Applications and Uses of Quantum Sensors

Measuring PPFD

Quantum Sensors and Meters - line quantum under a plant canopy

Our quantum light sensors (SQ series) have a cosine-corrected head and a domed head for improved self-cleaning characteristics and long-term stability.

The original SQ/MQ-100, SQ/MQ-200, SQ/MQ-300, and SQ-400 series quantum sensors feature an innovative blue lens that improves the accuracy of these quantum sensors and meters. The pigments in the lens filter incoming light for an improved spectral response. These sensors are a lower-cost option that are excellent for all light sources, except for most LEDs, where post-measurement correction factors need to be applied to achieve accurate readings.

The SQ/MQ-500 full spectrum quantum sensors feature an improved detector that provides excellent measurements under all light sources, including LEDs, right out of the box.

The MQ quantum meters can be ordered with a built in sensor (MQ-100) or a meter attached to a sensor via cable (MQ-200, MQ-300, and MQ-500 series). The MQ-200 and MQ-500 quantum meter is ideal for aquarium use.

Our quantum meters (MQ-series) include data recording capability. The MQ-100, MQ-200, and MQ-300 quantum meters include sun and electric calibration with each meter. The MQ-500 quantum meters are calibrated for all light sources.

Each quantum meter can store up to 99 manually recorded measurements. In automatic mode, measurements are made every 30 seconds and averages are stored every 30 minutes. Daily totals are also calculated and the past 99 days are recorded. The AC-100 communication cable must be purchased to download data to a PC.

The USB Smart Quantum Sensor also features datalogging capabilities. It can be connected directly to a computer for taking spot measurements or graphing and datalogging real-time PPFD using the included software. The senor can also act as a stand-alone datalogger and has an internal memory capable of storing 10,000 user-specified periodic measurements that can be downloaded to a computer.

Greenhouse Applications

Line Quantum Sensors in Greenhouse

Quantum sensors are often used to quantify the light available in greenhouse settings. The line quantum sensor is especially helpful, as it provides a spatial average. Quantum Sensors and Quantum Meters measure Photosynthetic Photon Flux Density (PPFD) in µmol m-2 s-1.

Dr. Erik Runkle of Michigan State University has used the Line Quantum Sensor in greenhouses to record the photon flux during plant growth. A Model SQ-313 is shown here mounted on a cross bar.

Blanchard, M. G., E. S. Runkle , 2006. Temperature during the day, but not during the night, controls flowering of Phalaenopsis orchids. Journal of Experimental Botany, 57 (15):4043-4049

Coral Aquariums

Waterproof Par Meter / Quantum Sensor for measuring PAR in coral aquariums

Sufficient lighting is vital for growing healthy coral. There are two critical components to adequate lighting for aquariums, intensity and spectra. Zooxanthellae is the algae that lives on the coral and through photosynthesis, provides glucose, glycerol, amino acids and oxygen for the coral. Light (or photons) in the wavelengths of 400 to 700 nanometers is responsible for photosynthesis and is referred to as Photosynthetically Active Radiation (PAR) or Photosynthetic Photon Flux Density (PPFD). This range is also referred to as Quantum.

The Quantum Meter (model MQ-210 and MQ-510) manufactured by Apogee Instruments is ideally suited for use in aquariums. The sensor head is potted solid and completely sealed. There is no hollow cavity for water to eventually penetrate and cause measurement errors. The logging capability of the meter allows you to monitor light levels on a half hour basis for 99 measurements and stores a daily total for measurements made over three months.

The appropriate light intensity for a coral reef tank is about 20 to 25 µmol m-2 s-1 for each gallon of water for aquariums 24" deep with a minimum of 10 µmol m-2 s-1 per gallon (Citation: Aquarium Lighting: Spectrum and Intensity by Drs Foster and Smith). For example, if you had a 25 gallon tank you would need approximately 500 µmol m-2 s-1.

Journal Articles

Dana Riddle Reviews the MQ-500/510 on Advanced Aquarist

Guan, D. X., J. B. Wu, X. S. Zhao, S. J. Han, G. R. Yu, X. M. Sun, C. J. Jin, 2006. CO2 Fluxes Over An Old, Temperate Mixed Forest In Northeastern China. Agricultural and Forest Meteorology, 137:138-149.

Leakey, A. D. B., C. J. Bernacchi, F. G. Dohleman, D. R. Ort, S. P. Long, 2004. Will photosynthesis of maize (Zea mays) in the US Corn Belt increase in future [CO2] rich atmospheres? An analysis of diurnal courses of CO2 uptake under free-air concentration enrichment (FACE). Global Change Biology, 10(6):951-962.

Lefsrud, M. G., D. A. Kopsell, R. M. Augé, AJ Both, 2006. Biomass Production and Pigment Accumulation in Kale Grown Under Increasing Photoperiods. HortScience, 41(3):603-606.

Muckle, Edward, 1997. PDFSpace Scientists Bring Light Research Down to Earth. Greenhouse Business, Vol. 3, No. 5, May 1997.

Pennisi, S. V., M. van Iersel, S. E. Burnett, 2005. Photosynthetic Irradiance and Nutrition Effects on Growth of English Ivy in Subirrigation Systems. HortScience, 40(6):1740-1745.

Prior, SA, H. A. Torbert, G. B. Runion, H. H. Rogers, D. R. Ort, R. L. Nelson, 2006. Free-Air Carbon Dioxide Enrichment of Soybean. Journal of Environmental Quality, 35:1470-1477.

Riddle, Dana, 2005. Product Review: A Comparison of Two Quantum Meters - Li-Cor v. Apogee. Advanced Aquarist Online, Vol IV, July 2005

PDFAquarium Frontiers Product Review Harker, Richard "A Quantum Leap in PAR Meters"