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
Wildfire Prevention in the Sierra Nevada Region with the Yuba Watershed Institute
Though recent wildfires have sparked new conversations about wildfire management and response, groups like the Yuba Watershed Institute have been monitoring the forests and water resources of the Sierra Nevada region for decades, managing approximately 5,000 acres of land with the Bureau of Land Management (BLM) and about 7,000 acres in private land partnerships. The goal of the Institute is to work with local communities and land agencies to improve watershed and forestry management through informed practices and public outreach. The goals of the Yuba Watershed Institute are three-fold: Improve the ability of fire suppression agencies like the California Department of Forestry and Fire Protection ( CAL FIRE ) and the US Forest Service.
Read More
Wave Sensors Integration with NexSens Buoys: A Cutting-Edge Solution for Wave Measurment
Real-time wave data supports accurate weather prediction, safe and efficient maritime operations, and provides valuable safety and operating condition information for recreation and commercial fishing. Understanding wave dynamics also helps with the design of protective coastal structures like seawalls, breakwaters, and jetties. It also supports better prediction of their impact on sediment transport and coastal geomorphology. Wave data is a key factor in qualifying and designing offshore wind farms and harnessing kinetic energy for electrical generation. It helps with the understanding of ocean-atmosphere interactions and contributes to studies of sea-level rise and climate change impacts.
Read More
Spring 2025 Environmental Monitor Available Now
In the Spring 2025 edition of the Environmental Monitor, we highlight partnerships across the world and the importance of collaboration between government agencies, universities, environmental groups, local communities, and other stakeholders. From great white shark research in Cape Cod to monitoring fisheries in Lake Erie, this latest edition underscores partnerships that connect stakeholders in a watershed through environmental data. With an emphasis on data sharing, a combination of real-time and discrete sampling keeps the public and partners informed of environmental conditions. Our writers also sought out science professionals dedicated to working with peers within and outside of the environmental sector.
Read More
