I came across another company that has cold elliptical reflectors. An interesting note is the average life is rated at 1000h. Does this apply to all cold reflectors or is the life dependent on the type of coating used? If a cold reflector needs to be replaced every few thousand hours, we may as well just take our chances with spherical first surface reflectors.
Gordon
http://www.dwdmfilter.com/reflectors/elliprfl.htm
Gordon
http://www.dwdmfilter.com/reflectors/elliprfl.htm
Make your own ellipse, coat it with heat resistant glue (not contact cement obviously), and press mylar strips ~15degree wedges onto the surface.
How do you make an ellipse? Locate your 2 focuses and tie a loose string to the points. the surface the string sweeps out when you slide something like a small bead along it is an ellipse.
How long for the string, how to anchor the focci, etc you will have to decide based on the size and materials.
How do you make an ellipse? Locate your 2 focuses and tie a loose string to the points. the surface the string sweeps out when you slide something like a small bead along it is an ellipse.
How long for the string, how to anchor the focci, etc you will have to decide based on the size and materials.
I thought mylar reflected >95%??
"Mylar can be aluminized, allowing reflection of up to 99% of light and heat. Like aluminium foil, aluminized Mylar has a shiny reflective side and a dull side. Mylar does not tear easily, like tin foil and aluminum foil."
from:
http://en.wikipedia.org/wiki/Mylar
You mean I gotta scrape out my new reflector? U sure about a heat hazard?
This is a heat shield made of mylar:
http://www.aircraftspruce.com/catalog/eppages/mufflerheatshieldkit.php
"Mylar can be aluminized, allowing reflection of up to 99% of light and heat. Like aluminium foil, aluminized Mylar has a shiny reflective side and a dull side. Mylar does not tear easily, like tin foil and aluminum foil."
from:
http://en.wikipedia.org/wiki/Mylar
You mean I gotta scrape out my new reflector? U sure about a heat hazard?
This is a heat shield made of mylar:
http://www.aircraftspruce.com/catalog/eppages/mufflerheatshieldkit.php
dupont mylar specs
http://www.dupontteijinfilms.com/datasheets/mylar/overview/h67160.pdf
Originally i didnt want to use mylar with a MH bulb, but I think if its not close its ok.
Im still cheesed that I can't use CF bulbs btw.
http://www.dupontteijinfilms.com/datasheets/mylar/overview/h67160.pdf
Originally i didnt want to use mylar with a MH bulb, but I think if its not close its ok.
Im still cheesed that I can't use CF bulbs btw.
And it wont be close in a reflector? lol. Aluminium foil will burn too. A 250w MH will burn the paint off of a coke can in about 6mins, they run at 300deg c.
One thing you got to look at, how are you going to fit mylar in a sphere evenly? Ill be honest with you, its easier and just as cheap to just buy a reflector, its also safer.
The surface of mylar is no where near as good as a profesional coating. Mylar isnt that flat for starters under a microscope, and the stuff that is, will cost you an arm and a leg.
Trev🙂
300C is good to know. Yes, that is above the mylar melt point. So you are saying our projectors can double to roast the spuds in a pinch.
Ive been looking for a good reflector buy havnt had any luck. Ive checked out the film industry par30s- not ideal. Anyone tried the reflector from a multimedia projector after the bulb has burnt out? They have integrated ballasts in the fixture?
Ive been looking for a good reflector buy havnt had any luck. Ive checked out the film industry par30s- not ideal. Anyone tried the reflector from a multimedia projector after the bulb has burnt out? They have integrated ballasts in the fixture?
I have and they work great though not all are what we realy are after on our lcd sizes. No doubt most wont work unless you know what you are looking for. I have an eliptical here aswell. Ill post that up asoon as ive finished making the light unit for it my thread in a day or 2.
Depending what your after, i may have a spare one laying around here if your interested.
What size is your lcd?
Trev🙂
Will mica be a better substitute for the mylar in this application? I vaguely remember mica as being very shiny.
strange thing
I see very few cold spherical reflectors, but more than one source for cold elliptical reflectors. But for a lot of DIY projectors, a cold spherical reflector would be a terrific easy-to-add item.
On the other hand, why do you even need an elliptical reflector to be cold? It does not reflect light back through the lamp arc, and the light gets focussed to a point where it would be very easy to put a surplus flat hot or cold mirror. Those run about $5 US!
And what's the deal with a 1000 hour life on that dichroic coating? That sounds pretty useless! Maybe it would be better to make an ordinary elliptical reflector from polished aluminum and add the external (and easily replaced) dichroic mirror.
I see very few cold spherical reflectors, but more than one source for cold elliptical reflectors. But for a lot of DIY projectors, a cold spherical reflector would be a terrific easy-to-add item.
On the other hand, why do you even need an elliptical reflector to be cold? It does not reflect light back through the lamp arc, and the light gets focussed to a point where it would be very easy to put a surplus flat hot or cold mirror. Those run about $5 US!
And what's the deal with a 1000 hour life on that dichroic coating? That sounds pretty useless! Maybe it would be better to make an ordinary elliptical reflector from polished aluminum and add the external (and easily replaced) dichroic mirror.
Think about it guy, our arcs are big, not all light goes to F2 point, also there are back reflctions that go back to the bulb. A cold mirror on its own wont cut it. Dichoric doesnt filter all heat and the shape of an elllipsidal is basically like an oven. Surface coating efficentcy is another issue.
Not sure, the one i have doesnt have a life rating, and ive never had a problem with other dichoric gear (both new and used). Ive seen some cold mirrors have a life on them too from time to time, aswell as IR filter. Realy the life rating is questionable, its going to depend on what wattage source you run through it, (which they dont state).
Trev🙂
I e-mailed the company listed in the beginning of this thread but got no reply. If anyone does know a source of reflectors I would appreciate any info. Right now It looks like I'll be polishing an aluminum bowl.
I'd be looking for a reflector to use with a 15" LCD if that helps.
I'd be looking for a reflector to use with a 15" LCD if that helps.
Interesting ...
the page from a chinese company website looks indentical. let me see if I can still find some contacts in Beijing ...
Ace, what is your refelctor's spec ?
EDIT:
I see. HB optical is a company based on Northeast China. Thus I think the price wont be too steep ( I wonder if Walmart will carry their products 😀). I will send them an email asking for price soon. But we might need to have large enough order to have them sell to US.
It would work great with CDM-T lamps. CDM-T or HQI-T lamps are fairly cheap from europe, last time I checked you can get one about $20-30, and CDM-T doesn't need special type balasts which means we can find cheaper balasts (~$50) than those used for HQI. With Ace's statement of improved results with CDM-T / ellipsoidal reflector, more people will be convinced to use CDM-t lamps.
the page from a chinese company website looks indentical. let me see if I can still find some contacts in Beijing ...
Ace, what is your refelctor's spec ?
EDIT:
I see. HB optical is a company based on Northeast China. Thus I think the price wont be too steep ( I wonder if Walmart will carry their products 😀). I will send them an email asking for price soon. But we might need to have large enough order to have them sell to US.
It would work great with CDM-T lamps. CDM-T or HQI-T lamps are fairly cheap from europe, last time I checked you can get one about $20-30, and CDM-T doesn't need special type balasts which means we can find cheaper balasts (~$50) than those used for HQI. With Ace's statement of improved results with CDM-T / ellipsoidal reflector, more people will be convinced to use CDM-t lamps.
F1 = 17mm
F2= 145mm
D=98mm
Center hole size 22mm
Im not sure if i like the look of the ones from bejing, they are classed as standard and they have a very short lifespan. Mines classed as industrial. Ill ring the place up where i got mine from tomorrow to see if mine does have a life lol best to be safe then sorry, even then id still use em. They dont cost that much considering the performance gain.
Trev🙂
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