Skin treatment device with radiation emission protection

The present invention relates to a skin treatment device (1, F). The device comprises a radiation source (13) in a housing, such that radiation can be emitted through an exit opening in the housing. It further comprises at least one skin presence sensor (43, 63) capable of measuring the presence of skin (7) in a number of respective positions, and a control unit (37). The control unit (37) is constructed to determine a covered portion of the exit opening (15) from a measurement signal of the skin presence sensor and to restrict emission of the radiation (13) to the covered portion of the exit opening (15), e.g. by modifying the control of a radiation beam manipulator (11), or by controlling radiation-blocking means, such as blinds, in the exit opening (15). The invention provides a more efficient and yet safe treatment device (1, 1′), since a larger exit opening (15) can be selected, while unwanted emission of radiation (13) through uncovered portions of the exit opening (15) is still prevented.