Defying The Inverse Square Law

[Budsbunny]

To give you a feeling of the accuracy of the Galactica app on Iphone 6+, well it is not accurate at all, but basically we knew all that. This is how it acts up:

On the picture at A, on the left, you see how I do my tests. The light bulb is in fixed position and so is my phone. Let’s say I have a reading of 8000 LUX at A If I keep the app “ON” and I put my hand in between and take it out again (at C), the app will give each time a different reading that can vary to +1500 LUX or -1500 LUX. I do this 5 times and take the average, it’s the best I can do for now. At least the app behaves with all the different tests the same.

 

[Budsbunny]

These are the final cones I have tested, each is tested with **no liner, **paper liner and mirror film on the inside.

Here you see the different patterns each liner creates.

These are my test results, the color codes speak for themselves I guess.

The results of the aluminum flower pot are pretty close together.
Maybe I will test different kind of paper.

 

[Budsbunny]

Galactica consistency + Liner choice + Final light pattern

Well, first things first, the inconsistency of the app that I mentioned in an earlier post is absolutely not the case! What happened is that I had a light in my back and with me moving around during the readings I got those fluctuating readings. So I did some tests again and I got always the same reading with doing each test 5 times. So I don’t speak about the accuracy as I don’t know but the reading is always the same and consistent.

So I have made my choice as cone and have decided to use white paper as inside liner. White paper is a much better reflector than aluminum, it is easy to manipulate and I have lots of it, time to do a paper/liner test. Below you see the results and the way I tested. Because of a different testing method you cannot compare the outcome with previous tests. The outcome was a surprise as I read that dull white is the best as reflector, but the test shows otherwise.

So the Costco paper is my (final?) choice for now. I have measured the light pattern on the paper and projected it onto the existing light panel in the chest. Sorry for the quality but I had to take a picture of my screen, there are windows behind me that create some light spots. Below is done in AutoCad 2016

• Fig 1 is the top view of the chest with the panel in grey with 9 bulbs in it.
• Fig 2 is the light pattern of 1 bulb at 34 cm distance
• Fig 3 is the top view of the panel with 9 patterns, pretty good cover I think (also on 34 cm)
• Fig 4 is as previous but I replaced the center bulb with a fan, so everything is in the panel. Still not a bad cover I think.

Next step is to test the panel readings with 8 cones.

 

[Budsbunny]

February 24, 2020

Despite the Costco paper doing better with the single bulb test, the Epson mat paper came out better with the full test in the chest. Results shown at 3 different distances.

 

[The Celt]

I don't know the angle off the diode, do you?

Typical diodes without a focusing lens are close to 180degrees, some have a lens right on the diode and can range from 90 to 115 degrees light cone.

Being household bulbs, it’s likely they are bare chips close to 180 degree light cone

 

[Budsbunny]

Typical diodes without a focusing lens are close to 180degrees, some have a lens right on the diode and can range from 90 to 115 degrees light cone.

Being household bulbs, it’s likely they are bare chips close to 180 degree light cone

Hi Celt, thank you for your input, it was more a rhetorical question though.....but I think you are right.

 

[Icemud]

I wanted to point out this diagram is not correct. Inverse square law does not apply to reflected or focused light. Inverse sqaure law only would apply to a single point source light that photons equally spread in all directions.

Think of it this way, if you have ever had a flashlight with a "zoomable" lens from spot to flood patters. Same light, same wattage so why does the intensity change when you "zoom" the light... because the light is focused differently, therefore square inverse law would not apply.

Although it can be used as a reference to explain light scattering, the formula itself would only apply to stars in the sky and other single point source lights that emit in all angles without being focused, redirected or reflected. (similar to a "edison" style filliment bulb, although not exactly perfect, light is allowed to emit omni-directional.

LED's also technically don't apply to square inverse law because there is actually reflection within the diode itself, and the light is only projected out a single direction, not omni-directional.

Square inverse law really is just a way to measure light scattering away from a point light source, the further away, the more light scatters, the less intense.

 

[Budsbunny]

I wanted to point out this diagram is not correct. Inverse square law does not apply to reflected or focused light. Inverse sqaure law only would apply to a single point source light that photons equally spread in all directions.

Think of it this way, if you have ever had a flashlight with a "zoomable" lens from spot to flood patters. Same light, same wattage so why does the intensity change when you "zoom" the light... because the light is focused differently, therefore square inverse law would not apply.

Although it can be used as a reference to explain light scattering, the formula itself would only apply to stars in the sky and other single point source lights that emit in all angles without being focused, redirected or reflected. (similar to a "edison" style filliment bulb, although not exactly perfect, light is allowed to emit omni-directional.

LED's also technically don't apply to square inverse law because there is actually reflection within the diode itself, and the light is only projected out a single direction, not omni-directional.

Square inverse law really is just a way to measure light scattering away from a point light source, the further away, the more light scatters, the less intense.

Thank you for pointing that out. I got the image that is shown (and that you show) from Google and it shows up on many other sites, it does not say what light source it is.

The point is, that I am trying to show how you can increase the intensity by reflecting light on “it’s way down”, coming back to the area where the other light is, and in that way trying to make it possible to use simple led household bulbs.

It is not my intention to say the Inverse square law is wrong and with saying “defying” I am trying to say “increasing density” but if you have a problem with that I apologize. I also think that nobody gives a damn about this law and reflection within the diode itself as long as their plants get enough light and grow well.