Abstract: In an apparatus using optically excited atomic media, such as an atomic frequency standard, a source providing a controlled emission of light for exciting the D1 and/or D2 resonance lines of an alkali gas, such as rubidium or cesium, is controlled by an output generated by digital electronics from the light intensity signal of a light sensor for light transmitted by the alkali gas, an output for representing ambient temperature, and a light intensity-ambient temperature algorithm to substantially eliminate changes in light intensity due to light source aging for the purpose of reducing changes in temperature sensitivity of the apparatus as a function of time and the light-shift contribution to the frequency aging of the standard.

Abstract: In the generation of frequency-modulated interrogation frequencies for atomic frequency standards, the modulation characteristics can be tailored to the frequency discrimination characteristics of a physics package. The rate of phase change of a digital pulse train providing a frequency-modulated component of interrogation frequency for an atomic frequency standard can be varied, for example, by multiplexing a plurality of differently phased (delayed) pulse trains to vary the rate of phase change in a digital interrogation frequency component, or by effecting phase delays and phase advances through the addition and subtraction of pulses of a digital interrogation frequency component.

Abstract: An apparatus for providing excitation of a vapor discharge lamp includes a control circuit for controlling an oscillator circuit during an ignition mode of the vapor discharge lamp to establish and maintain a substantially constant DC voltage at an output of an oscillator transistor and to establish a current flow through the oscillator transistor at a first current level sufficient to ignite the vapor discharge lamp, and for controlling the oscillator after ignition of the vapor discharge lamp to maintain the substantially constant DC voltage at the output of the oscillator transistor while reducing the current flow through the oscillator transistor from the first current level to a second current level, and in preferred embodiments, includes circuitry to suppress unwanted blocking oscillations and optimize the dynamic range of the control circuitry.