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Three basic technical questions on diodes and freq

drjava

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1 are 455nm and 405nm lasers both "pumped" by infra red? I think I read that anything above 660 in pumped?

2 If they are, is some of the burning they produce really the result of IR contamination?

3 At a given MW power, are all of the frequencies 660, 455, and 405 equivalent in burning effect? The lower frequencies are closer to IR so might be hotter, but the higher ones have more energy per photon (but maybe less photons for a given output power. If there is a component of IR contamination, the it may really depend on that?
 

chipdouglas

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No. The 405, and 445nm LD's we use are diode based. Not DPSS like all greens. many colors come in DPSS though and you can get blue in DPSS. i am not sure of 405nm though.

and the hight in number you go is closer to IR.... so 405 is furhter way than 445 which is further away that 635. IR, i believe starts at 780nm.

And pleaes post your questions as questions. somebody might google this and see your statements as facts.


michael.
 
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qumefox

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1) No. 405nm and 445nm are both diode laser wavelengths..

Though just to be confusing, 404nm is available by direct doubling an 808nm pump. :D More than a bit pricy to go that route though.

2) There is no IR in diode lasers.. Unless they happen to be IR diodes..

3) as Chip said. 405nm is on the opposite end of the spectrum than IR. 405nm is on the UV end. Shorter wavelengths have higher energy, but 'burning ability' really just depends on material absorption. And more things will absorb UV than NIR, so therefore in the visible and near visible ranges, higher frequency (shorter wavelength) lasers 'burn' better.
 

chipdouglas

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^^^ in reference to the hobbyist, all greens are dpss. So it is not even worth mentioning lol. The op (no offence drjava) doesn't even know the difference between uv and ir wavelengths. So there is no point in talking about unobtainable diodes.


michael.
 

drjava

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Thanks, Perfect.

Of the common diodes we buy, only green is pumped.
MW for MW higher frequency (shorter wavelength) has more energy and probably better material absorption.

Of visible things, in general, they reflect most of the color we see. So green objects would absorb green badly, red objects absorb red badly.

I wonder if anyone has recorded "seconds to burn or pop" of various colored balloons with lasers of various wavelengths at given power and at similar beam diameters and distance.

Table columns for example might be:

Time to pop microseconds, color of balloon, wavelength of laser, distance to target, diameter of beam, measured actual MW of laser

Though the color of balloon and type and thickness of latex would add uncontrolled variables. All balloons would have to be the same brand and inflated to exactly the same pressure.

Good science fair project for someone with lots of lasers, a power meter, and a noise triggered timer.
 

piferal

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@Michael, do you want one like this?

Well, maybe not have to wait long, and soon find within in some pico projector :rolleyes:


 

Cyparagon

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1 are 455nm and 405nm lasers both "pumped" by infra red? I think I read that anything above 660 in pumped?
No, although it may have been true (in the case of solid state lasers, anyway) a few years ago when your text was written.
 

chipdouglas

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@Michael, do you want one like this?

Well, maybe not have to wait long, and soon find within in some pico projector :rolleyes:


that only has 2 wires. our 445's have 8. is that an actual diode from somewhere or just a 3d drawing?
 

Helios

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As far as measuring which wavelength will pop a balloon first - don't bother. There are way too many variables for anyone to test this at home. Balloons will vary in thickness depending in how inflated they are, it would be extremely difficult to build and/or collect diodes off the exact same power in all wavelengths, the slightest change in the focus of the lens can cause huge changes in power density. Frankly in the end it won't make any difference - if a 100mW of 405nm pops a balloon 1 hundredth of a second faster than a 100mW of 650nm will that really be the determining factor for your purchase?

If all your after is burning than you must also factor in price. You can get 1500mW of 445nm for cheaper than you can get 300mW of 532nm.

In the end burning will get old so you will just buy yourself a lighter and find yourself more concerned with build quality and unique wavelengths.
 
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qumefox

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that only has 2 wires. our 445's have 8. is that an actual diode from somewhere or just a 3d drawing?
The number of wires depends on the power the diode needs. My guess is the greens the pico's will be using won't be higher than 50mW or so, and thusly, doesn't need a large number of bonding wires.
 

piferal

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From the 2 link that I put, the most powerful in CW has "only 75mW" but nice anyway :)
 
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qumefox

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Yes but i'll certainly take 75mW of 520nm for a sane price though heh.
 




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