Currently, no feasible testing methods are available which allow a cost-effective and in-line non-destructive testing of adhesive bonds. However, thermography has a great potential for the detection of defects in a fast and reliable way. Limitations of the resolution of commercially available infrared cameras usually require a repositioning of the setup to inspect the surface of large parts. This paper presents a new concept for an automated testing method for the thermographic inspection of large-scale bonded parts, which is based on scanning strategies using infrared mirrors. The concept was evaluated by an industrial reference application.