For the practical use of anisotropic materials such as high-performance fibre composite materials, a pre-condition apart from the mathematical determination of the mechanical properties is above all the availability of reliable criteria for optimizing structural components on an experimental basis. The latter are provided by the photoelastic measuring method in the form of the surface-layer technique. It was optimized at the Institute of Engineering Mechanics at the Clausthal college of advanced technology specifically with regard to the stress analysis of fibre reinforced structural components. Basic principles and representative results of this method are introduced. (For figures and references see German text p 76-80).