Match's Mods: Homemade Integrating Sphere

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

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.

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.

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

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
www.labsphere.com
And their coating products page: http://www.labspherestore.com/category-s/8.htm
as well as a highly technical data page about their coatings: http://www.labsphere.com/products/reflectance-materials-and-coatings/white-coatings/6080-white-reflectance-coating.aspx
Best wishes

Well… I found a globe …:slight_smile:

great idea. thanks!

Welcome to BLF!
Match’s coating was plain flat white paint without BaSO4 what I remember, but his sphere was made many years ago and Match is not around here anymore.
A BaSO4 coating can indeed be 0.96 if done well, but I doubt that DIY formulations containing BaSO4 will be anything close to that, and even if someone did a good job at it, the experiment for testing the reflective value is difficult without proper laboratory equipment. And then you also want to measure the reflectivity across the spectrum…

I don’t really understand the concepts behind an integrating sphere, I wish there were an affordable one just because I’d like to test my mods. This would certainly be reflective, but aside from putting a hole in it ruining the structural integrity/shape I assume there are many other reasons it wouldn’t work that I’m unaware of. https://www.amazon.com/TONIFUL-Hangable-Aluminum-Metallic-Decoration/dp/B07X655671

Seems like there is a decent market for this and data logging light meters, I’m mildly surprised we don’t see some package deal priced well out of China.

If you are willing to pay loads of money for shipping from EU, you can get a 50 CM (around 20”) eps ball that makes a fantastic sphere. They’re about $40 US, but shipping will easily be that much. That will handle reflectors up tp 110 mm and many tens of thousands of lumens. I have a 30 cm one I use for testing and it’s great. You need a calibrated light or one of verified outout to set the multiplier for getting your relative lumen values, but once calibrated, you can get very close (5-10%) to the actual output. Djozz has a great tutorial for it on here to where you don’t need a baffle, ND filter or diffuser…you measure the light through the wall of the sphere and that works. Mine is only good for reflectors up to 65mm, so I built a lumen tube. Point is, there are options for integrating devices that don’t cost hundreds or thousands of dollars.

Thanks. I really should make one some day.

I see people referencing calibrations. I am sure it would take me a long time to catch up on the people and their methods, but would a sphere like that get me at least 5% precision?

If under a couple hundred total cost, time tweaking and learning is my concern, though I can totally see enjoying that process.

It’s worth it in the long run. It took me probably 10 flashlights (including a loaned Makkua calibration light) and several hours of work to get my multiplier/calibration right. You need to test different sizes and types of reflectors, flooders, throwers, different tints and cri to get it dialed in. I found Fenix, Thrunite, and Olight are good samples to test your calibration with since they use constant current drivers for consistency and their factory numbers are pretty trustworthy. I think 5% is a bit far out, but not impossible. Generally, 10% is considered acceptable and totally realistic. Just be patient and take your time, have fun with it.

Thanks!

I did find that thread and even asked if TA might build another. The Ace named a decent price for sure, but I said I would pass (for now). He need not wonder, while I learn enough to know what I need.

there is a vitamin jar lid over the sensor. I calibrated it by adding a couple pieces of printer paper and kleenex, until my meter read, what I though the output of the light I put on it was supposed to be, per manufacturer.

at the time I use a light called a Lumintop AAA Copper Tool, that had a 0.8 lumen low, and I calibrated to that.

later I got an HDS, which is supposedly calibrated to 200 lumens. My meter said 210 lumens, so I added a bit more tissue paper, and viola, bobs your uncle

example of using the light meter to check for output fluctuations (regulation):

I’d probably mount a smaller ball to it to house the sensor inside, this will allow you to run huge output into the ball too.

Thanks, I should just start experimenting. Best way to learn anyhow. I do have a cheap meter.

Hello guys,

luckily I found this topic before starting work on my sphere. I would be very happy to have your opinions and suggestions regarding this project.

Currently I have all the material to work:

  • 50cm (0,65ft) diameter polystyrene sphere
  • primer for polystyrene
  • pure white paint
  • sandpaper for paint
  • 300g / m2 white A4 cardboard (0.98 oz/sq ft)

1) I would like to drill the sphere in order to have a hole also to be used with very large torches if the opportunity arises.

So I had thought of a hole of 13cm diameter (5,1"). What do you think about it? is the hole too big?

2) I have doubts about the size of the deflector to be inserted inside. How big does it have to be?

3)Are there any other tips or suggestions I can have before starting work?

Thank you.

Hi guys,

I found the time to start working on my sphere:

1) I drilled the sphere creating two windows for input and output.

2) I painted the inside with the polystyrene primer.

The primer dries very quickly, after 3 hours I gave the second coat. It's yellowish and doesn't cover much but it's necessary to create a stable base to paint on. I also made some withe cardboard baffles, but I have to choose the right size, I'll do some tests later.