My green laser pointer beam turns red when shined through olive oil

My green laser pointer beam turns red when shined through olive oil

Fluorescence. Everyone saying the oil absorbs the green light leaving only red is incorrect, since the laser only emits light at a single wavelength or color. The oil molecules absorb the green light, bringing them to an excited state. They then de-excite, emitting a lower energy photon in the process. Red light is lower energy than green.

someone give explanation

since the laser only emits light at a single wavelength or color.

That's not entirely true. Commercially available green laser pointers are implemented using frequency doubling of light at twice the wavelength. This infrared light on the other hand you usually get by pumping with a GaAlAs laser at 808nm. Cheaper lasers don't filter the infrared contributions away so that the pointer actually emits light at 532nm, 1064nm and 808nm.

What you actually end up seeing in the oil, however, is fluorescence resulting from the 532nm light as you have described it.

This infrared light on the other hand you usually get by pumping with a GaAlAs laser at 808nm.

I mean, duh.

I concur. Do you concur?

How many things have you shined it through?

I concur.

Source: Am Genghis Khan.

If the answer isn't "all the things," OP isn't doing lasers right.

How do you know it doesn't turn green whem shined through air

Colorblindness increases

Hey, I'm pretty sure we're related! Me and about 30,000,000 others.

What if it's "all the SMALL things?"

L-A-S-E-R

Light

Aemitting

Sdiode

E

R

Huzzah! My thesis is finally relevant outside of the lab.

This is actually the mechanism that I am using to write my thesis. I'm a mechanical engineering masters student using what is called "laser-induced fluorescence", or what is also known as LIF, to study the presence of hydroxyl in a combustion flame. Every molecule has various energetic states, but they normally rest in the ground State (lowest energy). When a molecule is brought to a high energy state, it becomes unstable and drops back to the ground State, emitting light of a certain wavelength. Because a laser light has very concentrated energy due to being in a tight beam, lasers are used to excite molecules to measure how much of a certain molecule is present in a mixture of various kinds of molecules.

Example: Imagine you have a rapidly changing mixture of methane, propane, and a few other things, and you want to know how much methane is present at all times in the reaction. You can hit the mixture with a beam which is tunable to the wavelength necessary to energize the methane to a state at which it will de-excite and fluoresce, and then using very expensive camera with a lens made to record the fluorescence wavelength of the methane, you can study visually record the presence of methane in the reaction.

Red and blue/purple lasers are done by getting semiconductors that directly emit light at those wavelengths. Unfortunately the direct emission lasers in the green spectrum are stupidly expensive, so commercial green lasers are what's called a DPSS (diode-pumped solid state) laser.

A Gallium Aluminum Arsenide laser diode emits light at 808nm. It's cheap and cheerful, and emits light in the Infrared region which means it's useless for looking at, but works great as a source of light. The GaAlAs diode shines into a piece of Nd:YAG, (Neodymium-doped Yttrium Aluminium Garnet), which is a garnet made of Yttrium and Aluminum, with some Neodymium thrown in to taste. When our 808nm photons (light particles) hit this crystal, some of them run into a Neodymium atom and kick it into a higher energy state. It doesn't like this and tries gets rid of that extra energy. Quantum mechanics says this energy gets emitted as another photon of a wavelength specific to what atom is trying to get rid of what amount of energy. For Neodymium, getting smacked by an 808nm photon kicks it up to the level where it spits out a 1064nm photon to get back to ground level. Now we've got a 1064nm laser, which is still useless to look at.

These 1064nm photons fly into a piece of KTP (Potassium Titanyl Phosphate) which is a frequency doubler. It sucks up two 1064nm photons and spit out one 532nm photon, which is squarely in the green region of the spectrum.

needs more first-letter capitalization in order to be a full-on Jaden Smith tweet

LET'S GO BOWLING!

it's me one of ur many cousins

The olive oil is just angry.

Then it would be true care. Truth brings.

edit: Aaaaand that song is stuck in my head.

Note to the reader, the listed wavelength are not visible to the human eye, so the green laser still only emits one wavelength of visible light.

How Do You Know It Doesn't Turn Green Whem Shined Through Air?

FTFY

Yup, still looks green to me

Ga = Gallium

Al = Aluminium

As = Arsenic.

GaAlAs means that those three elements are integral to the laser diode. Visible light is ~400-700 nm wavelength. The 808 nm light produced by the laser comes out at 808 nm unchanged, and 1064 nm, which are invisible infrared rays. It also exits as 532 nm light which is between 400-700 nm on the part of the spectrum corresponding to the color green.

When "shone" is the word you're looking for.

Not now, Roman! kills prostitute

So, red lasers are just green lasers filled with olive oil. Got it!

Gonna play that Lorde song into some olive oil and see if I hear a Tiësto song in the oil.

~810nm is in the near infrared and nominally not visible, but from my personal experience working with lasers at this wavelength you can still see it faintly.

Green on the other hand is the color that the eye is most sensitive to, so even if the green light is much less intense by multiple orders of magnitude it still will appear much, much brighter than the near-infrared light.

Wat

Tl;dr photons hit atoms and exit with different wavelenghts. From 808nm -> 1064nm -> (two combine into a smaller wavelenght) 532 nm, which is green. Thank you for the great explanation!

Congratulations, you're color blind

Whem*

You lost me at "The"

The thickness of the olive oil is slowing down the light making it red, thus red lights at intersections.

Green light goes in, red light comes out. You can't explain that.

As a colorblind person, it looks green all the way through. I guess I'll just have to take your word for it.

The laser turns red because it went through virgin olive oil.

Ehhhh not now, Roman. Maybe later. I'm busy.

As a colorblind person, fuck this post.

It's me, another cousin! ..can I borrow your lawnmower?

its a somewhat pinkish-red line going through the oil. It's pretty blatant so if you struggle to see it you might wanna take some red-green colourblind tests.

same hue in the liquid as the entirety of this red laser posted further down by /u/catalyst518

its a somewhat pinkish-red line going through the oil. It's pretty blatant so if you struggle to see it you might wanna take some red-green colourblind tests.

same hue in the liquid as the posted further down by /u/catalyst518

I'll take one lift Your ride best trip Always I know You'll be at my show Watching, waiting, commiserating

Say it ain't so, I will not go Turn the lights off, carry me home Na, na, na, na Na, na, na, na, na, na, na, na, na, na, na

Late night, come home Work sucks, I know She left me roses by the stairs Surprises let me know she cares

Say it ain't so, I will not go Turn the lights off, carry me home Na, na, na, na Na, na, na, na, na, na, na, na, na, na, na

Say it ain't so, I will not go Turn the lights off, carry me home Keep your head still, I'll be your thrill The night will go on, my little windmill

Say it ain't so, I will not go Turn the lights off, carry me home Keep your head still, I'll be your thrill The night will go on The night will go on My little windmill

The AlGaAs diode pumps 808nm light through an ND:YAG medium, where then 1064nm light is emitted and sent through a KTP crystal in order to utilize frequency doubling to convert a portion of the infrared 1064nm light into the green 532nm light emitted from a laser pointer.

Am laser expert, can confirm

Thats because of the oil

As a laserologist, it actually stands for Light Amplification by Stimulated Emission of Radiologist

The fluorescence shines in all directions and is not collimated like the original laser beam. That's why it appears brighter in the oil than the green beam, even though it is much less intense:

While the green light needs to be scattered from it's original path in order to land in your eye, the red light is emitted equally strong in all direction and therefore more light is collected in your eye.

The laser beam stays green, but part of the energy of the laser beam is converted to red light inisde the oil and this red light is emitted uniformly in all directions.

Hey cousin, let's go bowling!

AEMITTING

Fluorescence of olive oil and other vegetable oils

Please fluoresce

It relies on harmonics, and generating a second order harmonic with twice the frequency of the input. The gist of it is that the first photon isn't enough to trigger emission from the KTP, so the KTP is stuck in a half-cocked state until a second photon smacks it to impart the rest of the energy.

No idea since it looks green to me but I'm colorblind. You should take a colorblind test and see.

This is what's happening. You get a similar effect if you use a blue laser pointer. A bonus with that is the blue will also work in tonic water. The quinine fluoresces in that case.

Seriously, what's up with that? It still looks green to me but I'm fairly certain I'm not colorblind? Is this supposed to look bright, fire truck red?

Similarly, my cheap 405nm laser glows green in this glass ball. 

http://i.imgur.com/cI3EYCg.jpg

Similarly, my cheap 405nm laser glows green in this glass ball.

Maybe you just have superpower eyes.

Huh, didn't even notice that.

People downvoting this are not familiar with /sub/shittyaskscience

Edit: ah, looks like the trend has been inverted now :)

Yeah we got it.

lower energy photon

So.. Jeb Photons?

It's not fire truck red but it is unmistakably red. Try an online color blind test it sounds like you might be

But then what does that laser stand for?

Can we just say ~182 nm?

I conquer

Wow, never thought I'd see a Catch Me If You Can reference out in the wild.

I hate whem that happens.

That's a great question! Yes it could happen, however, there are many forms of optics that can reduce the beam power if it's too high. And in the case of my thesis, the combustion reaction has already been induced before the beam is used.

Exactly! When you slow a particle down, you make it angry. Because it's not moving as fast as it wants to in nature. That makes it red with anger. This, explains why red cars get more speeding tickets.

But that looks orange?

I actually didn't know I'd be so interested in the topic until I had already been accepted into the program. I want to pursue a career in rocket engine testing and design, and because this research topic is relevant to engine testing (and because I could get my tuition paid and a monthly stipend on top of that) I decided I'd take the position. I love it now, though!

It is very expensive. Our lasers cost more than half a million dollars each. The camera we are using costs around $200,000.

Don't you have photoshop?

Great explanation. You've shone some real understanding.

Lots of people in this thread are using "shined" like it's a word too. It's driving me nuts, but I'm not enough of a Grammar Nazi to correct them all...

This didn't make much sense to me since fluorescence microscopes often use oil immersion (which would cloud up the image if oil itself were fluorescent at these wavelengths), but it turns out olive oil has impurities that are fluorescent: http://cdn.intechopen.com/pdfs/27027.pdf

I should've concurred! Smh

/sub/colorblind

You've never owned a laser pointer have you?

It actually stands for Laser Aperture Signal Emitting Relay

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Here's a sneak peek of /sub/colorblind using the top posts of the year!

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Thank you - scrolled down just hoping someone else had noticed this.

Shone.

Not entirely true actually.

Those shitty DPSS lasers will output red and green simultaneously(because the lenses arent great and don't convert all the light)

its far more noticeable when you are in cold temperatures or when you are nearing the end of the battery life but there is usually red

https://www.repairfaq.org/sam/glpmca1.gif

Not entirely true actually.

Those shitty DPSS lasers will output red and green simultaneously(because the lenses arent great and don't convert all the light)

its far more noticeable when you are in cold temperatures or when you are nearing the end of the battery life but there is usually red

It's pretty clearly red to me, not like fire truck red but it's clearly red.

“Tiger got to hunt, bird got to fly; Man got to sit and wonder 'why, why, why?' Tiger got to sleep, bird got to land; Man got to tell himself he understand.” vonnegut

Seeing these lyrics typed out caused me to realize for the first time that "Say it ain't so, I will not go turn the lights off" is not meant to be interpreted as one sentence. Like the singer wasn't refusing to go get the light switch.

Whoops.

Activation of photoreceptors is probabilistic based upon the wavelength, not absolute sensitivity AFAIK.

Hence why astronauts see bright flashes of light as other random high energy particles pass through their eyes and periodically cause activation.

Quantum effects will result in Armin van Buuren.

On the other hand,

It's me, one of your many enemies.

Green light actually falls into the range of 180-185 nm wavelength. Crazy. Or bullshit. Who knows.

Does adding energy in this fashion to a highly flammable gas mixture have the potential to be a tiny little bit explodey?

The oil molecules absorb the green light,

This isn't true, this doesn't work with more refined oils.

Olive oil contains a lot of "contaminants" compared to other oils, what you're seeing here is I think chlorophyll getting excited and dropping back.

Olive oil also appears red under UV light, as do most plants. (because of the chlorophyll).

Radiologist emissions getting stimulated, eh? Nice.

Bitten by a radiactive laser

I disagree. It's probably something else

Why didn't I concur? I blew it, didn't I?

Get laser

Shine it on every object you see, which is a perfectly normal act for a human being with a laser.

Here you go: http://i.imgur.com/c6hUp2K.jpg

Laser listed as 625-680nm, <5mW.

Here you go:

Laser listed as 625-680nm, <5mW.

To chime in on this one, a couple of years ago when i studied photonics we tested a cheap laserpointer another student brought in to our lab. And while the output of the green light was within the limitations, the infrared part was way over anything allowed. So be extra carefull when you handle green laser pointers. Even if the visible part might be okay the infrared part might still fuck up eyes very fast.

Interesting!

According to that paper, vitamin E fluoresces at 525 nm though. 525 nm is green, not red.

Chlorophyll fluoresces at 681 nm, which is red.

Edit: Additionally, that laser (probably) shines at 532 nm (with possibly some longer wavelength contamination). So that light would be too low energy to excite vitamin E.

You can tell because of the way it is. Lasers.

https://youtu.be/a0ndGKFP_DY

This video by Brainiac is really good, with more examples