Polishing reflector for better throw?

[things]

Hey, I've just purchased a DX light.

Reading a few of the reviews, apparently this thing has a very wide flood. A friend of mine on IRC told me that I can get better throw by polishing the reflector? Is this true? And if so, how should I go about it?
This will be my first real "torch", so sorry if I am wayyy off base

Cheers,
Dan

 

[DM51]

Welcome to CPF, things.

Your friend has given you very bad advice. It isn't possible to polish reflectors properly. All you will do is make the surface duller and less efficient - it won't reflect as much light. And if it was a flood beam before, it will be even more flood afterwards, but dimmer.

 

[things]

Alright then

Is there any cheap alternatives to get a better throw (Apart from selling the light and getting one with better throw )

If not, I can deal with it, but it would be nice if I could increase the range slightly

 

[DM51]

You might be able to replace the reflector with a smooth (SMO) one, or one with a "light orange peel" (LOP) surface. That depends on the light, size etc.

Alternatively, does your budget rule out keeping that light and buying a 2nd one? That way you would have one with a flood beam and another one with good throw. Both have their uses.

 

[kramer5150]

You should post this to the flashlight modification sub forum. Other members have polished Aluminum, but I dont think it is easy to obtain the equivalent reflective efficiency as a properly coated reflector. IMHO your best bet is to replace it all together with a smooth one. I just got a smooth reflector for my DIY modules and it does increase throw a noticeable amount.

What is the DX SKU number of the light? (do not post the URL, mods will delete it).

 

[Gunner12]

Which light do you have?

As said before, it's a bad idea to polish the reflector. The reflective coating is fragile and can be easily broken.

If the reflector is made of Al, and you know what you are doing, you can polish away the reflective coating and polish the Al to a mirror polish, but the geometry can be off and Al oxidized quickly(making it dull) so it's not recommended.

:welcome:

 

[LukeA]

Welcome to CPF, things.

Your friend has given you very bad advice.

This isn't necessarily true. If you're going to polish it, you need to get the surface down to the base metal below all coatings on the aluminum.

After all, NASA is switching to polished aluminum first-surface mirrors.

A flashlight reflector doesn't really need 10-angstrom flatness, so the polishing can be done at home.

The atmosphere sealed inside the head of a flashlight won't cause noticeable oxidation of an unfinished aluminum surface in a reasonable timeframe. I have a reflector I made a year ago by polishing aluminum and it's been sitting out unsealed in open air all this time and only now is it showing the slightest sign of clouding.

The above only pertains to metal, not plastic, reflectors.

 

[bluepilgrim]

Polishing a plastic reflector with a reflective coating on it will destroy the surface, and then you have to send it out to be recoated with aluminum, using vacuum deposition equipment -- figure at least $50. Aluminum can be polished, and it can also be overcoated with silicon dioxide or othe protective coating. Do a search on 'telescope mirror coatings' and you can learn more.

While the optics in a flashlight is not 'precision' you don't want to throw them off too much or end up with a bad surface. There is all sorts of information about polishing optics you can find by searching about telescope making. I doubt you could improve the reflector much over the factory supplied surface, though, unless it was really bad.

If the surface of aluminum has deteriorated to where polishing would help, you could use red jewelers rouge (very fine red iron oxide), but don't use anything at all gritty or coarse. A bit of that on a soft cloth, with some water and a little soap would do, using your finger (or just your finger -- which will get a bit stained). There are other things you could such as making up a wax or pitch lap, and other optical techniques, but that get's more involved and you should look up those techniques used for optical work.

For all the work and such, I'd say it better to just buy a new reflector if needed.

Throw is not primarily due to the polish, but the shape of the reflector, or where the bulb sits in relation to it's focal point -- and you aren't going to change that by polishing.

 

[Federal LG]

:welcome:

 

[things]

Hey, it's SKU 15691

Going by the reviews, it looks like a nice light, especially for the price, though seems to have a large flood

Thanks for the idea's guys

-Dan

EDIT: Apparently this has a "Stippled Aluminium" reflector

 

[R@ndom]

I was thinking 'this guy may have an e01 in which a polish will increase output' then I read the last post.

 

[polkiuj]

U want throw? Carry a magnifying glass. It'll work (almost) like an aspheric, giving crazy throw but highly unusable.. xD

 

[LukeA]

Hey, it's SKU 15691

Going by the reviews, it looks like a nice light, especially for the price, though seems to have a large flood

Thanks for the idea's guys

-Dan

EDIT: Apparently this has a "Stippled Aluminium" reflector

If you're polishing a reflector used with a multi-die emitter like the P7, you will probably be unhappy with the result. You will increase throw, but you'll then be able to see the dark region between the dies projected as a dark cross in the center of the beam.