Full-field cavity enhanced microscopy techniques

The number of probe particles that is detected on a single pixel of a micrograph is finite, either due to source (low power), detector (low dynamic range) or specimen damage constraints. The sensitivity of an otherwise perfect microscope is then limited by the statistical fluctuations in the number of detected particles. It is thus crucial to strive for the optimal signal-to-noise ratio per detected photon. Here we analytically and numerically compare three different contrast enhancing techniques that are all based on self-imaging cavities: CW cavity enhanced microscopy, cavity ring-down microscopy and multi-pass microscopy. We show that all three schemes can lead to sensitivities beyond those achievable with a single pass.