Precision Linear Measurment

[mkindler]

I work for a company that makes precision rotary rest equipment. The project I am currently working on is slightly different from our typical product. I have designed a machine that moves a 10"X10" mounting platen on a partial sphere having a radius of 50'. The travel range is +/-9 deg in azimuth and elevation. We are currntly planning on using our theodolite (Wild T2) to verify position and pointing accuracies. My problem is, I need to find a way to verify the 50' radius. What type of equipment or methods are available to measure this distance to +/-.010". Sorry for the long post. I was searching the internet and thought someone here may be able to help me.

 

[IRstuff]

What's your pass/fail criteria? Does the +/- 0.010 take into account the measurement system test accuracy ratio, e.g., is this the product spec or the tester spec?

I'm assuming that you actually don't need to measure 50'? Your description implies that the z-axis travel of the platen is only around an inch?

How many points are you planning on measuring?

There are range of products that could meet you requirements:

> surface profiler such as those used by semiconductor manufacturers:

http://www.wyko.com/html/product_bymarket_proddetail.asp?ProductID=99&MarketID=2

http://www.wyko.com/html/product_bymarket_proddetail.asp?ProductID=132&MarketID=4

Both these exceed your measurement requirement.

> laser range scanners such as:

http://www.rieglusa.com/new-site/products.htm#scanner

Wasn't able to run across one that meets your requirement outright though, although there are laser rangefinders such as the SICK DME3000 that has about 0.006" resolution, but the accuracy is considerably lower.

> Coordinate metrology systems used in the aircraft industry:

http://www.brownandsharpe.com/mfg/mfg7/mfg7art1.html

> Likewise, you could conceivably build your own version of a Dektak, using the X-Y position part of your system to position a probe or a proximity sensor near the platen. TTFN