Laser Measurement

[buzzp]

I am trying to locate a laser measurement sensor (diffuse style because range is up to 8 feet) which operates in -40C to 70C environments. All the ones I have found are -10 - 50C. Anyone have any suggestions as I continue to review all the laser sensor mfgs websites?

 

[analogkid2digitalman]

Looking for distance measurement/displacement or prox (part present or not)?

Wheels within wheels / In a spiral array
A pattern so grand / And complex
Time after time / We lose sight of the way
Our causes can't see / Their effects.

 

[nbucska]

Hi Buzzp:
I would appreciate if you could tell me the URL
of the companies you have found.

If you tell me more perhaps I can help with a solution.

 

[buzzp]

Need distance measurement with analog out (prefer 4-20mA). Target is present.
Thanks in advance.

 

[nbucska]

What is the distance min/max?
Speed and acceleration of the target?
Max. size and weight of the retro reflector?
Accuracy?
Is the zero calibration on turn-on acceptable?
Pressure range ?



<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[analogkid2digitalman]

Would it be possible to house a unit in a temperature/humidity controlled enclosure to extend the temperature range?

Wheels within wheels / In a spiral array
A pattern so grand / And complex
Time after time / We lose sight of the way
Our causes can't see / Their effects.

 

[IRstuff]

This one covers one end of your requirement:

http://www.sickusa.com/live/master/datasheet.asp?PN=1026518&FAM=Measure

TTFN

 

[ScottyUK]

Try the following web link:

http://www.trelectronic.com/

They have quite a selection of laser measurement devices.



----------------------------------

If we learn from our mistakes,
I'm getting a great education!

 

[buzzp]

Ill check out some of the links above. Some of them, I already have. Thanks for the responses and Ill post what I found.
Here is more info.
range - 0 to 8'
pressure - atmospheric
humidity - 100% desired but likely hard to find w/o paying way to much
acceleration - really slow
speed - perhaps 6"/minute
accuracy - +-0.25%
linearity - 0.1%
one time calibration at set-up not start-up, in other
words, we would set the zero and span when we install
the unit for the first time and it would have non-
volatile memory
retroreflective should fit on top of a 3" diameter shaft where weight is not an issue (I thought all these were basically plastiv).

 

[buzzp]

The heated enclosure is another option but not preferred.

 

[buzzp]

As you see from my accuracy spec, lasers are not required here. A photoelectric of some sort would work as well. But again, temperature seems to be the issue.

 

[nbucska]

I was thinking at Zeeman laser which is very accurate,
( can be submicron ), can follow you speed specs but
it looses the zero when you turn it off or interrupt
the beam and needs rezeroing.

You could compensate for the temperature.





<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[buzzp]

Nbucska, Ill check out zeemans other products. Some of the ones referenced above have the temp rating I am after.

Anyone use any other photoelectrics with this temp range? Problem here is the enclosure the sensor is in may be heated but the medium the 'light' passes through will not so it would be nice if the sensor was not heated so any temp correction built-in to the sensor could be used. I am guessing, however, that the speed of light is minimally affected (if at all) by temperature variations unlike sound waves so maybe this is not a big deal. Anyone know if this is semi true or not?

Thanks for all the help.

 

[nbucska]

The speed is affected by pressure and temp. but the correction is wellknown and takes simple calculation.


<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[nbucska]

HP makes lasers based on Zeeman effect: In magnetic field
the laser emits two frequencies ( around 2MHz apart)
This is multiplied by a PLL and a counter compares the doppler shifted with the reference .

I am using them and they are very reliable.

<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[buzzp]

With my application, the temp coefficient of the speed of light is most certainly negligible (only 8').
One of the units someone posted above has a heated enclosure to accomadate the wide temp range. I was thinking this would help the electronics but not the medium the beam travels through. I am guessing it is not even a consideration at this small distance, maybe I am wrong.
Thanks again.