Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Green VS 445 really??

justinjja

justinjja

0
Joined
Mar 2, 2011
Messages
692
Points
0
So this calculator Dot: (532nm 150mw) vs. (445nm 2000mw)

Shows 150mW of green is brighter than a 2W 445 is that true?

I am mainly interested in how visible the beam is shooting it into the sky at night.

I am guessing it is not right, but how much green would be equivelent to 2W of 445,

Reason for not trusting it, I have a 638nm red, I have to push it to about an amp for it to look as bright as my M140 running at 1.8A,
Both Are using the 3 element glass lenses

I dont have a laser tester but from what I have read my 445 should be under 2W and my red should easily be over 300mw
 





LaZeRz

LaZeRz

0
Joined
Feb 19, 2011
Messages
2,549
Points
63
Yes, the measurements are correct.

The 635 isn't as bright because of its horrid divergence. A single mode 635 @ 200mW would appear as bright as a multimode at around 750mW.

The thinner the beam, the greater the percieved brightness.
 
lasersbee

lasersbee

0
Joined
Sep 20, 2008
Messages
17,622
Points
113
Laser brightness is subjective....
You will need a Laser Power Meter to actually
know the power of your Lasers...

I can go to the local Highway and say.. that car is running
faster than the other one... but I would not be able to
know their precise speeds..


Jerry
 
Last edited:
styropyro

styropyro

0
Joined
Jun 13, 2007
Messages
5,410
Points
113
I think that calculator includes Rayleigh scattering, which has more of an effect at the blue side of the spectrum.

edit: It says so at the bottom of the page. :D
 
Last edited:
ekeup

ekeup

0
Joined
Dec 2, 2011
Messages
93
Points
0
styropyro said:
I think that calculator includes Rayleigh scattering, which has more of an effect at the blue side of the spectrum.

edit: It says so at the bottom of the page. :D
Click to expand...

Hehe, who reads the fine print? j/k

OK, that makes sense...

Rayleigh_sunlight_scattering.png
 
Last edited:
justinjja

justinjja

0
Joined
Mar 2, 2011
Messages
692
Points
0
So the smaller the diameter of the beam the brigher it will aprear in the air?
I would have thought that a wider diameter would hit more dust particles and apear brighter, No?

And if a smaller beam diameter is brighter, then a green will be even better then a a blue right, because the blue beams dont have the best beam characteristics do they?
 
LaZeRz

LaZeRz

0
Joined
Feb 19, 2011
Messages
2,549
Points
63
justinjja said:
So the smaller the diameter of the beam the brigher it will aprear in the air?
I would have thought that a wider diameter would hit more dust particles and apear brighter, No?


And if a smaller beam diameter is brighter, then a green will be even better then a a blue right, because the blue beams dont have the best beam characteristics do they?
Click to expand...

Depends. Bad divergence results in a less "intense" so to speak beam.

Pretty much but it depends which green. Some use multimode pump diodes.

A 100mW green with excellent divergence would appear around as bright as a 400mW green with bad divergence, example: Firedragons/o-like high powered greens.
 
Last edited:
InfinitusEquitas

InfinitusEquitas

0
Joined
Mar 27, 2011
Messages
14,125
Points
113
justinjja said:
So the smaller the diameter of the beam the brigher it will aprear in the air?
I would have thought that a wider diameter would hit more dust particles and apear brighter, No?

And if a smaller beam diameter is brighter, then a green will be even better then a a blue right, because the blue beams dont have the best beam characteristics do they?
Click to expand...

That is correct. The smaller the initial beam diameter, and the better the divergence, the brighter the beam will appear to be, since the power density of the "tighter" beam is higher, and more photons will be interacting with particulates in the air.

Think of it is as a spot light vs a flood light, or in terms of water pressure if that helps.

lasersbee said:
Laser brightness is subjective....
Click to expand...

I find this to also be EXTREMELY true.

While I'm sure rhd's calculator is accurate, it does not take into account beam diameter, divergence, and has absolutely no way to take into account individual sensitivity to different wavelengths.

To me 638nm does not appear anywhere near as bright as 445nm... but that's me:p
 
LaZeRz

LaZeRz

0
Joined
Feb 19, 2011
Messages
2,549
Points
63
InfinitusEquitas said:
While I'm sure rhd's calculator is accurate, it does not take into account beam diameter, divergence, and has absolutely no way to take into account individual sensitivity to different wavelengths.

To me 638nm does not appear anywhere near as bright as 445nm... but that's me:p
Click to expand...

Probably got to do with the sh!tty divergence. :p
 
InfinitusEquitas

InfinitusEquitas

0
Joined
Mar 27, 2011
Messages
14,125
Points
113
LaZeRz said:
Probably got to do with the sh!tty divergence. :p
Click to expand...

Even looking at the narrow edge of the beam, 500mW of 638nm does not appear anywhere near as bright as 350mW of 445nm to me.

I would LOVE to have a corrected beam in a handheld. Would probably be amazing. With the 500mW diodes coming out now, it would be a treat to have 1W of corrected power.
 
Last edited:
LaZeRz

LaZeRz

0
Joined
Feb 19, 2011
Messages
2,549
Points
63
you can get 200mW single mode 635 diodes with 660nm divergence and i've been told they look about as bright as 700mW's of multimode 635.
 
InfinitusEquitas

InfinitusEquitas

0
Joined
Mar 27, 2011
Messages
14,125
Points
113
LaZeRz said:
you can get 200mW single mode 635 diodes with 660nm divergence and i've been told they look about as bright as 700mW's of multimode 635.
Click to expand...

Interesting. I might just have to do that.

I actually got the o-like 635nm because it was originally supposed to use the optnext diode... but they switched to the mit$u because they weren't hitting 200mW with it.
 
LaZeRz

LaZeRz

0
Joined
Feb 19, 2011
Messages
2,549
Points
63
Yup. I just wish we had 500mW single mode 635's. Would be bright as hell :eg:
 
Ablaze

Ablaze

0
Joined
Oct 19, 2011
Messages
462
Points
0
I have defiantly found the chart to be off in respect to the single mode 450nms. I never thought about why, but this makes sense. It's a great tool and I don't mean to put it down in any way, but it misled me when I tried to order a 450nm.

Looks like the data table should be corrected.
 
sopark4000

sopark4000

0
Joined
Sep 29, 2011
Messages
800
Points
0
Ablaze said:
I have defiantly found the chart to be off in respect to the single mode 450nms. I never thought about why, but this makes sense. It's a great tool and I don't mean to put it down in any way, but it misled me when I tried to order a 450nm.

Looks like the data table should be corrected.
Click to expand...

Agreed. While the calculator is a good guide line I have found that IRL it's not that reliable for example with the calculator I did a comparison of 175mW of 532nm vs. 1,150mW 445nm (my DL hulk vs. my survival laser) and it says the 532 should be 2.18x brighter than the 445. In real time this is way off. As others have said brightness is very subjective from person to person but even then I have had over 10 different people compare the lasers I mentioned side by side on the same night with the same air conditions and everybody agreed that the 445 without a doubt had the brighter beam. So like I said that calculator is a nice reference tool but it definitely does not dictate what you will see in the field.
 
You must log in or register to reply here.




Top