Insane Infrared LASERs! | Banned eBay seller's laser breaks my record | How many photons a second?

Added: 2026-06-01

[00:00:02]Hi!

[00:00:03]Time to get a little more crazy than usual for me.

[00:00:07]I have an invisible, infrared laser that I am pretty sure will break a current record on my laser rainbow.

[00:00:13]I will test how close its power and wavelength are to the eBay-listing.

[00:00:18]And also explain why this high a power is extra impressive for an infrared laser.

[00:00:24]Here's a brain teaser for you.

[00:00:26]Which laser emits the most photons: A 500 mW violet laser or an infrared of half the power, 250 mW?

[00:00:36]Let's find out!

[00:00:40]When experimenting with a laser, wear safety glasses suitable for its wavelength and power output.

[00:00:46]Especially when using invisible, infrared lasers.

[00:00:50]And don't breathe any smoke.

[00:00:55]Let me warm up with a laser that eBay recalled for safety reasons.

[00:00:59]A first for me and a bit of a paradox since this should be the weakest of the infrared lasers I have bought on eBay.

[00:01:06]How does this policy-violating laser perform?

[00:01:12]Its wavelength is around 975 - 976 nm.

[00:01:17]Great - close enough to the advertised 980 nm.

[00:01:21]Its power is advertised as 1 mW and under 5 mW - naughty naughty.

[00:01:27]But to the knowing there are indications in the listing of 30 mW.

[00:01:33]Here's how strong it really is.

[00:01:45]23 milliwatts.

[00:01:47]I thought it would be a little more?

[00:01:49]But then I realized something.

[00:01:52]While the two batteries I put in the laser are not heavily used, they are not factory fresh either.

[00:01:58]Second try - this time with brand new batteries.

[00:02:07]OK - now it is 27 mW. Closer to 30.

[00:02:12]A good example of how important fresh batteries can be for max power.

[00:02:17]But all in all, I don't feel like 27 mW at 976 nm stands out enough to qualify for the laser rainbow.

[00:02:26]Though for future experiments it is just nice to have an infrared laser that is not a fire hazard.

[00:02:33]Next up is a laser I do expect to set a new record - at 808 nm near infrared.

[00:02:40]The current recordholder outputs a respectable 178 mW.

[00:02:45]However, you might have seen I have a 370 mW laser at around 808 nm: The hair removal laser!

[00:02:54]Lots of info about lasers in that video - such as the little but important detail to know about in this warning.

[00:03:01]But the laser beam from this one is highly divergent after a fixed focus spot and it can only be on for like 3.5 seconds at a time.

[00:03:11]So again, I don't feel like the beauty blasting laser truly qualifies for the laser rainbow.

[00:03:17]My strongest 808 nm laser is actually much, much stronger.

[00:03:22]The pump diode in the Laserglow Hercules is a 2500 mW 808 nm laser diode made by nLight.

[00:03:31]That one would stand out on the laser rainbow as the third strongest.

[00:03:36]I just don't have access to its internal, infrared beam.

[00:03:41]What I do have is this eBay laser.

[00:03:44]Focused to a small spot, it burns electrical tape so fast that the video looks sped up.

[00:03:50]But this is real time.

[00:03:52]Surely, this will beat the current 178 mW record and even the hair frying laser.

[00:03:59]Going by the listing, this laser is somewhere between 1 and 1000 mW.

[00:04:05]Time for a reality check.

[00:04:14]Its wavelength peaks at 803 nm.

[00:04:17]That's fine - within a reasonable spec of +/- 5 nm for a direct diode laser without temperature control.

[00:04:25]How powerful is it?

[00:04:43]Hm. Max 614 mW - with a battery charged to 4.1V.

[00:04:50]I have mixed feelings about that.

[00:04:53]Second try for good measure.

[00:04:55]This time with the laser power meter set to a manual range of 2W to avoid the annoying max bug in it.

[00:05:07]Alright - 614 mW it is.

[00:05:11]I was hoping for something closer to a full watt.

[00:05:15]Maybe they had to dial it down in power to avoid overheating in this cheap laser host?

[00:05:20]5 nm under nominal for a direct diode laser can be an indication of a cold-running, underpowered diode.

[00:05:28]More on the subject in an earlier video of mine.

[00:05:32]With that said, over 600 mW of laser light is always a lot.

[00:05:37]I would like to see the invisible beam from it.

[00:05:40]If I use my homebuilt beam dump to hide the bright laser spot and remove the infrared filter in my camera we might see the beam in midair.

[00:05:50]Errh - not really.

[00:05:53]Air does not scatter infrared well as explained earlier.

[00:05:57]A trick for enhancing beam visibility on a low budget, I have used since I was young, is... Dust!

[00:06:14]Still underwhelming for 600+ mW - if only I had some smoke.

[00:06:20]Wait a minute... Yes, there it is.

[00:06:30]An invisible beam made visible.

[00:06:37]After a short, important message, I will show how this laser is strong enough to ignite metal.

[00:06:42]And how you can calculate the enormous number of photons any laser emits.

[00:06:55]A huge thank you to all my patrons!

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[00:07:01]It's really appreciated and important for a niche channel with monthly quality uploads like mine.

[00:07:07]For just a dollar a month you can help me out too and get full access to all my posts on Patreon.com Link in the description, Thank you.

[00:07:17]Burning black tape is a relatively easy task but igniting metal is not.

[00:07:23]Yet, I believe this laser packs enough punch to ignite steel.

[00:07:28]In the form of steel wool.

[00:07:30]Here's a pound of it, but I will use less. Inside. On my dinner table.

[00:07:37]First, a try with the beam focused to infinity.

[00:07:43]No, metal is hard to ignite - with light.

[00:07:47]Now, with the beam focused into a small, intense spot.

[00:08:40]Beautiful - like a small firework.

[00:08:44]I think I can go a bit bigger without burning down the table.

[00:08:55]Aw, not a full burn and picky on spot size.

[00:08:59]I wonder how it can be improved for a complete burn?

[00:09:08]Looking at the fire tetrahedron missing fuel is not the issue.

[00:09:13]Some of it was still left.

[00:09:15]The chemical chain reaction is also available.

[00:09:18]The burn continued by itself long after I removed the initiating heat source - the activation energy of the laser spot.

[00:09:26]But heat could still be the issue.

[00:09:29]A compressed lump of steel wool with a lot of strands touching each other can act as a heat sink.

[00:09:35]Sucking heat - energy - out of the reaction fast by the decent thermal conductivity of low-carbon steel.

[00:09:42]The oxidizer, oxygen in the air in this case, could also be the issue.

[00:09:47]There might not be enough air or convection near the steel if the wool is too compressed.

[00:09:53]Fluffed steel wool might be the solution.

[00:10:15]Wow - that was more energetic and a full burn.

[00:10:19]I need a bigger water bath.

[00:10:22]I find it fascinating that nothing but light starts this sparkling metal burn.

[00:10:28]Click like if you do too.

[00:10:42]Obviously, a lot of photons on a small spot is needed for this.

[00:10:46]How many photons does this laser actually emit?

[00:10:50]The formula for calculating it is fairly straightforward.

[00:10:54]The tricky bit is dividing by a very small number, Planck's constant, giving a very large result.

[00:11:01]However, the Windows calculator can handle this just fine in one go - in its scientific mode.

[00:11:17]The number of photons emitted by the 614 mW 803 nm laser is... Oh my.

[00:11:30]2.5 quintillion photons per second.

[00:11:34]That's 2.5 million million millions photons a second!

[00:11:40]No wonder the light from this laser makes an impact.

[00:11:44]From the formulas, we can also tell that a longer wavelength equals lower energy.

[00:11:49]Infrared light carries less energy per photon than visible and ultraviolet light.

[00:11:55]Brings us back to the intro question.

[00:11:58]Which one emits the most photons?

[00:12:00]The half-power infrared laser emits 21% more photons.

[00:12:06]Making it the winner. Did you guess right?

[00:12:09]This explains why the infrared lasers are not the strongest in my collection.

[00:12:14]IR lasers have to emit more photons than the visible lasers just to match their power.

[00:12:20]Until we meet again in the next video, I recommend watching the video on the infrared hair blaster.

[00:12:27]Hope you enjoyed this video enough to click like and perhaps subscribe for more like it.

[00:12:32]In any case, thanks for watching. Bye for now.