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AMULET A dvanced M etrology U sing L as E r T racers. John Dale. Project Aim. To take Frequency Scanning Interferometry (FSI) from the lab into a product. Tunable Laser. Reference Interferometer: L. Measurement Interferometer: D. Measurement Interferometer: D2.
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Project Aim • To take Frequency Scanning Interferometry (FSI) from the lab into a product
Tunable Laser Reference Interferometer: L Measurement Interferometer: D Measurement Interferometer: D2 Frequency Scanning Interferometry (FSI) Absolute measurements • Used for several projects in Oxford • ATLAS • LiCAS • MONALISA • Ratio of phase advance is equal to the ratio of the lengths • Reference interferometer is an absolute length scale • Can determine D if L known • Scalable • Any number of measurement interferometers Intensity Time Intensity Time
Project Tasks • Improve FSI Technique • Practicality • Stability • Traceability • Implement FSI in a laserTRACER • Reduce equipment cost • Simultaneous multiple length-measurements
LaserTRACER • Developed by NPL, PTB and marketed by Etalon AG • A self tracking laser interferometer • Automatically follows retro reflector • Uses differential interferometry with a frequency stabilised laser Intensity Frequency Stabilised Laser Time
Why Absolute Measurement? • Differential measurement • laserTRACER tracks retro reflector • If Absolute measurement system added • No problems with beam breaks • Switch from one target to the next • Divergent beam allows simultaneous measurements
Current Reference Interferometers • Evacuated folded path reference interferometers • Bulky • Expensive • Difficult to thermally stabilise • We require • Compact • Can be thermally stabilised • Long term stability 1.2m
Compact fibre reference interferometer • Fibre Reference Interferometer • Compact (Coiled) • Cheaper • Dispersion • Experimental Prototype under construction • Fluid bath • Insulated • Temperature monitored • Optical length with submicron stability • To be developed into a product
LaserTRACER Implementation • Install into LaserTRACER head • Take advantage of: • Tracking capabilities • Stabilised construction • Market presence • Many possible configurations • Multiple measurement interferometers
Reduced Laser Cost • Working with laser manufacturers • Produce simpler stripped down frequency scanning lasers. • Lasers which better suit FSI • Laser is significant cost, reduction could open other markets.
Why are they useful • Particle Accelerator/Detector Alignment • CMM and CNC Calibration • Require calibration 1-4 times per year • With absolute measurement capabilities, calibration much quicker • Combined CMM and CNC machines. • Absolute distance measurements capability • Especially interesting at large machines (20-30m) • Small machines if cost reduced. • Metrology assisted assembly • Fitting of aeroplane wings
Summary • Project will lead to a product: FSI enhanced laserTRACER • Generate Intellectual property • NPL and Etalon AG have established market presence • laserTRACER has an established customer base • On the market in 4-5 years