A laser device for treating skin is provided which includes a handholdable housing； a laser member arranged within the housing emitting an output beam； a capacitance sensor arranged at the first end of the housing which includes a plate surrounding and defining a window through which the output beam exits, the plate having at least three segments with each flexibly movable in and out of a common plane, each of the segments being connected to an electrode, the electrodes operating to determine dielectric constants of a skin surface； a signal and control storage device communicating with the sensor comparing input signals of measured dielectric constant values to a stored standard dielectric constant value, and wherein emission of the output beam is activated to fire only when all of the at least three segments align in a plane and sense the stored standard dielectric constant value.
