Xenon colors answered (technical)

duodallas · 12-30-2003, 04:28 PM

Happened to have a Minolta CS100 color meter at home so I measured the spots from the headlamps on the wall a few feet from the car. Because of the short distance there was some variation over the Xe spot, because some parts of the arc are hotter than others. I think the measurements are a good average.

First off, the color does change pretty drastically in the first two minutes. The first measurement I took was about 5400K, and as the lamp warmed up the CCT dropped to 4100K (red arrow and dots), which isn't that blue, BTW. What is happening is the mercury is evaporating as the lamp heats up, and the 585nm line of the mercury makes the arc become more yellow. Straight Xenon would have a color temp of 6000K or so. I think the mercury and some halogen in the lamp work to clean the tungsten off the bulb surface. Just a guess.

For grins, I measured the high beam halogens. They have a CCT of 3900K, but are much greener than a 3900K blackbody. Lastly, I measured the PIAA H3 (I5455) fog lamps, and they are a good match to the Xenons when warmed up.

Stoney · 12-30-2003, 04:54 PM

PIAA bulbs -- The "15455" is the "super white," billed as 3800K. The "super plasma" which I am using (by mistake) actually match the Xenon well, but are billed as 5000K. They don't seem terribly blue to me, though.

Can you describe the Y axis of your chart?

Thanks, this is very useful.

duodallas · 12-30-2003, 05:49 PM

The cones in the eye have a blue-yellow, a green-magenta, and a cyan-red sensitivity. From experiments the sensitivity of the eye to light at various wavelengths can be reduced to three values, X, Y, and Z. A two-dimensional projection of this space is the x and y in the graph. Blue is about .145,.08, green about .30, .64, and red about .65, .35 in x and y. White is about .33, .33, meaning that X, Y, and Z are about the same.

See the link for more.

explaination of XY color space

PaulW · 12-30-2003, 06:57 PM

larrs8 · 12-30-2003, 07:10 PM

2.7tDallas · 12-30-2003, 07:32 PM

2.7tDallas · 12-30-2003, 07:34 PM

Stoney · 12-30-2003, 08:01 PM

duodallas · 12-30-2003, 08:22 PM

based on some work that I did, as is the DLP Cinema projector. Color science is one of the things you have to know at the system level.

If you get a chance to go to CES, stop by the TI booth.

duodallas · 12-30-2003, 08:25 PM

12-30-2003, 04:28 PM	#1
duodallas Junior Member Account #: 5196 Join Date: May 2000 Posts: 1,284	Xenon colors answered (technical) Happened to have a Minolta CS100 color meter at home so I measured the spots from the headlamps on the wall a few feet from the car. Because of the short distance there was some variation over the Xe spot, because some parts of the arc are hotter than others. I think the measurements are a good average. First off, the color does change pretty drastically in the first two minutes. The first measurement I took was about 5400K, and as the lamp warmed up the CCT dropped to 4100K (red arrow and dots), which isn't that blue, BTW. What is happening is the mercury is evaporating as the lamp heats up, and the 585nm line of the mercury makes the arc become more yellow. Straight Xenon would have a color temp of 6000K or so. I think the mercury and some halogen in the lamp work to clean the tungsten off the bulb surface. Just a guess. For grins, I measured the high beam halogens. They have a CCT of 3900K, but are much greener than a 3900K blackbody. Lastly, I measured the PIAA H3 (I5455) fog lamps, and they are a good match to the Xenons when warmed up. __________________ 2008 A3 s-line, Xe 2000 A6 2.7T 2003 Aprilia Scarabeo 150 2006 Suzuki VL800 C50 2003 Troy built front drive 21" mower

12-30-2003, 04:54 PM	#2
Stoney AudiWorld Super User Account #: 230 Join Date: Mar 2000 Posts: 5,267	That is the "super white" PIAA, I see from this page.... PIAA bulbs -- The "15455" is the "super white," billed as 3800K. The "super plasma" which I am using (by mistake) actually match the Xenon well, but are billed as 5000K. They don't seem terribly blue to me, though. Can you describe the Y axis of your chart? Thanks, this is very useful. __________________ A6 (C5 platform) FAQ Stoney's Picture Library Email: jds@sonolithics.RemoveThisPart.com 2001 A6 4.2L, Sport, Premium, Nemo Blue, Melange Interior

12-30-2003, 05:49 PM	#3
duodallas Junior Member Account #: 5196 Join Date: May 2000 Posts: 1,284	A brief explaination of x and y... The cones in the eye have a blue-yellow, a green-magenta, and a cyan-red sensitivity. From experiments the sensitivity of the eye to light at various wavelengths can be reduced to three values, X, Y, and Z. A two-dimensional projection of this space is the x and y in the graph. Blue is about .145,.08, green about .30, .64, and red about .65, .35 in x and y. White is about .33, .33, meaning that X, Y, and Z are about the same. See the link for more. explaination of XY color space __________________ 2008 A3 s-line, Xe 2000 A6 2.7T 2003 Aprilia Scarabeo 150 2006 Suzuki VL800 C50 2003 Troy built front drive 21" mower

12-30-2003, 06:57 PM	#4
PaulW AudiWorld Super User Account #: 22012 Join Date: Jul 2001 Posts: 18,107	NIce write up, thanks! __________________ _________________________________ Paul Waterloo 01 S8 Black on Black Lots of Electronic Mods D2 A8/A8L/S8 FAQ Digest

12-30-2003, 07:10 PM	#5
larrs8 New Member Account #: 55922 Join Date: May 2003 Posts: 90	duodallas....may I ask what you do for a living?

12-30-2003, 07:32 PM	#6
2.7tDallas AudiWorld Expert Account #: 5503 Join Date: May 2000 Posts: 25,171	optical engineer - DLP patent holder __________________

12-30-2003, 07:34 PM	#7
2.7tDallas AudiWorld Expert Account #: 5503 Join Date: May 2000 Posts: 25,171	why don't you guys just hook a USB cable from skull to skull __________________

12-30-2003, 08:01 PM	#8
Stoney AudiWorld Super User Account #: 230 Join Date: Mar 2000 Posts: 5,267	Mine doesn't need that much bandwidth. ;^) __________________ A6 (C5 platform) FAQ Stoney's Picture Library Email: jds@sonolithics.RemoveThisPart.com 2001 A6 4.2L, Sport, Premium, Nemo Blue, Melange Interior

12-30-2003, 08:22 PM	#9
duodallas Junior Member Account #: 5196 Join Date: May 2000 Posts: 1,284	Lately, projector design. The DLP TV's are... based on some work that I did, as is the DLP Cinema projector. Color science is one of the things you have to know at the system level. If you get a chance to go to CES, stop by the TI booth. __________________ 2008 A3 s-line, Xe 2000 A6 2.7T 2003 Aprilia Scarabeo 150 2006 Suzuki VL800 C50 2003 Troy built front drive 21" mower

12-30-2003, 08:25 PM	#10
duodallas Junior Member Account #: 5196 Join Date: May 2000 Posts: 1,284	Worthy of the FAQ's page? __________________ 2008 A3 s-line, Xe 2000 A6 2.7T 2003 Aprilia Scarabeo 150 2006 Suzuki VL800 C50 2003 Troy built front drive 21" mower

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