whats the difference between mw and nm?

i know nm is the wavelength which determines the color our eyes interpret, but is mw the amount of power that goes towards the laser module? so in other words the higher the mw the brighter the laser?

Yes.

Laser light is electromagnetic radiation, like light, radio, X-Rays...

A signal can be expressed in wavelength OR frequency. Light (lasers) are usually expressed in wavelenth -> nanometers... a nanometer = 1 billionth of a meter.

The FREQUENCY of light is measured in terahertz ... trillions-of-cycles-per-second... which would be cumbersome, so I guess just referencing the wavelength is easier.

Wavelength; here is a snippet from a chart I saved:

Wavelength nm, color, type
--------------------------------------------------------------------
405 violet diode laser
441.6 He-Cd violetish blue
445 violetish blue diode laser
458 deep blue DPSS
473 turquoise-blue DPSS
488 main green-blue argon wavelength
532 green DPSS
543.5 green He-Ne
593.5 orange-yellow DPSS
594.1 orange-yellow He-Ne
612 red-orange He-Ne
632.8 red common He-Ne
635 less-common red diode laser
647.1 red krypton laser
650 common low cost red diode laser

Click to expand...

milliwatt = 1 thousandth of a watt. So a 1000mw laser = 1 watt.

i see, and for each nm, there are different brightnesses? like 405 violet diode laser 10mw, vs 405 violet diode laser 50mw

wavelength is also what will affect the brightness of what you will see
example.
532nm green diode 50mw
808nm infrared diode 1w
because our eyes only see up to 700nm (apparently) the green laser will win in terms of brightness.

And yes there are different powers for each diode, 10mw vs 50mw the higher the power on that single wavelength means more brightness

Hope that helps and hope im right

zipzappydude said:

but is mw the amount of power that goes towards the laser module? so in other words the higher the mw the brighter the laser?

Click to expand...

When we talk about power of a laser (normally in mW=milliwatts)
it's the power of the light that comes out of the laser.

It can be measured by an LPM.

With DPSS lasers there is an amount of unwanted IR light that emerges the laser too if not filtered.
Normally (or at the good lasershops) the amount of IR-power doesn't count to the measured power of the laser.

And yes, from the same wavelength higher mW means brighter laser.
Just with the look of the eye the quadruple of power seems to be about double as bright.

zipzappydude said:

i see, and for each nm, there are different brightnesses? like 405 violet diode laser 10mw, vs 405 violet diode laser 50mw

Click to expand...

No.

Wavelength has no direct effect on brightness. You can get a 1 mw 660nm red, or a 200mw red, or a 380 mw red... there is supposed to be a new diode out soon that maybe can produce 500mw red. Some HugeBrain MadScientist might some day craft a zillion watt red and poke holes in the moon.

You can get different powers of green, violet, blue, yellow, infrared...

It's just that for different wavelengths, there are different TECHNICAL levels of difficulty in MAKING the diode or the DPSS.

Green DPSS is somewhat difficult. They get hot. They are complicated. Thats why you only see up to 200mw in most cases, or an occasional one that is higher than that.

There was a breakthrough about a year ago that resulted in 1 to 2 watt blues (445nm). But that is NOT a direct function of the wavelength per se... it has to do with how easy or hard or complicated the DEVICE ITSELF is to manufacture.

(EDIT) Yes, Xuaodian has a point that I forgot to mention; your eyes are most sensitive to green, and LESS sensitive to blue, violet or red. So milliwatt-for-milliwatt, greens will "look" brighter, even though they really aren't.

I have a 200mw green that is very bright. I can see the beam really well.
I have a ~380mw red, almost TWICE as strong as the green, but the beam itself "looks much fainter" than the green.

so if i was looking for a good durable blue laser, probably 445m, would a 50 mw be ample? im looking to make a black room bright blue with a single click

Contradicting myself here but anything above 5mw you should invest in some laser safety glasses, your more likely to find a 1w> 445nm laser cheaper then a 50mw as there is a certain projector where the diodes get harvested in big quantities.
Also a laser is focused light (not something for flooding rooms in light), if you are looking to fill a dark room with light there are some outrageously powerful leds out there.

zipzappydude said:

so if i was looking for a good durable blue laser, probably 445m, would a 50 mw be ample? im looking to make a black room bright blue with a single click

Click to expand...

This is impossible to answer.

At what point do you consider a room "bright blue"?

What are you shining it on to? A black wall will reflect very little light, a white wall will reflect the majority.

I know someone has already told you this in another thread and I dont mean to beat a dead horse but you sound like you need to read a lot more before you start posting any more questions. You are not the first person to come here with limited knowledge. Many members did not join as experts and have asked these questions many times over in the past. Just type key words into the search bar and absorb all the information you can.