Better Laser diode wavelength

[Jimmylee]

Hi, all
Recently, I've read a few topics about laser diodes from Topics Covered of Diode Laser in this Guide. I'm wondering if wattage matters more than wavelength or vice versa. For example is 300 mw 80nm better or 500mw 808nm . I think 80nm NUV , near ultra violet , and 808 nm is NIR , near infra red . I've heard that less wavelength (higher frequency) is better while higher wattage is better but now these two options (808nm 500mw and 80nm 300mw) are hard to choose from.

Is there any idea? Many thanks.

 

[betwixt]

They are two completely different parameters. Some wavelengths are better for some jobs and some powers are preferable over others. It isn't a trade-off or compromise situation.

Brian.

 

[FvM]

80 nm is probably a typo. Please check. As far as I'm aware of, there's no solid state emitter working in this range.

Apart from this obvious point, "better laser wavelength" is an application dependent question. You didn't yet tell a word about your application.

 

[Audioguru]

Maybe he is trying to burn an intruder or the mailman.

 

[Jimmylee]

Thank you for replies. I found a 808nm 1W but its a bit expensive for me , and it's my first cnc thing . But I found another one which was 405nm 200mw . Not sure if it's better than the 500mw 808nm but I guess more expensive = better And another weird thing I saw is that the Blue/Purple laser goggle (200-450 , 800-2000) was green , red laser goggle was blue and green laser goggle was red. Is that correct?

 

[c_mitra]

Thank you for replies. I found a 808nm 1W but its a bit expensive for me , and it's my first cnc thing . But I found another one which was 405nm 200mw . Not sure if it's better than the 500mw 808nm but I guess more expensive = better

You need to do some homework.

It is the power and the density that is important. Perhaps an IR leaser may be still better, in terms of energy efficiency. The cost of laser diodes goes up with power.

And another weird thing I saw is that the Blue/Purple laser goggle (200-450 , 800-2000) was green , red laser goggle was blue and green laser goggle was red. Is that correct?

The goggles are designed to absorb the particular wavelength. A piece of glass that is blue in color does not absorb blue light, it absorbs red light and it transmits blue light and blue is the complementary color of red. You can go to a science lab and take the absorption spectrum of that goggles and convince yourself.

There is nothing weird. There are three primary colors and three complimentary colors. But more specifically, the goggles must absorb that particular wavelength and transmit all others.

 

[KlausST]

Hi,

If I´m not mistaken some plastics (maybe metals and other materials, too) are sensitive to some wavelengths and insensitive to other wavelengths.

--> an internet search is your friend ;-)

Klaus

 

[c_mitra]

Hi,

If I´m not mistaken some plastics (maybe metals and other materials, too) are sensitive to some wavelengths and insensitive to other wavelengths.

--> an internet search is your friend ;-)

Klaus

You are right, as usual. But I do not understand why people do not like to search and get an answer themselves.

For the laser to be used in a CNC, that particular wavelength must be strongly absorbed by the material you are planning to cut. Many plastics do not absorb in the visible range (say acrylic, polycarbonate, polystyrene etc etc) but almost all work with IR very well. Metals reflect strongly (even IR) and to compensate we need to use higher power. But we have few lasers at IR wavelength and we must use what is available at high power (that means CO2). Diode lasers have short coherence length and can be useful for small work only. That is my understanding.