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Hey all, I was just thinking about how to focus a flashlight beam into a tighter line while preserving the light at the same time. Lenses or something like that a good idea?
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Focusing Flashlight Beam?
- Thread starter swimrocks495
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You can focus it to a tighter line but not the same as a laser.
Laser has single wavelength while flashlight produce light with many wavelengths. each wavelength will probably focus different because of different speed.
If I'm wrong then please correct me guys, I'm not sure about this.
:beer:
Cel
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Using a better focusing reflector?
I believe an aspheric lens does what you want. like this one but which is out of stock
PRECISION PCX ASPHERIC LENS 50MM DIA, 35MM FL - Surplus Shed
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hoo7h
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Wrong, different wavelengths have the same speed, which is the speed of light, but different frequencies.
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^Wrong. The speed of light changes depending on the medium it is in. Different wavelengths change speed differently. This is why lenses work. Source.
The different colors are focused differently when it comes to LEDs, but only slightly. This usually comes in the form of a white dot with a slight halo that is either blue or red depending on the focus.
The different colors are focused differently when it comes to LEDs, but only slightly. This usually comes in the form of a white dot with a slight halo that is either blue or red depending on the focus.
Cel
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And that's why you can see rainbows, can make the light "split" trough prisms...
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The actual Reason you cant focus an LED is because the emiter on an led is not a point source,
the different colors only play a small role in your inability to focus an led.
An led's emitter is ~1mm
a lasers emitter is like ~10 micrometers, 100,000 times smaller.
Meaning with the same lens, an led will diverge 100,000 times more than a laser
the different colors only play a small role in your inability to focus an led.
An led's emitter is ~1mm
a lasers emitter is like ~10 micrometers, 100,000 times smaller.
Meaning with the same lens, an led will diverge 100,000 times more than a laser
Last edited:
ryansoh3
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Very true.
As a former flashaholic, I can say that there are basically two ways to get near-coherent beams from LED's.
The first is to use an aspherical lens. You can change the beam in this light by moving the lens closer or further from the LED:
X2000 Flood-to-Throw Zooming Glass Optics Cree P4-WC LED Flashlight (1*18650) - Free Shipping - DealExtreme
The second way is to use a huge reflector. Note that LED's with larger area need bigger reflectors to create a coherent beam. Even though an XP-G2 (~480lm) LED produces less lumens than an XM-L (1000lm), it will throw farther because the die size is much smaller than that of the XM-L.
Check this light out:
Located here: MaxaBeam vs. the Moon
The Maxabeam is only 1400 lumens yet blows every single LED or HID light off.
Cheers! :beer:
As a former flashaholic, I can say that there are basically two ways to get near-coherent beams from LED's.
The first is to use an aspherical lens. You can change the beam in this light by moving the lens closer or further from the LED:
X2000 Flood-to-Throw Zooming Glass Optics Cree P4-WC LED Flashlight (1*18650) - Free Shipping - DealExtreme
The second way is to use a huge reflector. Note that LED's with larger area need bigger reflectors to create a coherent beam. Even though an XP-G2 (~480lm) LED produces less lumens than an XM-L (1000lm), it will throw farther because the die size is much smaller than that of the XM-L.
Check this light out:
Located here: MaxaBeam vs. the Moon
The Maxabeam is only 1400 lumens yet blows every single LED or HID light off.
Cheers! :beer:
Last edited:
hoo7h
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Wrong again, the speed of light decreases only in the len, once it go out from it, the speed increases again.
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Medium is another word for material.
hoo7h
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As prove,
If we put a big number of diamonds in a line, and then we turn the light on, when the light be slow enough so we can see it moving ?
Cyparagon
You are an ignorant narrow minded person, you gave me a bad rep because you cant replay.
If we put a big number of diamonds in a line, and then we turn the light on, when the light be slow enough so we can see it moving ?
Cyparagon
You are an ignorant narrow minded person, you gave me a bad rep because you cant replay.
Cel
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Wrong, you hoo7h, are ignorant and annoying.
You won't see the light moving, cause it has to reach your eyes first! And it can't do that if it is still in the diamonds.
Even if you make a long line of them, you would still need a camera with a lot (few billions?) of frames per sec.
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ryansoh3
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Hope the time stamp works. If not jump to 1min 5sec.
Cheers! :beer:
