# Why Green Lasers Soo Expensive as compared to Red?



## ViReN (Aug 1, 2004)

Hi All,

I am not new to red lasers, but new to green, blue, purple ones...

When i checked in this seciton of the forum to find about these, i got to know that these are damn expensive.... must be atleast 20-40 TIMES the red ones...

why is this so ? any clues ?

-ViReN


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## The_LED_Museum (Aug 1, 2004)

Green diode lasers are a lot different than those common red lasers you see all the time. 

In a 640nm red laser pointer, there's a red-emitting diode and a lens to collimate (focus) the beam. 

In a 532nm green laser (pointer or larger size), there's a BIG infrared laser diode that generates laser light at 808nm, this is fired into a crystal containing the rare-earth element "neodymium". This crystal takes the 808nm infrared light and lases at 1064nm (yes, deeper in the infrared!). This 1064nm laser light comes out of the NdYV04 (neodymium yttrium vanadium oxide) crystal and is then shot into a second crystal (containing potassium, titanium, & phosphorus, usually called KTP) that doubles the frequency to 532nm - the bright green color you see. This light is then collimated (focused) by a lens and emerges out the laser's "business end". Just before the lens, there's a filter that removes any stray IR (infrared) rays from the pump diode and the neodymium crystal. You don't want that stuff in your green beam, trust me. /ubbthreads/images/graemlins/smile.gif 

This is why green diode lasers are so much more expensive than red ones. Lots of itty bitty parts, and they all need to be aligned by hand. If the polarisation is "off", one or both crystals need to be turned. With red diode lasers, you just slap in the diode and slap a lens in front of it.


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## korpx (Aug 1, 2004)

*Re: Why Green Lasers Soo Expensive as compared to*

Hiya,

I'm no expert but if you check out the image on the link below you can see some obvious differences in the electronics but even more so in the optical section of the two lasers.

Why the green laser needs all those more optics I do not know but it sure does give a hint why green is so much more expensive than red at the moment.

thinkgeek: green vs red laser


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## ViReN (Aug 3, 2004)

*Re: Why Green Lasers Soo Expensive as compared to*

Thanks C /ubbthreads/images/graemlins/smile.gif

Now i Know why .... so another question to add... Who makse Brightest / High Power Green Lasers & What about the Red Ones (Quality preffered to cheap chinese  )

-ViReN


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## ViReN (Aug 3, 2004)

*Re: Why Green Lasers Soo Expensive as compared to*

korpx ... Thanks /ubbthreads/images/graemlins/smile.gif

It was a visual representation what C said /ubbthreads/images/graemlins/smile.gif

Great information, thanks again

-ViReN


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## Frangible (Aug 31, 2004)

*Re: Why Green Lasers Soo Expensive as compared to*

So what would happen if you removed the neodynium crystal, but kept the KTP frequency doubler in? Would it be shifted to a more blue-like color? Or is that wavelength not sufficient to activate the KTP crystal?

EDIT: My bad, 404 nm is violet to the human eye, not blue.


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## The_LED_Museum (Aug 31, 2004)

*Re: Why Green Lasers Soo Expensive as compared to*

To the best of my knowledge, KTP (potassium titanyl phosphate) has a very narrow acceptance band; I don't believe very much will happen if you expose it directly to the 808nm laser radiation from the pump diode.
If this combination generates any 404nm radiation at all, it will be very, very weak; probably a few microwatts maximum.


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