Here is the easiest way to convert light intensity into different units.
http://www.egc.com/useful_info_lighting.php
Dear John Flores-McLaughlin
Thanks so much for your valuable response. I Find some mode information about this conversion.
The Photosynthetically Active Radiation(PAR) measure of radiant power is important in evaluating the effect of light on plant growth. In 1972 it was shown by K. McCree (Agric. Meteorol., 10:443, 1972) that the photosynthetic response correlates better with the number of photons than with energy. This is expected because photosynthesis is a photochemical conversion where each molecule is activated by the absorption of one photon in the primary photochemical process.
PAR is defined in terms of photon (quantum) flux, specifically, the number of moles of photons in the radiant energy between 400 nm and 700 nm. One mole of photons is 6.0222 x 10 ^23 photons (6.0222 x 10^ 23 is Avagadro’s Number).
The Photosynthetic Photon Flux Density(PPFD), i.e., the photon irradiance, is expressed in moles per square meter and per second (formerly, Einsteins per square meter and per second).
There is not a general conversion factor between photon measurements and energy or light measurements for broad band radiation. However, a specific conversion factor can be determined for a given spectral power distribution, e.g., a particular light source. This is of practical value because conventional lighting calculation techniques can be used for design of plant growth areas and because color corrected light or illuminance meters can be used to measure PAR values. Some plant scientists want a conversion for the photon flux in the 400 nm to 800 nm band although it is not the standard PAR metric (see CIE Publication 106, Section 8, 1993); this conversion also has been included.
please see the attached pdf filll to obtain conversion factors from lm/m^ 2 (lux) to micromoles per second and per square meter,
The problem is more complex if you want to convert daylight illuminance in lux to PAR, since the solar spectrum changes with sun position and atmospheric conditions.
Here is the easiest way to convert light intensity into different units.
http://www.egc.com/useful_info_lighting.php
John_Flores-Mclaughlin; I interest your answer however would you provide us the reference of your attachment
Here is a publication which discusses the topic and provides formulas and constants for interconversion between different types of radiation sources in plant science:
Thimijan R, Heins R (1983) Photometric, radiometric, and quantum light units of measure: a review of procedures for interconversion. HortScience, 18, 818–822.
http://www.apogeeinstruments.co.uk/conversion-ppf-to-lux/
This link should help you.
Does anyone know how to convert lux into micromoles.m−2.s−1, but using LED lamps?
The link below should be helpful
http://www.egc.com/useful_info_lighting.php
http://www.egc.com/useful_info_lighting.php
Francisco, what is the kilolux & temperature of your LEDs? If you're using Phillips by any chance, here's a conversion chart.
http://docs.agi32.com/AGi32/Content/adding_calculation_points/PPFD_Concepts.htm
This article provides a good overview for those who want a detailed assessment and for those who want simple conversion constants as well.
https://www.licor.com/env/pdf/light/Rad_Meas.pdf
Many thanks everybody for some great information. It was very helpful and thanks for asking such a great question
Andrew
As a rough estimate I use the program Dialux which provides a reading of lighting power density in Watts per m square
a = PPFD = µmol/m²/s
d = PPFD x 10⁶ convert micromol to mol
k = constant = average of warm white LED = 3x10¯¹⁹ Joule Quanta¯¹
b = Watts /m²
Å = Avogadro's number = 6*10²³
From the Dialux given Watts/m² = b
b= k*Å*d
d=b/k*Å
a = d*10⁶
The constant varies with wavelength.
Richard lomax
d = PPFD x 10⁶ convert micromol to mol
r u sure ?
Thanx
the attached file may help for conversion of different light sources.
https://www.apogeeinstruments.com/conversion-ppfd-to-lux/
try to look onto this website
https://www.waveformlighting.com/horticulture/convert-ppfd-to-lux-online-calculator
this website great...
http://www.egc.com/useful_info_lighting.php
very helpful for calculation
No! You cannot perform this conversion unless you have calibrated your lux-measuring device to a know value of PAR. In addition, please note that many sensors, such a HOBO loggers (ONSET) are not photometrically calibrated! Without an initial measurement and know wavelengths of lux measurements, you cannot possibly make this calculation and get anything meaningful from it!
Hello,
You must know SPD (Spectral Power Distribution) curve of your light source. Then you can easily obtain PPFD factor from the SPD curve. There are some calculations based on given CIE 1931 luminous efficiency function V(λ). If further help is needed, feel free to ask.
cheghad conglomerate lipidha hastid
i didn't read all the commments but to be honest, i don't need to. maybe it's scientist A vs scientist B evidence, maybe it's just "never stop thinking correctly"-dilemma
https://www.apogeeinstruments.com/conversion-ppfd-to-lux/
something i wanted to add https://en.wikipedia.org/wiki/Daily_light_integral
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