Small compact calcium-beam optical frequency standard in Peking university and its new scheme

In this report, we will first present the most recent experimental progress of small compact Ca-beam optical frequency standard at 657nm wavelength at Peking university. Second, we will discuss our new scheme, which combining pre-pumping, shelving detection, and sharp-angle velocity selection detection. Comparing previous schemes, we expect the short-term stability can be improved at least by a factor of 30, and an expected factor of 10 for uncertainty in our new scheme since Doppler effect can be calibricated with higher accuracy.