A device for observing and analyzing optical singularities that deflects light and that are carried at the surface of or in the wall of a glass container possessing an axis of symmetry, the device comprising: - a diffuse light source presenting variation of a property of light along a variation direction; - at least one image acquisition device for taking at least one view of a container portion that might contain optical singularities observed from at least one viewpoint along an observation axis; - means for processing at least one view in order to analyze the singularities; - the device being characterized in that: - the light-emitting surface is positioned to illuminate the outside of the container, said surface being a surface of axial symmetry about a vertical axis parallel to the axis of symmetry of the containers, with the light property varying along a generator line of the light-emitting surface along the variation direction at all points of the light-emitting surface of axial symmetry, the surface of axial symmetry being a total or partial surface of revolution, - for containers of low transmittance, the image acquisition device is suitable for taking the view of the container portion from a viewpoint in order to receive the light beams coming from a portion of the light-emitting surface of axial symmetry that is situated on the same side of the container as the viewpoint, which beams are reflected by the surface of the container; or - for containers of high transmittance, the image acquisition device is suitable for taking the view of the container portion from a viewpoint for receiving light beams coming from a portion of the light-emitting surface of axial symmetry that is diametrically opposite from the viewpoint relative to the container, which beams are transmitted through the walls of the container. - a diffuse light source presenting variation of a property of light along a variation direction; - at least one image acquisition device for taking at least one view of a container portion that might contain optical singularities observed from at least one viewpoint along an observation axis; - means for processing at least one view in order to analyze the singularities; - the device being characterized in that: - the light-emitting surface is positioned to illuminate the outside of the container, said surface being a surface of axial symmetry about a vertical axis parallel to the axis of symmetry of the containers, with the light property varying along a generator line of the light-emitting surface along the variation direction at all points of the light-emitting surface of axial symmetry, the surface of axial symmetry being a total or partial surface of revolution, - for containers of low transmittance, the image acquisition device is suitable for taking the view of the container portion from a viewpoint in order to receive the light beams coming from a portion of the light-emitting surface of axial symmetry that is situated on the same side of the container as the viewpoint, which beams are reflected by the surface of the container; or - for containers of high transmittance, the image acquisition device is suitable for taking the view of the container portion from a viewpoint for receiving light beams coming from a portion of the light-emitting surface of axial symmetry that is diametrically opposite from the viewpoint relative to the container, which beams are transmitted through the walls of the container. - the light-emitting surface is positioned to illuminate the outside of the container, said surface being a surface of axial symmetry about a vertical axis parallel to the axis of symmetry of the containers, with the light property varying along a generator line of the light-emitting surface along the variation direction at all points of the light-emitting surface of axial symmetry, the surface of axial symmetry being a total or partial surface of revolution, - for containers of low transmittance, the image acquisition device is suitable for taking the view of the container portion from a viewpoint in order to receive the light beams coming from a portion of the light-emitting surface of axial symmetry that is situated on the same side of the container as the viewpoint, which beams are reflected by the surface of the container; or - for containers of high transmittance, the image acquisition device is suitable for taking the view of the container portion from a viewpoint for receiving light beams coming from a portion of the light-emitting surface of axial symmetry that is diametrically opposite from the viewpoint relative to the container, which beams are transmitted through the walls of the container.