Design and performance simulation of an advanced Kirkpatrick–Baez microscope with high resolution and large magnification for inertial confinement fusion diagnosis

The representation of the higher-mode signatures of the hot spot and the fine-scale features of Rayleigh-Taylor (RT) instability requires the diagnostic system to achieve a spatial resolution of 1-3 µm in inertial confinement fusion experiments. The former's demand has prompted the present proposal of an advanced Kirkpatrick-Baez (KB) microscope with large magnification and high resolution. We have employed a coaxial confocal optical configuration, combining elliptical concave mirrors and hyperbolic convex mirrors, to achieve the ideal imaging performance. Such a configuration has the advantage of increasing the system's magnification without decreasing the object distance. This microscope is expected to solve the current problem regarding the constraint of the system's integrated resolution by the detector's resolution bottleneck. The structural features and optical design of the proposed KB microscope are described in detail, and a preliminary assessment of its off-axis aberration and spectral response characteristics is presented. A simulation model based on ray tracing and physical processes is used to evaluate the mirror mounting tolerance limit and the microscope's ability to resolve RT instability structures. Our results demonstrated that the system can achieve a theoretical resolution of <0.1µ<i>m</i> in a ±150µ<i>m</i> field of view, a 35× magnification at an object distance of 190 mm, and a total system length of 5.5 m, namely a >25<i>%</i> increase compared to conventional KB systems.