The feasibility of employing laser Rayleigh scattering as pressure sensor in the medium vacuum region (1-10
3 Pa) was investigated by performing two experiments. The first experiment was aimed at demonstrating that such a pressure sensor could be realized. For this purpose, a YLF laser was used. The results were i) the stray light level was reduced to 2.7 Pa, and ii) signal linearity was obtained for the pressure range between 2.7 Pa and 1.2×10
3 Pa with an error of less than 7%. The second experiment was performed to demonstrate that a compact pressure sensor could be fabricated. For this purpose, a laser diode was used, and signals were successfully detected down to 130 Pa with an error of less than 9%. This means that the sensor will be realized if the detection lower limit can be improved by a factor of one hundred.
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