The device has an instrument (11) for acting on a biological tissue by creation of an optical phenomenon. A supply apparatus (12) supplies the instrument with electrical radio frequency power. An analyzer (21) determines light features i.e. signatures, of light produced by the action of the instrument on the tissue. A discriminator device associates the light features of the light to tissue features of the biological tissue. The instrument comprises a high frequency-electrode (14) connected with the supply apparatus over a spacer (13).
