With the thought of both concentrating the original beam of the SunDrop hosting the Nichia 083 as well as allowing the head to be host of light engines based on other LEDs with greater height, the SunDrop XR-U head was designed. The XR designates extended range, extended reach as well as compatibility with the Cree XR LED. I decided to throw in the U to designate universal although it may be broader in scope than reality would permit. Certainly there are a number of different LED's that could work below the sapphire lens in the XR-U head.
The lens in the XR-U is approximately .125" further above the LED compaired to the original SunDrop and the head shows this in the extra length. From the front end, the LED is magnified further in the XR-U (left):
I did some testing and evaluation of this head with a number of light engines:
The Nichia 083 and Cree XR-E light engines have been used in the original SunDrop and the Haiku, respectively. The Seoul P4 High CRI proto and Cree MC-E proto were built just for test and evaluation purposes.
The following beam shots were all taken from the same position with a Nikon D300 using a 20mm lens and exposure was the same manual setting for all.
I also put the XR-E light engine in a Haiku and the Seoul P4 High CRI light engine in a prototype Aleph head hosting a McR-27S reflector to get some sample collimated type beam shots for comparison to these flood beams.
The 3S drivers in the XR-E and Seoul P4 LE's are both set at ~ 600 mA on high level. The MC-E light engine is closer to 700 mA driving the 4 dice in parallel. The Nichia 083 LE is at ~ 330 mA.
There is measurable light loss with the XR-U head compared to the original SunDrop head because the lens is further from the LED. In the cases of the other LED's, their die are closer to the lens and the domes over the die wouldn't allow them to be situated much closer than they are.
In some comparisons made with the integrating sphere, it was interesting to see not only a drop in flux on the SunDrop VS SunDrop XR-U but a change in the measured CCT as well. Although the flux dropped, the CCT increased from 5600k to 5800k with the same Nichia 083B LE.
Spectrum and color info on the sample 083 based XR-U head:
Since I was evaluating the Seoul P4 High CRI LED, I also tested it in the integrating sphere while mounted in a XR-U head:
The outdoor beam shots don't show variations in tint or artifacts like a white wall would. In the case of the XR-U head, all of the light engines produced a relatively even and artifact free flood disk of light with noticible artifacts and tint variations limited to the perimeter of the disk. The Seoul P4 in the Aleph 27S proto (image below) has a noticible higher color temp in the spot portion of the beam compared to a warmer corona and spill, when viewed on a white wall.
The basic goal with the XR-U head is to provide a middle ground compromise between full flood (no secondary optics) beams and collimated beams which have high lux in their center and relatively low lux as you move from center out to the spill. The idea is to retain the even distribution of a flood but concentrated in a narrower viewing angle to allow you greater range.