METHOD FOR BLOW-MOLDING CONTAINERS

The invention relates to a method and the device for blow-molding containers (2). A preform (1) made of a thermoplastic material is first subject to a thermal conditioning operation along a transport path in the region of a heating section (24). Thereafter, the preform (1) is formed into the container inside a blowing mold (4) by applying blowing pressure. Subsequent to the blow-molding step of the container, a wall thickness is measured on at least one height level of the container. The measurement is carried out visually using a chromatically uncorrected lens (60, 61). The wall thickness (66) is determined by evaluating differences of the frequencies of reflection signals, wherein radiation having a first frequency of an outer surface (65) and radiation having a second frequency of an inner surface of the container are reflected. The respective differences in frequencies are associated with defined wall thicknesses.