This thesis describes the design, construction and optimisation of a rubidium spin exchange relaxation free magnetometer using only a single beam. The experiment is used to look at high bandwidth sensors which will ultimately inform a more compact version used for biomagnetic field detection. The optimisation of the sensor is discussed in detail highlighting the battle between magnetometry cell temperature, laser power and laser detuning, but also the effects the modulation parameters can have on the sensitivity. Two detection methods are used in this thesis: absorption and optical rotation. The differences in how these two methods operate are highlighted and how these differences affect the final result in the sensitivity. With both of the these methods reaching equal sensitivities above 10 Hz, the choice was made to progress further with the absorptive detection method due to its superior sensitivity in the lower frequency range. Limitations of the experimental setup are discussed with them being reached in various components. The limiting noise sources are thought to be the DAQ unit and vibrations introduced by the shield. A sensitivity of 35 fT/√ Hz with a bandwidth that extends out to 420 Hz is achieved, while clear areas for improvement are highlighted. Overcoming some of these limitations ultimately lead to a sensor with an improved noise performance of sub 20 fT/√ Hz. It is pointed out that the Johnson noise of the mu-metal shield is not far below the sensitivity reached here.
Date of Award | 15 May 2024 |
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Original language | English |
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Awarding Institution | - University Of Strathclyde
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Sponsors | EPSRC (Engineering and Physical Sciences Research Council) |
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Supervisor | Paul Griffin (Supervisor) & Erling Riis (Supervisor) |
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