Edge of dielectric coating as graded schlieren filter with a high damage threshold

A special cutoff filter is required at the Fourier plane of the imaging lens for the schlieren visualization technique. During short-pulse laser illumination, the energy density in the focal spot of the Fourier plane can surpass the damage threshold of commonly employed metals or metallic coatings used for filtering. While dielectric substrates have a much higher damage threshold, acquiring dielectric filters from commercial suppliers can be challenging. In this study, we present experimental and simulation results to demonstrate that commercially available, off-the-shelf, dielectric mirrors can serve as effective schlieren cutoff filters. These mirrors offer a much higher damage threshold, making them a viable alternative to traditional metal filters in high-energy laser applications.