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pcb121055

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Greetings everyone.
I am an electrical engineer with too many interests for my own good and have been entertaining several measurement projects for some time, figuring that a laser would be the key but other than my dimestore laser pointer, I have had no experience.
My first goal is to gain a general overview of lasers in the hopes of making good decisions about what I should be using. I have to say that safety is high on my list and wonder of there is a level that is effective for my use but minimizes potential issues.
At the outset, I don't want to burn or cut anything. I am looking for non-contact measurement of the vibration of various machines. The distance over which I propose to measure is a few mils to a few inches. Hopefully this is a low powered, tightly focused beam?
So... that's what I am about. Thanks in advance for any help :)
 

IWIRE

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Interesting. So are you planning on projecting a dot on the machine and measuring how much the machine moves in relation to the dot, or mounting the laser on the machine and measuring how much the dot moves, or is there some kind of a transmitter and receiver involved ? I guess you can tell I will be no help :)
But hopefully someone will.
Try the search bar at the bottom of the page, I have better luck with it than the little search box at the top.
Good luck ! Wish I could have been more help ! :beer:
 

pcb121055

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Hi IWIRE. I imagined that I would bounce a laser off of a flat spot on the machine and intercept the beam with perhaps a ccd or a photodiode to analyze the behavior at the point contacted. I have been studying photodiodes, phototransistors, etc... not sure which one to try yet. Thanks for looking :)
 

Rifter

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So you want a laser rangefinder with REALLY fast refresh(sample) rate by the sounds of it, that can be recorded to analyzed later im assuming?
 

pcb121055

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I guess one of the things to learn is the vocabulary. Wouldn't have come up with rangefinder on my own but it does make sense. I'm gonna say "yes". and the ability to store and analyze is a another yes. I don't know where this project ranks in difficulty but it sounds like it's gonna be fun :) I was looking at direct sensing of the reflected beam and also interferometry. any idea which of these would work better here?
 

Rifter

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I guess one of the things to learn is the vocabulary. Wouldn't have come up with rangefinder on my own but it does make sense. I'm gonna say "yes". and the ability to store and analyze is a another yes. I don't know where this project ranks in difficulty but it sounds like it's gonna be fun :) I was looking at direct sensing of the reflected beam and also interferometry. any idea which of these would work better here?
I have no idea if that's even correct vocabulary this is well above my knowledge of lasers. I do however know enough that I believe it is possible, and will be fun project :)

All a laser range finder does is report distance by reflection of beam back to sensor, if you could get a high enough sample and accuracy of measurement rate to be able to detect vibrations in the target I don't see why you couldn't use a laser for this.
 

Hap

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Welcome to the forums! :)

-Alex
 

IsaacT

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It sounds like you are setting up something similar to how people use lasers to listen in on conversations.

They bounce the laser off of a window, and the vibrations from the voices cause the laser to go off and on a phototransistor which is converted into audio data similarly to how CD's translate signals. But in your case you might just want the basic binary data. Which you could probably still do.

Check out these:

DIY Laser Spy Microphone

LucidScience - Build the LASER SPY DEVICE - Page 1 of 18

How to: Laser Microphone for Long-Range Spying | Hack N Mod

Its a quick and dirty way to do what you want. As far as lasers go, if you are using an IR sensor for the phototransistor you will need an IR laser. You shouldn't need much power.
 
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KapHn8d

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Welcome to the forums and good luck with your project... If there is anyone that can help you get this done, they'll be hanging around on LPF. :)

cheers!
/c
 

pcb121055

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Thanks for the welcomes everyone. I am having fun trying to put this project together... long way to go, i think. Feel kinda funny relating what I am trying to do to spying but I guess the parallels are unavoidable. Thanks for the links IsaacT, I will check them out immediately.
 




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