1. An optical method of inspecting articles ( 2 ) of transparent or translucent material with the help of a vision system ( 3 ), the method consisting: in illuminating the articles ( 2 ) with the help of a light source ( 6 ) having an angular spectrum that is adapted to the contrast selected for refractive items presented by the articles ( 2 ); in using an image sensor ( 5 ) for picking up the light that has passed through the articles ( 2 ) in order to make images of the articles ( 2 ); and in analyzing the images in order to detect the presence of light-refracting items; the method being characterized in that it consists: during a stage of referencing the vision system ( 3 ): in placing a reference standard ( 20 ) in front of the light source ( 6 ) and in the field of view of the image sensor ( 5 ), the reference standard ( 20 ) including at least one standard item ( 21 ) that refracts light in a known range of angles; and in taking at least one image of the reference standard ( 20 ) so as to measure at least the contrast in the image produced by at least one standard item ( 21 ) and corresponding to an optimized optical adjustment of the vision system ( 3 ); and during at least one stage of qualifying the vision system ( 3 ): in placing the reference standard ( 20 ) once more in front of the light source ( 6 ) and in the field of view of the image sensor ( 5 ); in taking at least one image (I) of the reference standard ( 20 ) so as to measure at least the contrast in the image produced by the standard item ( 21 ) and corresponding to the optical adjustment of the vision system ( 3 ) during this qualification stage; and in determining at least whether the contrast in the image produced by the standard item ( 21 ) corresponding to the optical adjustment of the vision system ( 3 ) during this qualification stage does or does not comply with the contrast in the image produced by the standard item ( 21 ) during the referencing stage.