reflector, reflector and reflector!!!!

[projectile]

thanks for so many replies guys
now i got a cdm light but its rated to last only 4000 hrs
maybe in our conditions, i think i will go for a hqi as it costs three times less and last around 3000h also i can get some good reflecters and condensers made.

btw guys i am going to a optics manufacterer in a day or two
and have not exactly decided as what spec of reflecters and condensers to ask for?

how is a aspheric condenser diff from dcx or pcx?
and how good is the one i have the specs are (as in the manual)

SIZE : 60mm dia. (39 mm rad …. 40 mm width)
b) FOCAL LENGTH : 75 mm

and also i am stuck finding uv filters i asked for one and for the price of a 6" x6" i can buy two entery level comm pjs

and anybody wants any custom stuff made send me the spec i will enquire.

[projectile]

ok guys i got it kinda figured out
for the reflecter to be used with a hqi its a 30% spehere say like
dia 75 mm and fl 65 mm so any smaller size would also be proportionately smaller but still be a 30% sphere is it?

is there any relation b/t reflecter dia and condenser dia?

[Guy Grotke]

I think you can get Lexan very cheap that removes about 90% of the UV. They also have a version of it (Lexan-XL) that removes a bit more, designed for exterior windows. I got an 11" by 14" by 0.93" piece at Home Depot for $4.57 US. Look for the specs online.

I can also suggest that the relationship between the size of the spherical reflector and the condensor lens is that they should cover the same number of radians of arc. Rays that go to the reflector will be sent straight back through the lamp into the condensor. (Assuming you have the lamp placed correctly at the focal point of the reflector!) If the reflector and condensor were both 2" from the lamp, then they should have the same diameter. Or if the reflector is 2" from the lamp and the condensor is 1" from the lamp, then the reflector should have twice the diameter of the condensor lens. Make the reflector too small and the edges of your image will be dim. Make it too big and you won't be able to get the bulb to the focal point.

One advantage of having a large reflector at a longer distance, is that the lamp arc will get reflected more like a point source. So more light will get to the LCD panel pointing in useful directions.

[projectile]

hi
today i went and picked up a few things

sperical reflecter 52mm dia fl=? , can i find it somehow
a bit small but at 4 usd its worth a try

150w hqi-ts with uv filter
wonder how much uv does it stop.

now am stuck at the condensers i have a range of 55mm pcx lens used by opticians . basically fl shouldn't be a problem will talk to the optics dude in a few days and try to get slightly bigger condenser.

also found a baush and laumb polycarbonate optical lens which stops 99.99% uv but is only 65mm in dia
also some kinda test setup from baush and laumb which tells as how much uv is getting thru , will test and tell.

[Guy Grotke]

I have read that the bulb envelopes do not block very much of the UV, even if they claim to be UV blocking.

Even a thin sheet of Lexan (polycarbonate) or Plexiglass (acrylic) will block more UV. So your acrylic fresnels do more than you think!

You can run your projector without a condensor until you get one that improves it...

[ace3000_1]

I have read that the bulb envelopes do not block very much of the UV, even if they claim to be UV blocking.

70 - 80%

Trev

[projectile]

yep a small hanging thingy is in the lamp which supposedly contains quartz , which would provide a blanket of quartz ions to do the job of uv filtering
in a perfect world the lamps filters 75% and futher we put another filter sort of which filters another 90% in effect what we have finally is neglegible hehehe
but firstly we don't know the wavelenghth of uv that effects the lcd and
then we don't know over which wavelength the quartz ions fail to do thier job and
even polycarbonate like lexaN ,,..WE don't know what wavelengths it fails to filter
so lets do as much as we can and hope for the best that our lcd lasts us a couple of years

i_eat_flowers buddy you might want to double check if the ionic filteration would work in your case where you haVE removed the bulb from original casing ...it might contain some kinda necesary gas ..you know ..it would be a shame if such a brilliant piece of engineering would fail to work...


btw ace my reflecter's dimension dictate that even if the lamp outer bulb is touching the edge of the reflecter the the arc would be 1.5mm off the fl
can i grind it down a bit or can a very highly polished reflecter be made from SS in a lathe

[ace3000_1]

can i grind it down a bit or can a very highly polished reflecter be made from SS in a lathe

If you want to fry your bulb go for it lol. I dont know where you got the quartz gas from cos its the outer jacket thats made out of quartz that blocks the UV, thats why they say when the outer jacket is broken or removed the UV levels are very high. That goes for all bulbs wheather they have UV block or not, its obvious those that do have the UV stop have a different strand of quartz glass made for blocking UV to its full exstent.

The metal thing your talking about in the bulb if its a ball is metal that is mixed with the halide gass, its in the actual arc tube. Now if your talking about the round metal peice thats on a rectangular peice of metal on the end of a wire, then thats the thermal cut off that stops us from restriking the bulb when its hot, it also ensures that our bulb will start as it helps the bulb to arc.

Trev

[Guy Grotke]

I think you can get aluminum to reflect more than stainless steel. Lots of telescope mirrors are first-surface aluminum on glass.

Instead of a spherical reflector, you could make an ellipse: That has two focal points, so the light does not get focussed back into the lamp arc. You could just mill a huge billet on a lathe (or even better a computer-controller milling machine), or you could make a model out of clay and then do a sand-casing of aluminum.

Polishing either SS or aluminum will take multiple passes with finer and finer abrasives, until you get a mirror finish.

[Guy Grotke]

I think you could combine an elliptical reflector with a spherical reflector, to get very high light utilization. In my drawing, the lamp is at one focal point of the black elliptical reflector. The blue rays hit that reflector and then go to the second focal point. The violet ray misses the elliptical reflector, but hits the red spherical reflector, bounces straight back, hits the elliptical reflector, and then goes to the second focal point.

If you size the elliptical reflector correctly, then the expanding cone of light going right from the second focal point fills your lower fresnel perfectly.

Anybody tried something like this?