Vapor-cell frequency reference for short-wavelength transitions in neutral calcium

We have characterized the molecular tellurium (Te2) spectrum in the vicinity of the 423 nm S01–P11 and 431 nm P13–P03 transitions in neutral calcium. These transitions are relevant to optical clocks for atomic-beam characterization and cooling (423 nm) and enhanced detection (431 nm). The use of a Te2 vapor cell as a frequency reference has many advantages over other laser stabilization techniques, and we discuss an application to measure the instability due to the second-order Doppler shift in a calcium beam clock.