Quantum Light Pollution Sensor

R9 450 - R14 100


This unique sensor is designed to detect trace amounts of stray light from 340-1040 nm. Many plants are affected by interruptions in dark periods even by extremely dim light (less than 0.05 micromole per m2 per second).

Apogee’s new Quantum Light Pollution Sensor is designed to detect photons from 340-1040 nm that are below the sensitivity level of a typical quantum sensor. Detecting stray photons that disrupt dark periods can be important in researching and preventing morphogenic effects such as hermaphrodism, stem elongation, and poor flowering in certain sensitive plants. These photons can even come from unexpected sources like street lights, signs, and IR security cameras.

The SQ-640 Quantum Light Pollution sensor is a self-powered sensor. The sensor features a rugged, aluminium housing that is fully-submersible and built to withstand harsh conditions, and high-quality cable terminating in pre-tinned pigtail leads for easy connection to data loggers and controllers. The sensor cable includes an IP68 marine-grade stainless-steel cable connector to simplify sensor removal and replacement from permanent installations for maintenance and calibration. Typical applications of Quantum Light Pollution sensors include incoming PFD measurements over plant canopies in indoor greenhouses or in growth chambers, and reflected or under-canopy (transmitted) PFD measurements in the same environments. Since the detector on this particular Quantum Light Pollution sensor is sensitive to radiation with wavelengths up to 1100 nm, beyond the range of wavelengths that influence plants, we recommend only using the SQ-640 sensors in indoor grow environments utilizing LED lights,



Spectral Response

The Quantum Light Pollution sensor (model SQ-640) has a spectral range of 340 to 1040 nm ± 5 nm.

The spectral responses 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.

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.


To ensure accuracy each sensor is carefully calibrated in controlled conditions and traceable to NIST reference standards. The full-spectrum sensors are pre-calibrated for all light sources.


The AL-120 Solar Mounting Bracket with Leveling Plate facilitates mounting the sensor to a mast or pipe. The AL-100 Solar Sensor Leveling Plate is designed to level the sensor while sitting on a flat surface or mounting to a surface.

Output Options

Available in multiple output options including self-powered, 0 to 2.5 V, 4 to 20 mA, and 0 to 5 V. Additionally, a digital "smart" sensor that uses USB communication and custom software to interface directly to a computer is available. Sensors are also available in SDI-12 digital readout.

High Quality Cable

Pigtail-lead sensors feature an IP68, marine-grade stainless-steel cable connector approximately 30 cm from the head 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.



  • Typical applications of traditional quantum sensors include incoming PPFD measurement over plant canopies in outdoor environments or in greenhouses and growth chambers, and reflected or under-canopy (transmitted) PPFD measurement in the same environments.
  • The Quantum Light Pollution Sensor uses a detector that is sensitive to radiation up to about 1100 nm, well beyond the range of wavelengths that influence photosynthesis and plant responses. This means this particular sensor should only be used for photon flux density measurements under LEDs

Please note: Apogee products are imported from the USA and due to the fluctuating exchange rate, prices are not fixed and may be subject to change. Requesting a quote before placing an order is highly recommended.