Evaluation of a fiber probe coupled with half ball lens for depth-resolved fluorescence measurements

The association of a beveled collection fiber with a half ball lens is here simulated in order to illustrate the enhancement brought by this simple method in depth resolved measurements, the latter being of major importance in the study of epithelial tissues. Indeed, in order to follow the carcinogenesis stage by a non invasive technique such as fluorescence or Raman spectroscopy, it is valuable to be able to discriminate the depth origin of the detected signal. The proposed probe design consists in a beveled collection fiber positioned on the center of the half ball lens flat surface with an off-axis excitation flat fiber. Depending on the bevel angle of the collection fiber, discrimination between the epithelial and the stromal layer can be realized.