Method and apparatus for the determination of the index of refraction of lens material

A method for determining the refractive index (n) of a material of a contact lens (1), the contact lens (1) having a first surface and a second surface defining a lens geometry there between, the method comprising the steps of:

• a) providing a lens holder (2) comprising an optically transparent bottom (21) and containing the contact lens (1),
• b) providing a wavefront sensor (4), the wavefront sensor (4) comprising a light source (40) and a detector (43) for receiving light coming from the light source (40) and having passed through the contact lens (1) contained in the lens holder (2) and impinging on the detector (43), thus generating signals at the detector (43) measuring the wavefront issued by the contact lens (1) with the wavefront sensor (4),
• c) providing an optical coherence tomography system (3) and obtaining data of a geometry of at least one section of the contact lens (1) with the optical coherence tomography system (3),
• d) communicating the measured wavefront from the wavefront sensor (4) and the data of the geometry of the at least one section of the contact lens from the optical coherence tomography system (3) to an analyzer (5),
• e) determining the refractive index (n) of the material of the contact lens from the data of the geometry of the at least one section (S) of the contact lens (1) and from the wavefront issued by the contact lens (1).