stardustsailor
Well-Known Member
That looks very impressive SDS, I'm glad that you'll be doing the analysis from now on
For reference these are my numbers for the CXA 3000K:
As you can see I've dabbled with the McCree relative quantum efficiency (RQE) too; However it doesn't seem relevant at all. It was measured with monochromatic low intensity light, but everything changes when you use 1) white light 2) high intensity light. PPF (in umol) tells a much better story, together with...Code:CXA 3000K Power in : 3.76 W (9.40V x 0.40A) Luminous flux : 457 lumen Efficacy : 122 lumen/W LER : 328 lumen/W Radiometric eff.: 37.1% Radiant flux : 1.39 W Rel.quantum eff.: 86.5% (McCree 1972 RQE data) Photon flux : 6.80 umol/s (1.81 umol/J, RQE adjusted 1.56 umol/J) PPF : 6.50 umol/s (1.73 umol/J) 420-480 nm blue : 10.0% power, 7.9% photons 620-680 nm red : 24.2% power, 26.9% photons Lux to photons : 67.3 lux:umol/m2/s
Blue light. I used only the range of blue that has the most morphological effect. The 420-480nm range is based on this action spectrum:
View attachment 3175796
(source)
Finally, you can see a "Lux to photons" number of 67.3. With this number everyone with a lux meter is now also the proud owner of a PAR meter. Simply divide the number of lux by 67.3 to get the PAR (in umol/m2/s). For example, 50,000 lux would correspond to 740 umol. Well at least in theory, and only for the CXA 3000K spectrum.
Not quite ....
Modern measurements done ,with a variety of different illumination types and schemes ,
as also with different species of plants ,come to confirm that the 1972 McCree RQE reference table ,is actually very
accurate regarding Chamber grown (or indoor grown ) plants ...
It seems that the RQE ,does not alter significally between species and/or illumination used ...
A bit different values from the McCree RQE values show the Field -grown plants ...
(Check Figure 1.9 here => http://plantsinaction.science.uq.edu.au/edition1/?q=content/1-2-2-chlorophyll-absorption-and-photosynthetic-action-spectra )
Still the McCree 1972 RQE ,is a valuable table/ curve to us ....
Check also here :
http://www.uccs.edu/~scastell/ges2050/web/lab_6/what_light_do_plants_need_2012-10-05.pdf
and here :
http://photobiology.info/Gorton.html
Thanx for the info on UV/blue region ..
Cheers.
. Chromaticity coordinates, however, provide only a relative measure of the ratios of the three primaries needed to match each spectrum color, whereas CMFs specify absolute energy values. In order to reconstruct the CMFs from the Wright and Guild data, it was assumed that the 
..It's engauge software ,that's simple and amazing ... )
