Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Using lasers to measure water level

N

nuthuram

0
Joined
Jun 19, 2009
Messages
1
Points
0
Hello
I am a noob to this forum and also to lasers. I am hoping to find some help with my senior design project for my bachelors.

I wont go into details about the project. Ill just mention the part i need help on.

I need to be able to use a laser to measure the water level in a cylindrical tank. the idea is that when the water level gets too low, more water will be pumped into the tank. Can i build a laser from computer devices that will enable me to do so?

Please help me i am desperate


thank you:thanks:
 





M

Murudai

0
Joined
Apr 28, 2008
Messages
2,235
Points
0
Water is, well, pretty see through. For laser sensors you tend to have something cutting the beam and a light sensor trips, but you'd have trouble with that with water.

Why don't you just use electrodes? That's how most basic water level sensing stuff works.
 
ThunderBird89

ThunderBird89

0
Joined
Mar 28, 2009
Messages
145
Points
0
If lasers are a must, you could use the reflecting beam from the surface of the water, and measure the round-trip time. This would require a pulsed laser, which is controlled by a clock, say that of an Arduino, those can be programmed to do your job.

Or, you could exploit the fact that water is only see-through in the visible spectrum. Go into near-IR, and you get pitch black. You can use that to break your beam, but that require several emitter-detector pairs of IR-lasers, which aren't exactly the cheapest thing...
 
lasersbee

lasersbee

0
Joined
Sep 20, 2008
Messages
17,622
Points
113
ThunderBird89 said:
If lasers are a must, you could use the reflecting beam from the surface of the water, and measure the round-trip time. This would require a pulsed laser, which is controlled by a clock, say that of an Arduino, those can be programmed to do your job.

Or, you could exploit the fact that water is only see-through in the visible spectrum. Go into near-IR, and you get pitch black. You can use that to break your beam, but that require several emitter-detector pairs of IR-lasers, which aren't exactly the cheapest thing...
Click to expand...

Maybe I'm missing something...
I just did a small experiment using an IR TV remote and
an IR Photo diode driving n LED through a Transistor...

I can't see the pulsing IR from the TV Remote but the small
IR circuit can...

I got a clear plastic container and shone the TV remote
through it to the detector and the detector saw it.

I then added water to the container... and the detector still
saw the TV Remote pulses through the water...

Where did this (Pitch Black) info come from... or did I do
something wrong....:thinking:

I tried the same thing withe a 660nm 5mW red laser and got
the same results (I know that 660nm isn't near IR)..:cool:


Jerry
 
Last edited:
ThunderBird89

ThunderBird89

0
Joined
Mar 28, 2009
Messages
145
Points
0
I built myself an IR webcam last year, and when testing it, I looked at all sorts of things, fabrics, money, cola, and water. Cola was transparent, but water was opaque. That's where it came from, though I default to you in this case. Any ideas on what were different? maybe the sensor difference could account for this?
 
lasersbee

lasersbee

0
Joined
Sep 20, 2008
Messages
17,622
Points
113
ThunderBird89 said:
I built myself an IR webcam last year, and when testing it, I looked at all sorts of things, fabrics, money, cola, and water. Cola was transparent, but water was opaque. That's where it came from, though I default to you in this case. Any ideas on what were different? maybe the sensor difference could account for this?
Click to expand...

If Cola was transparent and water was opaque... maybe the camera was
showing a negative image...:thinking: I don't know....

@FML... I think the OP said his "senior design project" was:-
"to be able to use a laser to measure the water level in a cylindrical tank"


Jerry
 
Last edited:
ThunderBird89

ThunderBird89

0
Joined
Mar 28, 2009
Messages
145
Points
0
Probably not negative, because I could see my hand behind the bottle of cola and not behind water. Or if yes, it's a very strange kind of negative. But okay, let's scratch the IR laser tripping method.

This leaves us with bouncing the laser off the surface to measure round-trip time. And what else?
 
Tech_Junkie

Tech_Junkie

0
Joined
Jan 2, 2009
Messages
11,800
Points
0
Does water bend laser light? If it does you could put a sensor at the level you want it to trip a timed fill. As it fills the light might bend enough to go off the sensor, thus resetting the fill timer.
 
ThunderBird89

ThunderBird89

0
Joined
Mar 28, 2009
Messages
145
Points
0
Tech_Junkie said:
Does water bend laser light? If it does you could put a sensor at the level you want it to trip a timed fill. As it fills the light might bend enough to go off the sensor, thus resetting the fill timer.
Click to expand...
From what I saw, no, or only minimally. it does, however reflect off the surface at low angles. And that gives me an idea:

We shine a laser into the tank at an angle, so it reflects off the surface, and stays inside the water. This means it hits the opposite wall. Since the angle is constant, but the distance travelled changes with the level of water in the tank, so will the point of reflection, and consequently, so will the laser's location on the opposite wall. Installing a series of sensors there can tell us where the laser is, which would give us the water level.

How about this one?
 
D

Deleted member 8382

Guest
The only way I imagine to use a laser in that way is with the refraction. As the water level goes down the refraction angle will change and so the point in the bottom will move.

Shining the laser inside the tank from a concrete angle, and measuring where the dot is with the X water level, then you just put an optical sensor outside the tank (need to be transaprent). The sensor will be activated on this level.
 
ThunderBird89

ThunderBird89

0
Joined
Mar 28, 2009
Messages
145
Points
0
This raises the question though: if the tank is transparent, why not use a sharpie? :D

But yes, this is more or less what I was saying.
EDIT: I retract this, I didn't read carefully. Yes, you're right, refraction could be used as well.

The sensors could be placed inside the tanks as long as the contacts are kept insulated but this is a different matter to discuss, for now let's nail down the rough idea and technique, then we can worry about the details and engineering :)
 
Last edited:
Tech_Junkie

Tech_Junkie

0
Joined
Jan 2, 2009
Messages
11,800
Points
0
I dig this project but its not very practical. Wouldn't this be funny if this guy was in some government project, picking our brains for a solution to their problem. Hey why pay for thousands of dollars of R&D when we can jump on this forum for free? LOL We are doing this guys homework though, and he is a n00b. So I'm done brain storming. DO YOUR OWN HOMEWORK LOL.
098.gif
 
lasersbee

lasersbee

0
Joined
Sep 20, 2008
Messages
17,622
Points
113
nuthuram said:
Hello
I am a noob to this forum and also to lasers. I am hoping to find some help with my senior design project for my bachelors.

I wont go into details about the project. Ill just mention the part i need help on.

I need to be able to use a laser to measure the water level in a cylindrical tank. the idea is that when the water level gets too low, more water will be pumped into the tank. Can i build a laser from computer devices that will enable me to do so?

Please help me i am desperate


thank you:thanks:
Click to expand...
There seems to be too much info missing to design a
laser "something"......

We still need to know...

- the diameter of the tank...
- the total depth of the tank...
- is the tank vertical or horizontal [EDIT]
- the type of material and thickness of the tank..
- What are you actually measuring.... just the High and Low level...
or do you need to measure the entire levels from Max to Min....

[EDIT]
BTW...nuthuram for a guy that is desperate... you haven't even check
your own Thread since you posted it yesterday morning...:whistle:


Jerry
 
Last edited:
Tech_Junkie

Tech_Junkie

0
Joined
Jan 2, 2009
Messages
11,800
Points
0
lasersbee said:
There seems to be too much info missing to design a
laser "something"......

We still need to know...

- the diameter of the tank...
- the total depth of the tank...
- the type of material and thickness of the tank..
- What are you actually measuring.... just the High and Low level...
or do you need to measure the entire levels from Max to Min....

Jerry
Click to expand...

There is an old saying. Make yourself look inferior, and the superior will naturally take over LOL.

I use this all the time with my brothers...
cool2.gif
 
You must log in or register to reply here.




Top