Common path Michelson interferometer based on multiple reflections within the sample arm: sensor applications and imaging artefacts

We present a simple common path dual beam interferometric sensor platform using a low-coherence source. In our implementation we exploit (in a controlled manner) the multiple reflections within the sample arm to provide the reference arm. This simple setup removes the need for a separate reference arm and allows an alternative architecture for using low-coherence sources in interferometric sensors. We demonstrate the sensor characteristics by using it as a vibrometer and displacement sensor (without directional sensitivity). Vibration frequencies from 50 to 300 Hz were measured with 1% precision while displacements from 6 to 24 µm were measured with 125 nm precision and 625 nm resolution. We discuss improvements, limitations and potential applications. Lastly, we point to the artefactual appearance of this sensor in optical coherence tomography setups. (technical design note)