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frequency doubler crystal?

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LAN_403

Shrad

Tue Mar 15 2011, 04:27PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

you can find stock KTP crystals for doubling 1064nm to 532nm easily

what you may find to double 1064nm to 532nm, but it's harder and for greater powers, is LBO (lithium triborate) which is more efficient and has better damage treshold

BBO and LBO are also used to double IR light and get 473nm or 457nm, but they are more difficult to find, and require massive knowledge and tools as the cavities are really hard to get to lase (less gain, narrower bandwidth, polarization sensitive, temperature tuned, and so on)

keep in mind that a nonlinear crystal has to be cut along a crystaline axis matched to a temperature, a wavelength and many other parameters

KTP is used for green, yellow and red (yellow is usually SFM, sum frequency mixing, 1/1321 + 1/1064 => internally doubled => 590-ish nanometers)

LBO is used for UV to green

BBO is used for UV to green also, but essentially in external cavities with modelocking

there are many other crystals like KNBO3 for UV to blue, LiLO3 for IR (1550nm), and the like...

the best way to get used to laser construction is a red or blue diode with optics, then constructing a low power green from basic parts, then finally the medium power green (between 100mW and 500mW) from separate crystals

for more power, a linear cavity is not enough, you need a L-fold, Z-fold or ring cavity, which is unaccessible even to most of the experienced laserists

one day I tried doubling a 976nm IR diode to 438nm using a KNBO3 cut and coated for that wavelength... not to say I never managed to do so

if you want to get in the field more deeply, consult photonlexicon.com where you will learn it from the scientific point of view, but if you only want a big burning laser pointer they will flame you

any accident with such pointers will make legislation worse than it is and we, laserists, will not be able to obtain lasers anymore

this is the main reason laserists from lasershow forums and the like flame so much the pointer guys, as they don't seem to understand some information the former give them about security

otherwise, lasers are a wonderful thing if you don't limit to the burning side ^^ plenty of physics, light, high voltage, vacuum, power...

just use them wisely ;)

haxor5354

Tue Mar 15 2011, 09:44PM

Registered Member #2063 Joined: Sat Apr 04 2009, 03:16PM
Location: Toronto
Posts: 352

no laws against chemical lasers yet right?

Shrad

Tue Mar 15 2011, 10:44PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

there are

chemical lasers are mostly flash-pumped, or argon pumped

flash pumped lasers are pulsed and each pulse is in the kilowatt to megawatt range, depending on laser power

there are some abilitations needed to use such lasers legally as even a specular reflection of such a pulse would be powerful enough to cause retinal damage

I have no special knowledge of these laws, but they exist and you can find some documentation on sams laser faq for instance

there are also pulsed lasers like the TEA or nitrogen lasers, but you need a liquid dye to get visible wavelengths, and despise their dim look, the pulses are also really powerful, kilowatt range

I have a nitrogen laser head I need to rebuild, it needs 20 nanosecond pulses of says 20kv with corona pre-ionizing of the gas... maybe one day I'll have time to do it, but there are more projects I have to complete

first, a tesla coil, then a 2kV 100mA power supply for my HeCad lasers, then the nitrogen head... and no time to work on this

Dr. ISOTOP

Wed Mar 16 2011, 04:04AM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

There are no laws against the ownership/use of Class IV lasers (yet).
@OP: I challenge you to build a working chemical laser. Not gonna happen.

Shrad

Wed Mar 16 2011, 08:09AM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

yes, there are no laws about using it personally, but for things such as powerful pointers or YAG lasers in handheld units, if you take them with you in the street and point it to things, you are subject to be arrested, the device to be confiscated and you could be charged as they are considered as weaponry in most of the countries when they are over class 3A

anyway, I think there is much more fun expreimenting at home than pointing at planes or cars...

lately I crossed a car of young idiots on the highway, pointing a green laser at every car... if I had the opportunity I'd have done anything to scare the crap out of them and make them stop... they were targetting the cars mirrors, silly them

Dr. ISOTOP

Wed Mar 16 2011, 04:05PM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

In the United States you could be fined for using a Class 3b or higher laser without proper safety precautions, but no more than that.

Shrad

Wed Mar 16 2011, 05:25PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

in saying "laws against" I was meaning all that sort of things, like fines, sues and the like...

English is not my mothertongue so sometimes there are confusions spreading in the texts ;)

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