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
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.
A non-uniform light field under a plant canopy is difficult to characterize with a single sensor or multiple sensors arranged in a line because the light field can vary considerably from point to point and over a line.
To solve this problem, 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.
Sensors that use multiple photodiodes potentially induce large uncertainty in measurements because each photodiode can drift independently of the others. 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
Caring for the Chesapeake: Supporting the Iconic Bay Starts with Good Monitoring Data
The Chesapeake Bay is enormous: the Bay and its tidal tributaries have 11,684 miles of shoreline—more than the entire U.S. west coast. It is the largest of more than 100 estuaries in the United States and the third largest in the world. The Bay itself is about 200 miles long, stretching from Havre de Grace, Maryland, to Virginia Beach, Virginia. But the Chesapeake Bay isn’t just enormous--it’s enormously important. The Chesapeake Bay Program reports that its watershed covers about 64,000 square miles and is home to more than 18 million people, 10 million of which live along or near the Bay’s shores.
Read More
Treating Harmful Algal Blooms: A Natural Progression
Some of us happen upon the subject of our life’s work by accident, some of us are born into it, and some of us ease into it over time. For Tom Johengen, Research Scientist for Cooperative Institute for Great Lakes Research (CIGLR) and Director of Michigan Sea Grant , choosing to study Harmful Algal Blooms (HAB) was “a natural progression” from his days as a grad student investigating best management practices for controlling nonpoint source nutrient pollution. “I’ve been the research scientist with CIGLR since my postdoc in 1991, 31 years, and I’ve been the Director of Michigan Sea Grant for the past 3 years. When I began my postdoc with CIGLR we were just starting to study the impacts of the recently invaded zebra mussels.
Read More
The Coevolutionary Arms Race: Fungus-Growing Ants and Social Parasites
Despite the negative stereotypes surrounding social parasites, Rachelle Adams, Assistant Professor at The Ohio State University, knows just how important host-parasite relationships are to evolution. Like many ecologists, Adams, Assistant Professor at The Ohio State University, found her passion for nature in childhood. “It began when I was a kid. I had this general interest of nature, and I loved to spend time in the forest, exploring,” she recalls. Her desire to work with wildlife was solidified in college. “I didn’t know exactly what direction I was going to head in but the ecology and evolution classes I took were really central to shifting my perspective on ‘what is biology.’ It opened my eyes to seeing nature in a different way,” she explains.
Read More
