445 nm & Astronomy

[Down with Umbrella]

Oops chaoslord I just noticed your edit.

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.

Hmm regarding use for star pointing. Would it be fair to say a home build dvd diode salvage would be just as effective and comparable as the opnext 638?

What I'm saying is it worth the extra money building an opnext diode build when you could just use a 650nm diode. They tend to have an output of 170-200mW

However in theory the 638nm could be slightly more visible to the human eye and with 30mW more. In the scheme of things this might be negligible.
It would be nice to compare two builds in the op application.
Seoirse009 project for you!

 

[BowtieGuy]

I think it would probably be fine, maybe even better for serious star pointing. I like mine, but it may be too bright for actual astronomy use.
I checked the "relative laser beam brightness calculator", and it shows that 650nm at 200mW is 44% as bright as 232mW of 638nm.
At the very least, you'd have a nice little 650nm to play with, and some money in your pocket!

 

[blasterman]

As an ex amatuer astronomer I can tell you with certainty that any generic greenie in the 20-40mW works great for star pointing. Next choice is the common 200mW red. Both are cheap and common.

Last choice is 445-450nm. By the time you hit visible power levels compared to the greenie you have a potential eye hazard if you strike a reflective object and they just suck batteries faster.