Match's Mods: Homemade Integrating Sphere

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Chicago X
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Here’s a bump for the Xsphere.

I took an inflatable beach ball that was advertised at 24 inches across, imagine my surprise when it was actually nineteen !!!

With the vinyl being so thin, I chose to not prepare the surface for removal, as it will be a far smoother surface than I could make with paper mache.

I used Elmer’s Glue-All for the adhesive, and went to town with a bunch of newspapers from the kindling pile.

I could have made the entire thing from dollar bills, and it would STILL have been cheaper than a lab-grade sphere…

Here it is, drying after a round of paint, and a taped-up circumferential cut. I will need to carve out the light and sensor ports when the meter arrives. Barium sulfate is also en route, so we’ll see how that stuff works out.

http://wardogsmakingithome.org/index.html

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Match
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Looking really good, ChicagoX! Did you already mount the baffle on the inside? Reason I ask is because it might be hard to line up the sensor/flashlight holes and baffle with the sphere already together.

Another thing I was thinking: If you’re interested I could make a regulated drop-in with a known output to mail to you…

In fact, that may not be a bad idea to do and use it as a pass-around with the rest of the folks who’ve done this or something similar. That way we’d all be on the same page.
Bort
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Chicago X wrote:
Here’s a bump for the Xsphere.

I took an inflatable beach ball that was advertised at 24 inches across, imagine my surprise when it was actually nineteen !!!

With the vinyl being so thin, I chose to not prepare the surface for removal, as it will be a far smoother surface than I could make with paper mache.

I used Elmer’s Glue-All for the adhesive, and went to town with a bunch of newspapers from the kindling pile.

I could have made the entire thing from dollar bills, and it would STILL have been cheaper than a lab-grade sphere…

Here it is, drying after a round of paint, and a taped-up circumferential cut. I will need to carve out the light and sensor ports when the meter arrives. Barium sulfate is also en route, so we’ll see how that stuff works out.


Barium sulfate?

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Bort
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Match wrote:
Looking really good, ChicagoX! Did you already mount the baffle on the inside? Reason I ask is because it might be hard to line up the sensor/flashlight holes and baffle with the sphere already together.

Another thing I was thinking: If you’re interested I could make a regulated drop-in with a known output to mail to you…

In fact, that may not be a bad idea to do and use it as a pass-around with the rest of the folks who’ve done this or something similar. That way we’d all be on the same page.
I’ve been considering building one of these as well, a known output sample is insanely necessary! What is the sample?

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

Match
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Bort wrote:
I’ve been considering building one of these as well, a known output sample is insanely necessary! What is the sample?

Dunno…haven’t built it yet Wink
I’m thinking something along the lines of a P-60 drop-in. An XM-L with a floody lens would be ideal, since it would really test the “integrating” of the sphere.

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Match wrote:
Bort wrote:
I’ve been considering building one of these as well, a known output sample is insanely necessary! What is the sample?

Dunno…haven’t built it yet Wink
I’m thinking something along the lines of a P-60 drop-in. An XM-L with a floody lens would be ideal, since it would really test the “integrating” of the sphere.


How do you know the exact lumen output though, this is the problem i’ve been thinking about, there are no markings on an xml saying which bin it is (we have to trust what we buy is correct), and even in the same bin there is a minimum luminous flux.

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

Chicago X
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Match wrote:
Looking really good, ChicagoX! Did you already mount the baffle on the inside? Reason I ask is because it might be hard to line up the sensor/flashlight holes and baffle with the sphere already together.

Another thing I was thinking: If you’re interested I could make a regulated drop-in with a known output to mail to you…

In fact, that may not be a bad idea to do and use it as a pass-around with the rest of the folks who’ve done this or something similar. That way we’d all be on the same page.

That’s a very generous offer – I would very much like that, thanks !!!

I have not mounted the baffle nor made the final cuts, as I don’t have the dedicated meter in-hand. I made an off-axis circumferential cut in relation to the valve hole to allow for 90-degree placement of the two openings, and resealed it with a single layer of masking tape prior to putting on the first coats of paint. It will take but a small pass with an exacto to rend the sphere in twain for baffling and barium sulfate coating.

Bort wrote:
Barium sulfate?

It’s the same stuff that you ingest in the chalky milkshakes (or enemas) to provide contrast in G.I. tract radiology scans.

It is also used to provide a fantastic diffusion coating for integrating spheres, minimizing any favoritism of throwers over floody torches.

http://wardogsmakingithome.org/index.html

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Match
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Bort wrote:
How do you know the exact lumen output though, this is the problem i've been thinking about, there are no markings on an xml saying which bin it is (we have to trust what we buy is correct), and even in the same bin there is a minimum luminous flux.

 I think you may be a bit confused.  What I intend on doing is piecing together a drop-in (spec's aren't that important), and then testing it in my I.S. and obtaining the numbers for it that way, then passing it along.  It's a rather crude way to calibrate I.S.'s, but really the only practical way...  It will also ensure that my future lumen numbers match ChicagoX's and anyone else who would like to use the calibration drop-in.

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Match wrote:

Bort wrote:
How do you know the exact lumen output though, this is the problem i’ve been thinking about, there are no markings on an xml saying which bin it is (we have to trust what we buy is correct), and even in the same bin there is a minimum luminous flux.

 I think you may be a bit confused.  What I intend on doing is piecing together a drop-in (spec’s aren’t that important), and then testing it in my I.S. and obtaining the numbers for it that way, then passing it along.  It’s a rather crude way to calibrate I.S.‘s, but really the only practical way…  It will also ensure that my future lumen numbers match ChicagoX’s and anyone else who would like to use the calibration drop-in.


i understand

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

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I used a light with known consistent output, my sc60, to calibrate mine. After that I tested against others like my Ti to confirm it is consistent and accurate. I don’t know about a home made drop in with so many variables. Sounds sketchy to me. I know mine is accurate. If you don’t already have an ANSI rated light, borrow one from someone nearby or buy one.

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JohnnyMac wrote:
…If you don’t already have an ANSI rated light, borrow one from someone nearby or buy one.

I have several ANSI-rated lights, but I like the idea of having more comparative samples.

It’s also a great excuse to buy a Zebralight…

http://wardogsmakingithome.org/index.html

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I think the drop-in is a good idea. I think I am pretty accurate with the lights i have to test but it would be a good comparison. Another reference point. Sphere is looking good X.

Piers said " ....but who wants enough light, when you have the option for far too much "

Match
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Langcjl wrote:
I think the drop-in is a good idea. I think I am pretty accurate with the lights i have to test but it would be a good comparison. Another reference point. Sphere is looking good X.

JohnnyMac, Langcjl hopefully makes my point a little more clearer. If there's a bunch of us with I.S.'s, it would be nice to have one light or drop-in to use as a reference that we can pass around. As far as a homemade drop-in with so many variables, as long as it's current regulated it won't matter in the slightest.  The drop-in lumen rating won't be calculated off of any data sheet, but rather in my I.S. then passed on. 

I thought my explanation to Bort was clear on this intent...but hopefully this helped a little more.

Meh... NURSE!  WHERE ARE MY PILLS?!?! 

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Match wrote:

Langcjl wrote:
I think the drop-in is a good idea. I think I am pretty accurate with the lights i have to test but it would be a good comparison. Another reference point. Sphere is looking good X.

JohnnyMac, Langcjl hopefully makes my point a little more clearer. If there’s a bunch of us with I.S.‘s, it would be nice to have one light or drop-in to use as a reference that we can pass around. As far as a homemade drop-in with so many variables, as long as it’s current regulated it won’t matter in the slightest.  The drop-in lumen rating won’t be calculated off of any data sheet, but rather in my I.S. then passed on. 

I thought my explanation to Bort was clear on this intent…but hopefully this helped a little more.

Meh… NURSE!  WHERE ARE MY PILLS?!?! 

Would you have to qualify which light the drop in was used in, such as a single 18650 light, versus a 3AA light, or a 26650 light? Or which exact batteries were used? I hear “regulated”, but I’m still wondering what would happen if a battery that was marginal in amperage or voltage wouldn’t mess up the test?

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I’d love to make one of these spheres, but I just can’t justify the money for lights I’m going to get rid of anyhow. Sad

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Chicago X
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Old-Lumens wrote:
I’d love to make one of these spheres, but I just can’t justify the money for lights I’m going to get rid of anyhow. Sad

From a pure marketing standpoint, I don’t see how you can’t justify making one.

Nudge, nudge.

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For all you intelligent guys out there, this might help with using Barium sulphate or Potassium sulphate coatings in a sphere.

It's all way beyond me, but it looked good, LOL.

EDIT:

Also, here's a recipe for making a stronger paste, for paper mache'

and here's where to get the "resin glue".

 

You know, if I've gone this far.......

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Old-Lumens wrote:

For all you intelligent guys out there, this might help with using Barium sulphate or Potassium sulphate coatings in a sphere.

It's all way beyond me, but it looked good, LOL.

EDIT:

Also, here's a recipe for making a stronger paste, for paper mache'

and here's where to get the "resin glue".

 

You know, if I've gone this far.......

Imused white glue and water with newspaper on mine. Took forever to get enough layers on it to be stiff enough on its own. 
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JohnnyMac wrote:

Old-Lumens wrote:

For all you intelligent guys out there, this might help with using Barium sulphate or Potassium sulphate coatings in a sphere.

It's all way beyond me, but it looked good, LOL.

EDIT:

Also, here's a recipe for making a stronger paste, for paper mache'

and here's where to get the "resin glue".

 

You know, if I've gone this far.......

Imused white glue and water with newspaper on mine. Took forever to get enough layers on it to be stiff enough on its own. 

Ya, but you know me... Have to do it differently. Like making the first layer of newspaper out of "gores", so the inside has very neat seams. Using the weldwood for stiffness and longevity. Using some type of fabric like denim or strong cotton, for more stiffness, etc, etc, etc. LOL, it's got to be a challenge and it's got to be a one of a kind. I just don't know any different.

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What it the wavelength range of “white” leds. From 3000k to 7000k.

500nm to 700nm?

I’m looking at all possible coatings and just want to know the range. I don’t expect I would do any testing on RGB leds.

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Old-Lumens wrote:
What it the wavelength range of “white” leds. From 3000k to 7000k.

Almost all the light for white LEDs of any color temp is between 425 and 750 nm. There is a pretty significant peak at 450 nm and virtually nothing below 425 nm.

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So when you shine the light inside the sphere, do you shine it straight at the baffle? I'm assuming so given the point of it is to stop light going stright from the torch to the sensor.

Defintely building one of these Smile

- Matt

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No, you shine at the opposite wall. The baffle actually means an imperfection in the sphere geometry and thus is something bad, but direct light from source to detector is much worse.

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What about making the first layers out of white paper?
I want such a sphere too and I thought that if we all get our olight i6s(I guess a lot of us have ordered this light) we can calibrate our spheres to each other…

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I just found and read through this entire thread. And dangit! Now I’ve got to build one too! Wouldn’t ya know my son just burst a 20” rubber ball and we threw it away?

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Figured I’d give this thread a good ol’ necro bump.

Going to try my hand at making one of these spherical beauties in the coming weeks. No idea what I’ll use for the calibration… And I’ll need a light meter!

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Funny, I just started at one just yesterday, before you dug this thread out Smile , only 25 cm (10ish inch) diameter because I do not have space for a bigger one, but using the 'match' method. No idea when it is ready, or if it is any good at all, but it has been a loooooong time since I last did paper mache Smile

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Barium sulphate,out of date epoxy/polyester resin is quicker and stronger,after an initial papier mache layer,ping pong ball for light baffle,it's round so no direct reflections.Also,I might make a second light meter hole just to check the readings are the same.In theory,an IS puts out an even spread of light everywhere,that's the point!Always good to check.I stuck a layer of plastified foil(ground coffee packet)opposite the light source on the principle that ,for any excaping light through the sphere,throwers will lose more than flooders and hence underread.Opinions welcomeWink

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Considering that you can buy a 16” strofoam sphere for $40, I would not waste my time messing with paper mache, etc. The styrofoam spheres that are now available seem to all be made with a flat surface on the ends of the interior. I made a sanding jig by tracing the sphere inner radius onto a 3/4” thick board, cut the board, placed sandpaper over the edge, and sanded the flat spot to match the sphere radius.

Instead of barium sulphate, a light sanding with fine sandpaper on the interior of the styrofoam sphere will remove the sheen and perform pretty much as well as the sulphate/latex paint coating.

Epoxy/polyester can yellow with time. I would not use it.

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texaspyro wrote:
Considering that you can buy a 16” strofoam sphere for $40, I would not waste my time messing with paper mache, etc. The styrofoam spheres that are now available seem to all be made with a flat surface on the ends of the interior. I made a sanding jig by tracing the sphere inner radius onto a 3/4” thick board, cut the board, placed sandpaper over the edge, and sanded the flat spot to match the sphere radius.

Instead of barium sulphate, a light sanding with fine sandpaper on the interior of the styrofoam sphere will remove the sheen and perform pretty much as well as the sulphate/latex paint coating.

Epoxy/polyester can yellow with time. I would not use it.


How much to ship that foam to Canada, plus styrofoam does not reflect all the light striking it, i have styrofoam boxes that i can put a light in and see maybe 10% coming out the other side (maybe 3/4 thick), i would assume the paint will reflect more of the light, now mind you if the light penetration is linear with increasing brightness then a calibration should compensate when taking readings, if i had some calibrated lights of very varying brightness it would be a worthy experiment (unless you already did it and have data to share)

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

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