The Legendary BLF Integrating Sphere starts here! (Delivered)

It’s our ‘BLF’ Integrating Sphere… suggest an alternative size (with a link) and if members like it more, we will switch. Remember that larger might affect packaging and shipping costs a little.

I do not know of any, my point is that larger means less artifact errors
BTW the coating is barium sulfate iirc

Hey Josh, great idea! Put me down for one, please.

yea… There’s a nice used one here for just $2400.00 we’re not pretending to compete with that.
http://www.bmisurplus.com/products/54201-lapshere?gclid=Cj0KEQjwipi4BRD7t6zGl6m75IgBEiQAn7CfF5DijkpvRDI9C7mOIweEMD_t1ptfNxXJBlAA8z1YwNwaAhyb8P8HAQ

Its a nice small(er) size, and i notice there is no direct line of sight from the light source to the sensor.

Yea I planned on that feature too.

I think a BLF IS is a great idea, but a lot more discussion/tweaking is probably going to be needed. Regarding the above, I am not sure that a 15cm IS would be practical/useful, especially with some of the larger (and higher-powered) lights out there. Not to mention, I am guessing that 15cm is an OD measurement, so the actual ID is probably a lot smaller. For those not metrically inclined, 15cm is just a hair shy of 6 inches. You would probably even have issues trying to mount a meter to it. Not to mention, I think the port sizes (source and meter) need to be fairly small in relation to a sphere’s ID, which would be nearly impossible with a 6” sphere used for a variety of different size flashlights. Anyway, good on you for getting the ball (uh, sphere) rolling!

A couple more issues that might be worth discussing/addressing:

  • Ideal sphere size/diameter?
  • Interior coating?
  • Exterior coating?
  • Baffle (size/material/placement/etc.)?
  • Ports (size/material/placement/etc.)?
  • Stand?

Carry on!

obviously the exterior must be coated with 1” thick titanium, how else could we be sure the sphere will resist compression forces from the zombie apocalypse :smiley:

I was thinking pre-preg carbon fiber, cured in an autoclave. But yeah, I guess Ti would be OK. :smiley:

Since this is budget light forum i suppose we can use a not so heavy option :sunglasses:

djozz did a 15 cm one here. Maybe he can comment.

Great idea and I hope this really pans out.
May I suggest that you have some way to make the opening adjustable so that a light as small as a convoy s2 all the way to a acebeam k70 will fit.

15cm would work for small lights and lower lumens, but to use something like a SRK or a large head/High output light, the sphere should be larger. 40cm or bigger. I have seen actual integrating spheres for sale that were "designed for flashlights" and the size was about 12" in diameter, but it was for smaller flashlights. There is information about the size of the entrance port compared to the diameter of the sphere and there are some scientific rules about that. I would just have to go find the info out again.

EDIT:

http://nvlpubs.nist.gov/nistpubs/ScientificPapers/nbsscientificpaper447vol18p281_A2b.pdf

https://www.uleth.ca/phy/naylor/documents/pdf/2008_Noble_reflectance_characterization.pdf

I know there is a bunch more out there, with just a google search

Yes! Yes! Yessss!
I’m in, always wondered why no one on BLF wanted to make a standardized calibrated budget sphere.
Thanks!
Keith

Yay Keith!

As for the size, I will look for a bit bigger since that is being requested. But not only can I make white inserts to accommodate different sized heads, there’s the whole data point calibration. There’s no need for the data to be linear, which seems to be the fear of the small sphere with big lights.

I already have the exact same meter, but would be interested if you would sell all the rest of the package-without meter.

Polygon & Unknown00101, Yes you can avoid the cost of the meter by using your own IF you mail me your meter to perform the deviation calibration with.

I’m in.

IIRC (and I my not as I’m on my second coffee and not quite alive yet), the openings should not exceed 5% of the total inner surface area of the sphere.

Phil