Apogee Instruments' 400-750 nm Extended Photosynthetically Active Radiation (ePAR) sensor is designed for making total photon flux intensity measurements of wider ranges than traditional PAR sensors that measure 400-700 nm.
Apogee's cutting-edge ePAR sensor was created in 2021 as an upgrade to our ePFD sensor and designed to measure the newly defined 400-750 nm ePAR radiation range that research has shown to be photosynthetically active, beyond the traditional 400-700 nm range (read article here >). Many next generation LED fixtures, the sun, and other light sources emit these newly confirmed Far-red photosynthetic wavelengths, but they have not been measurable by traditional 400-700 nm PAR meters until now. Much of the transformative work to define the ePAR range was conducted by Dr. Shuyang Zhen and Dr. Bruce Bugbee at Utah State University's Crop Physiology Laboratory. The most recent article by Dr. Zhen and Dr. Bugbee can be found in the New Phytologist. A few of the many articles by these researchers discussing ePAR can be found in Greenhouse Management, Plant, Cell and Environment, Frontiers in Plant Science, and at Fluence.
Is PAR really 400-700 nm? The McCree Curve Revisited with Evidence ePAR should be the New Standard
Spectral Response
The ePAR sensor has a spectral range of 400 to 750 nm ± 5 nm. The spectral response can be seen in the graph below.
Accurate, Stable Measurements
Sensors are cosine-corrected to maintain their accuracy when radiation comes from low zenith angles. The sensors measure PFD with a cosine response accurate within ± 5 % at 75° zenith angle. Long-term non-stability determined from multiple replicate quantum sensors in accelerated aging test and field conditions is less than 2 % per year.
Typical Applications
Total ePAR intensity measurements over plant canopies in all growing environments, monitor and adjust grow lights, research plant morphogenic activity, and photobiology studies.
Calibration
To ensure accuracy each sensor is carefully calibrated in controlled conditions and traceable to NIST reference standards. ePAR sensors are pre-calibrated for all light sources.
Rugged, Self-cleaning Housing
Patented domed shaped sensor head (diffuser and body) facilitate runoff of dew and rain to keep the sensor clean and minimize errors caused by dust blocking the radiation path. Sensors are housed in a rugged anodized aluminum body and electronics are fully potted.
Pigtail-lead sensors feature an IP68, marine-grade stainless-steel cable connector to simplify sensor removal for maintenance and recalibration. Cable is shielded-twisted pair wire with a TPR jacket for high water resistance, UV stability, and flexibility in cold conditions.
Warranty and Support
All Apogee products are backed by an industry-leading four year warranty and outstanding customer support.
