Device for inspecting the surface of a transparent object, and corresponding method

A method for inspecting a foil-type transparent object having a first surface on a top side and a second surface on a bottom side of the foil-type transparent object with a device, wherein the device comprises a camera and at least one light source,

• wherein with electromagnetic radiation emitted by the at least one light source a line-shaped area of the first surface is illuminated from above or the second surface is illuminated from below,
• wherein an illumination takes place at a predetermined angle (α) to a respective illuminated surface,
• wherein with the camera an intensity of the electromagnetic radiation reflected back is detected in at least one section of the line-shaped area,
• wherein the predetermined angle (α) is less than or equal to 15°,
• wherein the electromagnetic radiation emitted by the at least one light source is predominantly linear and s-polarized, wherein a degree of contamination of the illuminated surface is determined on a basis of the intensity detected by the camera,
• wherein an object-side end portion of an optical path of the camera is defined at one end by a deflection mirror and at an opposite end by the illuminated surface of the foil-type transparent object, and,
• wherein the deflection mirror is partially transparent and the at least one light source is arranged behind the deflection mirror as seen from the foil-type transparent object.