Diode Laser Pointers

[toobfreak]

30 years ago I bought one of the first laser pointers on the market at Radio Shack that put out a cool red dot. Can't remember what I paid for it but it has been suggested $40.00, another source suggests $80. What is cool is that it puts out a really small, sharp red dot, enough to be just perfect for in room pointing at charts and displays, but not so bright that it glares at you. Looking close at the label, the reason for the really small, sharp, clean dot is probably because it outputs only 0.8mw, which is actually perfect for its intended use. It is just perfect for driving pets crazy without being too bright or dangerous to them. The extra cool thing (now) is that it was made in Japan. Try to find one from Japan now!

It's downside is that it takes three N batteries, and after a few years, these wear out or go bad needing replacement and won't take a common battery like a AAA. Worse, everyone sells them in 2 packs, so you have to buy four batteries to get the three you need.

Recently I needed a better laser pointer which was plainly visible in bright daylight and ordered a new, stronger green laser to replace an old, really cheap green one that had died on me. Naturally, Amazon sent me a red one. But I got it at a steal with built in rechargeable Lith-ion battery built in and USB plug for only $7.98 and it puts out about 5X as much power, indoors, the red dot glares and scintillates from the brightness and outside at night, it easily projects a mile. In daylight it can be seen too if you know where you are looking for it.

So I also bought another green laser from another company because I really needed a green one and found a Class III for $25 that is probably around 50mw I think though the label says <200mw. Indoors, it hurts your eyes to look at the dot more than a few seconds and outdoors at night is like a light saber with a bright green beam placing a bright green dot easily a mile away and I'm sure much farther if I could find something that far away and had a person with binoculars to tell me they see it.

It runs on a big lith-ion battery which come with a recharging base and I got two batteries. You can also swap out part of the case and run it on two smaller lith-ion batteries or leave that part out and shorten it to run on just one. This laser actually has a key lock and keys to lock the thing so that unauthorized people can't pick it up and play with it. This thing places a bright green dot easily seen in my yard in broad daylight and I'm sure much farther, which is what I was after.

So I was going to send the new red laser back (which went up to $13 before it became unavailable) then dug out my old Radio Shack and cleaned it up (still almost like new) and doing some research, found the model number and battery type. Then I discovered I still had some N batteries in stock! They were dated good till 2015 though. So I took them out of their packaging, put three in the laser and it still works! But the dot isn't as bright as I know it should be but considering the batteries were dated good to 2015, I'm impressed it works at all!

So now I have a quandary. I have the new green laser but it is really too bright for indoors, even in daylight it is a green torch, and I was going to return the red laser to Amazon because I really don't need it and have the old Radio Shack one I like better for indoor use, but I'd only get $7.98 for the thing and if I bought new batteries for the Shack model, it would cost me more than that for the batteries! And since I rarely have need for the thing, they'd just lay around and go bad again.

So now I'm left with keeping the Shack laser because it is 30 years old, and cool, classic made in Japan and great for presentations, I'd just need to buy batteries for it which I can't use for anything else I have, keeping the other red laser from Amazon because it ain't worth returning and is much brighter, plus the new green laser which is so bright that in subdued light, you can actually see the beam going across the room, has a safety lock and came with two interchangeable lith-ion batteries and a charging base so you always have a fresh-charged battery, that I'll actually need in the upcoming future!

So I think I'll contact Amazon to return the new red laser, maybe they will say F it and tell me to just keep it, not worth their expense of paying for the return shipping. As much as I like my old Shack laser, I have no need for it enough to justify buying new batteries for it that'll just lay around going bad in the package.

Meantime, I've looked at and considered even more powerful green lasers in the 700-1000mw range that would cost at least $200 up and their beam could be seen in full sunlight which could even light matches and burn stuff, but that's a lot of bread for something I have no real need for, and frankly, those aren't safe to play with without safety goggles. My new green laser is about as bright as I think is safe to fool around with indoors with unshielded eyes and even at that, after a couple minutes, your eyes start to hurt. Really too bright to use indoors for any length of time and as a pointer giving a lecture, would have people in the front row probably falling backwards off their chair. So I may be lased out. Outside at night, this new green laser is so bright that even pointing it at the sky or distant safe surfaces, I worry that someone will be alarmed at it and call the police.

Meantime at least, I've resurrected my 30 year old classic Shack laser and I'll play with it until its very old batteries finally die again.

 

[BasicHumanUnit]

Yeah, the Green lasers are too bright for using in close proximity.
I would say 100 yards or more?

Those green lasers can make decent defensive weapons. They can temporarily (or permanently) blind an attacker.
I even heard that you can stop a Hawk from attacking a baby bird etc with them.

 

[Baron Von Murderpaws]

 

[deannalw]

I do that when startled as well.

 

[toobfreak]

Those green lasers can make decent defensive weapons. They can temporarily (or permanently) blind an attacker.

Definitely. I've considered that. Black and held in the hand, it wouldn't be very noticeable until too late. Even just flashed across the eyes for an instant even in full daylight with the green one I have now would definitely take you out blinded for at least many minutes-- more than long enough to get away or immobilize your attacker and might very well leave them with permanent eye damage, even blindness. Not a toy.

 

[Bob Blaylock]

A couple reasons why green lasers look brighter than red lasers of comparable power.

First the human eye just happens to be most sensitive to green. This is reflected in the anatomy of modern digital camera sensors, in which half of the pixels are green-sensitive, while red- and blue-sensitive pixels each make up a quarter.

Another is that because the wavelength is shorter, a green beam is much more subject to Rayleigh scattering. In a dark room, even in clean air, you can see the beam of a green laser, because of this scattering. A red laser, with a much longer wavelength, doesn't scatter as much, so you cannot see its beam unless there is dust or smoke or something in the air to scatter it.

 

[JGalt]

30 years ago I bought one of the first laser pointers on the market at Radio Shack that put out a cool red dot. Can't remember what I paid for it but it has been suggested $40.00, another source suggests $80. What is cool is that it puts out a really small, sharp red dot, enough to be just perfect for in room pointing at charts and displays, but not so bright that it glares at you. Looking close at the label, the reason for the really small, sharp, clean dot is probably because it outputs only 0.8mw, which is actually perfect for its intended use. It is just perfect for driving pets crazy without being too bright or dangerous to them. The extra cool thing (now) is that it was made in Japan. Try to find one from Japan now!

It's downside is that it takes three N batteries, and after a few years, these wear out or go bad needing replacement and won't take a common battery like a AAA. Worse, everyone sells them in 2 packs, so you have to buy four batteries to get the three you need.

Recently I needed a better laser pointer which was plainly visible in bright daylight and ordered a new, stronger green laser to replace an old, really cheap green one that had died on me. Naturally, Amazon sent me a red one. But I got it at a steal with built in rechargeable Lith-ion battery built in and USB plug for only $7.98 and it puts out about 5X as much power, indoors, the red dot glares and scintillates from the brightness and outside at night, it easily projects a mile. In daylight it can be seen too if you know where you are looking for it.

So I also bought another green laser from another company because I really needed a green one and found a Class III for $25 that is probably around 50mw I think though the label says <200mw. Indoors, it hurts your eyes to look at the dot more than a few seconds and outdoors at night is like a light saber with a bright green beam placing a bright green dot easily a mile away and I'm sure much farther if I could find something that far away and had a person with binoculars to tell me they see it.

It runs on a big lith-ion battery which come with a recharging base and I got two batteries. You can also swap out part of the case and run it on two smaller lith-ion batteries or leave that part out and shorten it to run on just one. This laser actually has a key lock and keys to lock the thing so that unauthorized people can't pick it up and play with it. This thing places a bright green dot easily seen in my yard in broad daylight and I'm sure much farther, which is what I was after.

So I was going to send the new red laser back (which went up to $13 before it became unavailable) then dug out my old Radio Shack and cleaned it up (still almost like new) and doing some research, found the model number and battery type. Then I discovered I still had some N batteries in stock! They were dated good till 2015 though. So I took them out of their packaging, put three in the laser and it still works! But the dot isn't as bright as I know it should be but considering the batteries were dated good to 2015, I'm impressed it works at all!

So now I have a quandary. I have the new green laser but it is really too bright for indoors, even in daylight it is a green torch, and I was going to return the red laser to Amazon because I really don't need it and have the old Radio Shack one I like better for indoor use, but I'd only get $7.98 for the thing and if I bought new batteries for the Shack model, it would cost me more than that for the batteries! And since I rarely have need for the thing, they'd just lay around and go bad again.

So now I'm left with keeping the Shack laser because it is 30 years old, and cool, classic made in Japan and great for presentations, I'd just need to buy batteries for it which I can't use for anything else I have, keeping the other red laser from Amazon because it ain't worth returning and is much brighter, plus the new green laser which is so bright that in subdued light, you can actually see the beam going across the room, has a safety lock and came with two interchangeable lith-ion batteries and a charging base so you always have a fresh-charged battery, that I'll actually need in the upcoming future!

So I think I'll contact Amazon to return the new red laser, maybe they will say F it and tell me to just keep it, not worth their expense of paying for the return shipping. As much as I like my old Shack laser, I have no need for it enough to justify buying new batteries for it that'll just lay around going bad in the package.

Meantime, I've looked at and considered even more powerful green lasers in the 700-1000mw range that would cost at least $200 up and their beam could be seen in full sunlight which could even light matches and burn stuff, but that's a lot of bread for something I have no real need for, and frankly, those aren't safe to play with without safety goggles. My new green laser is about as bright as I think is safe to fool around with indoors with unshielded eyes and even at that, after a couple minutes, your eyes start to hurt. Really too bright to use indoors for any length of time and as a pointer giving a lecture, would have people in the front row probably falling backwards off their chair. So I may be lased out. Outside at night, this new green laser is so bright that even pointing it at the sky or distant safe surfaces, I worry that someone will be alarmed at it and call the police.

Meantime at least, I've resurrected my 30 year old classic Shack laser and I'll play with it until its very old batteries finally die again.

Right before the GW era recession hit, tech companies were throwing away dumpster-fulls of tech, when I lived in the DFW area. One of the things I found was a 10" long by 2-1/2" diameter industrial laser that ran on a 12V gel cell battery. I have no idea what the output was, but that thing was so bright my eyes would get irritated from playing with it.

There was a lot of other stuff I pulled out of some of those dumpsters. I once had a whole pickup truck bed full of Silicon Graphics workstations, including O2, Onyx, IP30, Iris Indigo, Indy R5000, Octane, and all the IRIX cdroms to go with them. They were fun to play with, and I learned a little about UNIX on those.

 

[BackAgain]

30 years ago I bought one of the first laser pointers on the market at Radio Shack that put out a cool red dot. Can't remember what I paid for it but it has been suggested $40.00, another source suggests $80. What is cool is that it puts out a really small, sharp red dot, enough to be just perfect for in room pointing at charts and displays, but not so bright that it glares at you. Looking close at the label, the reason for the really small, sharp, clean dot is probably because it outputs only 0.8mw, which is actually perfect for its intended use. It is just perfect for driving pets crazy without being too bright or dangerous to them. The extra cool thing (now) is that it was made in Japan. Try to find one from Japan now!

It's downside is that it takes three N batteries, and after a few years, these wear out or go bad needing replacement and won't take a common battery like a AAA. Worse, everyone sells them in 2 packs, so you have to buy four batteries to get the three you need.

Recently I needed a better laser pointer which was plainly visible in bright daylight and ordered a new, stronger green laser to replace an old, really cheap green one that had died on me. Naturally, Amazon sent me a red one. But I got it at a steal with built in rechargeable Lith-ion battery built in and USB plug for only $7.98 and it puts out about 5X as much power, indoors, the red dot glares and scintillates from the brightness and outside at night, it easily projects a mile. In daylight it can be seen too if you know where you are looking for it.

So I also bought another green laser from another company because I really needed a green one and found a Class III for $25 that is probably around 50mw I think though the label says <200mw. Indoors, it hurts your eyes to look at the dot more than a few seconds and outdoors at night is like a light saber with a bright green beam placing a bright green dot easily a mile away and I'm sure much farther if I could find something that far away and had a person with binoculars to tell me they see it.

It runs on a big lith-ion battery which come with a recharging base and I got two batteries. You can also swap out part of the case and run it on two smaller lith-ion batteries or leave that part out and shorten it to run on just one. This laser actually has a key lock and keys to lock the thing so that unauthorized people can't pick it up and play with it. This thing places a bright green dot easily seen in my yard in broad daylight and I'm sure much farther, which is what I was after.

So I was going to send the new red laser back (which went up to $13 before it became unavailable) then dug out my old Radio Shack and cleaned it up (still almost like new) and doing some research, found the model number and battery type. Then I discovered I still had some N batteries in stock! They were dated good till 2015 though. So I took them out of their packaging, put three in the laser and it still works! But the dot isn't as bright as I know it should be but considering the batteries were dated good to 2015, I'm impressed it works at all!

So now I have a quandary. I have the new green laser but it is really too bright for indoors, even in daylight it is a green torch, and I was going to return the red laser to Amazon because I really don't need it and have the old Radio Shack one I like better for indoor use, but I'd only get $7.98 for the thing and if I bought new batteries for the Shack model, it would cost me more than that for the batteries! And since I rarely have need for the thing, they'd just lay around and go bad again.

So now I'm left with keeping the Shack laser because it is 30 years old, and cool, classic made in Japan and great for presentations, I'd just need to buy batteries for it which I can't use for anything else I have, keeping the other red laser from Amazon because it ain't worth returning and is much brighter, plus the new green laser which is so bright that in subdued light, you can actually see the beam going across the room, has a safety lock and came with two interchangeable lith-ion batteries and a charging base so you always have a fresh-charged battery, that I'll actually need in the upcoming future!

So I think I'll contact Amazon to return the new red laser, maybe they will say F it and tell me to just keep it, not worth their expense of paying for the return shipping. As much as I like my old Shack laser, I have no need for it enough to justify buying new batteries for it that'll just lay around going bad in the package.

Meantime, I've looked at and considered even more powerful green lasers in the 700-1000mw range that would cost at least $200 up and their beam could be seen in full sunlight which could even light matches and burn stuff, but that's a lot of bread for something I have no real need for, and frankly, those aren't safe to play with without safety goggles. My new green laser is about as bright as I think is safe to fool around with indoors with unshielded eyes and even at that, after a couple minutes, your eyes start to hurt. Really too bright to use indoors for any length of time and as a pointer giving a lecture, would have people in the front row probably falling backwards off their chair. So I may be lased out. Outside at night, this new green laser is so bright that even pointing it at the sky or distant safe surfaces, I worry that someone will be alarmed at it and call the police.

Meantime at least, I've resurrected my 30 year old classic Shack laser and I'll play with it until its very old batteries finally die again.

Long post.

 

[scruffy]

I have an idea.

Get yourself two of those little motors, the kind they use on Arduinos. Just hook the up to 5 volts so they go round and round

Then you glue a little mirror to each one, and point the lasers so they bounce off one mirror and then the other, and you can do Lissajous patterns and have a poor man's laserium.

 

[toobfreak]

First the human eye just happens to be most sensitive to green.

Sure. Mainly because this is the colour the eye was most met with developing from all of the green flora around us to sense the world with. AS such, even optics, when they are developed and tested are usually optimized for and tested at around 530 nm.

This is reflected in the anatomy of modern digital camera sensors, in which half of the pixels are green-sensitive, while red- and blue-sensitive pixels each make up a quarter.

Gee, you'd kind of think it would be the other way around with more red and blue pixels so that all of the colours come out looking even to the eye, being that the eye would need fewer pixels to see green just as well.

Another is that because the wavelength is shorter, a green beam is much more subject to Rayleigh scattering. In a dark room, even in clean air, you can see the beam of a green laser, because of this scattering. A red laser, with a much longer wavelength, doesn't scatter as much, so you cannot see its beam unless there is dust or smoke or something in the air to scatter it.

You've just explained in large part why the sky is blue, sunsets are red, and also defined the operational limits of optical microscopes in relation to the wavelength of light.

 

[toobfreak]

Right before the GW era recession hit, tech companies were throwing away dumpster-fulls of tech, when I lived in the DFW area. One of the things I found was a 10" long by 2-1/2" diameter industrial laser that ran on a 12V gel cell battery. I have no idea what the output was, but that thing was so bright my eyes would get irritated from playing with it.

There was a lot of other stuff I pulled out of some of those dumpsters. I once had a whole pickup truck bed full of Silicon Graphics workstations, including O2, Onyx, IP30, Iris Indigo, Indy R5000, Octane, and all the IRIX cdroms to go with them. They were fun to play with, and I learned a little about UNIX on those.

Gotta throw out all of that nasty old stuff in order to keep the budget as high as possible for the following year!

 

[toobfreak]

Then you glue a little mirror to each one, and point the lasers so they bounce off one mirror and then the other, and you can do Lissajous patterns and have a poor man's laserium.

Actually, I have a multi-test meter that has a component tester mode that generates that pattern at varies set frequencies so that you can graph the reactance of solid state components vs. their pure resistance to analyze their state and condition vs. an ideal, good or new part in troubleshooting and QC.

But as far as the laserium is concerned, I can either fire up a small planetarium I have for that which projects the night sky, in a room or, believe it or not, all these new lasers now come with an effects gimmick you can screw on the front which breaks up the lased beam into patterns--- as you twist the thing, you get various patterns from a rows of bright dots to a whole bunch of tiny mixed dots or anywhere in between, which I don't have any real interest in but can be fun to play with occasionally as it fills the room with stars.

All said, these pointer things are amazingly cheap for the technology compared to the old days back when places like Edmund Scientific was first introducing He-Neon bench lasers for holography.

 

[HereWeGoAgain]

I have a laser pointer that shines the shape of the middle finger.
Great fun in a crowd.

 

[toobfreak]

I have a laser pointer that shines the shape of the middle finger.
Great fun in a crowd.

That would be useful for Biden and Buttigieg's next press meetings to shine behind them or on their foreheads as they stand there lying and telling us why it took them nearly a month to respond to and even acknowledge the nation's worse ever toxic train wreck in a white, rural, straight Ohio community.

 

[Bob Blaylock]

First the human eye just happens to be most sensitive to green. This is reflected in the anatomy of modern digital camera sensors, in which half of the pixels are green-sensitive, while red- and blue-sensitive pixels each make up a quarter.

Gee, you'd kind of think it would be the other way around with more red and blue pixels so that all of the colours come out looking even to the eye, being that the eye would need fewer pixels to see green just as well.

That might make sense in displays, to have more red and blue pixels, and fewer green pixels, to allow for the eye being less sensitive to red and blue than to green. But I think nearly all modern color displays have equal amounts of red, green, and blue.

In the case of camera sensors, they have more green pixels, because they are trying to mimic the color sensitivity of human eyes.

 

[toobfreak]

That might make sense in displays, to have more red and blue pixels, and fewer green pixels, to allow for the eye being less sensitive to red and blue than to green. But I think nearly all modern color displays have equal amounts of red, green, and blue.

Perhaps the proportions of colours of each are adjusted or controlled in post-processing of how the display is shown.

In the case of camera sensors, they have more green pixels, because they are trying to mimic the color sensitivity of human eyes.

That is something I have to cogitate on, as it seems to me Bob that if the sensor is already producing more green to other colours to correct for the eye, then the eye also sees more green viewing the resulting camera images as part of its natural bias around 550nm, that would result in double indemnity. Obviously something I need to look deeper into. Perhaps a question I will post to other members of my own science forum.

 

[toobfreak]

That might make sense in displays, to have more red and blue pixels, and fewer green pixels, to allow for the eye being less sensitive to red and blue than to green. But I think nearly all modern color displays have equal amounts of red, green, and blue. In the case of camera sensors, they have more green pixels, because they are trying to mimic the color sensitivity of human eyes.

Well Bob, I did a little digging into this and was directed toward what they call a Bayer array, something I've not thought about in a long time.

I know that with the old analog CRT picture tubes, the shadow mask producing the picture elements over the phosphor were likewise: RGBRGBRGBRGB. But with digital colour sensors, the challenges are different. The explanation I found for the disparity in having more green pixels was that the redundancy with green pixels over red and blue is to produce an image which appears less noisy and has finer detail than could be accomplished if each color were treated equally, naturally as it is in the GREEN that the eye sees most of the image, and as such, why noise in the green channel is needed to be and is much lower than for the other two primary colors by doubling the pixels, as you would want, as naturally, noise in the green channel is where the eye will best see noise first and most.

And from there, it gets deeper into mathematics and other processing and filtering to suppress noise like moire patterns and the like. So I guess that does make sense.