Enhancement of imaging depth and definition for optical coherence tomography by using sodium chloride agent

Sodium chloride (NaCl) water solution of different concentrations has been applied to human fingers to improve the imaging depth and the definition of optical coherence tomography images. It is found that the saturated NaCl solution of 36% concentration leads to the most effective enhancement, which is observable 1 min after the agent is applied to a sample surface. In contrast, for unsaturated NaCl agent of less than 30% concentration, both imaging depth and imaging definition first decrease for the initial few minutes and then increase. In general, reduction of NaCl concentration results in not only less enhancement of image quality but also longer leading time for the effect to be seen than that with saturated solution.