Low-power optical vibration detection by photoconductance monitoring with a laser speckle pattern

We present a quantitative evaluation of the performance of a photoconductance-monitoring sensor array in a speckle-based vibration detection configuration. The device is found to be capable of detecting nanometer-amplitude vibrations in a single shot with incident intensities of only a few microwatts per square centimeter at kilohertz frequencies. This performance indicates that the photoconductance-monitoring array requires approximately 3 orders of magnitude lower intensity to achieve the same displacement sensitivity as competing technologies, such as photo-electromotive-force detectors.