IN-SITU MEASUREMENTS OF SHAPES AND THICKNESSES OF OPTICAL PARTS BY FEMTOSECOND 2-COLOR INTERFEROMETRY

Simultaneous measurement of the surface shape and determination of the thickness of a lens were performed using the same optical configurati on, utilising temporal localisation and the high peak power of femtose cond optical pulses with; two-colour interferometry. Femtosecond two-c olour interferometry (FTI) derives good stability in measurements due to the near-common path and easy alignment even though the coherence o f the laser is low. The FTI could even be used for in-situ dimensional measurements of complex optical parts with low reflective surfaces an d rather tight curvatures.