My latest work.


Laser lab setup.


Reflection of a water drop (20 micro-L) on glass.


Digital mockup (DMU) of the drop.

hehe...I get paid to play with lasers.

Poster is going to be presented at the Ohio Section of the American Physics Society Conference at Wayne State University (WSU) in Detroit on March 31st - April 1st.

I think that eventually, we are going to be using a scanning electron microscope (SEM) to verify and validate the results as well.

tee hee tee hee , then I'd be paid to play with a SEM as well. w00t! Can't wait.

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What's the practical applications of this? It's been a LONG time since I was in a physics lab.
-MF

so is that rflection showing the water molicules or somthin??????

Didnt you take off or something? I seem to remember a thead with that in it.

I don't know what's going on but it looks nice

what does it do? does it look at aberitions in a fluid droplet? how powerful is said laser?

Quote: Originally Posted by Sparky Didnt you take off or something? I seem to remember a thead with that in it.

Glad I'm not the only one who remembered

Looks cool. Not sure what exactly you are doing [bending the light?] but looks cool.

Umm does it matter if he says "potention resignation" and comes back to say hi? In my book I think if someone comes back to say Alo then thats fine.

Quote: Originally Posted by post_break Looks cool. Not sure what exactly you are doing [bending the light?] but looks cool. Umm does it matter if he says "potention resignation" and comes back to say hi? In my book I think if someone comes back to say Alo then thats fine.

Exactly. It's not like he came back in and said "I forgot how lame you guys are and wanted to remind you about it". This strikes me as a pretty legit thread

Quote: Originally Posted by _Sexy_Pants_ Exactly. It's not like he came back in and said "I forgot how lame you guys are and wanted to remind you about it". This strikes me as a pretty legit thread

He can roll back in any day he wants, not my site. However, when someone draws attention to themselves in a such a manner as saying that he might be leaving a website.....mind you "a website" than i find it extremely difficult not to remind said person about their gay thread. The kind of peeps that make those threads are the kind of people that always wander back, and pretend that their not really tools, when in fact they prove it over and over again. So welcome back alpha, hope to see more of your gibberish on the sweeet a$$ programs that you use at your sweeeet a$$ job.

Could not say it better than Sparky just did.

i have no idea whats going on

Right. So aren't you going to tell us what the point of this experiment was or even better, the point of this thread? Is it just you bragging about being paid to "play" with lasers? And just out curiosity what do waterdrops and lasers have to do with thermodynamics?

Now, now. He posted calmly, no need to get mean. Let's see how much assistance he can provide with all of his infinite knowledge.

Well from the title of the thread, it looks like Alpha's examining the morphology (shape) of water drops via laser measurement.

Can't really see the point myself, but that's just me - I'm done with lab experiments.

I've used an electron microscope in studying various materials and thin film properties and know that you'll have a heap of fun - but yeah - I think that you should have made it a little more clear as to what you were trying to achieve.

Better yet - put it into plain english.

People here are REAL people from all walks of life and don't necessarily have the same understanding of (or interest in, for that matter) the same things as you.

You may actually get some genuine acknowledgement if everyone can have an inkling of what you are doing.
If you aren't prepared to do this - then think about why you're posting it.

Just some frendly suggestions mind you.

is this that game where you trace the light? i did it in pre-school and i remember it was very fun.

but yeah....What does it do? and how can the members here (including myself) make this usefull?

Quote: Originally Posted by alpha754293 My latest work. Laser lab setup. hehe...I get paid to play with lasers. Poster is going to be presented at the Ohio Section of the American Physics Society Conference at Wayne State University (WSU) in Detroit on March 31st - April 1st. I think that eventually, we are going to be using a scanning electron microscope (SEM) to verify and validate the results as well. tee hee tee hee , then I'd be paid to play with a SEM as well. w00t! Can't wait.

Interesting. Don't you get a lot of diffraction from all the dust motes in your non-clean room? Looks as though there might be quite a bit of ambient light also. Will that skew your results?

Quote: Originally Posted by Monsignor Funkibut What's the practical applications of this? It's been a LONG time since I was in a physics lab. -MF

Quote: Originally Posted by 4x0n Right. So aren't you going to tell us what the point of this experiment was or even better, the point of this thread? Is it just you bragging about being paid to "play" with lasers? And just out curiosity what do waterdrops and lasers have to do with thermodynamics?

Quote: Originally Posted by beachbum86 is this that game where you trace the light? i did it in pre-school and i remember it was very fun. but yeah....What does it do? and how can the members here (including myself) make this usefull?

It's used to determine the angle that the drop makes with the surface that it sits on.

I'm actually NOT using the diffraction image, but rather the reflection.

This is developed as a proof-of-concept measuring process. Other imaging techniques include 2D imaging, and that is very much dependent on the direction of the light source. (Additionally, if you take a picture from any side, it doesn't and can't tell us what we can determine with this method.)

Other measuring techniques involve actually touching the drop. Another one uses additives in the fluid to make it easier to be detected.

in our case, we're not allowed to make contact with it, and we can't use any additives because it will react with it, and adversely affecting other aspects of the experiment/project.

For the longest time, the assumptions of sessile drops are the following:

a) It has a circular footprint

b) If there are any changes in the shape along the edge, it still remains "straight".

c) The angle that the outer edge makes with respect to the surface that it sits on is the arctan of the height of the drop and the distance from the edge to the center of the drop.

In our experiments, we actually didn't expect that there is the factor of very very small shapes taking part in it.

The way that the experiment works is that if you point the laser at the drop, it will reflect a portion of the light. By putting up a "screen", knowing the distance from the center of the laser (where it makes "contact"), and the height of the reflection, we can calculate the reflection angle. That then, can be used to calculate the angle that the drop makes with respect to its surface. (Given as "gamma" in the schematic below.)



So why do it? Well, for one thing, evaporation of a droplet is very much dependent on that angle. The higher the angle, the faster the drop evaporates and vice versa.

(Without going into too much detail, that's ONE of the reasons why this is being developed. This project is partially government funded.)

Other applications can also include biomedical applications (potentially using it as a "surface scanning" technology), fuel injectors of various kinds, dehydrating foods. (Those are some that I can think of).

Pretty much anything that deals with drops of liquid, and so long as you can focus the beam small enough, there really isn't much in the way of limitations as it what it CAN'T do.

Another idea is to combine it with a wind tunnel, and look at the changes in the shape of a drop there, and how that affects evaporation. Or purposely tilting the surface that the drop sits on, and looking at its effect.

In one of the test that we did, we put very small drop of water on brass, and the surface of the brass (and how it affected the droplet) lit up like a Christmas tree.

So, without having to use a SEM, you can get a pretty good idea as to what's going on.

I'm sure that if we spent more time on it, we can attach a scale to the image that we "see" on the screen, but for the time being, all I know is that there's a lot going on there geometrically.

Quote: Originally Posted by beachbum86 so is that rflection showing the water molicules or somthin??????

No. What we're currently seeing is "teeth" along the edge there. We think that it has something to do with the surface, surface energy, the drop itself, and a whole bunch of other parameters.

Quote: Originally Posted by carbongraphite what does it do? does it look at aberitions in a fluid droplet? how powerful is said laser?

I believe that we are using a 65 W laser, IF that. It's a very low power laser.

Not that there is also no other optical equipment being used to focus the beam, as this is a proof-of-concept only. (In our literature review, we found only three papers that had anything remotely to do with it.)

Quote: Originally Posted by joecoin Interesting. Don't you get a lot of diffraction from all the dust motes in your non-clean room? Looks as though there might be quite a bit of ambient light also. Will that skew your results?

Um...yes and no. We don't have a clean room. In fact the people that are funding this contract don't even have access to a clean room.

Yes, there will always be particulate matter atmosphereically (locally and globally). No, because prior to each measurement, everything is cleaned off with 91-99% I.P.A.

On top of which, I don't care about the diffraction. It's the reflection that I'm interested in. During the measurement, the lights are off (except for light from my laptop, and also a small desk lamp). No, it does not skew the results because we measure distances using the ultra non-precise elementary-school grade ruler.

Tolerances on the measurements are as follows:
distance from center of laser to screen: +/- 1 mm
height: +/-1 mm
corresponds to a contact angle tolerance of +/- 0.2 deg.

Variation on contact angle with the same drop ranges from standard deviations of 0.5 to 7, due to geometry (as a function of drop size, liquid, and substrate material).

Quote: Originally Posted by alpha754293 It's used to determine the angle that the drop makes with the surface that it sits on. I'm actually NOT using the diffraction image, but rather the reflection. But but but, you are still shooting that laser beam through a bunch of airborne particles. How can they have no effect? This is developed as a proof-of-concept measuring process. Other imaging techniques include 2D imaging, and that is very much dependent on the direction of the light source. (Additionally, if you take a picture from any side, it doesn't and can't tell us what we can determine with this method.) What is the concept you are attempting to prove? Other measuring techniques involve actually touching the drop. Another one uses additives in the fluid to make it easier to be detected. in our case, we're not allowed to make contact with it, and we can't use any additives because it will react with it, and adversely affecting other aspects of the experiment/project. For the longest time, the assumptions of sessile drops are the following: a) It has a circular footprint b) If there are any changes in the shape along the edge, it still remains "straight". "Straight" with respect to what? What edge? c) The angle that the outer edge makes with respect to the surface that it sits on is the arctan of the height of the drop and the distance from the edge to the center of the drop. The distance from the edge at any given point? In our experiments, we actually didn't expect that there is the factor of very very small shapes taking part in it. The way that the experiment works is that if you point the laser at the drop, it will reflect a portion of the light. By putting up a "screen", knowing the distance from the center of the laser (where it makes "contact"), and the height of the reflection, we can calculate the reflection angle. That then, can be used to calculate the angle that the drop makes with respect to its surface. (Given as "gamma" in the schematic below.) So why do it? Well, for one thing, evaporation of a droplet is very much dependent on that angle. The higher the angle, the faster the drop evaporates and vice versa. So the angle is not fixed? (Without going into too much detail, that's ONE of the reasons why this is being developed. This project is partially government funded.) Sorry to hear that... Other applications can also include biomedical applications (potentially using it as a "surface scanning" technology), fuel injectors of various kinds, dehydrating foods. (Those are some that I can think of). Pretty much anything that deals with drops of liquid, and so long as you can focus the beam small enough, there really isn't much in the way of limitations as it what it CAN'T do. Another idea is to combine it with a wind tunnel, and look at the changes in the shape of a drop there, and how that affects evaporation. Or purposely tilting the surface that the drop sits on, and looking at its effect. In one of the test that we did, we put very small drop of water on brass, and the surface of the brass (and how it affected the droplet) lit up like a Christmas tree. So, without having to use a SEM, you can get a pretty good idea as to what's going on. I'm sure that if we spent more time on it, we can attach a scale to the image that we "see" on the screen, but for the time being, all I know is that there's a lot going on there geometrically. No. What we're currently seeing is "teeth" along the edge there. We think that it has something to do with the surface, surface energy, the drop itself, and a whole bunch of other parameters. I believe that we are using a 65 W laser, IF that. It's a very low power laser. Not that there is also no other optical equipment being used to focus the beam, as this is a proof-of-concept only. (In our literature review, we found only three papers that had anything remotely to do with it.) Um...yes and no. We don't have a clean room. In fact the people that are funding this contract don't even have access to a clean room. You might want to suggest they provide you with such a room. Yes, there will always be particulate matter atmosphereically (locally and globally). No, because prior to each measurement, everything is cleaned off with 91-99% I.P.A. That helps to a point. On top of which, I don't care about the diffraction. It's the reflection that I'm interested in. During the measurement, the lights are off (except for light from my laptop, and also a small desk lamp). No, it does not skew the results because we measure distances using the ultra non-precise elementary-school grade ruler. But but but, you are still shooting that laser beam through a bunch of airborne particles. How can they have no effect? And I find it a little scary that you are using such non precise instruments. Tolerances on the measurements are as follows: distance from center of laser to screen: +/- 1 mm height: +/-1 mm corresponds to a contact angle tolerance of +/- 0.2 deg. Those are hug tolerances, IMHO. Variation on contact angle with the same drop ranges from standard deviations of 0.5 to 7, due to geometry (as a function of drop size, liquid, and substrate material).

Are you saying that the angle around the periphery of the drop, where it makes contact with the surface, varies by as much as 7mm?

In case anyone was wondering why alpha is now a probationary user, it is because he is so damn smart he thought it would be funny to mess with an admin. Yeah, smart guy. I don't know why, but when I picture this dude I see young McFly from Back to the Future but with a pocket protector and acne.