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How do yellow lasers work?

Rammstein

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Alright so how do yellow lasers work and when (like how many years) will the price of yellow lasers drop to be about $50 for a 1mw or something around that? I think yellow lasers are really cool but are completely out of the price range so i am not worrying about them yet.
 



Trevor

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Yellow lasers work just like our favorite green lasers.

With green, two 1064nm photons are collided to yield a single new photon of twice the energy and half the wavelength.

With yellow (593.5), two wavelengths must be lasing from the neodymium doped crystal - 1064nm and 1342nm. Two of these photons are collided to yield a photon of the summed energy and a shorter wavelength.

With 589nm, the combined wavelengths are 1064nm and 1319nm if my memory serves.

Yellow HeNe's at 594.1nm are expensive because they're rare and are gas lasers.

577nm OPSL lasers are still new technology and will be quite expensive.

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To answer your question, DPSS yellow is never going to get "cheap." It will always be expensive relative to other DPSS wavelengths because the process is so complex. Yellow HeNe's will only get more expensive.

577nm OPSL is probably your best hope for a cheap yellow... I'd look for it in 5-10 years... ><

-Trevor
 

JordanPereira

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Green lasers in the late 90's were around the same price as yellow lasers are today. Don't expect them to gradually lower in price anytime soon.
 

frankwi

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Trevor, I would +1 you if I could. Thank you for explaining what I've been wondering myself, in terms I can understand !
 

rhd

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Green lasers in the late 90's were around the same price as yellow lasers are today. Don't expect them to gradually lower in price anytime soon.
In all fairness, the OP did ask how many "years". So it's actually a decently realistic perspective he has. It will be "years", but I bet that before 2015 we'll see a yellow for under $50.

That said, technology changes so quickly these days that I wouldn't totally rule out a yellow diode by that point. That said, there's very little legitimate mainstream need for a yellow diode.

Although, there was also very little legitimate need for Furbys, but science still made em.
 

Trevor

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In all fairness, the OP did ask how many "years". So it's actually a decently realistic perspective he has. It will be "years", but I bet that before 2015 we'll see a yellow for under $50.

That said, technology changes so quickly these days that I wouldn't totally rule out a yellow diode by that point. That said, there's very little legitimate mainstream need for a yellow diode.

Although, there was also very little legitimate need for Furbys, but science still made em.
The DPSS process for yellow is so ridiculously touchy... I really don't think we'll ever a yellow DPSS pointer (at the two wavelengths we see today) for under $50.

OPSL is promising though.

(Also, I'm pretty sure the 2W model of that is $15,000.)

Glad you guys found my explanation useful. :)

-Trevor
 
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rhd

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The DPSS process for yellow is so ridiculously touchy... I really don't think we'll ever a yellow DPSS pointer (at the two wavelengths we see today) for under $50.
You could certainly be correct - this is all a bunch of speculation. But I can still remember (vividly) looking at $300 green lasers and thinking "oh my god, who would ever spend that much on a laser (haha), will that ever be something I can afford?"

And I'm sure that back then (it's really not THAT long ago) the concept of 532nm DPSS seemed pretty tough, especially to make portable. But progress is progress.

Maybe a more interesting question is what do you think will happen first? A yellow DPSS for under $50, or an alternate source of yellow, made into a portable?
 

Meatball

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One thing to consider, if an amazing use and sudden reason to need 589nm everyday arises, the pointers would be mass produced in China, and would drop in price just like the greenies did.

Supply and demand has always driven product prices even more than technological complications have.
 

Trevor

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You could certainly be correct - this is all a bunch of speculation. But I can still remember (vividly) looking at $300 green lasers and thinking "oh my god, who would ever spend that much on a laser (haha), will that ever be something I can afford?"

And I'm sure that back then (it's really not THAT long ago) the concept of 532nm DPSS seemed pretty tough, especially to make portable. But progress is progress.

Maybe a more interesting question is what do you think will happen first? A yellow DPSS for under $50, or an alternate source of yellow, made into a portable?
Well... here's the thing. With green, you can prettymuch pump in 808nm and watch your KTP "shit out a stream of photons," as our friend goninan_bl00d says. Because the process is relatively simple, Chinese manufacturers can spew them out like no other.

With our two flavors of DPSS yellow, the conditions for the production of the desired wavelength are much more stringent. The systems require real engineers to produce.

If the incident beams aren't perfectly phase matched, you get green (or red, maybe). If the crystal is misaligned, the pump wavelength gets all over the carpet.

Even CNI systems thoroughly vetted by Laserglow have been known to sometimes emit green.

Random ChinalaserCo, LTD. isn't going to be able to build these until they've reached the level of CNI. Since this requires a degree in photonics, that is not going to happen.

A yellow diode will happen first, or small-scale OPSL will get cheap.

One thing to consider, if an amazing use and sudden reason to need 589nm everyday arises, the pointers would be mass produced in China, and would drop in price just like the greenies did.

Supply and demand has always driven product prices even more than technological complications have.
589nm lasers exist for the purpose of sodium guide stars for use with adaptive optics in astronomy. There's definitely demand and an application, but I don't see it going into mass production. That being said, I'm not sure why CNI makes 589nm systems - they're certainly not what's getting used in telescopes.

The places we get our cheap equipment from are from mass-produced sources.

Having cheap data reading/writing wavelengths makes sense - but we've long passed the data density where yellow would make sense. That's out.

Display is our next best source. But... why use yellow when a larger range of colors can be made with R/G? Again... that's out.

I think our best source moving forward is going to be science still, but in the form of surplus equipment. We get our "cheap" argons and exotic HeNe's this way. Cross your fingers that people will start throwing away equipment containing 589nm lasers in the next few years. :D

-Trevor
 

rhd

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Very interesting. +rep
I had no idea that we used 589 to make artificial stars. Very cool.

What do we use 593 for then?
 

Trevor

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Very interesting. +rep
I had no idea that we used 589 to make artificial stars. Very cool.

What do we use 593 for then?
I suspect they might have been invented to replace 594.1nm HeNe's.

As for what those were used for... I suspect fluorescing particular dyes in medical research or doing particle detection or something.

Dye fluorescence is my number one guess though. With that you can generally slide a few nanometers in either direction with no ill effects. 650nm and 635nm lasers have largely supplanted 632.8nm HeNe's in this field for this reason.

Shame though... I love HeNe's. :(

-Trevor
 

Flaminpyro

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I could be wrong here but I don't think we are using them to make artificial stars with but rather using the 589 wavelength as a tool in studying the stars.
Someone else speak up please...


Very interesting. +rep
I had no idea that we used 589 to make artificial stars. Very cool.

What do we use 593 for then?
 

rhd

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I believe that what I read explained that we use them to excite a particular element in our atmosphere, which causes this element to product light as an artificial guide star for use in astronomy with telescope guiding. Something like that.
 

goninanbl00d

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That element would be sodium.

These sodium guide stars, as they're called, are used to measure atmospheric distortion of incoming light. A powerful 589nm laser is used to excite these atoms in the upper atomsphere, causing them to emit light at 589nm. This light is then used to calibrate instruments appropriately. That's how the whole guide star thing works in laymans' terms. For a slightly better explanation:

Laser guide star - Wikipedia, the free encyclopedia

There.

The reason why 59/4nm DPSS yellow is so damn finicky is because you're taking a dominant line (the 1064) and a weaker (by magnitudes) line (the 1342) and making them lase at the same time, in the same medium.

Long story short you're trying to get an extremely weak line to lase at the same time as neodymium's strongest line. Of course, the 1064nm line will be stealing energy (and lots of it) from any other line. Good luck; have fun. Because it ain't easy to get working.

There's a lot that can go wrong, as Trevor said. It's not something that's easy to do. 593.5nm DPSS was finicky, and often the 1342nm line would stop lasing altogether, resulting in a green pointer.

Of course, outside of lab use, there isn't much need for DPSS yellow (unlike with the cheap greens, there's no need to mass-produce them). Maybe one day we'll see cheap DPSS yellow, but I'm more willing to bet that we'll see direct diode or even OPSL yellow earlier. In the grand scale of things they'd be so much easier to make. (maybe not OPSL, but definitely direct diode).

Besides, the lasers used in the sodium guide star systems are never DPSS. They're too unstable for that sort of work.

They're all amplifier-based systems which either amplify the output of a ring dye or other (can't remember the type) laser that can be tuned to have an extremely low spectral bandwidth. This is then amplified in a fibre laser to the power levels required.

It's been a while since I've looked into this stuff; sorry for the shoddy explanation.
 




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