how to get specific color lasers

[bright n hot]

i'm trying to get a handle on how each color laser is constructed, and their various strengths and weaknesses, to make a choice on my first diy build. any input would be welcome.

this is what i've learned so far:
~405nm: violet color, diodes available in br burners, great burners, fluorescence
~473nm: blue color, obtained by lengthening the wavelength of a 405nm using crystals, rare unique color, not great at burning or terribly bright
~510nm: green color, obtained by shortening the wavelength of 700nm+ infrared diodes, most brilliant color to the human eye so great brightness, not a great burner
~570nm-590nm: yellow through orange colors, obtained by altering some other native wavelength diode (?), unusual colors, not great burners, not as bright as green
~650nm: red color, most common diode, not as bright as green, not a great burner
>700nm: infrared invisible beam, diodes available in dvd burners and for direct purchase, hard to work with and dangerous because you can't see the beam, not a good burner

anywhere i've got the wrong idea, or am leaving out something important about a particular wavelength, let me know. i realize burning is a difficult way to summarize a wavelength since there are so many other factors, but i am just comparing basically one wavelength of each color against each other.

is it possible to purchase diodes that emit wavelengths other than violet, red, and ir? or is every other color solely available through precision alignment of crystals that change one of those three wavelengths?

thanks in advance for any advice or input!

 

[daguin]

473nm (blue), 532nm (green), and 593nm (yellow) are all produced by pushing Infra-Red light through different crystal structure.

635nm (orangish red), 660nm (red), and 405nm (violet) are all diode type lasers

The Infra-Red lasers are diode type. There are many more than just 700nm. There are also UV lasers.

Red laser light is a fine "burner." You just need to burn "dark" material. Infra-Red lasers are magnificent burners (mostly because of the higher outputs available). All of the colors will burn. You just need to get a high enough output and get the beam focused. A 30mW green pointer that is "focused to infinity" will not burn. A 500mW focused green beam will burn your skin off

You haven't even begun to touch on gas lasers

For your first build, make a red or a violet.

Peace,
dave

 

[gotwake424]

Daguin, Glad you are back! I have a quick question tho- How much of a difference will I see between 635nm and 660nm? Will I be able to see that the 635 is more orangish without having to compare it to my 660nm red?

Thanks

 

[daguin]

Daguin, Glad you are back! I have a quick question tho- How much of a difference will I see between 635nm and 660nm? Will I be able to see that the 635 is more orangish without having to compare it to my 660nm red?

Thanks

'Tis a question for the ages . . . . . "What will 'I' see?"

I do not believe that one can "see" a difference between 635nm and 660nm without having them side-by-side. However, that does not preclude some being able to see that difference. I know that I cannot. Most people just describe 635nm light as looking "brighter" than the red laser light that they are used to seeing. Does a 632nm HeNe laser look "orangish" to you?


Peace,
dave

 

[chipdouglas]

a note about green lasers. their wavelength in the pointer community is 532 nm. and greenies are know by the process that makes them.... DPSS. diode pumped solid state.

 

[Ash]

Just so you understand what the inside of a DPSS laser looks like, here's a diagram:

The two crystals used fro green are:
Neodymium Doped Yttrium Orthvanadate (Nd:YVO4) and
Potassium Titanium Oxide Phosphate (KTiOPO4 )
The first one changes the 808nm (infrared) light to 1064nm and the second crystal doubles the frequency of the 1064nm (higher ir) light (causing the wavelength to split by 1/2) to 532nm (visible green).
Blue lasers (473nm) are similar, but use different crystals.

 

[chipdouglas]

what's and ND:yag crystal? all the info i have read on these forums says an ND:yag is the frequency doubling crystal. and the KTP is the wavelength dividing one? Help please.

 

[FireMyLaser]

If one is very curious about a how a particular wavelength looks like you can just go get a LED for cheap. Sure they are somewhat broadband but not too much. You'll easily compare the difference between a 635 and 660nm LED.

 

[bright n hot]

thanks, especially to daguin and ash! this is just the kind of feedback i was hoping for. repped

 

[Cyparagon]

The beam of a 635nm laser looks identical in color to that of a 660nm laser. The dot, however, is noticeably more orange.

 

[pullbangdead]

what's and ND:yag crystal? all the info i have read on these forums says an ND:yag is the frequency doubling crystal. and the KTP is the wavelength dividing one? Help please.

Nd:YAG is neodymium-doped yttria-alumina-garnet. The crystal itself is a crystal composed of a mixture of yttria (yttrium oxide, Y2O3) and alumina (aluminum oxide, Al2O3). When you do it right and very carefully, one of the crystal habits that yttria-alumina can take is commonly known as garnet, which has the chemical composition of Y3Al5O12. I've attached a phase diagram of the yttria-alumina system, and you can see the line of composition where YAG can form. YAG is a cubic crystal structure, and the neodymium typically replaces yttrium in the crystal lattice. This gives energy levels between which electrons can oscillate, allowing light to be emitted, and allowing lasing. With the YAG, there's no frequency doubling or anything like that, you're just optically pumping the laser.

KTP is then a non-linear crystal, which doubles the frequency of the light that is emitted by the YAG laser. Non-linear crystals are a much more complicated subject unto themselves.