Light Engine not working chew well!

[ELiTeHaYDeN]

Hi there, I have built a light engine from the various bits and peices I have lieing around and the limited amount of tools I have.

It consists of a Reflector and Condenser/IR Glass from a Elmo A305 OHP and a Diylabs 400w HQI Double-ended Lamp.

After consulting Ace3000 he informed me that the R1 for such a reflector could be aqcuired by placing something in front of the reflector and moving it back and forwards untill the reflection produced was the same size as the object being reflected, I have done this and found it to be 2cm from the Rim of the reflector, so hence I have placed the bulbs centre at that point.

Now I have this dead centre, measured everyhitng to the mm its perfection... but with the lamp running I can remove the reflecter and there is no difference in brightness! What the hell is going on? I tried running it out of the projector box, and the same thing happened the intensity does not increase with the reflector behind the lamp.

Im Baffled, as pictured, Reflector down the back, Arc, then condensor then IR/UV Glass.

This lamp Barely beats my old HUGE sylvannia 400w Lamp with bigger Arc and no reflector/condenser.

Old Setup (no fresnells in there in PIC)



New Light engine, same box, same LCD.

[ace3000_1]

Move the bulb out a touch buddy, it looks abit too close going on your last pic. Its either that or its not close enough.

What condenser are you using and whats its specs?

Its fairly typical not to see much of a difference without using a condenser with a spherical reflector. The realy only gain that you can see with a spherical reflector is with a condenser in place aswell.

I recomend placing the condenser in there and ajusting the lamp to reflector distance until you get the ultimate result, then ajust the condenser to suit the lcds size.

Trev

[ELiTeHaYDeN]

Originally posted by ace3000_1
Move the bulb out a touch buddy, it looks abit too close going on your last pic. Its either that or its not close enough.

What condenser are you using and whats its specs?

Its fairly typical not to see much of a difference without using a condenser with a spherical reflector. The realy only gain that you can see with a spherical reflector is with a condenser in place aswell.

I recomend placing the condenser in there and ajusting the lamp to reflector distance until you get the ultimate result, then ajust the condenser to suit the lcds size.

Trev

Im using the Condenser from the A305(reflector was from here too) its 75mm in diameter and the focal appears to be around 200mm...

Moving the reflector closer to the bulb results in a far brighter image but it hotspots(brighter centre, dimmer edges) a little almost as if I cant get the Arc close enough to get it even(reflector right at outter envolope), but it appears that the light is actaully becoming parallel the closer I put the reflector not reflected back to the source.. If I hold my finger above the reflector at the height of the rim, my finger fills the entire reflector, does this mean its actaully a parabolic reflector? however, elmo had their setup configered almost identically to mine as it is now.

Edit: Re not seeing any difference in brightness with condesner not in place = I always had the Condenser in place whilst testing(removing reflector etc)

And in the last Picture the bulbs centre Arc is actaully 2cm away from that reflector.

[ace3000_1]

Moving the reflector closer to the bulb results in a far brighter image but it hotspots(brighter centre, dimmer edges) a little almost as if I cant get the Arc close enough to get it even(reflector right at outter envolope), but it appears that the light is actaully becoming parallel the closer I put the reflector not reflected back to the source..

Yeah its going parallel, have you tried to move the condenser closer at this stage?

If I hold my finger above the reflector at the height of the rim, my finger fills the entire reflector, does this mean its actaully a parabolic reflector? however, elmo had their setup configered almost identically to mine as it is now.

Its doesnt mean its a parabollic reflector, thats probally its half radious mark which looks about right for that shape. Maybe they had your system running in a parallel way, some do this and its realy not what we want on your bulb. From looking at its shape the reflector looks to have a radious of 50mm so your bulbs arc needs to go there for it to be run in a spherical manner.

When i said to have the arc tube the same size reflected, that isnt exact, but its darn close. Try to move the bulb in and out abit to see what you get, and take into acount that the arc is in the center of the arc tube so thats your measured arc line.

Trev

[ELiTeHaYDeN]

So r1=1/2d ?

so r1 = 25mm (diameter is 50mm)

I thought this was how you get the parallel focal point?

Did you mean Diameter instead of radious above? meaning the bulb arc needs to be 50mm away from the reflector?

[ELiTeHaYDeN]

Ace, do you have any reflectors availible that you would be happy to ship to new zealand?

Paypal is the only payment option availbile to me.

[ace3000_1]

The r1 is the focal point you want, its typically 2x of the reflectors stated focal as they are measured in a parallel manner.

So 2xF = R1

R1= Radious

If you run your lamp at the R1 spec then you will get the light going back to the arc. If you run the lamps arc at its focal, then the light will be reflected parallel.

Another way to find the focal is to go out in the sun, point the reflector as acuratley as possible to the sun, place your finger in the light path and there should be enough light to show a point of light on your finger. Measure this dstance when its at its smallest point and you should have the R1 spec.

I can send you a reflector to NZ, it would be best if you sent me an email though

Trev

[ace3000_1]

Originally posted by ELiTeHaYDeN
So r1=1/2d ?

so r1 = 25mm (diameter is 50mm)

I thought this was how you get the parallel focal point?

Did you mean Diameter instead of radious above? meaning the bulb arc needs to be 50mm away from the reflector?

Yeah na i was right i probally just worded it wrong, it always helps with pictures imo.

You cant go on a diameter of the reflector because the majority of the reflectors arent half of the sphere.

If you have a ball and the center of that ball is 25mm from the inside outer, then the R1 would be 25mm, (inside diameter 50mm). To get parallel light half the R1.

So you are right in a way but we cant go on the diameter of the reflector because its not a half sphere.

Trev

[ELiTeHaYDeN]

Ok tried the sun thing, the focal point is level with the rim of the reflector, so the focal point is its depth.

[ace3000_1]

Ok so you got the light going back to a very small point on your finger and your finger was level with the rim?

Trev