Dark-field circular depolarization optical coherence microscopy.

Optical coherence microscopy (OCM) is a widely used structural imaging modality. To extend its application in molecular imaging, gold nanorods are widely used as contrast agents for OCM. However, they very often offer limited sensitivity as a result of poor signal to background ratio. Here we experimentally demonstrate that a novel OCM implementation based on dark-field circular depolarization detection can efficiently detect circularly depolarized signal from gold nanorods and at the same time efficiently suppress the background signals. This results into a significant improvement in signal to background ratio.