Abstract: Systems and methods measure a physical parameter of a first substance having an absorption feature that varies based on the physical parameter. A tunable-frequency laser may transmit a first laser beam through the first substance and a second laser beam through a second substance having an isoclinic point. A first output is based on an intensity of the first laser beam transmitted through the first substance, and a second output is based on an intensity of the second laser beam transmitted through the second substance. Controller circuitry locks a first frequency of the first laser beam to the absorption feature based on the first output, and locks a second frequency of the second laser beam to the isoclinic point based on the second output. Measurement circuitry calculates the physical parameter of the first substance based on a difference between the first and second frequencies.

Abstract: Systems and methods for stabilizing laser frequency based on an isoclinic point of an atomic or molecular medium are provided herein. A system may include: a transmission cell containing a gas and configured to transmit light from the laser, the gas having an absorption spectrum with an isoclinic point; a photodiode generating an output based on an amplitude of transmitted laser light; and circuitry configured to tune the frequency of the laser to the isoclinic point of the absorption spectrum based on the output. The absorption spectrum may have first and second overlapping peaks respectively corresponding to first and second transitions of the gas, the isoclinic point being a saddle point between the first and second peaks. The first and second peaks may have substantially equal amplitude as one another and/or may broaden substantially equally as each other as a function of a physical parameter of the gas.

Abstract: Systems and methods for stabilizing laser frequency based on an isoclinic point of an atomic or molecular medium are provided herein. A system may include: a transmission cell containing a gas and configured to transmit light from the laser, the gas having an absorption spectrum with an isoclinic point; a photodiode generating an output based on an amplitude of transmitted laser light; and circuitry configured to tune the frequency of the laser to the isoclinic point of the absorption spectrum based on the output. The absorption spectrum may have first and second overlapping peaks respectively corresponding to first and second transitions of the gas, the isoclinic point being a saddle point between the first and second peaks. The first and second peaks may have substantially equal amplitude as one another and/or may broaden substantially equally as each other as a function of a physical parameter of the gas.

Abstract: Systems and methods for stabilizing laser frequency based on an isoclinic point of an atomic or molecular medium are provided herein. A system may include: a transmission cell containing a gas and configured to transmit light from the laser, the gas having an absorption spectrum with an isoclinic point; a photodiode generating an output based on an amplitude of transmitted laser light; and circuitry configured to tune the frequency of the laser to the isoclinic point of the absorption spectrum based on the output. The absorption spectrum may have first and second overlapping peaks respectively corresponding to first and second transitions of the gas, the isoclinic point being a saddle point between the first and second peaks. The first and second peaks may have substantially equal amplitude as one another and/or may broaden substantially equally as each other as a function of a physical parameter of the gas.

Abstract: Systems and methods for stabilizing laser frequency based on an isoclinic point of an atomic or molecular medium are provided herein. A system may include: a transmission cell containing a gas and configured to transmit light from the laser, the gas having an absorption spectrum with an isoclinic point; a photodiode generating an output based on an amplitude of transmitted laser light; and circuitry configured to tune the frequency of the laser to the isoclinic point of the absorption spectrum based on the output. The absorption spectrum may have first and second overlapping peaks respectively corresponding to first and second transitions of the gas, the isoclinic point being a saddle point between the first and second peaks. The first and second peaks may have substantially equal amplitude as one another and/or may broaden substantially equally as each other as a function of a physical parameter of the gas.

Abstract: A frequency change detector splits a frequency standard signal into two undelayed frequency signals, one of which is delayed by a predetermined amount. The delayed signal is then mixed with the undelayed frequency signal into a mixed signal that is further filtered and amplified for providing an output signal indicating frequency changes of the frequency standard signal. The mixed frequency signal indicates frequency changes of the original frequency standard signal without reference to another frequency standard. This frequency change detector is well suited for use on satellites as an early warning detection of changes in on-board atomic frequency standards.

Abstract: An RF-discharge lamp stabilization system for preferred use in a Rubidium atomic clock, senses acoustic oscillations of plasma ions in the 20.0 kHz range to assess the performance of the lamp for determining radio frequency parameters of the lamp while the lamp is in operation and while the performance of an atomic clock is influenced by the plasma character, with lamp spectral outputs being actively stabilized for improved vapor-cell clock performance.

Abstract: Frequency stabilization of an atomic system is improved by closed loop stabilization of the power level of an atomic excitation signal. A second harmonic atomic Rabi response varies with excitation power level so that power modulation of the atomic excitation and demodulation of the second harmonic response produces a power error signal for closed loop power level control using a voltage controlled attenuator. The atomic system also includes conventional frequency stabilization closed loop control using a voltage controlled oscillator. Both power and frequency modulation of the excitation signal generate a complete atomic response from which both power and frequency error signals are generated for both power and frequency closed loop stabilization.

Abstract: A stabilized atomic clock system uses a stabilized 780.2 nm pump laser for exciting rubidium-85 atoms fluorescing to optically pump rubidium-87 atoms both contained in a gas cell enclosed in a resonant microwave cavity for broadcasting a 6834.7 MHz microwave signal matched to Rb87 hyperfine ground states which are insensitive to pump laser wavelength fluctuations of the pump laser providing the fluorescence optical pumping of the Rb87 atoms to create a population imbalance sensed by a stabilized 794.7 nm probe laser transmitting a probe beam through the cell to a probe laser photodetector generating a probe laser signal used to stabilize the microwave signal to the atomic system and used to generate a constant frequency tick rate signal that is consequently insensitive to pump laser frequency drift due to reduced light shift coefficient.