Project Cancelled - O-L's IS - How Not to make a budget Integrating Sphere

EDIT: 08-05-2012

Since things didn't work out as planned, and since I don't want to expend more funds into this, I decided to cancel the project. I just do not see any payback with this IS and since I do not even own one ANSI standard light that could be used as a test light, it's a little foolish to do this in the first place. Luckily, I was able to return the majority of the stuff, so I only lost a couple bucks on it.

Thanks for being patient and understanding.

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I got to stop reading threads here. Now I'm going to make an Integrating Sphere.

I've been looking and reading here and at CPF, about spheres and I have been scouring the net as well.

I found a couple interesting documents on them, Here and Here.

I want to make a really expensive sphere, but not this time, so I backed off on all the stuff I was going to buy and went to Wal-Mart for a ball, some glue and the Dallas Morning News. I will leave a couple links to stuff, in case anyone wants the info, after reading the articles above.

Here's what I got at wally world:

a1

50/50 mix of water and Gorilla wood glue.

Here's the design I Think I am going to do:

a2

Here's a link to how I intend to make the first layer or two, of paper mache'.

Here's a link to the meter I ordered.

As always, I post this before I have even started, Tongue Out don't ask me why, I don't know.

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Here's the links to some of the stuff I was going to use, if I had the bucks to do it that way.

Styrofoam ball

Titanium Dioxide

Resin Paper Mache Recipe

Weldwood Plastic Resin Glue

Varathane

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This may be a long project, as I don't have too much time right now, to do it.

08/03/12------------------------------------------------------------------------------------

I set up the first layer of newspaper, to be a set of 8 gores that will cover the ball, as you would make a globe out of paper. If you haven't seen this document, you might not know what I'm talking about.

Here's a couple of photos:

g1

First thing is to measure the circumference of the ball. It came out to 45-1/2", so I used two sheets of newspaper to get the right width. Then the height of the paper has to be 1/2 of the width. Well the paper is 24" and 1/2 the width is 22-3/4"... So I am going to use it anyhow and just let the ends overlap.

g2

I'm not going for perfect here, just going for a little neater first layer, so the inside of the sphere will have less seams. I just folded the paper three times in width, which gives me 8 sections and then I drew the gores with a marker, a string and some eyeballing. Read the document, if you want to know the exact procedure here. As I say, it's off a little, but on the plus side, so there will be a little overlap versus not enough to make open seams. Instead of keeping it all together after cutting out the scrap, I will cut out the 8 gores separate, so it's easier to handle with the glue mix and placement.

It's late, after 1AM, so that's all for tonight...

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Good Luck with the build OL!! I need to get myself a meter too.

I really wouldn’t recommend your intended design, however. The placement of your meter is not optimal plus the way you plan to fit it recessed into a tube will shelter it from the light you are looking to measure. The meter should face into the sphere plus optimally be 90 degrees from the light source.

With the flashlight at 9 o’clock, your meter should be at 6 o’clock. You have it at 7:30 but perpendicular to the light source. I wouldn’t recommend that. :wink:

Here’s an extract of the Caltech .pdf:

Well, I stand corrected. Go for it. Not what I read when building mine but whatever works, works. :wink:

Great deal on the Mastech meter. I think i paid double and i purchased a bench top power supply…

Good luck on the build

Do you have any documentation on why that is? I would be very much interested in that.
I have been searching everything I can find and most documentation does not apply to LEDs. This excerpt (from this document) explains my reasoning. I am not a scientist and I do not claim to be, but common sense would tell me that this is the best way:

“Sources that are neither Omnidirectional or Unidirectional
Other light sources, including laser diodes, fiber optic illuminators,
fiber optics, and reflector lamps are neither highly
directional nor omnidirectional. These light sources can be
placed near the entrance port of the sphere so that all of the
light is directed into the sphere. The sphere spatially integrates
the light before it reaches the detector”

Figure 21, in the document, shows a good view of that method in operation.

A led is neither omni-directional, nor unidirectional. Unidirectional would be something like a laser or a fiber optic. Omni-directional would be a light bulb, or other sphere that emits light in all directions at once. LEDs emit in a certain degree of direction, such as an XM-L at 130 degrees. That is neither Omni-directional, nor Unidirectional.

For me, “the norm” does not always mean “the right”, but often it’s just taken for granted as being right. I am just questioning what is right and what type of light an led is.

I seriously would love to see some published documentation that shows 90 degrees, with a baffle is the best way.

EDIT: Sorry, Chicago was more on the ball than I was.

Good choice with the Mastech meter. I like mine a whole bunch. Scales to 4 or 5 different output levels up to 200,000 lux… The peak hold feature is really nice to have when you are taking throw readings from more than 1 meter away.

I didn’t post that to say that you were incorrect, only that that’s where O-L got the info.

I would think that a lot would depend on the ‘sweet spot’ of the meter, or at what range the meter is the most accurate.

Anybody else here trying to picture OL at the ball tower in the toy-section at Wal-Mart trying to get the one he really wanted from the top of the pile???

:party:

LOL

You know, the ball tower was just about empty. This wal-mart has a small tower and it sits on a shelf, but it’s still 9 feet tall. The only 14” balls left, were the gray see thru one I got and a pink see thru one. The gray one was on the bottom, so I had to “move several smaller balls, to get it out. The procedure would have been great for a viral video.
Some old guy with a really miserable look on his face, muttering to himself and trying to reach inside the tower and toss the balls up out of the tower, finally getting the one he wants. Then he carries it all round wal-mart, while he stops to look at flashlights, glue and crafts.

The nice thing is that at 6’3” and about 230#, when I look miserable, no one ever comes near me. They just stay clear. That’s the way I like it. :wink:

What is it with all you giants? I’m at 6’ and 225# and you guys all make me feel like a little kid when I stand anywhere near you and I’m not a small guy. For some reason a lot of my local friends are either over 6’2 or less than 5’10. O-L is 6’3”, ChicagoX and Langcl are 6’5”, Foy is 6’3” or 6’4”…probably many more I’m not aware of. LOL!

O-L, as far as my info, I don’t have any links but the digging I did along with what Match found in his research and recommended is why I went the way I did. So far it seems to work perfectly as my results match that of manufacturer specs. This weekend I will test my new SC51F in my IS against Zebralight’s claimed ANSI specs. So far my SC60 and Thrunite Ti are right on.

Maybe I should have said 5’3”, LOL

I would imagine that in a small sphere (less than 36”), it probably does not matter that much, since all we are really doing is measuring a known source (an ANSI certified light) and then using a division factor that matches the ANSI value. I don’t think it matters when it’s done that way, since we aren’t measuring the sphere itself, to see how viable it is. We aren’t testing the sphere’s reliability, only the reliability of ANSI lights, which actually tells nothing of the ability of the sphere itself. Other than a blatant mistake, like painting the inside black, we don’t know much and we really don’t have to, except, possibly we aren’t as “correct” as we think, on some of the super low output or super high output lights and for our stuff, it Does Not Matter.

I’m sure doing it the way y’all have works well. That’s been proven. I am just asking is it the right way, is it just the known way, or is there a different way? I just like to question things instead of accepting things.
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I still want to know who killed……. never mind. :stuck_out_tongue:

The whole point of sensor placement in an IS is to avoid direct measurement from the source before the light hits the sides a few more times and gets spread out. Putting it at the “bottom” relative to the source means that any light with >90deg beam risk hitting the sensor directly. It’s not a problem for most flashlights since they’re rarely so wide of a beam (except some headlamps/ zoom lights). Still, putting it closer to the source on the ball makes it slightly wider application.

O-L,

I like what you've come up with for a design. I say Go for it! Since JohnnyMac, Langcl, and soon ChicagoX all have roughly the same design, I think it would neat to see how something different matches up. The key here is that all the light (spot and spill) gets integrated then somehow meanders over to the meter without any direct light getting measured.

As JohnnyMac mentioned, I also used a Zebra for initial calibration (3 of them actually: H51, SC60, SC600) as per my original build post. Once I calculated my correction factor I've found it to be very accurate from .09 lumens all the way on up!

Something I have always wondered…
Why don’t spheres diffuse the beam at the source? Couldn’t you place a sheet of white computer printer paper over the flashlight hole to severely diffuse and flood the beam. Start with that and calibrate your system around that. Wouldn’t that effectively completely negate the effects of lux and beam concentration?

Urethane (Gorilla)glue is messy to work with and expands while curing and is activated by moisture, so I’m surprised that you chose it. Mixing 50/50 with water says you must know something about it that I don’t. Can it really be thinned with water?

The Gorilla wood glue is not a urethane formulation, and does not expand.

Must have been about 6’6” when younger . . :slight_smile: