A simple, low-cost conductive composite material for 3D printing of electronic sensors

3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes (‘rapid prototyping’) before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term ‘carbomorph’ and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes

The dependence of the intensity PDF of a random beam propagating in the maritime atmosphere on source coherence

Measurements of intensity statistics of a spatially pre-randomized laser beam propagating in a turbulent atmosphere along two horizontal links in close proximity to grassy ground and above a creek have been carried out in the fall of 2012. The pre-randomization of the laser beam was made by using a nematic Spatial Light Modulator placed at the laser source exit. The beam's phase is randomized with Gaussian statistics with zero mean and fully controllable degree of coherence. The receiver consisted of an amplified photodetector and data acquisition device which were used to capture the beam intensity fluctuations after propagation through turbulent media. The results for the intensity Probability Density Function (PDF), the Cumulative Distribution Function and, in particular, for the scintillation index are presented for a variety of the source's states of coherence and environmental conditions. The analytical PDF is reconstructed from the statistical moments of intensity with the help of the Gamma-Laguerre model. The results clearly illustrate the dependence of the shapes of the density functions on the level of the source's degree of coherence and on environmental parameters. It is shown that the optimal source coherence level may be experimentally found to obtain the narrowest profile for the intensity PDF

Scintillation reduction in pseudo Multi-Gaussian Schell Model beams in the maritime environment

Irradiance fluctuations of a pseudo Multi-Gaussian Schell Model beam propagating in the maritime environment is explored as a function of spatial light modulator cycling rate and estimated atmospheric turnover rate. Analysis of the data demonstrates a strong negative correlation between the scintillation index of received optical intensity and cycling speed for the estimated atmospheric turnover rate. •Over-the-water spatially pseudopartially coherent beam field test performed.•Multi-Gaussian Schell Model beam class was used for the test.•Strong negative correlation between scintillation index and phase screen cycling rate

Polarization-induced reduction in scintillation of optical beams propagating in simulated turbulent atmospheric channels

It is experimentally demonstrated that the class of partially coherent, partially polarized optical beams can be efficiently used for reduction in scintillations on propagation through turbulent air. The experiment involving the electromagnetic beam generation and its interaction with turbulent air simulator is discussed in details. The collected data is in solid agreement with the recently published theoretical predictions

Experimental study of electromagnetic Bessel-Gaussian Schell Model beams propagating in a turbulent channel

We report on experimental generation of Electromagnetic Bessel-Gaussian Schell-Model [EBGSM] beams via incoherent superposition of two mutually orthogonal electric field components, both originated from a laser source, whose phases are spatially modified by two nematic liquid crystal Spatial Light Modulators. The EBGSM beam is then passed through a weakly fluctuating turbulent channel and examined for contrast in its fluctuating intensity. It is demonstrated that after passing through turbulence the electromagnetic beam exhibits reduction in the scintillation index on the order of 50%, as compared with that for an equivalent scalar beam, in strong agreement with recent theoretical predictions. •Comprehensive experimental analysis of the scintillation index.•Bessel-Gaussian Schell model electromagnetic beams in propagating weak turbulence.•In-depth discussion of measurement procedure and data processing.•Scalar spatially pseudo-partially coherent beams compared to uncorrelated electromagnetic beams.•Scintillation index reduction by up to 50%

Measurements of partially spatially coherent laser beam intensity fluctuations propagating through a hot-air turbulence emulator and comparison with both terrestrial and maritime environments

Measurements of partially spatially coherent infra-red laser beam intensity fluctuations propagating through a hot-air turbulence emulator are compared with visible laser beam intensity fluctuations in the maritime and IR laser beam intensity fluctuations in the terrestrial environment at the United States Naval Academy. The emulator used in the laboratory for the comparison is capable of generating controlled optical clear air turbulence ranging from weak to strong scintillation. Control of the degree of spatial coherence of the propagating laser beam was accomplished using both infrared and visible spatial light modulators. Specific statistical analysis compares the probability density and temporal autocovariance functions, and fade statistics of the propagating laser beam between the in-laboratory emulation and the maritime field experiment. Additionally, the scintillation index across varying degrees of spatial coherence is compared for both the maritime and terrestrial field experiments as well as the in-laboratory emulation. The possibility of a scintillation index ‘sweet’ spot is explored

Measurements and comparison of the probability density and covariance functions of laser beam intensity fluctuations in a hot-air turbulence emulator with the maritime atmospheric environment

A hot-air turbulence emulator is employed for generating controlled optical clear air turbulence in the weak fluctuation regime in laboratory conditions. The analysis of the first and second-order statistical moments of the fluctuating intensity of a propagating infra-red (IR) laser beam through the turbulence emulator is made and the results are compared with bi-directional shore-to-ship maritime data collected during two 2009 mid-Atlantic Coast field tests utilizing single-mode adaptive optics terminals at a range of 10.7 km, as well as with a 633 nm Helium Neon laser propagating across land and water at the United States Naval Academy