Tire checking apparatus

Abstract

An apparatus for a laser interferometric tire checking in which a thermoplastic film serves as light sensitive layer, and in which optical members are provided in the path of the object beam diffusely reflected by the inner surface of the tire. By means of these optical members the spreading angle of the beam cone inciding upon the light sensitive layer is limited to less than 40.degree.. According to a specific embodiment of the invention, within the region of the radial central plane of the tire to be checked there is provided a mirror which is inclined relative to the last mentioned plane and is located in the path of the object beam which illuminates the inner surface of the tire to be checked and is reflected by this tire inner surface. According to a particularly advantageous embodiment of the invention, the tire and the mirror are turnable relative to each other parallel to the central tire plane. Furthermore, a negative lens system may be arranged in the beam cone of the object beam reflected by the inner tire surface onto the light sensitive layer. By means of this dispersion lens system, the spreading angle of the beam cone of the reflected object beam is, when inciding upon the light sensitive layer, narrowed down to less than 40.degree..

Dependencies are inferred from the claim text.