An optical method of inspecting articles of transparent or translucent material with the help of a vision system, the method consisting: · in illuminating the articles with the help of a light source having an angular spectrum that is adapted to the contrast selected for refractive items presented by the articles; · in using an image sensor for picking up the light that has passed through the articles in order to make images of the articles; and · in analysing 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: · in placing a reference standard in front of the light source and in the field of view of the image sensor, the reference standard including at least one standard item that refracts light in a known range of angles; and · in taking at least one image of the reference standard so as to measure at least the contrast in the image produced by at least one standard item and corresponding to an optimize optical adjustment of the vision system; and · during at least one stage of qualifying the vision system: · in placing the reference standard once more in front of the light source and in the field of view of the image sensor; · in taking at least one image of the reference standard so as to measure at least the contrast in the image produced by the standard item and corresponding to the optical adjustment of the vision system during this qualification stage; and · in determining at least whether the contrast in the image produced by the standard item corresponding to the optical adjustment of the vision system during this qualification stage does or does not comply with the contrast in the image produced by the standard item during the referencing stage. · in illuminating the articles with the help of a light source having an angular spectrum that is adapted to the contrast selected for refractive items presented by the articles; · in using an image sensor for picking up the light that has passed through the articles in order to make images of the articles; and · in analysing 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: · in placing a reference standard in front of the light source and in the field of view of the image sensor, the reference standard including at least one standard item that refracts light in a known range of angles; and · in taking at least one image of the reference standard so as to measure at least the contrast in the image produced by at least one standard item and corresponding to an optimize optical adjustment of the vision system; and · in placing a reference standard in front of the light source and in the field of view of the image sensor, the reference standard including at least one standard item that refracts light in a known range of angles; and · in taking at least one image of the reference standard so as to measure at least the contrast in the image produced by at least one standard item and corresponding to an optimize optical adjustment of the vision system; and · during at least one stage of qualifying the vision system: · in placing the reference standard once more in front of the light source and in the field of view of the image sensor; · in taking at least one image of the reference standard so as to measure at least the contrast in the image produced by the standard item and corresponding to the optical adjustment of the vision system during this qualification stage; and · in determining at least whether the contrast in the image produced by the standard item corresponding to the optical adjustment of the vision system during this qualification stage does or does not comply with the contrast in the image produced by the standard item during the referencing stage. · in placing the reference standard once more in front of the light source and in the field of view of the image sensor; · in taking at least one image of the reference standard so as to measure at least the contrast in the image produced by the standard item and corresponding to the optical adjustment of the vision system during this qualification stage; and · in determining at least whether the contrast in the image produced by the standard item corresponding to the optical adjustment of the vision system during this qualification stage does or does not comply with the contrast in the image produced by the standard item during the referencing stage.