bLu vs. tLu: IS confirms 65% conversion factor

[js]

MSI,

I suspect that you are right on about 2" vs. 3" reflectors.

NewBie,

Here is one of PaulW's threads: 500 Lumen Mag 3D and this may be the one from which Ginseng calculated the 65 percent figure.

It's truly interesting, because if I understand things correctly, the ceiling bounce test calculations are for an 1185 being run from 9 AA's. We now know that the A2 is really right around 75 lumens, and not 50 as it is quoted on the SF website. Using 75 instead of 50 yields 785 torch lumens for the 1185 on 9 AA cells, which is very close to what we now consider an 1185 light to be, using 9 decent AA cells.

Neat, neat, neat. Who says a ceiling bounce test is worthless? Not me, that's for sure.

But this, I think, is the jack pot of historical threads related to the 65 percent figure: Performance of Bright Lamp Configurations.

Enjoy.

 

[Luna]

Really nice to have some I.S. data to back up the renowned figure of 65%. I will continue to use the .65 fraction.. and btw.. my Mag100 figures do include the 65% calculation

Yes it is. This is good validation of my questioning of JS as to if the numbers have been tested.

It is a good safe number but you still have the situation where the 65% may be too low, like: the newer reflector with decreased bulb opening (~8% calculated), better glass 5-6% , aa larger reflector, Enhanced Al coating (8-10%). Of course these are individual numbers of each component alone, so the increase in the transmission line eff% will not be so great.


I just caution the assumption 65% is a catch all. This rule of thumb only applies to basic bulb-~2inch reflector(standard profile, not deep or shallow) combos. Optics and even LED-reflector combos will be different.

I'd still contend that nobody should advertise with this assumption alone, testing is imperative. 65% is only a predictive coeff (except in the given test case), not concrete in a jihadish sort of way

I don't think you will get better efficiency with the 3"

I 'think' you would. Here is my reasoning. A large portion of the losses are from 3 sources: backplane absorption (the hole), internal reflection and reflection back to the bulb. The hole is a given so write it off or silver the glass envelope under the filament (hint hint)

Now a reflector with the same depth will have a lesser amount of incident losses because less light will reflect back to the source or rereflect back to the reflector due to the changed geometry.

 

[js]

Also,

A third thread by our own renowned PaulW is Lumens Estimates for Aurora2 & Mag85 and is well worth checking out.

Actually any of PaulW's threads are well worth checking out. As well as any of Ginseng's threads and bwaites's threads and NewBie's threads and McGizmo's threads and Illuminated's threads, and so on and on and on. Very few people seem to realize what was just point out in a post above: the search function works great for finding threads and posts of a specified person. Just type in their username and if you want threads select "Threads started by user" and if you want posts, select the other one, and you can display post results in the form of individual posts or threads. Unfortunately, a lot of good stuff is hidden away in unlikely threads started by unlikely people, so it still is painful not to have the search function. But still, . . .

 

[bwaites]

Actually, the reflector tested had NO back opening, but a white potting compound in the hole.

The losses would have been LESS than a small hole, because the white is reflective.

The 65% figure is a close estimation, nobody I have seen has EVER posted it as a hard and fast figure.

I'm willing to bet that the number doesn't vary much, regardless of the size of the reflector, SO LONG AS THE COATING IS THE SAME. Different coatings will change that number somewhat, but metalized, vacuum coated reflectors as used by us will be close to the same.

Larger reflectors will collimate (sp?) the beam more effectively, but I bet there isn't much different in the losses depending on size.

Newbie probably has a way to show that using his knowledge of optics and equations, but it is over my head.

Bill

 

[js]

Yes it is. This is good validation of my questioning of JS as to if the numbers have been tested.

It is a good safe number but you still have the situation where the 65% may be too low, like: the newer reflector with decreased bulb opening (~8% calculated), better glass 5-6% , aa larger reflector, Enhanced Al coating (8-10%). Of course these are individual numbers of each component alone, so the increase in the transmission line eff% will not be so great.


I just caution the assumption 65% is a catch all. This rule of thumb only applies to basic bulb-~2inch reflector(standard profile, not deep or shallow) combos. Optics and even LED-reflector combos will be different.

I'd still contend that nobody should advertise with this assumption alone, testing is imperative. 65% is only a predictive coeff (except in the given test case), not concrete in a jihadish sort of way

Luna,

Did you actually read my post(s) above? Because,

1. This module which was tested had no glass in front of it at all. So my 2 percent reduction subtracted from the 70.7 percent due to it was probably on the low side. Thus there is no way to gain 5 percent due to the glass.

2. The reflector DID have the "enhanced aluminum coating", otherwise known as vacuum aluminizing, so there is no better coating that would increase the results by 8 to 10 percent.

You caution us all, do you? We shouldn't "advertise" based on the 65 percent figure? This "catch all" rule of thumb applies only to approx. 2 inch reflector that is not shallow or deep? The 65 percent figure shouldn't be applied in a religious-war kind of way?

Luna, who's doing that? Show me the place where it was ever anything BUT a rule of thumb.

No "thank you, js, for providing this info" but instead a "Yes it IS good to FINALLY have a real answer to MY questions--BUT . . .

Always the tearing down and picking apart. Always the badgering, poking, proding, arguing. Talking about how a hotspot can easily "hide 100 lumens" in a ceiling bounce test. In fact, aren't you the same person who said that a ceiling bounce test was worthless for determining a lumens total? And yet, here we have a confirmation of results originally gleaned from inventive ceiling bounce tests.

Aren't you the same person who said that an ohmic approximation was good enough for our use in this thread? And yet, it is easy to show that it is not.

Given that you called me an asshole on our last exchange, questioned my motives, educational claims, method for approximating the MN21 current (which by the way was for an upper bound so that the assumption of 100 percent LVR efficiency was actually moving the result in favor of your position of a higher draw current--but you never understood my reasoning in the first place, did you?) --

given all this, can you be surprised that I am really not impressed or concerned with the cautions and reservations and limitations you would like to impose on us all?

And who the hell is "advertising" anything anyway? We are just a bunch of amateurs trying to have fun and trying to do the best we can with what we have. If someone is willing and interested in making an estimate of the torch lumens of his light, where's the problem?

Although, look, if you want to start offering free integrating sphere tests at a cost to you of $125 a pop, then fine. Then you can say that testing is "imperative." In fact, why don't you do that--drop some cash on IS tests--then post your own, more complete thread on transmission efficiency. And then I'll post to your thread, OK?

It's posts like yours that really REALLY make me consider NOT sharing my information here on CPF at all. Tell me, what have you offered in the way of positive contributions here? Nothing that I can see except to qualify and limit everything that this thread is about.

Because, this thread is all about (or should be) the notion that we can do the best we can with what we have and a good helping of ingenuity. People like PaulW and Ginseng are ingenious and inventive enough to come up with a method for approximating the real output of our incan mods and all you can do is to try to tear it down. Talking about all the many reasons why it isn't valid, or is only valid in this one particular case and on and on.

I am perhaps being unwise in posting this in anger --because I AM angry at you and have been since the last thread where we crossed paths-- but at the moment I don't care and would much rather get these things out. I may regret it later, of course. We shall see.

 

[Luna]

What?

JS, are you unable to carry on a discussion in an adult manner? You send me a PM that you will never participate in a thread that I'm in and wished me to not ever contact you again. You now call me out directly in a post and do so with the closest impersonation of my 7 year old niece saying 'NeeNeerNeeNeer' .. .


My post was not in the least critical of you, I was taking to Andrew about advertising. Gees, like I said, what an ***.




#1:
You measured 70% and applied the losses of the glass and lip to get around 65%. I was reading your post.

#2:
Silvering and enhanced AL are not the same as vacuum aluminizing and both are greater in reflectivity on average. vacuum aluminizing with a non dialetric (standard al coating) will yield ~>85%, enhanced Al >93% and Ag >95%(initially)

Vacuum Al, doesn't mean it is enhanced.

"which by the way was for an upper bound so that the assumption of 100 percent LVR efficiency was actually moving the result in favor of your position of a higher draw current--but you never understood my reasoning in the first place, did you"

Huh? I haven't a clue when we discussed this or how it has anything to do with this thread. If talking in reference to the Mag60 vs the M6 again, then you have a poor memory. How many time did I say my only **question**, not statement , was the blanket assertion of the eff%. I however said the M6 is too expensive for a simple device.
...


Finally,

Look JS, if you wish to used the 65% for TIR, optics and LED based system go right ahead. I just wouldn't use the 65% for atypical. I'd imagine Newbie would concur with this particular assertion.

It would be like comparing the gas mileage of a hybrid and a SUV as being the same because they are both vehicles.

 

[Luna]

PS,

JS, most of the issue that you mention like paul's stuff were items that you assumed I attacked. I never did...I just asked if you had proof of 65 or if it was off the cuff. You now have proof. Why is it so hard for a person to ask a question or participate? You love to attack people's numbers, is it so bad that someone ask you about yours?

In fact, aren't you the same person who said that a ceiling bounce test was worthless for determining a lumens total?

No, I've even quoted my ceiling bounce number before we ever spoke

 

[Luna]

The losses would have been LESS than a small hole, because the white is reflective.

Understood. Reflective, to what degree? Id assume the potting wouldn't be too effective but I haven't a clue as to how much so.

 

[bwaites]

Short of a mirrored finish, white is the most reflective "color" out there, reflecting the full spectrum of light.

Trying to quantify it in so small a usage is ludicrous.

No one implicated that using the 65% figure was good for anything but a flashlight reflector, not TIROS, optics, or anything else.

However, an LED in an efficient reflector is not MUCH more efficient than a lamp, so I'm more than comfortable using that same 65% figure for REFLECTOR based LED lights.

As for your problem with js, it appears that you do all you can to antagonize him.

So far as I know, every metal reflector used by anyone on CPF is using vacuum metalization over aluminum. They all have essentially the same reflective profile. Higher reflectiveness is only in comparison to other reflective coatings, so a 10% gain in reflectivity vs standard aluminum coating is NOT equivalent to a 10% gain out of the reflector.

Nevertheless, the best estimate, confirmed by early testing, is that a normal, vacuum metalized flashlight reflector pushes about 70% of the light produced by a normal lamp out the front of the reflector. Approximately 5% of the light produced and reflected outward is then lost to the window (lens) and bezel of the light.

'Nuff said!!!

Bill

 

[Luna]

Short of a mirrored finish, white is the most reflective "color" out there, reflecting the full spectrum of light.
Trying to quantify it in so small a usage is ludicrous.

All I said in the post you replied to was, mirror the bulb on the backside to minimize backplane loses. What is the problem? We said the same thing

No one implicated that using the 65% figure was good for anything but a flashlight reflector, not TIROS, optics, or anything else.

And that is all I said! What is the problem? We said the same thing

However, an LED in an efficient reflector is not MUCH more efficient than a lamp, so I'm more than comfortable using that same 65% figure for REFLECTOR based LED lights.

Difference is that an LED like a lux is lambertian so backplane loses are already accounted for. In freespace they never radiate backwards due to the emitters topography. In this case the distribution pattern affects the losses.
You can put a mirror behind a lux and the IS result will still be about the same as having it in freespace. Do the same with a bulb and the results will be much different.

As for your problem with js, it appears that you do all you can to antagonize him.

His first post to this thread mentioned me so I came.(and another one in a around about way. You recognize that I hope

So far as I know, every metal reflector used by anyone on CPF is using
vacuum metalization over aluminum. They all have essentially the same reflective profile.

These same 65% figures are applied here for a Al film here on CPF too . Given the deep wallets about, I wouldn't be surprised to see people buying enhanced reflectors in the near future on CPF. Hence the simple mentioning and cautionary note. It wasn't critical of anyones contribution, just a simple statement. Once again we agree: typical components realize typical performance. What is the problem? We said the same thing

Higher reflectiveness is only in comparison to other reflective coatings, so a 10% gain in reflectivity vs standard aluminum coating is NOT equivalent to a 10% gain out of the reflector.

Of course not, did you read my initial post to the thread. Of course these are individual numbers of each component alone, so the increase in thetransmission line eff% will not be so great. What is the problem? We said the same thing

 

[Luna]

One last point, taking a bit due to all of your hidden attacks

QUOTE:The ohmic approximation is just plain way off.
Before a certain CPFer attacked me for using the re-rating formulas, I would have thought that they were so well established as to be common

ground here on CPF. But I learned that that was not the case. So I have inserted this post to the thread to support the use of the re-rating

formulas


Ohmic approx was used because you never provided *us* with the current at the baseline until after the fact. You told us the rerated

parameters and that the filament was near mealting as per Willie.

The ohmic approx is sufficient in this case but the both current and voltage measurements would have been better. You finally provided it and

guess what, it was appreciated. It just so happened that my measurements (and approx) yielded a measurement closer to brocks, not your guess.


I even gave the formula for determining the tungsten filament resistance.



T = -1.86(R/R0)^2 + 206.6(R/R0) +118

R= resistance of filament at temp
R0=roomtemp(0 really but no need to freeze it)


When the filament temperature is already in the 2800K+ range and the Tdelta is very low it approachs ohmic behavior . When the gradient is

large, it is classical nonohmic. If you can derive the resitivity at a particular temp, the change in R can be derived via the diffeq at the

new temperature. You provided the temperatures/color temp.



QUOTE: People like PaulW and Ginseng are ingenious and inventive enough to come up with a method for approximating the real output of our

incan mods and all you can do is to try to tear it down. Talking about all the many reasons why it isn't valid, or is only valid in this one

particular case and on and on.

I take it you missed my post last year outlining use of a digital camera,photoshop, ceiling bounce and a light of known output to derive

light box type of lumen estimates. I try to contribute to yah know...

march 9 2005

...I did one step more. I did a ceiling bounce with a white door being photographed in manual mode. I used a p60 with new batteries for

reference, the l2, u2 and u2 + l2.

I did a 25x25 point sample at a point in each picture to derive the rgb. I summed the components and applied a ratio to the known approximate

output results.

P60=1*65lumens=65 lumens (hard math) (22 was the r+g+b score)

L2 rgb score =33 33/22 * 65 = 97.5 lumens
U2 rgb score =41 41/22 * 65 = 121 lumens
u2+l2 rgb score =78 78/22 * 65 = 230 lumens

Of course there is error in the ccd due to the bayer filter and other issues. The system isn't technically sound but is isn't a bad estimation

assuming the p60=65lumens was a good calibration. So the simple test does help to back my claim of the difference between the two.

I'd imagine I can make it work better, including giving spectral results but it was more of a verification. I need to do the same without he

B65 battery and also the 3x123 u2 which seems to give about a 20lumen increase (just a test not a long term burn because I like the u2 and I

only have 3 levels vs 6 when doing this)

 

[js]

Sorry Luna.

You're right. I suppose I did call you out in mentioning the LuxLuthor thread, and that you were thus more or less obliged to make an appearance here, even though I did say in a POST (not a PM) that I was done with you.

And yes, while sometimes I can carry on an adult conversation, there are other times I fall short.

As for the 100 percent LVR efficiency, I am refering to this from the same SF/M6 thread I linked to above in the "this thread" hyperlink:

So you believe an ohmic "approximation" is not suffient here when dicussing a current a small temperature change. Oh well lets jump to emperical then.

I just measured the MN21 with 2 LG2400s(used a bit but with open terminal voltage of 7.98--full charged normally to 8.32v)

I=5.04
E=6.58

Here I'm getting 33 watt at 6.58volts

So now we now have enough information to used thve rerating formulas and your 6.86v since behand we never had enough info to accomplish this because you rejected Brocks data.

Ir = (Va/Vd)^0.55 * Id

Ir=(6.86/6.58)^.55*5.04

So using my measurements as the baseline and your voltage, that would be 35.38W at 6.86V/5.156A
Using brocks measurements would put your 6.86 at 5.22A, a little closer to 36 watts

Now if you still think that thermistic changes will play an appreciable role, you still can apply ohm law to to determine the resistivity of the tungsten filament.Just compare the approimation assuming ohmic and the rerated ones using your 6.86v and you will notice a mild difference of only 100ma. What is weird is that the rerating given a lower calculated resistance at the higher voltage which doesn't concur with reality.. Nor do my
measurements compare with your farout technique to come up with 4.9 to 5A via assumed L/w, 100% pack utilization and runtime.

PS Gee you are an *** sometimes, with me and AWR etc.... Also the lockups are because of the quote ubb code, I haven't been able to get thru since yesterday because of that

I went to a lot of trouble to make that post wth the "farout" assumption in it, which, by the way is only 2 percent away from the truth, and I did all of this because you asked me questions. And the thanks I got was for you to argue with me over extremely well established re-rating formulas and to belittle my post which attempted to come up with a current draw based on the information I had to hand at the time.

You can say I am an *** if you want, and there are certainly situations where I have made a-hole type posts, but in that thread I was only trying to be helpful and to answer the questions asked of me. And for the record, what I said to you in a POST was the following:

"And you know what else, Luna? I'm done with you. Don't PM me and don't post asking me any questions any more. And I sure as hell won't bother trying to post to any thread you're involved with."

Except of course my own threads, because how can I not be involved with my own threads?

So, speaking of my own threads, let's move on, shall we? To some constructive and helpful discussion.

For starters, I remember reading a lot of stuff about optical coatings in NewBie's Reflector coatings and in the visible range, I remember aluminum being pretty much the best, but it's been quite a while.

Maybe someone can speak more or less authoritatively on this subject for our benefit? NewBie maybe?

 

[tvodrd]

(Jar- give 'em hell!)

Larry

 

[andrewwynn]

I have noticed something when doing ceiling bounces.. The RT4 light which is supposed to be aprox. 440L.. actually estimates over 400 TL, so i think there is something to that 65% not being the right factor when considering LEDs.. Has anybody else done some simliar comparisons?

-awr

 

[NewBie]

(Jar- give 'em hell!)

Larry

Well, I'm a working man, and I've gotta head out early in the morning, so I will try and keep things very brief.

For now, IMHO, the generic 65% is a great way to hit a rough approximation.

If someone wants to use another number, I do feel that an integrating sphere is going to be the only real legitimate way of claiming otherwise.

Don't forget that AR coated lenses range from 0.2 to 2% reflectivity on each surface (front and rear), depending on whether it is a single coat, or a multilayer broad band coat. The skill of the chamber technician will affect the final outcome. You also incur losses in the glass lens, depending on whether it is common soda lime, "water white" (soda lime with reduced iron), borofloat, or various other types of glass. There are also two common types of AR coatings, Magnesium Fluoride and Silicon Dioxide. The Magnesium Fluoride coating typically will have a lower reflection amount, but the Silicon Dioxide is a bit tougher. Usually a good Silicon Dioxide AR coating will look green when done correctly, and you can judge the quality of the Mangesium Fluoride coating, as it should have a purple hue or tint in the reflection. Having the coating thicknesses done just right, means it is centered in the visible band, and you get some reflection on the red side and some off the blue side, with the least in the center (green). Thus the purple hue.

*BUT* AR coatings do not work as well when the light doesn't hit the surface perpendicular. As the angle increases, the percentage of reflection increases very significantly. This is something to take in account for if the diameter of the opening increases without increasing the depth at the same time.

As far as the effect of the rear hole, the reflector focal point would have a good amount of effect. In most reflectors, the bulb itself takes up a considerable portion of that "escape" area anyhow. If that escape area is further filled with a mirror, or even a white ceramic or whatever, it's contribution will be even less. Though one would really have to wonder, if it wasn't directing the light out the front, what real good those few lumens would be. Consider the area of the gap, or the "escape area", it's distance from the filament, create a sphere around the filament at that distance, and compare the area of the sphere to the gap/escape area (and remember not to include the area the bulb itself blocks)...

It would be a pretty trivial task to stick all this into a decent raytracing program and assign all the surface properties, and then re-run it with new propertes. It just takes time, which I do not have at the moment.

The reflector coatings are an important piece of the whole situation. Though I don't know if I'd personally buy just an Enhanced Aluminum, or Enhanced Silver. I'd be more apt to lean towards a protected enhanced aluminum or protected enhanced Silver. I did several posts on these coatings in the 2003-2004 timeframe, complete with quite a few links to references.

Boy, I sure wish the search function still worked, there is an awful lot of wonderful information we built up over the years. These special reflector coatings are nothing new, and we have discussed them several times before.

Unfortunately, standard Vacuum Deposited Aluminum is not quite the same as Enhanced Aluminum, though it usually is better than no coating. Additionally, I've seen multilayer stackups of various materials, that can attain +98% reflectivity, even with the Silicon Dioxide protective overcoat. Think of it kinda like a dichroic reflector, but used to further enhance the coatings even more.

Again, IMHO, the 65% is a *darn* good number to start with, until a given item is actually tested with an integrating sphere. At that point, with real numbers in hand, then one would be able to legitimately claim otherwise for that particular setup.

Oh, and on the ohmic thing. Doesn't the formula only figure for a filament in free space? One would have to consider the contribution of putting it in glass envelope, pumping it full of a gas, and the heat it would contain, as well as the contribution of cooling since there is a gas in there, and the air currents. One might want to also figure in the effect of the stand off wires to the whole situation. I've never seen the source for the formula, nor bothered to look up how it was produced. I'd also figure that how the filament was wound, single turn loop, single turn loop then wrapped in a larger loop, and the proximity of the other turns in the loop, as they'd radiate into each other. Also, something that comes to mind, is the halogen cycle... Now, once you contain all this in another housing, such as a reflector with a cover glass on the front, you in essence have formed yet another thermal containment chamber of sorts.

Just my quick thoughts on things, I really gotta hit the sack now, you guys have a great night, and even a better tomorrow.

 

[LuxLuthor]

I wish I knew as much about all these technical aspects as those speaking in this topic, but it was interesting reading from all parties....even if I only picked up some of what was being said.

Great topic, even with the :touche:

 

[js]

NewBie,

Awesome post! Was the thread of yours I linked one of the ones you were thinking about?

Larry,

Don't egg me on, man! I'm already too prone to that sort of thing as it is!!!

AWR and everyone else,

I thought it was obvious from my choice of forum for this thread (Incandescent) and from the PaulW threads I linked, and from my initial post, BUT, just to be clear:

***I only know about ican mods and I am only recommending the 65 percent figure as a good rule of thumb for INCAN mods. If anyone got the impression otherwise, I apologize. I have no idea what sort of conversion factor to use when considering LED's and optics or reflectors. No idea whatsoever.

As for the resistance versus temperature of Tungsten, NewBie's comments are right on. That formula is indeed for a bar of Tungsten in free space. First of all, when you coil the filament, the coils mutually radiate into each other and heat each other up, which is why the center-most coil reaches a higher temperature than the ones on the end. Then put the whole thing in a high-pressure fill gas (of any of various compositions) and throw in the halogen cycle and the relationship between CCT and filament resistance is anybody's guess.

And, I have learned from talking with the Carley engineer who designs their lamps, that measuring and determining CCT is not standardized. Welch Allyn, he informs me, always gets significantly higher CCT's from the same lamps than Carley does. You can even see this by checking out their web pages for xenon lamps and halogen/xenon lamps, then compare the range of CCT's with the www.walamp.com webstore specs for the Halogen lamps. (Click on webstore, click on Halogen, then move through the various pages).

I asked the engineer the question that Lurveleven and myself have been wondering about for many months now: "Why make a xenon lamp and NOT add a halogen to the mix to prevent blackening?"

According to someone here on CPF who used to work at a facility that made halogen lamps, he said that if you want to make the most efficient, highest pressure xenon lamp, you can not add any significant trace amount of a halogen because it will corrode the filament supports at the highest pressures. (I think that's a fair paraphrase).

But when I tried to pin this engineer down on the subject he more or less denied that there was any real reason NOT to add a trace amount of a halogen to prevent blackening over time, but only said simply that "it just isn't necessary" in the lower powered xenon lamps because they don't deposit much tungsten on the envelope anyway.

So now I'm no longer sure about the whole issue of xenon vs. xenon/halogen. And in fact, the WA lamps have a krypton fill which you think would mean slightly less efficiency than the xenon, but yet the WA lamps seem to have the highest efficiencies of any of the available halogen lamps out there, even when considering the SureFire lamps as well. Plus they can do them smaller than almost anyone else for a given power.

I am trying to get my hands on some real engineering manuals for lamp physics and design, but they are apparently almost all proprietary internal documents owned by companies like Sylvania and Osram. Still, the Carley engineer said he could maybe put something together for me. I sure have a lot of questions that such a manual could help me answer.

 

[Luna]

Newbie, hola.

quote: Newbie
As far as the effect of the rear hole, the reflector focal point would have a good amount of effect. In most reflectors, the bulb itself takes
up a considerable portion of that "escape" area anyhow. If that escape area is further filled with a mirror, or even a white ceramic or whatever, it's contribution will be even less. Though one would really have to wonder, if it wasn't directing the light out the front, what real good those few lumens would be. Consider the area of the gap, or the "escape area", it's distance from the filament, create a sphere around the filament at that distance, and compare the area of the sphere to the gap/escape area (and remember not to include the area the bulb itself blocks)...


This is why I think ultimately TIR like optics will be great for incand also. Capturing light from the front and the rear and redirecting it

forward.

The silvering of the bulb might not contribute too much (hard to say since it depends on the envelopes optical characteristics) but is will

help some (just like UCLvsLexan or ProGold on the electrical contact etc). If anything is will help reduce backplane absorption which of

course reduces the warming of the light


So what do you think of my the LED assertionYou alway contribute good, well thought-out information so comments would be appreciated.


(I'll hit the ohmic question in another post)


PS you can do a partial search on google using site:www.candlepowerforums.com and just add any other terms. Be sure to click on the cached

copy. Then do the profile thing to find the whole thread. I do wish the search was working though.

 

[NewBie]

Can anyone give me approximate reflector dimensions and hole size?
Lamp dimensions for the package, filament, metal base height?
Typical bulb lumens for the bulb?


When I get home tonight, *maybe* I'd have time to model something up, and toss in various surface parameters, and see how the numbers fall out.

Those were not the threads I was thinking of, I was thinking more about the one where I was talking about the losses, as the light travels from the source to the reflector and out, and the other thread where I gave a number of coating reference .pdfs


More info on AR. The multilayer magnesium flouride AR coatings are commonly known as HEA and BBAR. More information on the AR coatings can be found here:
http://www.molalla.net/~leeper/ar_coa~1.pdf

And some generic reflector coatings:
http://www.molalla.net/~leeper/refcoat.pdf

Perkin-Elmer's line was picked up by these folks, and they offer some great reflector coating information and services:
http://www.optiforms.com/4000services/4100opticalCOATINGS/41400ocREFLECTIVITYscience.html

Remember, take bare aluminum deposited coatings with a grain of salt, as they rapidly deteriorate upon exposure to air...

 

[Luna]

QUOTE:js***I only know about ican mods and I am only recommending the 65 percent figure as a good rule of thumb for INCAN mods. If anyone got the impression otherwise, I apologize. I have no idea what sort of conversion factor to use when considering LED's and optics or reflectors. No idea whatsoever.


No no no no no. I want criticizing your numbers. I just added the LED bit as a point to ponder.


QUOTE:js
As for the resistance versus temperature of Tungsten, NewBie's comments are right on. That formula is indeed for a bar of Tungsten in free space. First of all, when you coil the filament, the coils mutually radiate into each other and heat each other up, which is why the center-most coil reaches a higher temperature than the ones on the end. Then put the whole thing in a high-pressure fill gas (of any of various compositions) and throw in the halogen cycle and the relationship between CCT and filament resistance is anybody's guess.


If you know the current and voltage (which you measure), you can use ohms law to get the resistance at each level. Compare it at multiple input levels and you can see that it is *fairly* linear over 2800K (until melting)

Just about all conductive surfaces display a nonlinear resistance over a the range of power inputs. Even plain copper wire, it just isnt as pronounced as a tungsten filament. See below link since you don't want to accept my formula (which is by the way for a filament not a bar)


QUOTE:js
relationship between CCT and filament resistance is anybody's guess


CCT correlates well to the filaments temp(IIRC approx 300deg diff in the bulb types we are discussing since hotspots there is a temp gradient involved) . The filament temp directly governs filament resistance though. However, when you said that the data you provided from willie was "with the filament about to melt", we were no longer with CCT but actual temperature. Don't confuse CCT and actual filament temperature as being synonymous. However see below link, they seem to be ok with the concept at sylvania.




http://www.sylvaniaautocatalog.com/new_sylvania/tung_fila_lamps.htm

"Since the temperature coefficient of resistivity for pure tungsten is relatively constant over the range of lamp temperatures, it provides a convenient means for measuring the average temperature of a filament. "