Any Technology(Equipment) That Can Measure Distance Through Space And Water At The Same Time

[Mysa]

Is there an equipment that can measure a vertical distance as well as an angled distance first through space and secondly through water to a max depth of 100m with an accuracy of 10cm?

For example a vertical hole or a hole at an angle of 70 degrees.

Look forward to any suggestions/ideas from experts on this subject.

Regards

 

[IRstuff]

How much water? How much money do you have? How do other people in your industry currently do it?

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[itsmoked]

I would expect it's not too hard to measure distance to that accuracy thru 100m of water using Time Domain Reflectometry with the correct wavelength laser. And, that's with air then water, not thru, say, rain.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Mysa]

@ itsmoked,

thanks for you reply.

no, its not rain. Can you explain a bit more on how that could be possible for this application I'm looking for?

100m hole depth is a bit too much.
60-70m hole depth is more applicable to what I'm looking for.


thanks

 

[itsmoked]

Lasers operating in the blue-green spectrum can penetrate water well. So well that high speed data links are possible. I believe I saw one that exceeded 500m.

There is a catch of course.. The water has to be clear not filled with bubbles and floating dreck.

TDR essentially measures how long a transmitted pulse takes to return, and works with lots of things. Sound, fiber optics, water pipes, wire, dirt strata, whatever.

You launch the pulse, when it hits an interface of any kind there is usually a part reflected. Your setup just times the round trip.

The speed of propagation in the media at hand is looked up and with a little math you can calculate exactly how far the transmitted pulse traveled out and reflected and traveled back.



Keith Cress
kcress -

http://www.flaminsystems.com

 

[Mysa]

Thanks for the quick reply @ itsmoked,

the clear water you mentioned is going to be an issue here because the holes are open cut/drill blast holes and they are not clean.

Anything you think that can be capable of measuring distance a muddy/silty water?

 

[itsmoked]

If you're contemplating straight holes why not the tried and true weight on the end of a measuring tape? Very reliable, simple, and cheap. If you have to do dozens at a time mechanize the method a bit. Perhaps make a stand that sits over the holes and a jig that can be run with, say, a battery powered drill to retrieve the tape. Let gravity take it down.

Otherwise use sonar. A fish finder might work as they can show individual fish and should certainly be able to show the "bottom", and they won't care about murky water either.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Mysa]

@itsmoked

yes, the rope and weight at the end is the tried and true method and still works and that's what we are doing, but its labour intensive and If you have 1000 holes to measure and each of the holes are all about 40m long, that's whole lot of dipping you need and a lot of human effort that you have to use to dip all these holes.

For such deep holes like 40-60m depths, it takes about 1-2 minutes to measure each.

If there was a device that you could just hold over the top of the hole and just point down the hole and it measures the depth of the hole as well as the depth of the water in the hole and gives you the results in seconds, this would be a lifesaver.

 

[itsmoked]

Nope nothing that you can just point down at a water surface and get the depth. There are handheld acoustical water depth meters that you lower the transducer into the water a ~1/2 meter and push the button.

There are dozens of different brands here is one example:
[URL unfurl="true"]http://www.ebay.com/itm/Professional-Handheld-Ultrasonic-Water-Depth-Meter-Tester-Finder-Indicator-50M-H-/181730216444?hash=item2a4ff709fc:g:bDYAAOSwv0tVQFsT[/url]

I'd write several of the sellers and ask about using their products for well depth measurements.

Search: hand held depth finder
You want one that has a 'cabled transducer' so you have some distance you can lower the transducer down to your water surface.

Let us know what you find.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

The aforementioned green laser approach uses wavelengths around 532 nm, which is a highly non-eyesafe wavelength for lasers. Just as a reference, green laser pointers need to be less than 1 mW average power to be eye-safe. We built a green laser system once to detect underwater mines, it required a pulsed laser, whose single pulse energy averages to 135 mW; naturally, since it was pulsed, the eye-safety was even worse than with a continuous 135 mW laser, which would already be capable of popping balloons and igniting matchheads. In order to be accurate to 10 cm requires fairly high-end pulse and circuit design.

As a refinement to Keith's suggestion consider searching for "borehole depth measurement"

https://www.google.com/#q=borehole+depth+measurement

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[itsmoked]

Good suggestion IR.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[roydm]

To find the water surface take a normal tape measure.
An LED with a transistor and a battery to drive it.
A ground clip.
Ground the circuit
Lower the tape measure, when the tip hits the water it biases transistor On to light the LED.
I can't remember the exact circuit but it's quite simple.

For the hole depth, how about a well depth transmitter, mark the cable in feet/meters

Combine the two so when the metal of the depth transmitter hits the water surface the LED turns On, note the measurement then lower to the bottom to get the pressure (depth of water)

You may be able to combine the LED circuit with a sonic measurement so as soon as it touches the surface it turns LED On and indicates water depth in one step.