Beam Question (532nm)

Handheld are what he was talking about. You can find those over 200mw very easily.

J0SHUA said:

I want something that is extremely bright and visible at night (for pointing long distances), I would like to have the beam as thick as I can get it, and I'm not sure if a beam expander would do the trick but it sounds like it might help.

Click to expand...

A beam expander makes the dot more visible at range because it is smaller but it also makes the beam less visible.

I have a 10x beam expander with my 400mW 532nm handheld and while the spot is a lot smaller at long ranges the beam is much less visible, 10x the diameter means 10x less power per area.

For sky pointing the beam expander hurts much more than it helps.

Asmodian said:

A beam expander makes the dot more visible at range because it is smaller but it also makes the beam less visible.

I have a 10x beam expander with my 400mW 532nm handheld and while the spot is a lot smaller at long ranges the beam is much less visible, 10x the diameter means 10x less power per area.

For sky pointing the beam expander hurts much more than it helps.

Click to expand...

Ahhhh, okay. So for sky pointing, if I wanted an extremely bright beam, what would you advise...? Does going up to, or even over 400mw make any sense for sky pointing?

over 100mW, maybe 200mW, the beam tends to be a little fatter (from previous experience). My 100mW lazerer had a SUPER, I mean SUPER tight beam, loved it and was sad to sell it but oh well. While my HL532 450-500mW has a nice thick beam throughout. I dont know if its due to the differences in crystals used, diodes, etc.....I would think its due to the higher powered 808nm diode used but never really thought about it until now

400mW for sky pointing is HIGHLY visible and if you are doing it for star gazing or anything then I HIGHLY suggest against it. That much 532nm will DESTROY your night eyes. You wont be able to see the stars as well as a 100mW 532 or say a 300mW 650nm. 532nm is by far the WORST wavelength for star gazing/astronomy. A less visible/bright wavelength like the red side of the spectrum is way better. 300-400mW of 650 beats 100mW of 532nm for star gazing/night pointing any day. PLUS its less bright and less a chance to attract unwanted attention

J0SHUA said:

Ahhhh, okay. So for sky pointing, if I wanted an extremely bright beam, what would you advise...? Does going up to, or even over 400mw make any sense for sky pointing?

Click to expand...

No.

400mW is more then what is needed for sky-pointing. A 100mW 532nm is enough for the application, and costs only about $100, unlike the 400mW which costs upwards of $350.

J0SHUA said:

I have even seen some videos showing the beam ending and it seemed to me that different builds of the same 532nm seemed to travel farther than the others, and I wanted to know why?

Click to expand...

Have you thought that maybe it might be the camera? Perhaps the human eye is limited by the vanishing point, whereas the camera is additionally limited by the brightness of the beam as it progresses? Certainly the beam at a hundred metres away would be dimmer, and a camera may be unable to pick up a lower powered beam.

And seriously, if you wanted a laser for astronomy, don't bother with 400mW, 100mW of whatever. In fact, if you're stargazing in a dark area with little light pollution it's recommended to go for a low powered pointer in the order of 5mW or so. If you're near a city really you wouldn't need anything past 50mW.
I'd even suggest going for one of the newer 515nm lasers, even if they do cost a bit more, because they will provide more stable performance at lower temperatures.

Speaking of the 515nm lasers, how is the efficiency (of the diode)? I saw a quoted 3-5% but I'm not sure of that's reliable.

CheeseHasLeafs said:

Have you thought that maybe it might be the camera? Perhaps the human eye is limited by the vanishing point, whereas the camera is additionally limited by the brightness of the beam as it progresses? Certainly the beam at a hundred metres away would be dimmer, and a camera may be unable to pick up a lower powered beam.

And seriously, if you wanted a laser for astronomy, don't bother with 400mW, 100mW of whatever. In fact, if you're stargazing in a dark area with little light pollution it's recommended to go for a low powered pointer in the order of 5mW or so. If you're near a city really you wouldn't need anything past 50mW.
I'd even suggest going for one of the newer 515nm lasers, even if they do cost a bit more, because they will provide more stable performance at lower temperatures.

Speaking of the 515nm lasers, how is the efficiency (of the diode)? I saw a quoted 3-5% but I'm not sure of that's reliable.

Click to expand...

I had thought about that before (the camera thing), and after pondering everyone's thoughts, it had to have been an illusion, especially if all lasers no matter what wavelength or what power all have the same vanishing point.

And in all honesty, for the sake of this discussion, I had seen all sorts of different builds of 532nm, some beams look tiny and others look fat; me having no experience wanted to know how to make the brightest fattest longest beam that can be stuffed into a handheld which sounds like it will be one laser.

I also like stargazing once and a while, which sounds like this is going to be another laser..

And like many other people, I would LOVE to burn at long distances e.g., if I could pop a balloon from afar, that would be awesome (I work at a place that always has balloons around) :eg: which sounds like it's going to be another laser...

However, I really like what you said about the 515nm providing more stable performance at lower temperatures. I guess that since I live in New England, having a laser that can perform well in the cold would be a good thing. I never heard of this tho. When searching for it I had read something about a "direct diode" can withstand lower temperatures... not really sure what all that meant but it was in reference to the 515nm that you mentioned... what did you mean by the 3-5%???

Temp effects wavelength shifts; aka you will have a different wavelength at 95 degrees than you will at below freezing. FYI, nice to have a fellow masshole on the forum :beer: Not too many of us but hope you are one that stays

Im glad Im not in NE this winter, my dad is stuck there while my mom is in FL helping me after my surgery

Also- if your image has anything bright like the moon your laser beam will become quite weak in comparison in the photo

Livinloud said:

Temp effects wavelength shifts; aka you will have a different wavelength at 95 degrees than you will at below freezing. FYI, nice to have a fellow masshole on the forum :beer: Not too many of us but hope you are one that stays

Im glad Im not in NE this winter, my dad is stuck there while my mom is in FL helping me after my surgery

Click to expand...

Thanks Livinloud, I'm learning every single time I come here. I actually shut down the place I work at and have been on here reading for the last three or so hours lol. I plan on staying, it's actually kinda weird how obsessed I am about learning this stuff lol, plus, this place seems full of people who are very knowledgeable...

Yeah, you're lucky not to be here this winter, it is freakin cold... but just like NE, it's going to be 50 degrees tomorrow (like that's supposed to be nice or something) and then back to the low miserable temps we all hate. But yeah, hope your surgery went well and that you have a fast recovery! :beer:

hwang21 said:

Also- if your image has anything bright like the moon your laser beam will become quite weak in comparison in the photo

Click to expand...

This I was super curious about... I am big into photography and was thinking about doing something really cool with a bunch of different colored lasers. Then I thought about whether or not the lasers would even come out well in the picture. Is what you said true for all wavelengths, or are some better than others??? Thanks for pointing that out.

J0SHUA said:

Thanks Livinloud, I'm learning every single time I come here. I actually shut down the place I work at and have been on here reading for the last three or so hours lol. I plan on staying, it's actually kinda weird how obsessed I am about learning this stuff lol, plus, this place seems full of people who are very knowledgeable...

Yeah, you're lucky not to be here this winter, it is freakin cold... but just like NE, it's going to be 50 degrees tomorrow (like that's supposed to be nice or something) and then back to the low miserable temps we all hate. But yeah, hope your surgery went well and that you have a fast recovery! :beer:

Click to expand...

Lowest it was here was 30 degrees in the morning and then like higher 40s as the high. Today was mid 80s Not to gloat lol

Yes, I was the same way when I started. I still spend hours a day on this place. Every break at work is spent on here, after work is spent here, weekends is spent here......I do love this community! Bunch of great people, knowledgeable too!

J0SHUA said:

However, I really like what you said about the 515nm providing more stable performance at lower temperatures. I guess that since I live in New England, having a laser that can perform well in the cold would be a good thing. I never heard of this tho. When searching for it I had read something about a "direct diode" can withstand lower temperatures... not really sure what all that meant but it was in reference to the 515nm that you mentioned... what did you mean by the 3-5%???

Click to expand...

The 3-5% was a general question directed at persons more knowledgeable than me on the subject. The new diode greens are just that, new, and so the technology isn't exactly mature. They have lower efficiencies than the more well established and widely used lasers which have been around for longer.

And yes, they should provide more stable performance. Expect them to be a little more expensive though. DPSS greens tend to conk out at lower temperatures, or dim and mode-hop. I've never experienced this (I live in Australia, and it doesn't get too cold even here in Victoria) but it does happen.

J0SHUA said:

And like many other people, I would LOVE to burn at long distances e.g., if I could pop a balloon from afar, that would be awesome (I work at a place that always has balloons around) which sounds like it's going to be another laser...

Click to expand...

A laser that can quickly pop balloons unfocused isn't really going to be very safe to be waving around in a workplace. I'd advise against that. Keeping in mind that balloons at a distance will introduce a few extra factors, such as the fact that your hand will shake around a little and that will be magnified over the distance, making your dot waver around, which means that your laser will have to pop a balloon (which is an unspecified colour) faster than your hand can accidentally shift the dot. Definitely unsafe.

And at all you residents of the USA, it's going to be 43C on Tuesday here in Victoria. That's 109F. Mhmm. Boiling.

J0SHUA said:

Ahhhh, okay. So for sky pointing, if I wanted an extremely bright beam, what would you advise...? Does going up to, or even over 400mw make any sense for sky pointing?

Click to expand...

I will second what has already been said: not at all.

At 400mW the laser is much brighter than needed and drowns out the stars you point at, even the few bright ones you can see on a street lit urban night.

I would expect the amount of power that is optimal depends on the amount of particulates in the air. On a very clear night my 50mW 520nm diode laser has a faint but visible beam. This looks like a good power level for a green sky pointer to me though you could probably get away with lower power if only viewing from almost directly behind the laser.

J0SHUA said:

This I was super curious about... I am big into photography and was thinking about doing something really cool with a bunch of different colored lasers. Then I thought about whether or not the lasers would even come out well in the picture. Is what you said true for all wavelengths, or are some better than others??? Thanks for pointing that out.

Click to expand...

I do see something which hasen't been stressed as I scrolled through the thread.

Even though 50mW won't have a huge visible beam, please be careful where/when you decide to aim it at the sky. I know it's amazing to see your laser create a big green beam, I really do, but lately lasers and planes have started to become a growing conflict. The FAA has responded by recently declaring this as a terrorist threat and the consequences *if caught* are not in the least amusing. So pleeeeeaaaaseeee. Before firing it up make sure there aren't any planes, if the sky is cloudy I still wouldn't advise to do it, but you do as you please.


All I ask is that you have fun, be safe and keep this hobby alive my friend

Doesnt have to be directly at a plane, the law says at a plane or in its path of flight; which can be interpreted differently by everyone so basically NO WHERE in front of the plane. Behind it is safer but IMO if you see a plane in the sky, you don't use your laser. Make it simple and avoid issues