okie dokie.... new light meter is on the way finally..
lets see what kind of toys we have
2 hps 150 ballasts(cdm 150 dual lamp setup maybe?)
6x16 precon
4.5x6.5 precon
5x8(maybe 9) lens from busted 18" triplet for precon
LL standard pj lens
18" triplet, but only 4" wide, not so good focus on a 17" lcd
220mm 430x405 220mm fresnel
330 400x320 fresnel
coupla scratched up fresnels, 330,220
M59 ballast
4.5" alum. reflector from a fresnel light(anyone know how to poilsh aluminum?)
IKEA reflector
altman 6" elliptical reflector
2 different fiber optic faceplates(for diffusion of elliptical reflector artifacting)

eventually I'll go for the pro lens setup and probably a 19" widescreen with a dvi-hdcp input...but for now I may look for cheap 15" lcd tv and do a quick rear projection screen, maybe 60"? thinking the 150 might be just right for that
looking for a cheap cdm150 6mm bulb and trying to decide if it will run on the hps(s55) ballasts..hmmm may have to ask AV if I can hook up the 2-150w and run a 250watt ceramic off them...

we begin!

Ahhhhhhhhhhhh the recovery,,, excellent stuff,,,

hey elken..got any suggestions on a dual lamp setup?

I’ve been pondering the use of two 150W lamps for a while now. The only two ways I can see maybe working at the moment is two rear fresnels or perhaps two mirrors forming a triangle. Both of these methods only utilise one lamp for each half of the screen. What’s really needed, so that lamp differences aren’t noticeable, would be some way of mixing both lamps over the entire screen, I’m still thinking.

DJ

yeah, the "frankenfresnel" approach seems to be the most easily implementable one, but it would require some adjustments to each bulb as no 2 bulbs are exactly identical, whether the difference would be visible or noticeable is another question... I'm sure there must be a way to combine 2 beams.....I've seen some for lasers but the cost is a bit much.... wondering how much reflection loss would happen if you took took 2 setups with ellipsoidal ref. and aimed F2 so each one was on the same fiber optic faceplate? if you had a small enough elliptical, the angle wouldn't have t to be too great...maybe

Dazzzla

have you ruled out use of a tunnel totally.?

mikyd1954

may the testing force be with you !!

Trying to combine 2 sources is I think what seems unachievable to everyone so far..yet one of the pehaps most desired..to give that PJ the extra commercial type brightness push that perhaps the missus and friends would be happy with..Im sure it can be done..the trick is cheaply in a DIY way...all the power to you as you start on the journey..

Me Im just as interested as everyone to see what you find..especially as I would prefer a twin light setup for my planned rear pro.

CHeers

No just put it on the back burner for a while.

DJ

aye, doing it cheaply is the key... I think using mirrors, the faceplate might be the key(it would be the new source of the "arc") say you have 2 mirrors placed at right angles to each other...then aim the output of each bulb/reflector from below and in front of the mirrors(because obviously if you place them in front/perpendicular of the mirrors they'd have to be at a very oblique angle and the meeting place of the 2 would be not so good), so then the two beams(would cross each other at the faceplate, but minimizing the angle at which they hit the faceplate would be the key...and by using ellitptical refs you would gather more light than a spherical so the losses from the facep[late/reflections would be compensated for....I wish I was better(or even adequate!) at raytracing..... but likely the frankenfresnel is the first one I'll try....

You would probably need to allow for the angles of each elliptical to total the angle that the fresnel is expecting.

DJ

edit:
Using two may negate the need to blend the light using a faceplate or tunnel

I hate to be stupid, but after all these years I'm used to it
so... huh? (on both counts

ok, I think I see what you mean.....

Using the mirrors in this way...looks just like the patent for multiple light sources....yet they use commercial combined lamp-reflector, the reflector being parabolic.

ref attached image:
the lenslets even out the rays then the concave lens projects a small cone of light to fill the first fres.

mikyd1954

Curious to know what elliptical reflectors you have to do the testing...do you have any pics


cheers

right now, just a couple of rather large ones, an altman and a cooper*6 an 8" dia) that I'll test out to see what kind of aartifacting I get and whether the fiber optic faceplate helps diffues the artifacting....also trying to get some burned out bulbs with elliptical reflectors built in(overhead bulbs and my wife is going to run down to a video store and see if they have any burned out commercial pj bulbs...I'll try to cut out the currnet bobs and retrofit a cdm 150 into them...it'll probably be about a week before I can do even preliminary testing...
I downloaded that patent and will take a look at it sometime this week...

Yes..that patent..advise find somewhere quiet..a print out is best..it's tricky trying to reference all the drawings/ref numbers the author is constantly refering to..but some great info.. so it's worth the time...the authors company clarityvisual.com is still building 67" RPTV's like this.

question
When using elliptical how do you calculate find out what beam spread/angle the elliptical reflector would produce.

Asking in another way how do you figure what elliptical will work with (and what FL) 15 inch collimating fres.

Anyone have a rule of thumb method ?

Thanks

ummmm I always thought the point of an elliptical was to place F2(where the light rays converge) at the focal length of the fresnel, so the fresnel FL shouldn't matter (since you will be using the F2 point as the "arc", are you thinking of a PAR type reflector?

hoo boy....sometimes we just don't see whats around us every day... I was trying to think of ways to get a hold of a burned out commercial pj bulb to see whether I could retrofit a cdm150 into it, was thinking of going down to best buy or cc and see if they had any..well, my ne wlight meter came in yesterday and I've always wanted to measure this pj that sits one aisle over from me(projects current status of processes on the wall)..its an infocu DLP, measured it at avg 250 lux over about 2 sq. meter so about 500 lumens, windows desktop is very readable in all this light(though I measured and there is only 20 lux on the white wall its projecting on..goes to show you the importance of adjusting light so it doesn't hit the screen, even though its pretty bright in here)
anyway...yeah, thats right DOH! so I walked over to IT and they practically threw 3 old bulbs at me..1 is about 2" diameter(about OHP size?) the other 2 are 3" diameter, those look really promising..they're all in heavy plastic casings that I'm wondering if I can keep fairly intact for mounting? , the 3" dia. ones look like as long as I can cut them to slip the 10 in they should be good...and yes, I know they all have mercury in them, I'll be careful it'll be interesting to see the light pattern from them, though it will be a week or so before I get my bulbs and setup running probably, though if I get them cut, I have some little halogens around here that AV sent me a long time ago..
oh.... theres a wire that actully crosses from the tip of the arc cylinder to a hole in the side of the reflector...wonder how that doesn't artifact into the projection?

Hey mikyd, did you get the same meter as before or something different? Give us a pic or a link if you don't mind. Also, I'm curious on the reflectors your referring to, would it possible for more pics...or am I asking to much here??heheheehe...AHH..AHHH...AHHH

love your new sig..perfect for you

same as before, mostly cause its the cheapest....off ebay, 34.95 delivered in 4 days I think.... http://stores.ebay.com/AideTech-USA

you mean the altman and cooper? will see if I can take pics this weekend, the cooper I got from AV and I actually have 2 altmans(for the 360Q ellipsoidal stage light)


hey, taking apart the commercial pj lamo, looks just like rox' elliptical toy with the wire coming form the top of the "bulb chamber"

welll that was easy, took a burned out commercial pj bulb home tonight and about 10 minutes later I have a nice shiny reflector to play with, it has a couple of issues...well one main one but here it is:
Click to view attachment
its approx 3.5" in diameter

the focal point is about 1" from the outside bottom of the base (top of the pic) measuered where the original arc was(about a 2mm arc it looks like):
Click to view attachment
it has one small flaw on the inside and thats where a small hole was drilled and a wire went from the outside of the reflector to the top of the bulb thats the hole about middle left in the picture
the hole in the bottom of the reflector is about 9/16", the hole in the base is about 11/16 so some grinding will need to be done to fit the 150 in(about 20mm in diameter I think? with any luck it can be done without grinding the focal point away!
there was a glass plate glued at each of the 4 corners to the top(wide part) of the reflector but a little delicate jiggling with a screwdriver and it popped off, removed it mostly so that in case the 150 is too long , which I think it is... but altogether, the reflector is very thick, very sturdy, and really shiny and it is dichroic.... not bad for free
and man! is that one tiny little bulb that was in therethinner than a pencil it was set in a white ceramic holder that was glued with some white stuff to the reflector bottom..a little dremel cutoff wheel got rid of the glue/caulk and a little screwdriver fiddling and it popped right out....

Sim: heres the alltman and the cooper reflectors I have the altman is 6" dia. cooper is 8":
Click to view attachment

mikyd1954

Your prob right..I was looking for confirmation perhaps you have given it to me..
I think what I was thinking was that the angle of rays an elliptical produce would differ from elliptical to elliptical reflector..but like I say your probably right...DAZZZ ?

Great going...your getting quite a good testing set of reflectors !!!

...so the commercial reflectors look like they are parabolas...do you think ?

That question about the wire and artifacts...perhaps the wire is not seen because they were using either a light tunnel or lenslets to even out the rays.

To use an elliptical at its most efficient the angle should match the fresnel. If the elliptical’s angle is too narrow then it won’t entirely light the fresnel so a fresnel with a longer FL will be needed. If the elliptical’s angle is larger than required by the fresnel then some of the collected light will spill over the edges.

The arc wire is positioned though the side of the reflector to help hide it. It’s similar to the reason you can’t see an image of your finger on screen when you put it in front of the triplet. When the wire is returned back to the base close to the arc vessel it will become part of the object being projected by the reflector. Rox converted his G12 lamp for this very reason.


Most commercial reflectors are parabolic.

DJ

Thanks DAZZZ

Is their a formula for working out the expected produced light angle/spread from the dimensions of the elliptical reflector ?

We can then match the fresnel by design.

Or do we just draw to scale the reflector light ray path f2 and beyond to the fresnel to see & find out.

I just use the reflector’s diameter at its F2 to find the angle, either graphically or using math.
There is an equation that is used to actually determine the shape of the reflector if you were to design one. You can also use two nails, one at F1 and the other at F2, on a board and a loop of string to mark out an ellipse if you want to draw a 2D version.

DJ

It’s interesting to note that each of the reflector types can be forced to operate as any of the other types. A spherical can operate as a collimating, a diverging or a converging reflector. It just won’t be very efficient. A spherical is best at converging rays. A hyperbolic is best at diverging rays. A parabolic is best at collimating. An elliptical is a special animal, it is a converging reflector like the spherical but its shape is best suited to project an image to a second FL. So instead of being efficient at reflecting back to a single FL, like the spherical, it is best at reflecting to a second FL. Just as an example, if you position an arc at a spherical reflector’s FL it will project an image of the arc at its FL. If you then move the arc closer the spherical will project an image of the arc in front of its FL. The closer you move the arc to the spherical the more the image moves forward. It’s now working like an elliptical. If you continue to move the arc closer the arc image will project so far forward that it will now be collimating the rays like a parabolic.

I hope that made sense
DJ

Thanks for those expla's DAZZZ .. very helpful to me and I expect to others as well !!

Cheers

yeah, thanks dazzz... hmmmm... if the pj reflector is parabolic that will be interesting, if I could figure out what a flyseye array was I could try that patanet on multiple lamps!
so... a double ended 150 might actually be a btter choice for an elliptical(due to the wire crossing the open space in the ref as opposed to being right nest to the arc? well, it'll be interesting anyway!

mikyd1954

...you could try without the lenslets...just to see....have you seen the picture of the patent set up i posted yesterday I think it was

http://www.lumenlab.com/forums/uploads/pos...82035_thumb.jpg

http://www.lumenlab.com/forums/uploads/pos...81972_thumb.jpg

but you would still need the two lenses shown to get it to first fres..

did you post the patetnt kink tself? I'll check it out..... I have a couple more of the pj bulbs to strip so with any luck(sigh... I'll have everything next weekend..what kind of lenses are those in the pics?

I'm in the mode for ranting and if Mickyd doesn’t mind I can post some more in-depth views on the projected arc image of a reflector.

'what kind of lenses'....hmm that proprietory "relay lens" Im not sure I understand what it is.... DAZZZZ any idea??

The first lens looks like its collimating lens.

Patent link below..warning though need a quiet room..best to print out.
http://www.lumenlab.com/forums/index.php?a...st&id=25607

nope, any ranting by anyone is pretty much ok here
do go on...

thanks, its amazing you could read what I said, I am the worlds worst typist.... my wife says sometimes it even takes her a while to reverse letters and insert missing ones before she can figure out what I said.... and its not much better in person

Yeah...you had me a bit worried as to what kind of "kink" you wanted

Mikyd posted:
"did you post the patetnt kink tself?"

My PC has gone a bit wobbly, windows auto up date, I'll try to draw something soon

cool,, we shall wait...in the meantime.....(and please be gentle

so... patent wise........
looking at figure 12 it seems that the collimating produced by the
parabolic reflectors has nothing to do with the light needing to be collimated
to pass thru the fresnel and make it to the triplet(that collimation
in this design is still accomplished the same way as our pjs right?), the
parabolic reflector collimation is used only to blend the light togeher and then pass the collimated
light into the aspheric lens, then that lens will produce a focal point of light(virtual arc? I know
thats not what it is but...) that the "relay lens"(acting as what we call
a "precondenser"?) then sends to the rear/collimationg fresnel
and at that point its essentially an LL pj? well, except for the lens offsetting to increase the contrast...
did I get ANY of it right? or am I just patently foolish?

Sounds near the money..but Im gonna wimp out ...rather leave DAZZZ to comment and add any expla's...hope his PC fixes soon.

I'm guessing the "blending and light homogenization"(flyseye lenses) is how they get rid of the void/shadow produced by parabolic reflectors?

What kind of light meter did you get?

I'm also working on a dual lamp concept, but it is still in the design phase.

That about sums it up. You were close when you said virtual arc. It’s just an arc image though.

The proprietary aspheric lens has a rear surface that has been modified to correct for vigneting.


The lens array does even the light out but I think it has its limits. The obstruction caused by the arc tube and lack of reflective surface at the rear of the reflector is small in these comercial lamps so the lens array can cope but is this void were bigger I think it would struggle.

DJ

the pj bulb I deconstructed yesterday had about 12mm(roughly?) hole in the bottom of reflector ...
I'll need to increase it to about 20mm for the 150 to fit in....

Litherish pulled a Commercial apart ...it looks like he has a lenslet.

http://img208.imageshack.us/img208/9660/towelboxax6.jpg

be careful.....though Im sure your eyes gotta be better than mine.
it seems the testing is going to be more than interesting with a 150 in a commercial reflector or reflectors

well, I doubt my eyes are beter than anyones yeah it should be interesting anyway...I may try a small halogen bulb just to see what kind of spread the pj reflector has...