I took the closest possible parabola to it, there is no easy way to make a function that copies the intensity curve unless you use piecewise, which I might try to do, or might not
Anyway, it is pretty accurate. 0 to 100% intensity, –90 to +90 degrees.
Orange is the function, white is the intensity curve from cree.
Function is y=-.015x^2+100\left\y>0\right\
Green line at y=–1 indicates the degrees that are being collected by the reflector.
This is what the pattern for total light contained at different angles looks like:
It is a polar graph of sin(x)cos(x). Grapher web app here.
It is sort of an unexpected result. Although the light coming right off the top of the LED is the most intense, there is more light at the steeper angles to the side, and this results in the “lobes” in the graph. This is why the light collection efficiency of most aspheric lights is bad and the light collection efficiency of most reflector lights is good.
Thank you EasyB, that’s a very helpful visualization.
It’s almost incredible at first sight, itś hard to believe it’s based on that circle in the average radiation diagram.
It makes it seem miraculous how well an aspheric still throws.
Wow, just wow.
This isn’t anymore just a thread about a thrower, this is much more! Very awesome to see everyone putting their knowledge into this, never thought that we would really calculate and figuring out all that science about reflectors and stuff.
Yeah awesome
And it is very very cool to see that we have now calculated the reflector should be 112.5mm deep and not just blatantly upscaling the TN42 sizes. And highly impressive TN42 upscale is a tad “off” it seems so BLF has come up with better size then a pro company.
I don’t think there is anything special about any one particular diameter to depth ratio. As illustrated in Enderman’s pictures here , as the depth is increased the effective area increases, which increases throw, but after a certain point there stops being significant gain. The same can be said for the light collection efficiency; with roughly square dimensions the reflector is already collecting more than 75% of the light, and increasing the depth more results in only small improvements.
The reflector dimensions do affect the beam profile, so I think being able to simulate that would be helpful. Like DrJones did here:
Practically I think the 120x112mm size, or anything close to it, is fine and there won’t be significant changes to the beam unless the depth is changed drastically.
Without minimizing or diminishing anything you guys are doing, all of this is theoretical. Who is it that has the signature: “Theory sounds like a nice place, I’d like to go there one day, I hear everything works there.”?
It is almost exactly that, but If I had used cos then it would have overestimated the intensity a lot, the curve I overlayed is a lot closer except for the tiny bit at 80-90 degrees. It is basically just cos but a bit skinnier
Yes, just need to integrate it by spherical coords and we should be able to determine what % of total light is being captured and reflected.
That’s pretty much what I just added to the graph yesterday except instead of polar it is just a regular graph with degrees on the X axis.
Although I think this may not be necessary if I use spherical coordinates to calculate the intensity…so it’s just an intermediate step.
:+1:
