Novel laser interference lithography setup on the basis of beam splitting Kösters-Prism

The wavefront error of pulse compression gratings (PCGs) is a critical parameter for highpower ultrashort-pulse laser systems. Wavefront errors degrade focal spot quality and reduce peak intensity. Scanning beam interference lithography can minimize period variation across the grating and therefore lower the wavefront error. However, most systems rely on two-arm interferometers that require precision mirror positioning and are sensitive to misalignment. We present an alternative solution based on a beam splitting Kösters prism—two identical prisms bonded at the beam-splitting interface. The incident beam is split internally and undergoes total internal reflection at both hypotenuse surfaces, generating an interference pattern after exiting through the short output face. The common-path geometry equalizes optical path lengths, simplifies alignment, and reduces system cost. Our simulations predict that it is possible to achieve wavefront errors better than PV λ/10. 102