Investigation of motion control of piezoelectric unimorph for laser shutter systems

This paper presents the design and testing of a resonance frequency-tunable piezoelectric unimorph chopper and shutter that employ a magnetic force technique and magnetorheological fluid (MRF). This technique enabled to increase the frequency of the resonance up to 110% of the untuned resonant frequency. A piezoelectric unimorph cantilever with a natural frequency of 126 Hz is used as the laser beam chopper or shutter, which is successfully tuned in a frequency range of 126 - 270 Hz thereby enabling continuous control of the laser beam over the entire frequency range tested. A theoretical model based on variable magnetic field strength and MRF damping is presented. The magnetic force and MRF applied for damping of transient vibrations of the piezoelectric unimorph shutter have been experimentally determine

Control of piezoelectric scanner dynamics using magnetorheological fluid

The developed one-dimensional laser beam scanner, driven by a piezoelectric disctype unimorph actuator is presented in this paper. The dynamics of a piezoelectric actuator is analyzed. A magnetorheological fluid (MRF) damper is used to eliminate transient vibrations of the scanner eigen frequencies induced by the stepped driving voltage. Experimental results demonstrate the effectiveness of the MRF damper in residual-vibration reduction in the laser beam scanner

SiN foundry platform for high performance visible light integrated photonics

We present a high performance silicon nitride photonic integrated circuit platform operating at visible wavelengths, accessible through the commercial foundry, LIGENTEC. Propagation losses were measured across the visible spectrum from 450 nm to 850 nm. For wavelengths above 630 nm, losses were < 1 / in TE and < 0.5 / in TM. Additionally, sets of single mode waveguide-coupled ring resonators across three separate chips were tested and analysed. A peak intrinsic Q factor of 3.69 × 106 was measured for a single resonance at ∼635.3 nm, with an average value of 2.28 × 106 recorded over 10 peaks in a 3 nm tuning range. Analyses of the loss and coupling, as functions of bus-ring coupling gap and waveguide width, are also presented. High confinement, low loss devices realised on the chip-scale in a wide-bandgap material like silicon nitride are increasingly important for the next generation of integrated optical devices operating at visible wavelengths

Resolving plasmid structures in Enterobacteriaceae using the MinION nanopore sequencer: assessment of MinION and MinION/Illumina hybrid data assembly approaches

This study aimed to assess the feasibility of using the Oxford Nanopore Technologies (ONT) MinION long-read sequencer in reconstructing fully closed plasmid sequences from eight Enterobacteriaceae isolates of six different species with plasmid populations of varying complexity. Species represented were Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii, Enterobacter cloacae, Serratia marcescens and Klebsiella oxytoca, with plasmid populations ranging from 1–11 plasmids with sizes of 2–330 kb. Isolates were sequenced using Illumina (short-read) and ONT’s MinION (long-read) platforms, and compared with fully resolved PacBio (long-read) sequence assemblies for the same isolates. We compared the performance of different assembly approaches including SPAdes, plasmidSPAdes, hybridSPAdes, Canu, Canu+Pilon (canuPilon) and npScarf in recovering the plasmid structures of these isolates by comparing with the gold-standard PacBio reference sequences. Overall, canuPilon provided consistently good quality assemblies both in terms of assembly statistics (N50, number of contigs) and assembly accuracy [presence of single nucleotide polymorphisms (SNPs)/indels with respect to the reference sequence]. For plasmid reconstruction, Canu recovered 70% of the plasmids in complete contigs, and combining three assembly approaches (Canu or canuPilon, hybridSPAdes and plasmidSPAdes) resulted in a total 78% recovery rate for all the plasmids. The analysis demonstrated the potential of using MinION sequencing technology to resolve important plasmid structures in Enterobacteriaceae species independent of and in conjunction with Illumina sequencing data. A consensus assembly derived from several assembly approaches could present significant benefit in accurately resolving the greatest number of plasmid structures