A distributed temperature and strain sensing (DTSS) system based on Brillouin backscatter was used to measure changes during a 5 month period on an 9km length of fibre optic cable deployed next to a railway line, including on an embankment and a bridge. By measuring the amplitude and frequency of the Brillouin backscatter it was possible to determine both temperature and strain changes. Most of the strain changes occurred slowly over many weeks, however some rapid strain changes occurred on part of the embankment on one particular day. Temperature effects were dominated by the diurnal and seasonal variations of the air temperature. At a number of points along the cable there were small optical losses that varied with time, but the ability of the system to also carry out regular Rayleigh OTDR measurements meant that these losses could be accounted for, so they had minimal effect on the data.
We present a compact binocular head-up display for integration in a motorcycle helmet. A 2D MEMS-mirror reflecting laser beams enables the formation of a bright image superimposed on the user vision by means of retinal scanning. A 3d-printed prototype including the required optical components is presented and characterized. It fits the morphology of most users thanks to several degrees of freedom accessible to the user for fine-tuning.
We demonstrate the generation of dual-wavelength noiselike pulses in an Er3+ fiber laser. A ring cavity configu ration including a polarizer as saturable absorber induces a first series of pulses at the wavelength of 1550 nm via nonlinear polarization rotation. From the Raman gain of these pump pulses emerges a second series of Stokes pulses at 1650 nm. With an adequate control of the polarization states in the cavity, the Stokes pulses contain
67% of the total energy and reach a bandwidth of 84 nm in the U-band.
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