Effect of different spectrum on plants' growth

[ecofrog]

For my panels, Apogee simply doesn't work very well. Their meters have huge errors in anything over 660nm. The following ... If you really want to get an accurate reading you have to use a spectroradiometer.

In the past, working with only the few types of HID and T5 that was used, my Apogee worked out just fine because they were all the same so relativity was easy. But moving to LED's has made this technology somewhat useless as you point out. My .6 conversion from HPS to the topLED seems to be working out so far for fixture placement but I hear you on the need for a new meter.

I was looking at the relatively new AI-MK350S as opposed to traditional full spectroradiometer like Apogee PS-200. Mark @ AIBC says its the only meter i will need. I thought i would spend alot more time educating myself before deciding on exactly what meter i need but i certainly see the need for it with LED's, especially when growing multi crops or optimizing the same crop.

 

[Christine Green]

 

[Icemud]

I'm not in the industry by any means. I've just spent years and tens of thousands of dollars in research. If is can ever get my results to match all of my crazy hypothesis and find a manufacturer that will do the things I ask... well that's a different story.

Hosebomber is the man!!! Honestly you know more about LED lighting than anyone I have come across in the years I have been reseraching LED. We are valued to have you here with us Hosebomber!

 

[Icemud]

For my panels, Apogee simply doesn't work very well. Their meters have huge errors in anything over 660nm. The following is the correction amounts for Apogee sensors and LEDs:


LED Electric Calibration Error [%]
Blue (448 nm peak, 10 nm FWHM) -10.7
Green (524 nm peak, 15 nm FWHM) 5.8
Red (635 nm peak, 10 nm FWHM) 4.7
Cool White -4.2
Neutral White -6.1
Warm White -9.9
Red, Blue Mixture 2.7
Red, Green, Blue Mixture 3.5

This is a link to their lecture about LED lighting errors in readings https://www.apogeeinstruments.com/content/Quantum Sensors-LEDs.pdf

As you can tell, all companies have an issue with reading the info properly. If you really want to get an accurate reading you have to use a spectroradiometer.

Great post! This is the model that most LED manufacturers are using as well, so their advertised Umol readings are off. I did some research into this and it seems the only way to get accurate readings it to have a 10,000$ quantum meter or 1 step better but even more pricy, a spectroradiometer.

 

[Hosebomber]

The prices on spectroradiometers have come down greatly in the past few years. You can get cheap ones for ~$2500 and really good ones for ~$5000 now. It's still a bit outside of my "hobby" money range for now, but it may happen one day.

Ice, you are correct. Most panel makers use the Apogee MQ-200 or lesser quality meters.

 

[ecofrog]

The prices on spectroradiometers have come down greatly in the past few years. ... Apogee MQ-200 or lesser quality meters.

In the past, there were few lighting products so we didnt need to understand spectrum, we just bought bulbs and used the Apogee to place fixtures and measure DLI. But with LED's, spectrum R&D is almost infinite and the need for a more advanced meter is apparent as we are discussing. We can assume there will be more and more products coming online because of that need, which is great for us. Its just a matter of time before companies will start trying to sell meters on forums like this...

Is there any mechanical difference between the sensor of a PAR meter like apogee vs an advanced spectroradiometers? or is it all the same 'volt meter' technology and the higher functions come from software?

I have another question i dont seem to be able to get a decent answer to. Does the diode radiate equally thruout the 90degrees or are there 'hot spots'?

 

[Hosebomber]

There are major differences in the sensors. PAR meters just read all visible light and do not separate each spectra.

It varies from manufacturer to manufacturer, but in general LEDs produce a lambertian pattern.

 

[PakaloloHawaii]

Awesome thread

 

[ecofrog]

There are major differences in the sensors. PAR meters just read all visible light and do not separate each spectra.

It varies from manufacturer to manufacturer, but in general LEDs produce a lambertian pattern.

It seems from everything that i read that the separating into spectrum is all done with software as opposed to some specialized hardware in the sensor itself separating wavelengths which is good news as my smartphone has everything i need except a sensor and the program.

A bulb powered on a flat 180degree with a lambertian makes sense but when we buy 90degree led's (or any deg), does that mean we have what is left of the lambertian and reflector scatter in a full pattern of the reflected portion?

 

[Hosebomber]

It's still the hardware that identifies the wavelengths and the ppfd or number of photons received. The calculations to give output black body radiant temperature, lumens, lux, x and y cords., etc are all relatively easy in terms of processing requirements...

As for diodes of varying viewing angles, that is done with the base reflector installed under the chip when the diode is manufactured. Those photons that are released that would normally fall outside of that range are reflected/refracted prior to leaving the diode lense.

 

[love smoke1]

Thank you,sir.
some of your links are helpful.