Berlin 2001 – wissenschaftliches Programm

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A: Atomphysik

A 17: Posters Friday (Spectroscopy)

A 17.26: Poster

Freitag, 6. April 2001, 12:30–15:00, AT3

Absorption Measurements of the calcium 1S0-1D2 quadrupole transition — •Enrico Maccioni, Nicolo’ Beverini, and Andrea Ruffini — Dipartimento di Fisica E. Fermi, Universita’ di Pisa e INFM, via Buonarroti 2, 56127 Pisa ,Italy

The demand of stable frequency references has grown hugely in the last years. Two photons 1S0-1D2 transition of Ca on a cooled atomic beam can provide a very stable reference at 915 nm. In the frame of the realization of this project, a Ti:Sa laser will be locked on the transition by observing Ca vapour absorption on the correspondent quadrupole line at 457.5 nm.

The 457.5 nm radiation is produced in a KNbO3 crystal by Second Harmonic Generation (SHG) of the radiation emitted by a four mirror Ti-Sa ring laser. The laser cavity has been designed for astigmatism compensation and single-mode working. About 0.3 W of radiation at 915 nm is obtained, with a spectral line- width of about 10 MHz. The SHG process occurs by non critical temperature tuning at 140 degrees of the KNbO3 crystal and about 1 mW of radiation at 457.5 nm is available for Ca spectroscopy.

The Ca cell is a 60 cm long steel tube, closed by CaF2 windows, that can be heated up to 750-800 C. Finally the Doppler absorption of the 1S0-1D2 quadrupole transition is detected.