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

We have characterized the molecular tellurium (Te${}_2$) spectrum in the vicinity of the 423nm ${}^1{S}_0{-}^1{P}_1$ and the 431nm ${}^3{P}_1{-}^3{P}_0$ transitions in neutral calcium. These transitions are relevant to optical clocks for atomic-beam characterization and cooling (423nm) and enhanced detection (431nm). The use of a Te${}_2$ vapor cell as a frequency reference has many advantages over other laser stabilization techniques, and we discuss an application to measuring the instability due to the second-order Doppler shift in a calcium beam clock.