No lose reflector design

[zardoz]

A question.. if there's no air flow in the reflector, will it overheat? I mean, is it dangerous for the buld?

I don't think air flow heat issues will be your problem. I have a funny feeling that if you aren't carefull you will focus/re focus an awfull lot of the lamps rays back to their source ie: the arc tube. What this may result in? I have no idea..but I doubt it will be favourable. These lamps run hot by nature, I know people that run them in enclosures with allmost nothing for air flow and havent had issues yet (months of use)

zardoz

 

[gui_999]

You mean the UV?

Well if it's that.. maybe I could put a filter directly in the reflector

 

[zardoz]

I'll see if I can find a pictorial that gave me this impression. It was given me by a friend and former member, someone who has spent some considerable thought on the reflector issues.

zardoz

 

[zardoz]

This isn't quite the pic I was hoping to find...I really need to get better organized But it might give you some idea of what I'm talking about.

 

[gui_999]

What I can see is that since the bulb isn't a real "point of light", some light won't go where I want it to go.

 

[zardoz]

Yes and after you attach a spherical to the front of the eliptical I have a feeling that most light will be reflected back either towards the arc tube or back to some point between the arc tube and the lens on the open side of the sphere. Am I making any sense?

zardoz

 

[gui_999]

yeah your right. The purpose was to redirect thew light to it's origin ( the bulb :| ) and reflect it back to the condenser lens. So it was design this way hehe

I'll try to find a better way to this without reflecting the light at the bulb

 

[gui_999]

Well.. I'll try my first version of the reflector ( less light reflected than the second ). If it explode I'll let you know

And those bulb are cheap so

And I saw that some OHP use a spherical reflector to reflect light at the point of light, to be condensed with a lens.

 

[zardoz]

The way it was explained to me was that the spherical reflector needs to project the "image" of the lamp's arc tube to a point allmost imediately "adjacent" the arc tube itself. This is easiest to be seen by using "arc welders glass" to look through (something you need to use for any "look at the lamp" work).

zardoz

 

[gui_999]

Well I think I'll just buy a damn OHP..

 

[zardoz]

That's what I've done for the time being. I have a "few" stainless steel bowls that have been...uh.. "altered" that I have played with. I haven't given up the idea of using a 400 watt factory light yet..I have all the gear to experiment.
But for the moment I have more pressing things to do.

I've been down the road you are on and think it "will" work. I have a bowl/reflector that is eliptical and I have a smaller one that is spherical. The results I obtained from just messing around showed some promise...but the OHP came along and made life easier

zardoz

 

[gui_999]

I think I'll go at a 1$ shop gets some metal bowl! Building one is just too hard

 

[gui_999]

I want to use some reflecting tape or aluminium tape, but I need to know in celcius degrees how much heat come out from those 400W MH bulb. Anyone knows?

 

[Mavmesa]

Do not know max potential for heat. I think that the metal tape would be a good heat conductor of any IR it picks up and any air movement (fan) would allow effective heat exchange to the air and out of the box.

Ken

 

[Video Freak]

Just was thinking How would a Upside down Pyramid made of Glass where the " bottom" of the pyramid would be next to the glass stage and everything would be a mirror? am I just pulling stuff outa my A$$ or do I mabe have a Idea? HUmmmmm It has me thinking L8er

 

[zardoz]

Just was thinking How would a Upside down Pyramid made of Glass where the " bottom" of the pyramid would be next to the glass stage and everything would be a mirror? am I just pulling stuff outa my A$$ or do I mabe have a Idea? HUmmmmm It has me thinking L8er

Does it hurt?

zardoz

 

[Video Freak]

Sometimes, Once I found a Dodge viper up their, It was the coolest find ever.LOL

 

[gui_999]

That's what I've done for the time being. I have a "few" stainless steel bowls that have been...uh.. "altered" that I have played with. I haven't given up the idea of using a 400 watt factory light yet..I have all the gear to experiment.
But for the moment I have more pressing things to do.

I've been down the road you are on and think it "will" work. I have a bowl/reflector that is eliptical and I have a smaller one that is spherical. The results I obtained from just messing around showed some promise...but the OHP came along and made life easier

zardoz

I've bought some mixing bowls today, look alot like those ones. really alot! well.. its the same but mine are from Roscan
http://www.epinions.com/Rosle_3_pc_Stainless_Steel_Deep_Mixing_Bowl_Set__Mixing_Bowls_15671
just cost me 25$ CND

As soon I can find a 400w ballast in Quebec, I'll do some test

But I have some question now:
How should I place the lamp in the reflector?
Vertical, horizontal?

An externally hosted image should be here but it was not working when we last tested it.

And what should I use as condenser lens (all the details, diameter, focal length, type )

Thx

 

[zardoz]

As I understand it..I could be intrepting the diagram that I posted incorrectly.. but if your reflector is an "eliptical" you want to mount your lamp as you show in the left (gouche?) hand of your picture...if your reflector is "spherical" you would mount as per the right (droit?) hand of the image you posted. Hows my french?...unfortuneately thats about it for my vocabulary.

As for the condenser lens...you need to mount the lens at the focal point of your reflector. The spec for the condenser? I suppose you need to calculate the lens based on the reflector f/l...and from my limiting experimentation ...the shorter the focal length of the condenser the better.


Be advised..most of this is based on very "un-scientific" testing on my part.


zardoz

 

[Mavmesa]

Well...I just picked up a plastic light globe. I was looking for something that would be truely spherical that I could cut. I am only interested in a 70 degree square arc from the globe. I do not need a 180 degrees as I am only concerned about reflecting into the fresnel lens. If I mount it right, I should get a sizeable increase in light going through the fresnel lens without widening the virtual light source.

I just bought a dremel tool. I will cut out the arc I want tonight, line it with foil, and perform a test. If it appears to work as I want, I will paint the inside of the arc with heat resistant silver paint.

Ken