Device and method for transilluminating a film

An apparatus for transilluminating a film, comprising

• a transillumination region through which the film is guided,
• a film feed for feeding the film to the transillumination region,
• a light exit from which a light beam exits, the light beam transilluminating the film in the transillumination region,
• a film removal for removing the film from the transillumination region,
• a cavity having a light entrance opening and an exit opening and an interior surface constructed to be diffusely reflecting,
• a light source producing light entering the cavity through the light entrance opening, and
• an optical guide having a beam entrance end and a beam exit end,
• wherein the beam entrance end is arranged so that light exiting from the exit opening of the cavity enters into the optical guide at least partially through the beam entrance end.

An apparatus for transilluminating a film, comprising:

• a transillumination region through which the film is guided,
• a film feed for feeding the film to the transillumination region,
• a film removal for removing the film from the transillumination region,
• a housing, wherein the transillumination region is arranged outside the housing,
• a light source arranged inside the housing and producing a light beam exiting from a light exit, and
• an optical guide guiding the light beam exiting from the light exit along at least a portion of a path between the light source and the transillumination region, with the guided light beam exiting the optical guide transilluminating the film in the transillumination region.

A method for transilluminating a film, comprising the steps of:

• feeding the film to a transillumination region with a film feed,
• guiding the film through the transillumination region for transilluminating the film,
• illuminating a light entrance opening of a cavity having an interior surface formed to be diffusely reflecting with a light source,
• transmitting light exiting from an exit opening of the cavity at least partially to a beam entrance end of an optical guide,
• transilluminating the film with a light beam exiting from a beam exit end of the optical guide, and
• removing the film from the transillumination region with a film removal.