Spectral PAR meters and turnkey systems that measure and report PPFD, PPF, PBAR + more


Optimize your operations

The light visible to the human eye in the spectral range from 380-780 nm is also actively used by plants. This part of the electromagnetic radiation, which powers photosynthesis called PAR (Photosynthetic Active Radiation) is usually found in wavelengths from 400 to 700nm. German Industry Standard DIN Norm 5031- 10:2000 describes the curve which is a mathematical formula that defines the average plant “sensitivity” to certain wavelengths. This forumla is leveraged in our spectral PAR instrument firmware and software which automatically outputs PAR values using radiometric values from our spectroradiometer systems as a basis for our calculation.
It is important to understand that the visible light “brightness” is not effectively supporting process of photosynthesis because the PAR curve is very much different from V-lambda curve which we use for photometry (i.e. human vision related calculations). To optimize lighting system for horticulture application you need to provide enough radiation from a specific wavelength at the right time to maximize yields. Using lux, CCT or other vision related metrics to verify or quantify lighting for plants is a misinterpretation.
There are many different PAR meters and other radiometers available on market but the majority of them were designed and preconfigured for continuum day light spectra. For horticulture LED lighting, only properly calibrated and high quality instruments can provide dependable data for professional users.

One system, all metrics

Comprehensive horticulture lighting measurement systems that support PAR, PPFD, PPF and PBAR measurement in addition to spectral and colormetric quantities. Depending on your requirement different probes and integrating spheres can be connected to our calibrated spectroradiometer for professional horticulture light measurement.

Measure. Improve. Grow

We deliver more than high performance PAR meters. Expand your capabilities with our range of accessories or Spectrosoft Analysis software interface which helps to evaluate all radiometric and active radiation data required for accurate horticulture light measurement.

Faster and better results

Preconfigured horticulture light measurement systems help the user to measure LED growing lights faster. Carefully calibrated devices ensure you get dependable data and make right decisions on how to optimize lighting for plant growth.

Who are spectral PAR meters for?

  • Growing lights manufacturers
  • Scientists and testing laboratories
  • Agriculture fish and animal lighting users
  • Vertical / indoor farmers

What can you measure?

Photosynthetic Active Radiation (PAR) and Photosynthetic Photon Flux Density (PPFD)

For plant growers, biologists and scientists the most important data in the light requirements for plants is PPFD measurement (photosynthetic photon flux density). PPFD is a measure of the amount of light that actually reaches a plant. It can be described as the number of photosynthetically active photons that fall on a given surface each second. The measurement of light which stimulates plant growth includes the PAR spectra and is expressed in PPFD values in μmol/m2/s and PPF in μmol/s. Similar to human vision metrics where we are evaluating lux and CRI which is the amount of light and the quality of light for visibility, for plants we are using PAR and PPFD to evaluate the amount and quality of active radiation.

Plant Biologically Active Radiation (PBAR)

PBAR is a new metric that is becoming more popular as it covers extended wavelengths from 350 to 800 nanometers in the spectrum i.e. PBAR Flux. This metric recognizes that photopigments other than chlorophyll that are sensitive to a wider range of wavelengths have been discovered in plants. For this reason an extended spectral range measurement system is suggested.

Photosynthetic Photon Flux PPF (PPF)

For manufacturers of growing lights, PPF measurement is also an important metric. This evaluates the total amount of energy that is produced by a light source per second. It is similar to radiant power measurement and it can be made with an integrating sphere connected to spectroradiometer when the system is properly calibrated and the photosynthetic photon flux calculation is supported by the software. GL Optic offers a complete range of different sizes of integrating spheres from 48mm 500mm, 1m up to 2m integrating spheres which are ready for PPF measurement.
For laboratory applications, we recommend the Spectis 5.0 Touch PAR/PPFD meter which offers higher resolution detector and extended spectral range. All our spectrometers can also operate with a waterproof accessory GL Opti Probe 1.1.10 illuminance, which can work under water and measure the euphotic zone. The right equipment for the PPF measurements is GL Opti Sphere – available in diameter from 48 mm up to 2 m. To be able to analyze, compare and report all the data it is highly recommended to use GL Spectrosoft – laboratory grade software compatible with the GL Optic spectrometer.

Build your own set

The products below can be setup for specific industry uses…
GL Spectis 1.0 Touch Premium Spectral Light Meter

GL SPECTIS 1.0 Touch

GL SPECTIS 1.0 Touch is a must-have in agriculture, forestry and oceanography for:

  • setting up, controlling and making more efficient farmlands
  • evaluating environments of growth for all flora
  • learning more about the photosynthetic processes of plants and bacteria
  • researching the behavior of pigments in plants
  • projecting, manufacturing and controlling growing lights

GL SPECTIS 5.0 Touch

GL SPECTIS 5.0 Touch offers extended capabilities to scientists for:

  • laboratory grade tests
  • projecting, manufacturing and controlling growing lights (more advanced version with wide wavelength range 200-1050 nm)
  • setting up, controlling and making farmland more efficient
  • evaluating environments of growth for all flora
  • learning more about the photosynthetic processes of plants and bacteria
  • researching the behavior of pigments in plants
additional probes light measurement luminance


Select a GL OPTI PROBE as an accessory which:

  • can evaluate high intensity under water
  • measure light sources in PAR (works from 400 nm)
  • is waterproof and can work under water up to 1.5 nm (it is a length of fiber optic cable)
gl opti sphere 205 integrating sphere


Choose from a range of available integrating sphere options to:

  • evaluate and report PPF data
  • capture total energy and PBAR for product specifications
  • measure a range of lamp sizes with spheres available in 48mm, 205 mm, 500 mm and 2000 mm diameters
GL SPECTROSOFT light measurement software


GL SPECTROSOFT M software included in the package is intuitive, user-friendly, delivers results within seconds and features easy export and import functions. This is the ideal tool for a production environment and field work, as well as laboratories and can be used for various applications:

  • compare data collected at any time
  • analyze results in easy to interpret graphs and tables
  • create and customize reports in editable files including Excel, PDF etc.

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