Fabrication of hybrid optical line generator by direct machining.

In this study, a mold of a line generator consisting of a cylindrical lens array with a triangular diffractive grating was ultra-precision diamond machined with Moore 350FG 5-axis ultra-precision machine. The design and the simulation of the hybrid structure were performed using ray tracing and exact electromagnetic theory. The machined hybrid lens structure was replicated to a UV-curable polymer and was then characterized and tested. The optical measurements show that the hybrid element works as designed.

Micropatterned luminescent optical epoxies.

We study the fabrication and optical properties of micropatterned luminescent optical epoxy samples. Five different photoluminescent materials were added to epoxy resin to form luminescent epoxies of different colors and micropatterned gratings were imprinted on the surface of the samples. The absorbance spectra of the unpatterned epoxy samples were measured with spectrometer and the luminescence intensities of all samples were measured using custom made bispectrometer. The methods used in this work offer an efficient and straightforward way to produce micro- or nanopatterned luminescent optical epoxies for various applications, such as LED coatings and solar concentrators.

A beam branching method for timing and spectral characterization of hard X-ray free-electron lasers.

We report a method for achieving advanced photon diagnostics of x-ray free-electron lasers (XFELs) under a quasi-noninvasive condition by using a beam-splitting scheme. Here, we used a transmission grating to generate multiple branches of x-ray beams. One of the two primary diffracted branches (+1st-order) is utilized for spectral measurement in a dispersive scheme, while the other (-1st-order) is dedicated for arrival timing diagnostics between the XFEL and the optical laser pulses. The transmitted x-ray beam (0th-order) is guided to an experimental station. To confirm the validity of this timing-monitoring scheme, we measured the correlation between the arrival timings of the -1st and 0th branches. The observed error was as small as 7.0 fs in root-mean-square. Our result showed the applicability of the beam branching scheme to advanced photon diagnostics, which will further enhance experimental capabilities of XFEL.