Fiber endoscope with inflatable lens

In this paper we present a special fiber based endoscope with an inflatable lens. This endoscope is designed for photodynamic therapy (PDT), while reducing the external diameter of the treatment device. When the endoscope is inserted into the human body, a latex water fillable balloon attached to the endoscope is inflated in front of scope's tip acting as a lens, thus facilitating focusing of the optical radiation delivered by the scope, and consequently increasing the obtained irradiance. In our experiments we were able to improve the power density using the inflated lens by more than two orders of magnitude.