Having decided I want to make my own light fittings for our boat with LED 'lamps' (thus low power, 12 volts, and relatively cool running) I need to find some suitable material for the light to bass through.
I'm basically going to make very shallow wooden boxes with a (probably) rectangular window, they'll be in the sort of four to six inches by two inches sort of size.
So where can I get (or maybe scrounge) suitable transparent material which will diffuse the light a bit and, more to the point, mask the innards of the lights without too much light loss?
Etching the surface of a transparent material tends to be the most efficient diffuser, although it won't hide the presence of discrete light sources behind it. Might be worth looking for some etched glass, or roughing up one side of a piece of clear perspex or polycarbonate.
If you are using power LEDs, you might want to include an interlock to prevent operation if the diffuser is missing. They are too bright to be directly viewable without the possibility of harming your eyes, and you need to be careful when making the lights (run a much reduced current).
What you're really constructing is a "light box", which is (was?) widely used, for example, to preview photographic slides. They were also used in hospitals to look at x-ray films.
Traditionally the diffusion material was either acid-etched or opal glass, neither of which are readily available these days. Trying to acid-etch glass can be more a case of acid-etching yourself if you aren't careful.
Many years ago, as an impoverished youth, I ground the surface of a piece of glass to use in a home-made enlarger, using a bit of plate glass as a sort of surface plate and lots of "Vim" (remember it?) and water, with reasonable results. (123).
I'm sure a sign manufacturer would have lots of offcuts of acrylic material with which you could experiment.
It _might_ even be possible to try a bit of white Fablon (other sticky-back plastics might be available!), stuck to the back of a bit of clear acrylic.
Experiment!
(123) a baby-milk tin, (with a photoflood bulb inside), painted matt-black inside, attached to a bit of broom shank with an adjustable clamping arrangement; said diffuser leading the light to more or less the focal plane of an old folding camera, and a bodged negative holder with two bits of glass to hold the negative. It worked, although I never became a Paparazzi-type.
OK, thanks Andrew, I don't need to hide what's behind completely I just want to mask it a little.
No, I'll almost certainly be using the small smd type devices, this sort of thing:-
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I have several of these already on our boat replacing filament bulbs in existing fittings and they work well. I just want to add some more light in different places and suitable fittings are almost impossible to find, expensive and need to be converted to LEDs anyway so I might as well make them from scratch.
Expenive isn't it! Though I suppose it would make a lot of lights.
I actually have some offcuts of 8' x 4' sheets of similar material I used for a partition between two bookcases which make up a room divided but I'm not sure how translucent it is. I guess I can experiment with some sort of light meter.
I wonder if you can still get those defuses for lighting that looked like little prisms on one side of a piece of transparent plastic. You could cut this with care to fit into a ceiling opening to hide the fact that it had tubes and the prismatic effect was quite pleasing. I'd suspect some shop fitting suppliers might have this sort of thing.
Theatre lighting suppliers and have a riffle through their swatch books.
Youv`e been watching too much Fox News Andrew ;-)
or perhaps reading this guy
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g-your-eyes/
Remember when LEDs were put into EN60825 Laser Classification, Class 1 LED product?
and then quietly dropped back out of it , as it was realised that hype had exceeded reality.
Before start requiring key switches to be fitted to Maglite retrofits best to get it in perspective.
High power LEDs generate a large amount of optical radiation from a small area, power density is high, but crucially different from a laser is the light is not coherent.
As soon it leaves the surface of the emmitter it scatters in all directions, the inverse square law, double the distance , quarter the intensity , kicks in, even focussing optics or reflectors will not turn a current LED into a death ray.....
Blink and aversion reflexes will cut in long before exposure will ever reach a harmful level.
Power density from source 1 , the Sun is still much higher than any currently available Light Emitting Diode, but just like the Sun don`t intentionally stare into very bright LEDs for extended periods,
There seems to be a wave of hype along with the exposure to artificial optical radiation regulations that artificial light generation has been mastered so well that we must now fear the awesome light sources man has created, it`s not really so, keeping the lights on will remain possible , just be a lot dimmer than we used to have ;-)
Prismatic diffuser, polystyrene rather than acrylic, various patterns , greater light transmission than opal acrylic, thin stuff will cut with a pair of scissors, advantage over gel diffuser in that its rigid.
Suspended ceiling suppliers and skips of offices getting refurbed.
I just had a sheet of 'Flemish' patterned glass replaced. The old glass was 'translucent' with a grey 'smoked/steamed' effect; the replacement is much more transparent.
The glaziers said that a similar effect could be produced with grit blasting. This was the method used to mark car registration numbers on car windows using (ISTR) carborundum grit.
It was interesting that the 'smoked' effect on the old glass was discontinuous and wasn't in the 'valleys' of the pattern. They thought this had been done with an oilstone, carborundum paper or valve grinding carborundum grit.
Try some wet & dry paper and see what effect it produces.
I accidentally flashed myself in the eye last night with a two-cell Cree P3; the after-image was quite intense for a fair while. Definitely to be treated with a bit of caution.
Lidl have some film intended for doing a pseudo-etched glass effect on windows/doors for privacy. Some is printed with patterns in ink, but some looked to be feasible for DIY lamps.
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