right here I have a green laser pointer that I bought online. there's a good chance you've
seen one like this before, and in fact a lot of you probably own one of these. now I have mixed
feelings about these things. I mean yeah they're cheap, and they can be pretty educational, but
they do have some big problems. for one, they're often substantially stronger than advertised,
and yes this is a bad thing. I realize how ironic this sounds coming from me, but I mean these
things are sold as toys, so most people buying them have no idea how dangerous they can be to
the eyes. another big issue is that they can leak a dangerous amount of invisible infrared light,
and this can even happen from pointers with a dim green spot. this stems from the fact that they're
driven by a powerful infrared laser diode that powers a separate laser crystal, and then the
output of that is fed through a frequency doubling crystal to make green light. super interesting
physics really, just done here in a sloppy way that makes them dangerous. I'm not going
to spend this whole video talking about how these can burn your eyes out since I've already covered
the topic in a few videos already, but these can burn your eyes out! blinding risk aside,
these laser pointers can be a great educational tool. assuming you get one that's actually under
the five milliwatt power level they're supposed to be, they're great for demonstrating a bunch
of cool phenomena like refraction, diffraction, fluorescence, animal behaviors, and plenty more.
these blursed devices have stimulated scientific curiosity in millions of people around the world.
I mean seriously, my first green laser pointer changed my life! as a testament to these dangerous
little devices that have sparked curiosity in so many, i want to make a ridiculously huge
version of one of these. I mean it may not be the smartest thing I've ever done, but it should be
really really cool. so how do I go about scaling this up? well one way would be to simply scale up
every single component inside, but that's probably not the best approach. it turns out the technology
in these laser pointers is actually pretty old as far as lasers go. handheld green laser is driven
by a powerful infrared laser have been around for 30 years, and the idea of diode pumping goes back
to their early 60s. more recently, laser diodes that directly emit green light have
become available. I built my first handheld laser based on one of these nine years ago,
and in the past few years they've become available in commercial laser pointers. I like the idea of
a direct diode version for a lot of reasons, but the biggest is that I recently acquired
this terrifying piece of technology. this right here is a high-powered green laser diode array.
thanks to Biggie cheese and some sketchy operation deep in the heart of China, I was able to get my
hands on this. check out those scratched off part numbers. nothing suspicious there right? even more
hilarious is that the manufacturer denies that these even exist, so you know it's got to be good.
I have been waiting for years to get my hands on one of these things. in fact, my insane 100 watt
handheld laser build was based on similar cursed laser tech. I figured a green version of this
was inevitable given enough time, and close to three years later, it's finally here. obviously,
this thing is perfect for the mega scale laser pointer. since laser diodes are ridiculously
easy to kill, I guess I should probably run this thing on a bench supply to make sure it actually
works before I try building anything with it. alright here goes nothing. wow that is a lot of
light! I'm only giving it a fraction of its rated power there too, that's insane! this is going to
make the brightest portable laser I've built yet, and that's saying something. if you look closely
there you can see all the individual beamlets that make up the overall beam. that looks really cool.
ow! well it looks like my beam stop is about to catch on fire so I better kill it.
okay so the array runs fine on a bench supply, but how am I gonna power in the pointer? I mean it
takes like a hundred volts and I'd much rather not use a big string of batteries to get that kind of
voltage. hmm. I've always said that most problems in life can be solved with very powerful lasers,
but I don't have the laser working yet! this means I have to go with the next best option,
and that's microwaves. I've built a ton of fun stuff using microwaves over the years like Tesla
coils, coin melters, and even EMI testing devices. these were all based on classical microwave ovens
which have barely changed at all since they were invented over 70 years ago. now there
really isn't anything in these I can use to power my laser array, at least for something portable,
but it turns out there is a more modern microwave option that can. this right here
is an inverter microwave oven. it doesn't really look any different than a normal microwave but
it is a lot lighter. the reason being is that the heaviest part inside, the transformer,
has been swapped from a clunky iron one like this to a much smaller ferrite transformer.
I've opened this one up to show the fancy circuitry inside, but first I must say it,
the inside of any microwave oven is extremely dangerous. out of all the parts and materials that
get used by science hobbyists, none of them have the kill count of the microwave oven transformer.
seriously. one mistake with one of these and you're dead before you hit the floor. anyway
here's that cute little flyback transformer inside of this inverter oven. they're only a fraction of
the size of a typical microwave oven transformer like this, yet they still deliver the same power,
which is actually pretty terrifying. now the reason they can do that is because they're
switching at a frequency that's about 500 times faster. unlike normal microwaves, these
inverters are switched with a solid state circuit, specifically in a flyback converter configuration.
along with making them lighter, this makes them more efficient and also has the benefit of giving
true power control when cooking food. this flyback transformer will easily be able to power the laser
array, but it is going to need some modifications, as well as a new driver circuit to run it.
it's funny because if you try to run one of these open circuit in flyback mode, the voltage gets
too high and causes the windings to arc over which destroys it pretty much instantly. now in theory,
it probably wouldn't be that hard to get one of these inverter ovens to play music with a
microwave beam itself, but maybe I'll save that for a different video. alright so what's this
abomination? well, I've made a prototype drive circuit using a microwave flyback as a boost
inductor, along with a mosfet and 555 timer, and because this thing is so unbelievably cursed,
I'm testing it with some cheap LEDs before you know, hooking it up to my very fragile and
expensive laser array. and it works! so that means it's time for the real magic to happen [Music]
[Music] [Music]
[Music]
and here's the completed laser. it's not exactly the most elegant thing I've ever built,
but it's definitely the brightest. now i'll be honest, there really aren't many valid uses for
something like this because it's dangerous in nearly every single way possible. the blinding
risk is off the charts. the drive circuit can deliver a lethal amount of voltage and current.
the unprotected lithium pack inside might explode if something shorts out, and the beam itself is
a huge fire hazard. I mean really, the fact that it wasn't illegal to make is pretty much my only
justification. now regarding the whole fire hazard thing, ow! I actually consider this a
benefit. with a normal sized green laser pointer, it can be hard to light a match, even with the
overpowered ones. now can this laser light a match? well duh but let's test it out anyway.
very cool. I love how the smoke looks in the beam there.
Let's test it out on some other stuff like this paper bag here. yep, it lights it on
fire super easily. interesting how the dye in the bag colors the flame a bit green there.
let's try some thin plastic. hah it shoots through it pretty much instantly. what a great
metaphor for what it would do to your retinas if you weren't wearing goggles when using it.
here's some newspaper that's been dipped in a lithium chloride solution. mmm lithium.
this is always a fun one. here I have a celluloid ping pong ball. until recently,
ping pong balls were made out of highly flammable Nitro cellulose but nowadays they're usually made
from much less chemically exciting polymers. how unfortunate. speaking of nitrocellulose,
let's try that with a much higher nitrated form like in this flash paper.
yup, gone pretty much instantly. how about some balloons?
that never gets old. how about some flammable liquids? well, the laser can't actually light
them directly. since it's typically the vapors from a flammable liquid that burn, this means the
light passes straight through without heating it up. short of electric field ionization with like a
million watt laser, the only way to light this on fire is indirectly like with these matches here.
you gotta admit though, the effect is still pretty neat. right here I have a Crooke's radiometer.
inside there's a set of vanes that have one dark side and one reflective side, and they sit on a
spindle that's free to rotate. when exposed to a light source, the vanes on the radiometer spin
due to differential heating of the gas across each side of the vanes. so what happens when I
blast it with this huge laser? no surprise there, the vanes spin extremely quickly. it's probably
not great for the radiometer to be blasted with so much light there, but it is pretty awesome. I know
I said this thing doesn't have many legit uses, but here's one. I have some reactive chemicals
mixed on that microwave I'm scared to get close to, so I'm going to blast them with a laser
not exactly OSHA approved, it does get the job done. I can use the laser in place of scissors
too. the laser slices this electrical tape with little effort at all. how convenient.
if you're willing to call this thing a laser pointer, then it's by far the brightest one ever
made, hands down. it's six thousand times stronger than a normal laser pointer, and in fact it's
actually 60 times past the limit of the highest laser danger rating of all, which is class 4. that
being said this is not the most powerful portable laser I've built. at 30 watts of output power,
it's actually less than a third of the output power of my 100 watt blue laser build. even so
the green laser is substantially brighter, nearly four times brighter going off raw lumen output.
this is due to the fact that the eye is much more sensitive to green than blue. interestingly,
both of these lasers use roughly the same amount of input power, which means the green laser is
quite a bit less efficient. in fact green laser diodes and LEDs in general are not very efficient,
and this is currently an unsolved problem in engineering called the green gap. solving this
problem will lead to more efficient lighting with better color rendering than current LED options.
anyway I still haven't tested all of this Laser's burning capabilities. by sticking a lens on front,
I can dramatically increase the power density at close range. check out what it can do to a
block of wood now. it's hard to see it because the beam is so bright, but the wood is shooting
out a jet of fire where the beam hits it. gotta love some good old-fashioned pyrolysis.
this highly concentrated beam makes for some nice laser engraving. since the laser
pointer is so huge, it's easier to move the piece of wood in the beam than it is
to move the laser pointer itself, which is kind of awkward. now that being said,
I've done enough writing with huge lasers at this point that the outcome is more legible
than my normal handwriting. think it can melt a piece of soldering wire?
well that was easy. let's try that again with much thicker soldering wire meant for plumbing.
the melting metal there reflects most of the light that hits it so this process isn't very efficient,
and that beam that's being scattered around is downright terrifying. the burning flux core looks
pretty neat though so I guess it's worth it. oh there it goes! nice. let's try burning a CD. not
gonna lie, I miss the days of receiving these free AOL frisbees in the mail. I don't miss the days of
dial up though. oh cool the CD is literally on fire. let's try chopping the base off this cup.
honestly I think this would have been faster without the lens. it's nice to see that this
laser pointer doubles as a laser cutter as well though. a candle seems like an easy task,
so let's try that out. yep no problems there. the melting wax makes some really
cool patterns when the beam hits it. in fact, let's try shooting through the entire candle.
piece of cake. here I have an old camera. yeah yeah a starving kid could eat the camera I get it,
but this thing barely works as is, and I'm curious what it would look like by blasting
the laser straight into it. well I can definitely hear popping noises so that's gotta mean something
interesting is happening. here's what it looks like from the camera's view. the first blast
didn't do that much to it so I gave it a good long blast for good measure. it's funny because
I blinked several times while editing this footage because the idea of getting hit with a laser like
this without goggles is so horrifying to me. now honestly, the camera held up pretty well
to such a powerful laser being blasted directly into the lens, especially considering I've had
a camera destroyed by indirectly viewing the beam of a laser of lower average power. that laser was
Q-switched though so the peak power must play a much bigger role here. now even after several
seconds of direct exposure into this camera, I can still see out of it, although the image is
quite distorted. interesting. let's go ahead and cook that LCD screen for good measure.
yeah that actually gave a more impressive result than shooting it into the lens. oh it looks like
the camera doesn't want to close the lens anymore. rip in Peace Camera. earlier I talked about the
low efficiency of green laser diodes, but I want to point out that the efficiency of the
drive circuit in this thing is actually my best yet at 94 power conversion. now that being said,
it's probably the worst laser diode driver ever made that actually works as intended. I'm a fan
of using simple analog circuits and that's why I wanted to base my circuit on the 555 timer. I
also wanted to use a flyback topology because that's what the original microwave oven used.
well, it turns out, these two requirements are not very compatible at higher powers. I could
only get it to about half the output power I needed before my 1200 volt FET would avalanche
over. I could have just ditched the 555 and used a fancy flyback controller at that point, but
where's the fun in that? I ended up degapping the microwave transformer core and adding additional
windings to use it as a big inductor in a boost converter. repurposing the 555 circuit for this
was straightforward, and I easily achieved the 115 volts at roughly 2 amps I needed. however when I
stuck a current limiter in there to protect the laser array, everything fell apart. I'm using a
40 volt rated chip for this in 115 volt circuit, and although that may sound dumb, the actual
drop across it in operation is only a few volts, and it's a method I've gotten away with numerous
times in the past. however, I kept killing it on startup, and I realized it was because there's a
short window where the filter caps are charging where the voltage across it actually exceeds
the limit there, so I ended up just bypassing it for this brief moment there with this TVS diode,
which for the record, is an extremely cursed workaround because it just dumps this startup
pulse into this extremely sensitive laser diode array. now the the existence of this filter cap
here actually does prevent the laser diodes from eating that pulse, and in reality, by the time
these things are at threshold, the current limiter is actually already acting in regulation there.
now in hindsight, the the soft start on this power mosfet switch probably would have prevented this
from being an issue in the final build, but eh whatever. the TVS diode only solved one of the
problems though. for whatever reason the existence of the current limiter caused the circuit to start
screaming and draw huge amounts of current, as the 555 oscillator would drop into the audio
range. I racked my brain for longer than I'd like to admit trying to figure this one out, but what
ended up fixing it was moving this capacitor about a centimeter closer to the 555 chip. yep,
simply moving this capacitor a centimeter was able to kill whatever weird feedback loop was
being created. classic power electronics design moment right there. it's such a great field, but
man it's so stupid. it's funny because if you read the data sheets on some switching controllers for
circuits like this, they'll tell you to not even attempt to build a circuit on protoboard due to
the high frequencies and high parasitics involved. however I did it, and it worked, so fight me.
well that's about all I have for you today, so until the next time, stay safe and happy lazing!