You're not going to correct me?
Sorry; I have been in four and a half different time zones in the last ten days, and I was probably not at my best when I wrote post #37. I do not intend to talk down to you.
Light sources are easier to control when they are points.
This is sort of true and sort of not. It has been true in the past when all forward lighting used relatively simple imaging optics and a point source, for sure. But with the LED revolution, new imaging and non-imaging optical techniques alike have been making big, fast strides -- and while light source size is still an important factor, things are no longer as simple as "smaller = better" (this is strictly from the engineering viewpoint; stylists have varying but definite opinions on the matter of size vs. betterness).
Generally smaller points require smaller optics to control.
I don't agree with this in general.
HIDs came before LEDs, and usually have better beams than LED and halogen for this reason.
I can't agree. For one thing, the chronological order of introduction of a light source doesn't have a lot to do with the quality or safety performance of the headlamp that incorporates it. Some LED headlamps are better than some HID headlamps, and vice versa. Some LED headlamps are better than some halogen headlamps, and vice versa. There are good and bad implementations of every technology.
LEDs have an advantage over both because the point source does not move relative to the reflector.
This makes so little sense that I think maybe it's just not coming across the way you meant it. There are very few headlamps of any type in which the light source moves relative to the optics. There were a few reflector-type BiXenon headlamps (2nd-generation Prius, a few Volvo models) but mostly that kind of architecture did not find favor and in most headlamps of any type, the light source and the optics do not move relative to each other.
Moreover, most LED headlamps do not have a point light source, strictly speaking.
The biggest issues with LEDs for automotive use is the limited size of the optics relative to the die size, and the cooling of the diode, which is required at the light source.
Thermal management is certainly one of the important issues in the design of an LED headlamp, but it really is no longer the big obstacle it was a few years ago, and it is getting gradually less so as emitters and optics get better and so less power is disippated for any given amount of light in the beam. I don't think I agree that limited size of optics relative to LED size is one of the major constraints, but maybe here again I don't understand what you have in mind. Can you elaborate?
They're attempting to solve both of the issues by separating the blue LED die from the phosphor chip
I don't agree here, either. For one thing, there are no remote-phosphor LED headlamps. Remote-phosphor LED lighting does exist, but this technology has not been applied to automotive headlamps because it's not well matched for the application; it tends to generate a very homogenous, diffuse light rather than anything that could be readily manipulated into a controlled beam pattern.
Laser-activated remote-phosphor lighting (LARP) is what we're talking about in this thread. The distinction between an LED and a laser diode is not trivial, it's crucial. They aren't the same thing. The laser diode pointed at the remote phosphor plate generates a tiny point of very sharply delineated, very high luminance light, and that serves as the point source for the headlamp. This really is almost entirely different from the techniques involved with LED headlamps.
so the phosphor can be mounted in front of the reflector with minimal cooling.
It's not the phosphor that needs careful thermal management, it's the LED emitter/s or the laser diode(s).
