Match's Mods: Homemade Integrating Sphere

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texaspyro
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The reflectivity of the styrofoam is not much of an issue… it drops out when you calibrate the sphere.

With my sphere, I can do around 5000 lumens with the sensor mounted in the sphere. With the sensor mounted on the outside wall (using the styrofoam as a light attenuator) I can do over 600,000 lumens. The sphere is absorbing over 99% of the light.

Styrofoam is light… but bulky. Shipping to Canada should not be to bad. You might be able to find a local seller.

djozz
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texaspyro wrote:
The reflectivity of the styrofoam is not much of an issue... it drops out when you calibrate the sphere.

The reflectivity does matter in the type of IS we are building.

Not having build one myself I do not know how much it matters, but in this type of sphere the detector 'sees' the first reflection of the light. There are two scenario's in which that is not a problem: 1) the detector (luxmeter) is not angle-sensitive, i.e. it reads the same value for all incoming angles, or 2) the reflectivity is near 100%. If that is both not the case, the integrating sphere will be more or less sensitive to beam profiles: throwers will read different from flooders or bare leds. And that is precisely what we want to cancel out by using an IS.

At least my cheap luxmeter is not quite angle-insensitive, I found, so if I build an integrating sphere for it,  I will pay attention to a good reflectivity of the inner surface.

Again, it may be a bit theoretical, and in practice may not matter that much, but in theory at least a not optimal reflectivity is not just a matter of a different correction factor.

Sirius9
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Annnnd, now I have a desire to build IS. God dammit guys, you have a negative influence on me :bigsmile:
Luckily those fitness balls are way too expensive to destroy one…

 

unknown00101
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I contemplated using one of those that had been torn. Patch it up and inflate it just enough to get a sphere. Probably would be far too big to be practical, and it got thrown away anyway. Sad

texaspyro
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djozz wrote:

texaspyro wrote:
The reflectivity of the styrofoam is not much of an issue… it drops out when you calibrate the sphere.

The reflectivity does matter in the type of IS we are building.

No, for practical purposes the reflectivity does not matter much at all. White styrofoam is pretty darn reflective. Whether the surface reflects 95% of the light or 90% does not matter much once you calibrate your sphere… been there, tested that… Even with a rather tight thrower, the detector is seeing reflections from a LOT of angles… unless you are using a focused laser as the light source.

What you want to eliminate is a specular/non-difuse reflective surface that can direct a direct reflection of the light to the sensor. That is where the barium sulphate/sanding the styrofoam surface helps.

To test how well your sphere integrates, aim the light at different parts of the sphere and see how the readings change.

Sirius9
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unknown00101 wrote:
I contemplated using one of those that had been torn. Patch it up and inflate it just enough to get a sphere. Probably would be far too big to be practical, and it got thrown away anyway. Sad

No such thing as “too big” Big Smile

 

djozz
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texaspyro wrote:
djozz wrote:

texaspyro wrote:
The reflectivity of the styrofoam is not much of an issue... it drops out when you calibrate the sphere.

The reflectivity does matter in the type of IS we are building.

No, for practical purposes the reflectivity does not matter much at all. White styrofoam is pretty darn reflective. Whether the surface reflects 95% of the light or 90% does not matter much once you calibrate your sphere... been there, tested that... Even with a rather tight thrower, the detector is seeing reflections from a LOT of angles... unless you are using a focused laser as the light source. What you want to eliminate is a specular/non-difuse reflective surface that can direct a direct reflection of the light to the sensor. That is where the barium sulphate/sanding the styrofoam surface helps. To test how well your sphere integrates, aim the light at different parts of the sphere and see how the readings change.

Thanks for the practical input, I am too going to build an IS (yay!), so this helps knowing how fixed I need to be on small details (not apparantly).

texaspyro
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djozz wrote:
Thanks for the practical input, I am too going to build an IS (yay!), so this helps knowing how fixed I need to be on small details (not apparantly).

When I first got my sphere, I did not sand down the flat spots to make them spherical (I put the 4” diameter light port where one half of the sphere had the flat spot and the hole pretty much took up the whole flat area). The sphere still worked rather well with the flat spot on the other side of the sphere where the light hit it square on. There was maybe a 5% improvement in directional sensitivity after I sanded the flats down to a spherical radius.

My sphere sits on my kitchen floor and the room is lit by around 2500-10,000 lumens of room lighting. I have not opaqued the outside of the sphere. It works just fine and the room lighting does not appreciably affect the readings… unless you are trying to measure a small/dim light. I get around 1-2 lumens of room light leaking into the sphere. For dime lights I wait until night and turn off the room lights or just have my system subtract the background light level reading. (For color temperature testing of dim lights I use the darkened room).

jmpaul320
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heres a bump for this thread – I am currently on layer #4 of this giant glue ball of lumens Smile

Would you mind keeping the wrong flashlight?
Best wish, May
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Illuminaria
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For the US/UK users I see most people use Lux. 1 FC x 10.76 = 1 Lux. Other than way bigger numbers while using Lux, any reason not to use Foot Candles?

For whatever reason my 14.5” IS/Meter combo uses in LUX:10.40697674418605. The correction for 172/1790. After looking at the correction number for my (only) ANSI/NEMA FL-1 certified light of 172 lumens, I switched to FC on my meter. Basically same readings but now can use direct readout. I understand if I change meter or repaint sphere, everything changes.

I see that many others got correction numbers from 7.xxx to 12.xxx, so while fun, I would need to send IS, meter and light to BLF laboratories, INC? I like the suggestion to buy a few more calibration lights, so will continue to enjoy using the IS.

eebowler
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Going to build one of these! Big Smile Thanks Match!

My gratitude to those who are willing and able to help others (in whatever way you can)! Being human is more than just existing for yourself. Smile

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Welcome to the ball-of-light measuring group. Smile

That Canadian flashlight guy & Lantern Guru -Den / DBSARlight

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DenBarrettSAR wrote:
Welcome to the ball-of-light measuring group. Smile
!{height:800px; width:600px}http://i72.photobucket.com/albums/i187/Denbarrett/IntegratingSphere01_zp...!

What is the dome made of?

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"

 

eebowler
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Bort, you look different, did you cut your hair?

My gratitude to those who are willing and able to help others (in whatever way you can)! Being human is more than just existing for yourself. Smile

DBSAR
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Bort wrote:
DenBarrettSAR wrote:
Welcome to the ball-of-light measuring group. Smile !{height:800px; width:600px}http://i72.photobucket.com/albums/i187/Denbarrett/IntegratingSphere01_zp...!
What is the dome made of?

The sphere top and bottom halves were originally two large round thermoplastic salad bowls.

That Canadian flashlight guy & Lantern Guru -Den / DBSARlight

Bort
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eebowler wrote:
Bort, you look different, did you cut your hair?

I did, about a month ago

I also recently shaved, have considered selling a few lights, and started a new health regimen

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"

 

Bort
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DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Welcome to the ball-of-light measuring group. Smile !{height:800px; width:600px}http://i72.photobucket.com/albums/i187/Denbarrett/IntegratingSphere01_zp...!
What is the dome made of?

The sphere top and bottom halves were originally two large round thermoplastic salad bowls.


i think you could make more of your spheres and sell them for profit Smile

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"

 

DBSAR
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Bort wrote:
DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Welcome to the ball-of-light measuring group. Smile !{height:800px; width:600px}http://i72.photobucket.com/albums/i187/Denbarrett/IntegratingSphere01_zp...!
What is the dome made of?

The sphere top and bottom halves were originally two large round thermoplastic salad bowls.


i think you could make more of your spheres and sell them for profit Smile

The one i built above took a bit of time to build, not sure if there is any profit in it for the time and parts used. I have it calibrated very well now though.

That Canadian flashlight guy & Lantern Guru -Den / DBSARlight

Bort
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DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Welcome to the ball-of-light measuring group. Smile !{height:800px; width:600px}http://i72.photobucket.com/albums/i187/Denbarrett/IntegratingSphere01_zp...!
What is the dome made of?

The sphere top and bottom halves were originally two large round thermoplastic salad bowls.


i think you could make more of your spheres and sell them for profit Smile

The one i built above took a bit of time to build, not sure if there is any profit in it for the time and parts used. I have it calibrated very well now though.


But you can undercut professional model prices by a huge margin, perhaps by more then 90% Wink

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"

 

DBSAR
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Bort wrote:
DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Welcome to the ball-of-light measuring group. Smile !{height:800px; width:600px}http://i72.photobucket.com/albums/i187/Denbarrett/IntegratingSphere01_zp...!
What is the dome made of?

The sphere top and bottom halves were originally two large round thermoplastic salad bowls.


i think you could make more of your spheres and sell them for profit Smile

The one i built above took a bit of time to build, not sure if there is any profit in it for the time and parts used. I have it calibrated very well now though.


But you can undercut professional model prices by a huge margin, perhaps by more then 90% Wink

This would not likely be close to as accurate to a professional “laboratory” Integrated sphere.

That Canadian flashlight guy & Lantern Guru -Den / DBSARlight

Bort
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DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Welcome to the ball-of-light measuring group. Smile !{height:800px; width:600px}http://i72.photobucket.com/albums/i187/Denbarrett/IntegratingSphere01_zp...!
What is the dome made of?

The sphere top and bottom halves were originally two large round thermoplastic salad bowls.


i think you could make more of your spheres and sell them for profit Smile

The one i built above took a bit of time to build, not sure if there is any profit in it for the time and parts used. I have it calibrated very well now though.


But you can undercut professional model prices by a huge margin, perhaps by more then 90% Wink

This would not likely be close to as accurate to a professional “laboratory” Integrated sphere.


Of course, but since we like budget, a reproducible integrating sphere will suffice just like a Convoy will suffice vs a surefire Big Smile

I think you should create a build thread for your device, i am curious where you got those salad bowls

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"

 

DBSAR
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Bort wrote:
DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Bort wrote:
DenBarrettSAR wrote:
Welcome to the ball-of-light measuring group. Smile !{height:800px; width:600px}http://i72.photobucket.com/albums/i187/Denbarrett/IntegratingSphere01_zp...!
What is the dome made of?

The sphere top and bottom halves were originally two large round thermoplastic salad bowls.


i think you could make more of your spheres and sell them for profit Smile

The one i built above took a bit of time to build, not sure if there is any profit in it for the time and parts used. I have it calibrated very well now though.


But you can undercut professional model prices by a huge margin, perhaps by more then 90% Wink

This would not likely be close to as accurate to a professional “laboratory” Integrated sphere.


Of course, but since we like budget, a reproducible integrating sphere will suffice just like a Convoy will suffice vs a surefire Big Smile

I think you should create a build thread for your device, i am curious where you got those salad bowls

I thought it did, but realized that i never did a build thread on it yet.

That Canadian flashlight guy & Lantern Guru -Den / DBSARlight

djozz
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Nice work DBSAR!  It looks very handy with all the mounting options around it.

The accurateness of professional spheres has much less to do with the actual sphere, much more with the better measuring equipment and calibrated sources, a home made sphere like we make already has excellent integrating properties.

DBSAR
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djozz wrote:

Nice work DBSAR!  It looks very handy with all the mounting options around it.

The accurateness of professional spheres has much less to do with the actual sphere, much more with the better measuring equipment and calibrated sources, a home made sphere like we make already has excellent integrating properties.

Good point. for most of us the only way to “calibrate” our Integrating Spheres is calculations based on testing our stock known ANSI measured Lights, in my case is a few fenixes, Nitecores, Olights, thrunites, etc.

That Canadian flashlight guy & Lantern Guru -Den / DBSARlight

nisse
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Modding flashlights to advanced for me but messing with papier maché I am in!

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For the purpose of consolidating information regarding IS's here are a couple of links for those who may be interested in a source for Barium Sulfate products for the inside coating if one were to choose that method.

This is just one supplier that was mentioned in another forum. It is not known if they are more or less expensive than any others.

Labsphere, Inc.

A Halma Company
P.O. Box 70
231 Shaker Street
North Sutton NH US 03260
+ 1.603.927.4266 (ph)
+ 1.603.927.4694 (fax)
labsphere@labsphere.com
 
And their coating products page: http://www.labspherestore.com/category-s/8.htm
 
 
Best wishes
Boaz
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Boaz wrote:

Need to make one of these from a nice globe  

Did you say …6000 lumens ??  diggety …

 

> You forgot one more reason .. to impress your BLF buddies … Very cool

You are a good Dad …Now go out there and give that lil girl a set of new streamers for her bike and 2000lumen bike light that will make the neighbor kids cry .

Well… I found a globe ..:)

       καὶ τὸ φῶς ἐν τῇ σκοτίᾳ φαίνει καὶ ἡ σκοτία αὐτὸ οὐ κατέλαβεν

                            

       Dc-fix diffuser film  >…  http://budgetlightforum.com/node/42208

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great idea. thanks!

"How to choose flashlight, Main things in simple words":http://budgetlightforum.com/node/68418

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