520nm v. 532nm

olympus mons said:

Whats your budget?
Does it have to be 500mW? (Seems pretty high for star pointing)
Does size of host matter?
Focus able or fixed focus? I'd recommend fixed unless you think you're going to try to burn stuff.
Preferred duty cycle?
Do you want any Safety features such as delay, shudder, key or pin?
Type of switch, rear clicky, side momentary?

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budget is 400$ max. (though less is better)
500mW is preferred. not required.
I just want to ge able to point with only one hand, safely.
i'm not too big on optics and lenses you decide. part of that 400$ can go to come optics if reccomended.
duty cycle: 1 on : 1 off preferably, rated for 3-5mins.
I'm the only one handling this laser, so I only require a switch, though more safety measures are welcome.
switch is open, i don't mind.

These work fine for star pointing and are less than ten bucks, usually 50mw or more.

Military 532nm 5mW 303 Green Laser Pointer Lazer Pen Burning Beam 18650 Charger | eBay

If you go for more than 100mw, I'm thinking you just want power for the fun of it, as I, because the 50mw is enough for star pointing.

Alaskan said:

These work fine for star pointing and are less than ten bucks, usually 50mw or more.

Military 532nm 5mW 303 Green Laser Pointer Lazer Pen Burning Beam 18650 Charger | eBay

If you go for more than 100mw, I'm thinking you just want power for the fun of it, as I, because the 50mw is enough for star pointing.

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how far away can the beam be seen with those?

Alaskan has some good advice, no need for more than 50~100 mW of 532nm for "stargazing".
Spend the $10 on something similar to what he suggested, and then spend the rest of your budget on a high power unit of your choice for beam visibility.

For me personally, I like the red (638ish) wavelength at 150~250 mW. It's not the standard wavelength used for pointing out stars, but I find it's easier on my eyes.

Alaskan said:

My 1.4 watt 520nm flashlight, but it's divergence is far lower than any 532nm laser pointer using a normal 6mm diameter lens

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Alaskan, I know you have had them both side by side before and I can't remember the thread, but just from memory how close is the 07E in perceived brightness compared to the 7475?

I'm really enjoying my Custom Osram 515nm. It's a very nice color and at 5mw I can see the beam clearly at night. I'd highly recommend it if you are in the "build it" kind of mood.

A low power single mode 638 red laser would work fine too, once your eyes are adjusted to the dark because it will be far dimmer than green at the same power level but I'd definitely only use a single mode red, the multimode reds *might* spread out too fast unless you use a beam expander with them, IMO. BowtieGuy, is your red 638 a single mode? Maybe I'm wrong about that, but for pointing at a single little star in the sky I'm wondering if multimode laser diode pointers have a sharp enough beam for that or not. One thing I do know for sure, single mode diodes of any color have such low divergence you don't need a beam expander with them.

At night, an expanded 3.5 watt 07E 465nm blue diode doesn't seem that much different in brightness to a green 520nm 1.4 watt NDG7475T diode, if you use the RHD relative brightness program at this URL http://lsrtools.1apps.com/relativebrightness/?nm1=465&mw1=3500&nm2=520&mw2=1400&useRaleigh=on , it shows 3.5 watts of 465nm (or is the 07E 460nm?) blue to be only 40 percent as bright as 1.4 watts of 520nm green to be, but when I'm looking at them side by side, the blue doesn't seem that much weaker.

RedCowboy, I went through my photobucket library and found that photo you mentioned:



I'm thinking the 07E can go to 465nm, but maybe it is closer to 460nm, not sure.

I would recommend the 400mW 532 Crown Upgrade by Olike. Cost is only 180$ and mine is a very nice laser with IR filter, great beam and over spec.
They do have a 500mW for 240$ but TBH, you probably wouldn't notice a major difference. I'd rather save the 60$ and buy another laser from them since they combine shipping. They have a few nice 100mW 532 for less than 40$ that would be good for when you wAnt less power like indoors.

Next choice is would suggest is laser BTB PL532. They come in up to 800mW, but will be twice as much for the 400mW compared to Olike but are better quality laser. BTB are my current favorite company. Lots of safety features like plug, key, and shudder. Shudder's are really nice for keeping the lens clean especially if you plan on keeping in your pocket. I have a 600mW that avg over 800. Long duty cycle of about 3 min compared to the Olike which is a min on off.

Those would be my suggested lasers.

I agree, my vote is for the 400mW 532 Crown Upgrade by Olike.

Or see what LC has for sale. My Evos 532 I got from her are the tightest, most crisp beams I have ever seen. Both reach 200mW. Peak and avg 150mW. By far the nicest 532 I own, but much less power than you're wanting. Maybe see of she has a Krypton in 400mW. If not see my above reccoemdation.

Alaskan said:

At night, an expanded 3.5 watt 07E 465nm blue diode doesn't seem that much different in brightness to a green 520nm 1.4 watt NDG7475T diode, if you use the RHD relative brightness program at this URL Relative Laser Beam Brightness Calculator: (465nm 3500mw) vs. (520nm 1400mw) , it shows 3.5 watts of 465nm (or is the 07E 460nm?) blue to be only 40 percent as bright as 1.4 watts of 520nm green to be, but when I'm looking at them side by side, the blue doesn't seem that much weaker.

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I have a 465 running at 3 watts and a 520 at 1 watt running in side by side laser projectors. The 520 doesn't really show off it's superior brightness until I start pumping up the fog machines and get something in the sir. Then the 520 starts walking over the 465. At that point the 520 is dazzling, even with house lights turned on.

Ha, I hear you on that, it was snowing here last week and I took my 520nm 1.4 watt output laser with a big expander on it and with the snow particles in the air the beam sure was bright! I shot it over the tops of some trees 1000 feet away (never allowing the beam to get low enough to hit anything while at the same time watching for planes) and heard someone honking their horn on a road on the other side of the tree line... Wondering if I was distracting some ones driving I shut it down, but wow, bright!

Yep, green is incredible in fog, even 100mw 532 looks like a monster in a good thick fog.

This old pic is 3 hand held units @ around 100mw, you can see them just to the left of the mirror at the base.

Do keep in mind though, since you referred to astronomy, is the laser going to be used in conjunction with your telescope [as in alignment applications where it may be on all night] or are you using it to point things out?

Since you're way up there [I'm in Florida] air is typically drier and therefore lack of moisture for particles of the beam to bounce off of. My personal experience is that for alignment at most I'll need 15-20mW at 532nm, any more its too bright. If you will be using it to point out certain deep space objects, I'd keep it at 35mW max, any higher and it WILL wash out what you're trying to find. I'm not sure if blanket heaters exist for lasers, but if the temperature falls too low you're going to have problems. I would wrap a dew heater around it

Last time I tried my 100mW 520nm it was darn near useless beyond attracting unwanted crowds. Hope your experience will be better.

Illuminum3415 said:

Do keep in mind though, since you referred to astronomy, is the laser going to be used in conjunction with your telescope [as in alignment applications where it may be on all night] or are you using it to point things out?

Since you're way up there [I'm in Florida] air is typically drier and therefore lack of moisture for particles of the beam to bounce off of. My personal experience is that for alignment at most I'll need 15-20mW at 532nm, any more its too bright. If you will be using it to point out certain deep space objects, I'd keep it at 35mW max, any higher and it WILL wash out what you're trying to find. I'm not sure if blanket heaters exist for lasers, but if the temperature falls too low you're going to have problems. I would wrap a dew heater around it

Last time I tried my 100mW 520nm it was darn near useless beyond attracting unwanted crowds. Hope your experience will be better.

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I'm thinking of getting three. I have my one that is for aligning my telescope, and two others ( green and blue) that I plan on using for an interesting take on CTF. I will, however, need a cheap source of IR diodes that are between 5 and 1 mW. I'll search for some. Preferrably at 950nm.