Metrology Issues

9/11/07

Metrology Troubleshooting

• Advertised tolerance: +/-.0027” @40”; typical +/- 0017” @40’. Not sure what these mean. – We fall within +/-.0027” if we ignore outliers in data.– We see a scattering of data – numbers jump +/-.0027” – Our equipment may be working within advertised limits!

• Backed out of Windows updates- no effect.• Tried various versions of VeraSerf- no effect.• Changed computers – no effect.• Added new wireless network adapters – no effect.• May have a combination of problems.• Leika checked in RadWaste bldg. This is a low noise

environment. Not much difference.

Cloud drift over time (30’ away)Approx. 0.007” excursion

Approx. 8 mils

Other Notes• In build mode, the data would shift with time much more than previously. (screen data would

change )• Is it real mech. noise? Room may be moving.

– Pressure variation effects on wall & floor– Air currents

• When tested in Rad Waste to eliminate these, there was NO EFFECT.• Non mech. noise

– Grounding. With battery power, no effect.– EMI/RFI/wireless radio – changed network cards; checked with suppliers; don’t seem to be the problem.

• Mech. Noise – vibration, etc.– Looked at targets with optics – didn’t observe motion.– Temperature – varies in room 5-6 degrees at times in a shift.

• 2 effects: thermal growth of parts; parts shifting• There is a compensation function in VeraSerf which we need to learn more about.

– However, it’s not very sophisticated. Still need to resolve this one.

• Magnetic effects – Marked checked with manufacturer – they felt their equipment is not sensitive to the stray fields we have in the test cell; their holders have a stronger field.

• Bottom line: It’s not working far outside of its advertised values. We may have a number of small effects which are adding up to put us at the outer limits of the device accuracy.

Possible next steps

• Getting external experts (BNL? Fermilab?)• Plan to go to Farro to check out our serviced

laser tracker with our computer. • PLAN: proceed with measurements, but with

caution.– Develop standard procedures.

• Steve will call Joe Error at SNL and see if he’s willing to come to PPPL with his laser tracker and spend a few days here to check performance in our environment.