Method and apparatus for transmission measurement of the geometric structure of an optical component

Measurement procedure by transmitting the geometrical structure of an optical component (2), comprising the steps: - of illuminating the optical component with a first incident light (8, 10), whose wavefront is known, - of measuring ( 16, 18) the wavefront of said first light after transmission by said optical component, - of illuminating the optical component by a second incident light (12, 14), whose wavefront is known, - of measuring (16, 18) the wavefront of said second light after transmission by said optical component, - of calculating the geometrical structure of said optical component from the wavefronts measured in said measurement steps.