Composite materials, especially in aeronautics, often present themselves as thin structures of large lateral size. Their control is generally performed by pulse-echo technique using ultrasonic bulk waves. A way of reducing the inspection time could be to use Lamb waves. These guided waves present a relatively low attenuation which thus allows to inspect large areas more rapidly. Furthermore, one can select a propagation mode offering no « dead zone » inside the plate [1]. Lamb waves can be generated by piezo transducers with contact, water coupling or, more recently, with air coupling [1,2]. Research is underway to generate Lamb waves through imbedded optical fibers delivering laser pulses [3]. Then the inspection consists in detecting for each considered emission direction either an echo (reflection mode) or an increased attenuation (transmission mode) [1,2]. These indications reveal the presence of a defect in the insonicated area. Depending on the minimal size of the defects and of the induced diffraction pattern, the angular discretization of the « inspection web » around each emission transducer has to be optimized.