored varies, though many rely on a proxy approach wherein parameters are extrapolated from the measurement of a different parameter. An assistant professor at Cleveland State University, Brice Grunert, is working to improve current strategies and take a satellite approach to monitoring the Great Lakes.
Read More
