“Apogee quantum sensors measure photosynthetically active radiation (PAR). Single quantum sensors are used to take PAR measurements at the level of a plant canopy, while ‘Line quantum sensors’ contain multiple sensors for measuring a spatial average of PAR. All sensors are fully potted and weatherproof, and can be used to take underwater measurements. Apogee full spectrum quantum sensors (500 series) feature an improved spectral response from 412 to 682 nm and produce accurate PAR measurements under nearly any lighting conditions. Apogee original quantum sensors (100 through 400 series) are sensitive to light from 469 to 653 nm and produce accurate PAR readings in most lighting conditions but are not recommended for use under red and blue LED lights.” Typical applications include PPFD (Photosynthetic Photon Flux Density) measurement over plant canopies in outdoor environments, greenhouses, and growth chambers, and reflected or under-canopy (transmitted) PPFD measurements in the same environments. Quantum sensors are also used to measure PAR/PPFD in aquatic environments, including salt water aquariums where corals are grown.

The meter has a sample and log mode, and will record an integrated daily total in mol m-2 d-1. Sample mode will record up to 99 manual measurements. Log mode will power the meter on/off to make a measurement every 30 seconds. Every 30 minutes the meter will average the sixty 30 second measurements and record the averaged value to memory. The meter can store up to 99 averages, once full it will start to overwrite the oldest measurement with new ones. An integrated daily total will be recorded from the 48 averaged measurements (making a 24 hr period)