Development of thin gold release layer for fabrication of high-resolution full-shell x-ray optics

Alongside the development of high resolution, full-shell replicated X-ray optics, MSFC is also pursuing the development of advanced thin film coatings. As part of this research program, we are investigating thin release layers to enable a smoother shell release from the underlying mandrels during fabrication. It’s hypothesized that the release stresses contribute to the shell’s axial and azimuthal deformations which distorts the figure and reduces overall performance via HPD degradation. Historically, MSFC has utilized a passivated layer of potassium dichromate on the mandrels before plating to ensure shell release. However, other methods such as employing a thin layer of gold in place of this passivation may result in a smoother release, improving the resulting optic figure. Additionally, this gold film acts as a reflective X-ray coating, boosting the optic’s throughput. We present initial results from the development of thin gold release layers as a means to reduce release stresses during optic fabrication and improve overall figure, enabling future high-resolution, full-shell X-ray optics.