We report on the photonic variant of the previously introduced guided-path tomography (GPT), by demonstrating a system for footstep imaging using plastic optical fiber (POF) sensors. The 1 m × 2 m sensor head is manufactured by attaching 80 POF sensors on a standard commercial carpet underlay. The sensing principle relies on the sensitivity of POF to bending, quantified by measuring light transmission. The photonic GPT system, comprising the sensor head with processing hardware and software, covered by a mass-production general-purpose carpet top, successfully performs footstep imaging and correctly displays the position and footfall of a person walking on the carpet in real time. We also present the implementation of fast footprint center of mass calculations, suitable for recording gait and footfall. A split-screen movie, showing the frame-by-frame camera-captured action next to the reproduced footprints, can be downloaded at http://ieeexplore.ieee.org Index Terms-Footstep imaging, gait, "intelligent carpet," parallel center of mass algorithm (PCoMA), photonic guidedpath tomography (PGPT), plastic optical fiber (POF).

Fungal infections are becoming a global health problem. A major limiting factor for the development of antifungals is the high impermeability of the rigid and thick fungal cell wall. Compared to mammalian cells, fungal cells are more resilient to perforation due to the presence of this carbohydrate armor. While a few methods have been reported to penetrate the fungal cell wall, such as electroporation, biolistics, glass beads, and the use of monovalent cations, such methods are generally time-consuming, compromise cell viability, and often lead to low permeation rates. In addition, their use remains limited to in vitro applications due to the collateral damage that these techniques could cause to healthy living tissues. Presented in this study is a delivery approach based on the generation of transient breaks, or pores, in the cell wall. Breaks are generated by cavitation and shock waves resulting from the irradiation of gold nanoparticles with a femtosecond infrared laser. Such an approach enabled the delivery of membrane impermeable molecules (i.e., calcein and plasmid DNA) into Saccharomyces cerevisiae, a fungal model organism. This method is expected to exhibit high biocompatibility and holds potential for clinical applications for the treatment of fungal infections given that neither the laser irradiation nor the nanoparticles have been found to damage cells. Mechanistical aspects of photoporation, such as the proximity needed between the nanoparticle and the cell membrane for these processes to take place, are also discussed. Hence, the laser-assisted drug delivery approach described here is suitable for further preclinical evaluation in oral, vaginal, and skin mycoses where current treatments are insufficient due to host-related adverse reactions, poor fungal cell penetration, or risk of developing antifungal resistance.

In this work, we report a direct (non-iterative) algorithm to reconstruct the three-dimensional (3D) momentum-space picture of any charged particles collected with a velocity-map imaging system from the two-dimensional (2D) projected image captured by a position-sensitive detector. The method consists of fitting the measured image with the 2D projection of a model 3D velocity distribution defined by the physics of the light-matter interaction. The meaningful angle-correlated information is first extracted from the raw data by expanding the image with a complete set of Legendre polynomials. Both the particle’s angular and energy distributions are then directly retrieved from the expansion coefficients. The algorithm is simple, easy to implement, fast, and explicitly takes into account the pixelization effect in the measurement.

Abstract-We report first results on developing smart sensor systems for the automatic and frequent collection of animal weight and gait data, under the hostile conditions of a livestock farm. The novelty in our approach is to sense frequently the animals' floor contact, in suitably chosen locations, under natural and unobtrusive conditions. We demonstrate a pilot low profile rubberized mat sensor heads, delivering a large number of plastic optical fiber transmission measurements taken frequently from individual deformation sensors. The acquired data allows gait analysis from guided-path tomography images or by machine learning. We demonstrate weight estimation with accuracy better than 1% over a range suitable for deployment in pig farms.

Techniques to directly write localised refractive index structures in polymer optical fibres (POF) are presented, using UV (400nm) ultrafast laser with pulse lengths of 100 fs to create in-fibre gratings for sensing. No doping is necessary for photosensitisation so commercially available POF is used. An in-fibre grating consisting of a 1.8 µm wide refractive index structure with a periodicity of 189 nm was demonstrated in single mode polymer fibre with optimised laser processing parameters.Keywords: femtosecond laser, poly(methyl methacrylate), PMMA, polymer optical fibre, refractive index modification INTRODUCTIONPeriodic refractive index (RI) structures within optical fibres can sensitise them to strain or temperature (eg In Fibre Bragg grating), create filters and reflectors within the fibre, or access core modes for interaction with cladding measurands (Long Period Grating). Poly(methyl methacrylate) (PMMA) or Perspex based polymer optical fibres (POF)is of interest for strain sensing due to its increased sensitivity by 14% 1 compared with glass based fibre, biocompatibility, and good optical transmission in the visible region coincident with high brightness, low cost visible LEDs and laser diodes now commercially available. In 1999, the first inscription of tunable Bragg gratings in doped, single mode POF by excimer laser radiation, exhibiting Δn~10 -4 was reported 2 . The study of Fibre Bragg grating (FBG) based devices in POF was recorded, such as wavelength tunable filter 3 and fibre interferometry 4 . Permanent RI structures within bulk undoped PMMA directly written by femtosecond (fs) laser (Δn~5×10 -4 ) at 800nm, 40fs, 1 kHz repetition rate were demonstrated by Scully 5 , with longevity of several years. The photochemical mechanism was elucidated and effect of wavelength and pulse length on the multi-photon process related to bandgap 6 . A minimum diffraction limited feature size of 0.42 μm was achieved within bulk clinical grade PMMA by holographic writing at 387 nm 7 .This paper describes attempts to direct write photonic structures within the core of single mode POF under control at the required spatial resolution, within the constraints posed by the fibre curved surface, and the fibre itself acting as a cylindrical focusing optic, plus self focusing, and writing structures at depth below the surface. The overall aim is to evaluate the feasibility of inscribing highly localised Δn at an appropriate spatial resolution within the POF fibre core. EXPERIMENTAL DETAILSThe experimental arrangement for fs laser micromachining is shown in Fig.1. The fundamental output from a Spectra-Physiscs Spitfire Ti:Sapphire fs laser located in the Photon Science Institute at the University of Manchester with repetition rate of 1 kHz, maximum pulse energy of 3 mJ and pulse duration of 100 fs, was measured using a scanning autocorrelator. The 6 mm diameter laser beam was attenuated by a diffractive optic attenuator and wavelength halved to