WAVIEN COLLARS: This part bugs me.....

No idea, because it’s a non-linear increase per angle of light collected.
And the only “collars” tested so far have all been 60 degrees opening.
60 degrees is pretty good, allows for a reasonable focal length, and doubles the intensity, but it could be more than 2.2x if the opening was smaller.
If I could get a custom collar made by phoenix I would test stuff like 30 or 15 degrees to see what the trend is like.

Don’t really have a spare $2k at the moment though, and I doubt there would be hundreds of people interested in a group buy of a $50 reflector, this is budgetlightforum after all.

“This is a cheap price, and it’s not that hard to cut glass even with a Dremel.
I already cut some ZWB2 UV filter just with a standard cutting disk and then a grinding drum on my Dremel.
I would try it Smile”

I think X3 may be on to something principally becuz doing the rough top cut shouldn’t be difficult but most importantly the center hole can then be micro-incrementally sized/centered as you see fit. I think that’s huge.

Prolly need a real machinist like a MrsDNF or VoB to chime in here perhaps. IDK.

Of course 64mm-68mm may not be there to begin with for what you’re trying to achieve either. But as you say establishing a trend could make even those restrictive sizes useful.

Good to know I can cut glass with a regular dremel tool.
I would probably put the cutting tool on a mill at high rpm and then just go really slow to slice the top off.
And yes, slicing at different heights would give different size openings :slight_smile:

The only problem is that (based on the images from optolife) that focal length number is in front of the reflector, not the actual focal length of the reflector.
If you take a close look you can see that it’s not a perfect hemisphere, and if it was the 68mm diameter would make no sense, because the focal length should be half the diameter (not including the thickness).
So yeah, maybe I need to keep looking for true hemispherical reflectors.

They are really cheap though, maybe I could use them for testing regardless.
Not a lot of light is emitted at those extreme angles anyway.

Never mind, I found more spherical reflectors! Just on a different part of the site:
http://www.optolife.com/front_surface_mirrors.html

They’re really cheap, it’s worth to try it IMO :smiley:

Yeah I’m just confused about how the diameter is 4x larger than the focal length :stuck_out_tongue: it shouldn’t be much more than 2x the focal length (aka radius)

Also more spherical reflectors here, but none that make a perfect hemisphere, they are all slightly less: http://en.hb-optical.com/products_detail/productId=145.html

Next time I order form optolife I’ll get a bunch of different spherical reflectors to test out.
The products are cheap but shipping isn’t :stuck_out_tongue:

I see that Optolife can give a quote for custom. Hmmmm.

I think I saw a Raymond who’s online there. Maybe ask him why diameter vs focal doesn’t jibe?

I was confused about this too. According to this, focal length is half radius.
So optimal mirrors should have diameter close to 4x FL. So M026 is the only one looking good.
Quite big.
Well, maybe M048 would work OK too? Loses a lot of mirror area, but only in places of low intensity. Enderman, can you calculate light collection?

BTW, any hint on shipping costs?

ADDED:
I can’t help but wonder how much would cost M048 extended to full or near-full half-sphere, with factory-cut hole and cold mirror coating if we made a GB

You don’t really need a full hemisphere no ? I mean, your emitter is not efficient on 180° anyway ?
I can’t understand how the focal length can be different than the radius of the sphere :person_facepalming:

Obviously, if you put an emitter in the middle of the sphere, it bounces all light back.
But they try to do something different, to make parallel beam as if the mirror was parabolic. It somewhat works at small angles and not at all at higher ones, but is good enough to make a definition. And it turns out that according to that definition, the focal length is half radius.

In a true sphere/hemisphere/quarter-sphere/whatever… the focal length is the radius, because the focal point is exact center of the sphere. Anything else is not a sphere (or portion thereof). But, since these are reflectors, maybe there is some amount of extra material extending beyond the spherical portion?

Ok, so if you took a mirror-like Christmas tree glass ball decoration and precisely cut it in half, bored out/sliced off the existing hole where it hangs from the branch, you essentially could have a Wavien Collar?

Sounds too easy ’cause I’ve inadvertantly must’ve created about 2,000 of these over the course of my fumbled fingered years of trying to hang my delicate balls!!!

Glad I could be of tremendous help. :laughing:

On a serious note, I could conclude that what the Chinese call ‘spherical’ for this particular application is only an approximation to true spherical and is perhaps more relative to whatever type light source’s overall total exposed distance from the Wavien surface. These are used for projectors, no? I’m also thusly thinking mainly halogen type vertically constructed bulbs here.

Looks like the focal length is longer than the radius of the published diameters is because these are not full half spheres. So it appears the published diameters are of the product and not the actual spherical diameter. Here is diagram from one of the products:

Yup, I thot it looked ‘off’ just by the photos but I didn’t want to burst Endy’s bubble so soon.

What about taking your standard 100 watt incandescent bulb and slicing away on that?

Remember we’re also trying to help him establish a trend here. Bore hole dimension for solely testing purposes are transferable to whatever config he builds. One hopes. My biggest concern is then just how precise things have to overall be from test hemispheres to prototypes to then final product.

’Course what do you coat the inside of an incandescent bulb with to get an evenly applied mirror coat? Hmmmmm.

Powder coatings can be pretty precisely evenly applied I know that much. :student:

I bought an aluminum reflector for about 10$ from ebay what made for HID lights. It just arrived today and I think it will be good as a wavien collar after some cutting.
I also have some old XP-G2 S4 2B leds and a 120mm optolife aspheric lens :smiley:
Something bebast will be born. The optolife lens has gave me 1,7 million cd with dedomed XP-G2.

To quote Warren Zevon……

You’re gonna be an Excitable Boy. :laughing: :beer:

Hi, please click the “show more” button in that link you posted, it takes you to this: Mirror Equation
That equation only applies to small angles, where the sphere has a large radius and is close to a flat mirror. Also that requires the incident ray to be parallel.
If the source is AT the focal point of the sphere, then it looks like this:

The focal length and radius are the same.





Yeah as I mentioned earlier very little light is emitted close to 90 degrees from vertical.
It would be nice to have something that does extend down to 90 degrees though, like a wavien collar, for more accurate comparison.





Probably not, seeing from the images.
That would be counter productive for when they are used in projectors since an ellipsoidal reflector needs to collect the rest of the light.





No, that’s only the case when the listed diameter is cutting into the sphere, the problem is when the listed diameter is BIGGER than the sphere.
The problem is this:
64mm diameter, 16mm focal length.
If the focal length is the true focal length of the sphere, then the radius is 16mm, (see image above)
If the radius is 16mm, the diameter of the reflective surface is 32mm.
That would mean the glass is 16mm thick??? Nope, definitely not.

I think agro is right, they may be using that other method of measuring the focal length using parallel rays.
Which is not very good, since we all know that spherical lenses and reflectors have multiple focal lengths.

^

The diagram of the lens I posted shows clearly what Optolife is presenting as "Diameter". The full sphere with that focal point would have a larger diameter. Irregardless of wall thickness in this case. Re-pasting Optolife's diagram.

I actually said that this definition is OK only with small angles…

Focal length depends on the definition of a focal point.
That site defines focal point differently from what you or me expect, but they do so consistently with what we see on the Optolife site.
And on your picture, the light source is at certain unmarked point. And they don’t use the words related to “focus” at all. So it’s not too strong indication that this reflector maker considers “focal point” to be the centre of a sphere.

You’re right, it seems that convention is the center is twice the focal length, based on this:

The ones that have a diameter approx. 4 times the focal length are:
M025 (probably not available)
M026
M033 (probably not available)
M074 (lists two focal lengths, not sure which is correct one)

Best way to find out is to test them though, I’ll buy a bunch soon.
I found some others which aren’t listed on the website too, maybe they were discontinued.
http://www.optolife.com/front_surface_mirror/M025.html
http://www.optolife.com/front_surface_mirror/M033.html
http://www.optolife.com/front_surface_mirror/M040.html
http://www.optolife.com/front_surface_mirror/M069.html