The present invention is a flow control actuator capable of exciting a fluid via the coupling of edge tones generated along a wedge and resonance generated within a cavity. In the light blocking unit, a position on an aperture plane and a position in an optical axis direction of the exposure light are adjusted. This reflection layer is made of an AgPdCu alloy thin layer or an AgPdCuAl alloy thin layer. The two valves each include a valve body having a bore and serving as a valve seat, a plunger slidably fitted within the bore of the valve body and serving as a valving element, and a spring disposed on the bottom of the bore of the valve body and biasing the plunger to be in contact with the valve body.