Quick Shot

An echelon is an optic consisting of a series of rectangular mirror elements arranged in a staircase pattern. It can be used for a number of applications, including calibrating ultrafast streak cameras. The mirrored elements divide a single laser pulse into a series of temporally delayed segments. Shown is Research Engineer, Joe Katz, constructing such an echelon using a UV source to glue an additional mirror to the assembly. The orientation of the mirrored surfaces is monitored in real time to confirm their alignment while they are fixed in place with UV-cured optical cement. Additionally, an echelon can be used to correct large-scale pulse-front tilt introduced from a diffraction grating while maintaining angular dispersion. When used in a spectrometer, an echelon can compensate for path-length differences, allowing for picosecond time resolution with large-aperture beams. The optic was ground, polished, coated, assembled, and metrologized in-house at LLE.