445 nm & Astronomy

[seoirse009]

Are 445 nm lasers good for star pointing? Also, have any of you ever tried pointing with a high powered laser before? I read somewhere that high powered lasers can increase sky glow and make celestial viewing worse.

Thanks

 

[ChaosLord]

Red is generally considered the best for star pointing, mainly because it preserves night vision. Blue and green wavelengths can easily wipe out dark adapted vision, while 650nm or even 635nm (easier to see), will not.

 

[seoirse009]

Perfect advice. I can't believe I didn't think about red at all. I use a red flashlight while viewing my star maps, so that makes total sense. Thanks again Chaos!

 

[Down with Umbrella]

Red is generally considered the best for star pointing, mainly because it preserves night vision. Blue and green wavelengths can easily wipe out dark adapted vision, while 650nm or even 635nm (easier to see), will not.

I agree anything red would nice for star pointing in a higher mW. Unfortunately the mits 500 and the oclaro 700 put out almost 1W but the divergance is so bad I think they aren't not very useful.

Maybe you can tell me about that single mode opnext diode. Visible at night? Can others around you view it?

OP Yea... The blue tends to be really bright against a very clear night sky. The benefit however would be if you were viewing the sky early(sun had just set) the 30mW greenies just aren't powerful enough to point out constellations but a solid 1.4W 445 will be visible.

Edit: greens tend to be used for star gazing because the human eye detects that wavelength best. Therefore you don't need to have a very powerful laser to get a visible beam

 

[RB astro]

greens tend to be used for star gazing because the human eye detects that wavelength best. Therefore you don't need to have a very powerful laser to get a visible beam

Agreed with Umbrella, greens are used because low powers are adequate.
I use a 20mW green.
For red you do need a slightly higher power to get a good result.

RB

 

[ChaosLord]

Maybe you can tell me about that single mode opnext diode. Visible at night? Can others around you view it?

Oh yeah. I took it on vacation this past summer to patoka lake with my gf and her family. The sky was pretty clear and there was a lot less light pollution than we were used to. I tried a few different lasers, but the sinle mode 638nm was the winner.

The beam was easily visible if you are fairly close to the laser. The only time any one had trouble seeing the beam was if they we several feet away from me.

Edit: 635/638nm is definitely better, imo, than 650/660nm. Roughly the same power (~220mW) of 650 is a difficult for me to see and even worse for anyone around.

 

[Shakenawake]

a weak green or strong red will work. I find that high powered 638 do still disturb my night adapted vision some, 650 and 660 are better, but dimmer too, needing more mW to be as bright. the oclaro single mode 638 might be perfect though, I have such a laser, it's beam is nice and visible without being insanely bright

 

[seoirse009]

Thanks for the suggestions everyone. I think I will just get them all! Haha

 

[Down with Umbrella]

I think I will just get them all! Haha

You will. It happens.

 

[mortuus]

a lower powered 445 or 450 is good also if u like color blue, but ofc a 1w 445 is not really recommended... draws to much attention to yourself haha. 405 is not bad either i can use my 100mW and dont destroy nightvision and nobody else picks it up i bet.

 

[seoirse009]

What happened to toplaserpointers.com?

 

[USAbro]

I don't even think their a brand, just a scam link but could be wrong.

 

[mortuus]

its full of weird links on it.. strange site.

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[BowtieGuy]

I agree anything red would nice for star pointing in a higher mW. Unfortunately the mits 500 and the oclaro 700 put out almost 1W but the divergance is so bad I think they aren't not very useful.

Maybe you can tell me about that single mode opnext diode. Visible at night? Can others around you view it?

OP Yea... The blue tends to be really bright against a very clear night sky. The benefit however would be if you were viewing the sky early(sun had just set) the 30mW greenies just aren't powerful enough to point out constellations but a solid 1.4W 445 will be visible.

Edit: greens tend to be used for star gazing because the human eye detects that wavelength best. Therefore you don't need to have a very powerful laser to get a visible beam

I've got one of the Opnext single mode 638nm diodes at 232mW that is great for star pointing, plenty visible, yet not excessively so. It also seems quite visible from off axis.
I think I prefer the red over green for pointing; probably because my greens are too powerful to be used in this manner.

 

[SilverFire]

I think I said this before but I am not entirely sure if deep blue light will ruin your night vision.
Most modern submarines use deep blue overhead lights to preserve night vision.
So I would assume a blue laser would be ok.

 

[seoirse009]

Thanks for the links mortuus. Bowtieguy, I agree with you about red. It makes since to me. Hey Silver, I didn't know that about submarines, I guess I should it out in the future to know for sure.