Research Of Cold Atomic Beam Interferometer Signal Detection Technology

With the rapid development of atom optics technology, atomic interferometers graduallybecome a hot topic in the field of precision measurement. Atomic interferometers have a widerange of application prospects, because of its high sensitivity, absolute measurement,long-term stability inherent advantages in inertial navigation and basic physics research andother fields.Atomic light source is one of the basic elements of atomic interferometer, itsperformance directly determines the contrast of atomic interference fringes andsignal-to-noise ratio, which directly affects the accuracy of measurement. The performance ofatomic light source is tested and characterized, and the high performance atomic light sourceis optimized for interference. At the same time, the noise of atomic energy state measurementis the basis of high precision atomic interference measurement.Based on the atomic beam characteristics detection theory, using cold atominterferometry gyroscope as the research object, we designed the corresponding detectionsystem of the atomic beam characteristics. The whole detection system is composed ofhardware and software components, mainly consists of three parts: optical system, detectiondevice and software system. In the optical system, in order to obtain the laser source with highstability, we designed a special laser control system. The control system consists of a currentdriver and a temperature controller. Current is adjustable in the range of200mA, the currentcontrol accuracy up to1uA, The AC voltage noise RMS within3-100KHz bandwidth is lessthan300nA.The temperature controller uses highly integrated MAX1978as the main controlchip, driving the Thermoelectric Cooler (TEC) for temperature compensation, long-termtemperature drift is less than2mK. The system can be used to drive the DFB external cavitylasers and DBR lasers. It was used to drive an external cavity laser in the measurement system,with the saturated absorption frequency stabilization can meet the stability requirement of blocking light and probe light. The detection system based on detecting the fluorescencesignal of the atomic beam, the time of flight method used to detect longitudinal velocity andspectrum distribution of the atomic beam. In order to collect the fluorescence signal toimprove the SNR, designed special fluorescence collection device, using PMT asphotoelectric converter fluorescence signal detection. The software is written by LABVIEWwith virtual instrument interface, and embedded in a program by MATLAB algorithm, thedetected signal can be calculated, and real-time display.Cold atom interferometer gyroscope atomic beam characteristics were detected, and thedetection performance is analyzed. Experimental results show that the longitudinal atomicbeam of most probable speed is14.2m/s, the velocity distribution FWHM is3.9m/s,continuous atomic beam flux of about2.7×108atoms/s.The calculated system detectionresolution of velocity spectral distribution is0.16m/s, and the minimum detectable value ofatomic flux is about4.7×104atoms/s.