Paraboloid of revolution crystal spectrometer for equal optical path and high spectral resolution

We present an X-ray spectrometer for inertial confinement fusion (ICF) research, employing a paraboloid of revolution curved crystal geometry that simultaneously achieves: high spectral resolution, enhanced photon collection efficiency through the sagittal focusing of X-rays with equal Bragg angles, and strict equal optical path conditions across the operational energy range. The spectrometer's unique configuration, with detectors precisely perpendicular to the incident beam in the meridional direction, optimizes optical path alignment. To address the challenge of spectral broadening due to extended source sizes, we present a theoretical method for performance optimization. Simulations verify this approach achieves exceptional resolution (E/ΔE > 6600) and simultaneous tight focusing (sagittal spot diameter < 0.1 mm) while maintaining equal optical path conditions across the 7.7-8.3 keV energy range. Experimental validation using a Cu X-ray tube confirmed high-fidelity spectra with a resolution of E/ΔE > 2800 at Cu Kα₁ for extended sources (150 μm diameter), demonstrating simultaneous high photon collection efficiency for relatively large source sizes.