Method for measuring the optical quality of a given region of a glazing unit, associated measuring device

A method for measuring an optical quality of a region of a glazing of a road or rail vehicle, said region being intended to be positioned in an optical path of an image-acquiring device, the measuring method being implemented by a measuring device comprising an emitter and a wavefront analyzer, the measuring method comprising:

• emitting, with the emitter, a beam of light rays in a direction of said region;
• analyzing, with the wavefront analyzer, the wavefront of the light rays transmitted by said region, the analyzing comprising:
• generating a wavefront-error map,
• determining, on the basis of the wavefront-error map, at least one optical-defect map, of any optical defects present in said region of the glazing,
• wherein the analyzing further comprises:
• dividing the beam of light rays into a plurality of beams,
• generating an interferogram map, and
• on the basis of the interferogram map, computing a phase difference between the wavefront of the light rays transmitted by said region of the glazing and a reference wavefront, with a view to determining a final wavefront error used to generate the wavefront-error map, and
• wherein in the dividing, the wavefront of the beam of light rays transmitted by said region is made to propagate through a diffractive grid spaced apart from a wavefront sensor of the wavefront analyzer so that the beam of light rays is divided by diffraction, the diffractive grid comprising a grid and a diffractive optic contiguous to the grid.