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Focused LED instead of a traditional LD

HAXTIME

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This is only a theoretical question, for I could not find a practical comparison neither here, or elsewhere on the www.

If we were to take an N watt CO2 LASER, and an N watt LED panel, and then focus the entire light output from the latter, would the heat generated on a fixed point on a surface closely resemble that from the former, if their wavelengths match? Say 445nM.

AFAIK, LEDs are marginally less efficient than LDs, especially at large amperages. How would this perform at say, 40w?
 
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djQUAN

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A 3 Watt laser is different from a 3 watt LED. Since AFAIK laser diodes are rated on optical power meaning their light output. LEDs are rated at input power, the power they take in.

And then there's the light source size. The light emitting area of an LED is gargantuan compared to a laser diode's. Good luck focusing a large die area into a small point.
 

Pi R Squared

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This is only a theoretical question, for I could not find a practical comparison neither here, or elsewhere on the www.

If we were to take an N watt CO2 LASER, and an N watt LED panel, and then focus the entire light output from the latter, would the heat generated on a fixed point on a surface closely resemble that from the former, if their wavelengths match? Say 445nM.

AFAIK, LEDs are marginally less efficient than LDs, especially at large amperages. How would this perform at say, 40w?
A CO2 laser is far IR 10600nm so there is no comparison. If you take a laser diode and an LED the same wave length such as 445nm then what djQUAN said is correct, you wouldn't be able to get the same power density from the LED that you could get from the laser diode.

Alan
 

Bionic-Badger

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Yeah, even if the LED and the CO2 laser were outputting the same amount of watts of light, the CO2 laser's wavelength being in the deep infrared -- heat -- area of the spectrum means that more materials will absorb that light. Even between lasers of different wavelengths (650nm vs 405nm) of the same output power you'll find different burning abilities depending on the material being burned.

A more apples-to-apples comparison would be between lasers and LEDs of the same wavelength. For that, if you were able to concentrate all the energy from either onto the same spot they'd probably have equal capabilities when it came to burning, etc. It's more difficult to concentrate the output of LEDs in that manner than lasers though.
 

Nute

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I know this is a little off topic, but I have a question as well. I have always wondered if my 1200 lumen light could be culluminated with a large glass lens, and then focused with G2 lens, and possibly produce a white "dot". The reason I ask is, when you see 1200 lumens at night, it is clearly a unfocused beam. With that said, would it be possibly to focus it into a 5mm beam, and in turn make a "white laser" with a "dot"? This has always been a question lingering in my mind, as I am fascinated by the thought of a white laser.
 

dregalado331

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I tried it with all sorts of lenses but I could not do it. You might try pumping a ruby or emerald rod witj the 1200 lm light that might work. If you want details let me know.
 

TaterMay

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Correct me if I'm wrong, but wouldn't the LED scatter far too much to compare to the LED? Coherence is one of the defining properties of lasers, and also one of the main reasons the light is easily collimated, right? That's not to say you CAN'T focus LED light to as tight a beam as a laser diode. I just don't believe it will stay collimated over long distances as an LD would.
 

Moto154

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Laser diodes have resonator cavities, meaning the semiconductor p and n junction are sandwiched between two mirrors so to speak; although, the "mirrors" are often not conventional. As far as I know LEDs are simply light emitters. Laser diodes are true lasers since the light is amplified (technically a solid state laser). The aperture of the laser diode is incredibly small, meaning the bare diode will have a large divergence. Think of a ruby laser and how it would diverge, then think of that ruby rod being as small as a laser diode and imagine the divergence. Another problem that adds to this divergence is the cavity length; it is incredibly small, meaning there will be less distance for other less desired modes to escape from the cavity, decreasing beam quality.
 

steve001

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This is only a theoretical question, for I could not find a practical comparison neither here, or elsewhere on the www.

If we were to take an N watt CO2 LASER, and an N watt LED panel, and then focus the entire light output from the latter, would the heat generated on a fixed point on a surface closely resemble that from the former, if their wavelengths match? Say 445nM.
NO, because co2 lasers output invisible beams of light therefore can't have matching wavelengths.
 

steve001

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All that being said, You can put together a flashlight that burns as well as some high power lasers for about $30

http://laserpointerforums.com/f48/poorman-s-version-torch-32966.html

Or you might light to check this out.

https://en.wikipedia.org/wiki/PS10_solar_power_plant
That would depend on how you want to define a flashlight. But your typical flashlight using the highest output led emitter could not be built for such a cheap price. Also a single led emitter has a significantly larger emitting area than a laser diode. What this means in practice is the beam from an led if well collimated will have to have a significantly larger beam diameter because you'll need a wider diameter lens to collect all the light, hence a lower cross sectional power density.
 
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steve001

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I know this is a little off topic, but I have a question as well. I have always wondered if my 1200 lumen light could be culluminated with a large glass lens, and then focused with G2 lens, and possibly produce a white "dot". The reason I ask is, when you see 1200 lumens at night, it is clearly a unfocused beam. With that said, would it be possibly to focus it into a 5mm beam, and in turn make a "white laser" with a "dot"? This has always been a question lingering in my mind, as I am fascinated by the thought of a white laser.
Think this through. Visualize. You could collimate which means bring light into a column (not cullumate) with a wide diameter lens to capture all the light an aspheric lens would work, but focusing it onto a g2 lens would only expand the beam once the light passes that lens focal point. Did you visualize?
 




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