Any thoughts on building a light testing booth?

I'm working with a product development company based in Evanston, IL to design a new bike light. Were looking into testing a handful of bike lights already on the market. We want to measure things such as lux, lumens, etc. Has anyone had any experience building something like this or have any suggestions?

You may wish to ask here, too:

http://forums.mtbr.com/forumdisplay.php?f=124

You can map out the light output:

https://www.candlepowerforums.com/posts/3295637&postcount=212

IMHO the reason there are beamshots made of our DIY lights, or even better, riding video of lights in action, is that you need to light up trail or road and not a lab to judge light effectiveness.

phxinc said:

We want to measure things such as lux, lumens, etc. Has anyone had any experience building something like this or have any suggestions?

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Measuring Lux is easy, just buy a good light meter and place it at the spot where you want the light to be measured.

Measuring Lumens is more difficult. You have to integrate the output of the light over the entire area that is illuminated. You can use an Integrating sphere for that.

Look at this thread for starters: Building an Integrating Sphere ... Use the search function on this forum for more threads

For the electrical side of things, buy a multimeter to measure input voltage/ current.

Hope your effforts produce a usable bikelight

Willing to divulge what the design criteria are, or the end goal?

you might check the BikeCurrent archives on Topica. Andreas Oehler of Schmidt discussed building a rig for headlight testing. He had to be sure that the headlight met the German standards for the beam pattern. IIRC, the essence was that he had a detector that could measure intensity, and he had a method for positioning it at numerous points in a grid.

You may already have a test standard that requires testing the intensity at a specific distance, which should make things easier. Otherwise, I'd mention that there is a difference between the near-field pattern and the far-field pattern. Far-field is more realistic, but increases the size of the test facility required.

regards,
Steve K.

Thanks everyone for the input so far. I'm thinking we'll try and build a small integrating sphere like the ones posted here on the forums and see if we can get some accurate lumen readings.

I'll probably pick up a light meter and a multimeter like pe2er suggested to measure more of the simple things like lux and voltage/current.

BrianMC, I agree with you that we should be testing lights outside so we get a better feel for how these lights function in the environment they'll be used in. So I think we'll steer testing in that direction for overall beam distance.

Steve K, any chance you have a direct link to Andreas Oehler's post on BikeCurrent? I'm having a hard time navigating the site and the search keeps crashing when I look up his name. I'm very interested in how he built his testing rig as well as how he layed out the beam patterns into a grid format.

There is another thread on this forum you may find interesting: Let's design a road front light beam

It is an effort of the forum members to design a road front light beam with reduced glare for other road users. It also discusses the German StVZO rules for headlights.

I Would love to see some results of your measurements

PS: Found a further clue on bikeradar.com: Need user feedback for a new bike light design!

Forget about all that testing and measuring and numbers and stuff.

You should just send prototypes out to CPF cyclists for beta testing :wave:

Another question for you guys. We will be testing in multiple environments, one of which will be indoors. I've ordered some black foam core board to block out the windows. The walls are painted white however. Any thoughts on if we should paint the walls a different color or cover them to reduce reflectivity?

On a side note, anyone know anything about parabolic reflectors? Just started looking into them as an alternative to the typical LED light with reflectors behind them.

phxinc said:

Another question for you guys. We will be testing in multiple environments, one of which will be indoors. I've ordered some black foam core board to block out the windows. The walls are painted white however. Any thoughts on if we should paint the walls a different color or cover them to reduce reflectivity?

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I think white is fine. If you were trying to compare the results in your booth to those of form other booths, then you'd want the same paint. The DIYers here try to find a clear wall or ceiling to show beam patterns. A dedicated booth is nice.

phxinc said:

On a side note, anyone know anything about parabolic reflectors? Just started looking into them as an alternative to the typical LED light with reflectors behind them.

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They were mentioned a few times in this thread as a way to get the beams we wanted, but seemed a bit beyond the usual DIYer's budget for playing with bike lights.