# OLcontest, modified light: 20cm fresnel lens thrower

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kennybobby
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Please excuse if this is off topic, i was puzzled by the calculation. But after a little study it makes more sense—the lightmeter is calibrated to provide a Lux value for a 1 square meter area at the sensor and not just for the tiny sensor area.

Lux is a measure of the light energy hitting a target area. The units of Lux are lumens/m², where lumens is a measure of the light energy known as luminous flux, with units of cd-sr, candela-steradians. And of course area is measured in square meters.

Steradians are a unitless measure of solid angle, symbol Ω, which is the angle from the apex (light source) subtended by the area of the target. https://en.wikipedia.org/wiki/Solid_angle

i was assuming the target area was just the tiny sensor area, but it is effectively a 1 square meter target area. So the solid angle Ω subtended at 12.33 meters away is Ω = Area/distance² = 1m²/(12.33m)², or the target Area = Ω ・(12.33m)²/1m²

So to convert: lux = lumens/Area = candela-steradian/ Ω ・(12.33m)²/1m² ;

and solving for candela = lux ・(12.33m)²/1m²

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

djozz
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pinkpanda3310
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No matter how impressive the numbers are – the bat signal trumps everything !! Great project djozz

CNCman
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First class build djozz
I had no conception what a Fresnel lens can do until your build. I’m still new here and very impressed how well this works.
Every part of this build is very clean and neat. Great build work djozz

Think outside the box too long , cannot find your way back in.
Necessity is the mother of invention and the father is creativity.
Never give up, Never surrender. Make someone Smile today.

djozz
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Thanks, there is still little things to be done, like a name and some beamshots, I hope to do them during the Christmas holidays.

MtnDon
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joechina
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Location: Germany

may I suggest the Dutch thrower?
Or
Throwing Dutchman?

Awesome build!

A box of light

DSS
= Djozz’s Star Shooter

gchart
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The Flying Dutchman?

Grigio
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Location: Chiang Mai, Thailand

Ver licht?

djozz
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Location: Amsterdam

I had to finish it today, so here’s the final stretch.

Because the star and the batman projections were not what I wanted for this build, I tried a little spider. The shape was too difficult for the fretsaw, so I went for etching a thin copper sheet, for so long that the copper was eaten through by the FeCl3. I took a long time, and the cutout was not perfect, but the result was rather nice.

Still, this was not the final version. But here are some pictures. Both are at about 40 meters.

MtnDon
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I like the spider.

Maybe a slot for interchangable shapes

gchart
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That’s AWESOME djozz. If I saw that in real life, I’d be thoroughly creeped out (I hate spiders!)

djozz
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And now for the finished light!

Meet the Vir-O-blast C19. My pinstripe is certainly nowhere good enough to apply for a job at RR (link), but I still like my paint job.

The vir-o-blast c19 will not infect you, or cure you from anything (although this post may be the start of a new conspiracy theory ), but it may hopefully brighten up this dark winter a bit

Without the virus stencil in place and with the led die focused, the throw number of this build is over 4Mcd, but with the led die defocused and the stencil focused, the virus projection does 800kcd, still a significant number.

And some pictures of the finished light:

Tonight I will do a small video showing the zooming action, and still some loooooong distance shots showing the 4Mcd need to be made.

MtnDon
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G0OSE
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You know, somehow I missed this entire entry – lord knows how. It is amazing. Personally I am not going to be happy until I see a BLF logo in that thrower lol! (kidding of course)
fantastic work, well beyond anything i could muster! Good luck!

Xandre
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Cool

Regards Xandre

lumenzilla
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Awesome build, Djozz!
I’m thinking about numerous images to be projected using that flashlight.

Rdubya18
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I like it !

Sunnysunsun
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Haha that little viral addition takes the cake

thijsco19
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Looks great!

I love how ‘simple’ it is on the inside! Very clean build.

djozz
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thijsco19 wrote:
Looks great!

I love how ‘simple’ it is on the inside! Very clean build.

There is even no driver, the battery is wired directly to the led. I was contemplating building in a fuse for safety but that would cost current, I fear too much.
Zandar
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Fantastic build

djozz
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A sort video from the balcony without the virus stencil to show it is a zoomie. My 10yr son is the camera man so it is shaky, and the focusing of the my phone is a bit lousy but you get an idea. The big trees are at 30 meter, the very end of the square is 125 meter, the square is no match for 4.2 Mcd.

G0OSE
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I bet he’s proud of his Dad!

djozz
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G0OSE wrote:
I bet he’s proud of his Dad!

Well, he already takes his dad’s weird hobby with a grain of salt I’m afraid, no unreserved admiration . But he does like this one!
CNCman
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djozz wrote:
A sort video from the balcony without the virus stencil to show it is a zoomie. My 10yr son is the camera man so it is shaky, and the focusing of the my phone is a bit lousy but you get an idea. The big trees are at 30 meter, the very end of the square is 125 meter, the square is no match for 4.2 Mcd.

.
Great Video , it brings your light to life.
.

Think outside the box too long , cannot find your way back in.
Necessity is the mother of invention and the father is creativity.
Never give up, Never surrender. Make someone Smile today.

MascaratumB
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Uau, I hadn’t seen the final version, this is uber cool
Liked the name of the build too! Beware, you foolish virus

Well done

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joechina
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Cool
What about rubber feet to not scratch the bottom?

And a a handlebar mount for the bicycle ?

djozz
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So that you can light up where you are going to be in five minutes time

Skylight
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Very well done, djozz. Awesome build and finish.

That zoom function looks very interesting in your video. The different stencils are ingenious. That virus or the spider is going to freak out everyone who sees it.

I liked your build so much that I ordered myself a big fresnel lens. Never imagined what cool things can be done with this. 4.2 Mcd should throw incredibly far.