funder
Newly Enlightened
For some time, Surefire was considered to be "obsolete" in output by some flashaholics. Personally, I believe they never give up in pushing the light into higher output level. Their effort has been shown in recent lights such as P2X, M3LT and UB3T. Output is usually measured by the luminous flux (lumens), but the luminous intensity (candelas) is important as well. The later one is the measure of the throw which can be easily transformed into the illuminance (luxs) in a given distance ( intensity/d^2).
The theoretical limit of the throw (in candela) can be calculated by the given formula (refer the silides: http://www.slideshare.net/canfang/led-optics-in-flashlight:
Max intensity = luminance of light source x effective projective area x (refractive index of target/ refractive index of light source)^2.
For example, the max luminance of Cree XML is about: 1000/pi/(2e-3)^2 ~= 8.0e7 nits; The refractive index of the primary lens (dome) is about 1.5. A light with 50mm reflector or optics equipped with XML, it throw is bounded from above by:
8.0e7 x pi x (0.025)^2 x 1/2.25 ~=70000cds.
Some of such lights, such as UB3t, Thrunite catapult, have measured luminous intensity of 40000~50000cd, which is already approaching their theoretical limits.
Surefire new dominator UDR is first introduced in 2011 shotshow, at that time, it was claimed to has 2000lumens and 40,000cds. I am very surprised to read that in 2012 catalog the luminous intensity has been changed to 165,000cds, that's more than 4 times! Although we could assume that in 2011 catalog the number is underrate, the difference is still too large to be understandable.
So, what happens?
Let's compare U3BT and UDR, the later has a 5times of throw, but the bezel is just about 1cm larger in diameter. We could estimate the effective diameter of its reflector is 60mm,( 60/50)^2 = 1.44, which indicates the increase of the projective area contribute 44% in the increase of the throw.
In 2011 SS, the prototype UDR is equipped with a luminus CST90, which has a maximum luminous flux of 2700 lumens. Considering it has a larger die area (9mm^2 vs 4mm^2), its luminance is just slightly (about 20%) larger than Cree XML. So CST 90 cannot make the claimed throw.
Now let's go to the third term of the throw formula: refractive index. If the emitter is in the air instead of a dome lens, this term (usually much less than 1) can be removed and we can have a large increase in throw. We cannot remove the lens by ourselves because this will damage the emitter. Instead, we can choose the LED without lens, thus the Luminus CBT90 would be a perfect choice for the throw king. However, the dome lens works as a matching media in the LED thus the LED without lens will lose some luminance flux. In the official website, CBT90 only marked as 1800 lumens, which about 1/3 less than the CST90. And 1800lumens is not matching the claimed 2000 lumens of UDR.
Fortunately, it seems that luminus has some breakthrough in making high Binned CBT90 recently, in a very recent brief: http://www.luminus.com/products/PDB-001948_CBT-90_ProdBrief.pdf , they claimed over 2500 lumens. This emitter has a nearly same virtual area of XML (because of the magnification effect of dome lens in XML), but has a 2.5 times flux!
As a conclusion, we can say surefire managed to get some very high powered (50watts), very limited high binned CBT90 from Luminus and equip UDR with them. I believe these LEDs will continue to be very limited in availability thus it is difficult for the competitors to do so.
A new throw king? Let's wait and see.
The theoretical limit of the throw (in candela) can be calculated by the given formula (refer the silides: http://www.slideshare.net/canfang/led-optics-in-flashlight:
Max intensity = luminance of light source x effective projective area x (refractive index of target/ refractive index of light source)^2.
For example, the max luminance of Cree XML is about: 1000/pi/(2e-3)^2 ~= 8.0e7 nits; The refractive index of the primary lens (dome) is about 1.5. A light with 50mm reflector or optics equipped with XML, it throw is bounded from above by:
8.0e7 x pi x (0.025)^2 x 1/2.25 ~=70000cds.
Some of such lights, such as UB3t, Thrunite catapult, have measured luminous intensity of 40000~50000cd, which is already approaching their theoretical limits.
Surefire new dominator UDR is first introduced in 2011 shotshow, at that time, it was claimed to has 2000lumens and 40,000cds. I am very surprised to read that in 2012 catalog the luminous intensity has been changed to 165,000cds, that's more than 4 times! Although we could assume that in 2011 catalog the number is underrate, the difference is still too large to be understandable.
So, what happens?
Let's compare U3BT and UDR, the later has a 5times of throw, but the bezel is just about 1cm larger in diameter. We could estimate the effective diameter of its reflector is 60mm,( 60/50)^2 = 1.44, which indicates the increase of the projective area contribute 44% in the increase of the throw.
In 2011 SS, the prototype UDR is equipped with a luminus CST90, which has a maximum luminous flux of 2700 lumens. Considering it has a larger die area (9mm^2 vs 4mm^2), its luminance is just slightly (about 20%) larger than Cree XML. So CST 90 cannot make the claimed throw.
Now let's go to the third term of the throw formula: refractive index. If the emitter is in the air instead of a dome lens, this term (usually much less than 1) can be removed and we can have a large increase in throw. We cannot remove the lens by ourselves because this will damage the emitter. Instead, we can choose the LED without lens, thus the Luminus CBT90 would be a perfect choice for the throw king. However, the dome lens works as a matching media in the LED thus the LED without lens will lose some luminance flux. In the official website, CBT90 only marked as 1800 lumens, which about 1/3 less than the CST90. And 1800lumens is not matching the claimed 2000 lumens of UDR.
Fortunately, it seems that luminus has some breakthrough in making high Binned CBT90 recently, in a very recent brief: http://www.luminus.com/products/PDB-001948_CBT-90_ProdBrief.pdf , they claimed over 2500 lumens. This emitter has a nearly same virtual area of XML (because of the magnification effect of dome lens in XML), but has a 2.5 times flux!
As a conclusion, we can say surefire managed to get some very high powered (50watts), very limited high binned CBT90 from Luminus and equip UDR with them. I believe these LEDs will continue to be very limited in availability thus it is difficult for the competitors to do so.
A new throw king? Let's wait and see.
