Abstract: The apparatus is used for testing the surface structure of hollow, cylindrical regions of transparent, hollow bodies (e.g. bottles) moved along a track. It comprises an illuminating device (10), a conveyor (14) by means of which the hollow bodies (34) are moved through an inspection region, and an imaging device (12). The illuminating device (10) has several light sources (26) which are arranged so that, in every position within the inspection region (9), the hollow bodies (34) receive light at an angle of incidence such that the hollow bodies (34) act as wave guides and appear as secondary light sources with respect to the imaging device (12), so that the imaging device (12) yields a high-contrast image of the surface structures of the hollow bodies. The device is principally used for the testing of recycled bottles.

Abstract: A conveyor (12) moves the hollow bodies (18) over a circular path through an inspection region (20) in which the hollow bodies (18) are homogeneously illuminated by an illumination device (16). The light issuing from the hollow bodies (18) passes via a group (34) of four mirrors (34a-34d) and a deflecting mirror (36) to a matrix camera or line scanning camera (30). The mirrors (34a-32d) are plane mirrors which are inclined at an angle in relation to one another. The hollow bodies (18) execute one complete revolution about their longitudinal axis while passing through the inspection region (20). Therefore, the group (34) of four mirrors views a quarter of the circumference of the hollow bodies each time in succession. The inspection apparatus is particularly suitable for inspecting the threaded region of bottles and has the advantage that is does not need any moving parts.