Novel X-ray Refractive Lenses

[Background] The fourth-generation synchrotron radiation sources and X-ray free-electron lasers are characterized by low emittance, high brightness, and high coherence, presenting new requirements and opportunities for X-ray optical devices. [Purpose] This paper aims to explore the basic principle of X-ray lenses based on refraction and reviews their latest developments, addressing issues such as aberrations and material absorption for optimizing optical performance. Additionally, it introduces advanced manufacturing processes for X-ray refractive focusing lenses. [Methods] New design concepts were adopted to reduce aberrations and material absorption, improving lens optical performance. Advanced manufacturing techniques, such as embossing, two-photon polymerization, LIGA, semiconductor etching, and femtosecond laser processing, were employed to fabricate such complex lenses with micro/nano structure features. [Results] Significant progress has been made in reducing aberrations and material absorption in refractive lenses, which has optimized their optical performance. New phase plates have further enhanced the application effectiveness of the lenses. [Conclusions] Novel designs and advanced manufacturing processes have significantly improved the refractive lens performance and largely widened the usage scenario. X-ray refractive lenses will gain more application in modern synchrotron radiation sources and X-ray free-electron lasers.