Skin Treatment Device for Multi-Photon Based Skin Treatment

A skin treatment device using polarized light to initiate a multi-photon ionization process at a target position in skin tissue, the skin treatment device comprising:

• a light source constructed and configured for generating linearly polarized probe light and linearly polarized treatment light,
• a polarization modulator constructed and configured for controlling a polarization direction of the probe light and a polarization direction of the treatment light,
• a polarization sensitive sensor constructed and configured for sensing a level of depolarization of the probe light by sensing an intensity of back-scattered probe light from the target position at a predefined polarization direction of the polarization sensitive sensor, and
• a controller constructed and configured for receiving a measurement signal (Sm) from the sensor and providing a control signal (Sc) to the polarization modulator and the light source, the controller being configured for controlling the polarization modulator such as to scan the polarization direction of the probe light over a predefined range of polarization directions while receiving the measurement signal (Sm) and for selecting an optimum polarization (P1) direction for which the level of depolarization of the probe light is at a minimum.