Design of a free-space image-relay optical time domain reflectometer to measure fiber-optic time delays at inertial confinement fusionrelevant wavelengths

摘要

Fiber optics are an integral part of data collection, often used to transport visible and UV light to streaked spectrometersand photodetectors. Precisely measuring fiber-optic time delay (FOTD) is necessary for absolute data timing or fiberreplacement. An optical time domain reflectometer (OTDR) can be used to measure the fiber-optic time delay.Commercial OTDR’s measure only the fiber in telecommunications wavelengths in the IR. To measure fibers at relevantwavelengths for inertial confinement fusion experiments, a solution using a free-space image relay was devised at theUniversity of Rochester’s Laboratory for Laser Energetics (LLE), where readily available equipment has been used tomeasure the FOTD to within 2 ps at 526.5 nm as well as 351 nm, which is an order of magnitude better than the timingjitter between LLE’s Hardware Timing System and second-harmonic (526.5-nm) fiducial laser pulses.