Low-power integrated projection technology can play a key role in development of low-cost mobile devices with built-in high-resolution projectors. Low-cost 3D imaging and holography systems are also among applications of such a technology. In this paper, an integrated projection system based on a two-dimensional optical phased array with fast beam steering capability is reported. Forward biased p-i-n phase modulators with 200MHz bandwidth are used per each array element for rapid phase control. An optimization algorithm is implemented to compensate for the phase dependent attenuation of the p-i-n modulators. Using rapid vector scanning technique, images were formed and recorded within a single snapshot of the IR camera.
Abstract:An integrated silicon nanophotonic coherent imager (NCI), with a 4 × 4 array of coherent pixels is reported. In the proposed NCI, on-chip optical processing determines the intensity and depth of each point on the imaged object based on the instantaneous phase and amplitude of the optical wave incident on each pixel. The NCI operates based on a modified time-domain frequency modulated continuous wave (FMCW) ranging scheme, where concurrent time-domain measurements of both period and the zero-crossing time of each electrical output of the nanophotonic chip allows the NCI to overcome the traditional resolution limits of frequency domain detection. The detection of both intensity and relative delay enables applications such as high-resolution 3D reflective and transmissive imaging as well as index contrast imaging. We demonstrate 3D imaging with 15µm depth resolution and 50µm lateral resolution (limited by the pixel spacing) at up to 0.5-meter range. The reported NCI is also capable of detecting a 1% equivalent refractive index contrast at 1mm thickness. 195-199 (2013
We propose the use of airborne ultrasound for wireless power transfer to mm-sized nodes, with intended application in the next generation of the Internet of Things (IoT). We show through simulation that ultrasonic power transfer can deliver 50 [Formula: see text] to a mm-sized node 0.88 m away from a ~ 50-kHz, 25-cm transmitter array, with the peak pressure remaining below recommended limits in air, and with load power increasing with transmitter area. We report wireless power recovery measurements with a precharged capacitive micromachined ultrasonic transducer, demonstrating a load power of 5 [Formula: see text] at a simulated distance of 1.05 m. We present aperture efficiency, dynamic range, and bias-free operation as key metrics for the comparison of transducers meant for wireless power recovery. We also argue that long-range wireless charging at the watt level is extremely challenging with existing technology and regulations. Finally, we compare our acoustic powering system with cutting edge electromagnetically powered nodes and show that ultrasound has many advantages over RF as a vehicle for power delivery. Our work sets the foundation for further research into ultrasonic wireless power transfer for the IoT.
For over 30 years, protocols based on the mass spectrometry (MS) of permethylated derivatives, complemented by enzymatic degradations, have underpinned glycomic experiments aimed at defining the structures of individual glycans present in the complex mixtures that are characteristic of biological samples. Both MS instrumentation and sample handling have improved markedly in recent years, enabling greater sensitivity and better signal-to-noise ratios, thereby facilitating the detection of glycans at much higher masses than could be achieved in the past. The latter is especially important for the characterization of the biologically important class of N-glycans that carry polylactosaminoglycan chains. Such advances in data acquisition heighten the need for informatics tools to assist in glycan structure assignment. Here, utilizing mouse lung tissue as a model system, we present evidence of polylactosaminoglycan-containing N-glycans with permethylated molecular weights exceeding 13 kDa. We show that antennae branching patterns and lengths can be successfully determined at these high masses via MS/MS experiments, even when MS ion counts are very low. We also describe the development and application of a matched filtering algorithm for assisting highmolecular-weight glycan detection and structure assignment. Glycosylation is one of the most common and important post-translational modifications of proteins, yet it is also one of the most difficult to study because of its great complexity. Much of what we know about glycosylation, especially tissueand organism-specific variation, has been gathered via mass spectrometric profiling of detached glycans (1-4). International, multi-laboratory comparisons of MS 1 and chromatographic glycomic data derived from standardized glycoproteins have concluded that the MS analysis of permethylated derivatives of released N-and O-linked glycans is the most robust glycomics strategy with respect to both sensitivity and quantitative reliability (5, 6). MS/permethylation strategies were first implemented in the Imperial laboratory in the early 1980s, when fast atom bombardment MS was revolutionizing the analysis of glycopolymers (7). Notably, with the exception of MALDI superseding fast atom bombardment as the preferred method of MS ionization in the past decade, permethylation-based glycomic protocols remain virtually unchanged from those employed 30 years ago. Where there has been a dramatic change, however, is in the quality and quantity of data emerging from glycomics investigations. This is exemplified by the success of the Analytical Glycotechnology Core of the Consortium for Functional Glycomics, which has built a public database of MALDI-TOF profiles from human and mouse tissues and cell lines as a resource for researchers worldwide.Characterizing complex mixtures of most classes of Nand/or O-glycans is now a routine task for glycomics experts when working with a few micrograms of a glycoprotein sample or, for cell glycomics, about a million cells. However, this is not the case fo...
This paper presents electrical beam steering in an integrated 4x4 2D optical phased array (OPA) on a silicon on insulator (SOI) process enabling fast and repeatable beam steering for next generation projection, tracking, and imaging. IntroductionElectronically steered phased array transmitters and receivers in microwave and mm-wave range have been widely used in radar systems where their agile electronic control enables rapid tracking of multiple fast moving objects [1]. Recently high frequency miniaturized phased array transmitters and receivers have been subject of interest for ranging, imaging, and directional communication at microwave, mm-wave, and THz frequencies [2][3][4]. Optical phased arrays (OPA) based on the same principle at much smaller wavelength have promising prospects for ranging, communications, image projection, optical network switch boxes, free-space optical computation, etc. Since optical wavelengths are much smaller than their RF counterparts, larger number of elements can be integrated on a smaller chip. Recent developments have shown the feasibility of current silicon-based micro-fabrication for integrated OPA implementation [5][6][7][8]. Beam steering can be achieved using thermo-optic phase shifters where the delay for each path is changed via the thermal index change [6,7]. In this approach, the large thermal time constants limit the speed at which the beam can be steered making them unsuitable for real-time and fast applications, such as projection, optical switches, or computing. Thermal crosstalk between adjacent phase shifters presents another challenge to the thermal phase control approach, necessitating remedial action, such as large separation between thermal phase shifters that can limit the number of elements in the OPA. In [6], the second dimension of beam steering is achieved via an external change of the wavelength. MEMS based OPAs [8] overcome the cross talk issue; however, they still have limited operation speed and lower reliability due to limitation of mechanical structures.To overcome the speed and reliability limitations, PIN diode phase shifters that operate based on free carrier injection [9] are used in a 4x4 OPA in this work. Also, some level of amplitude control can be achieved, which provides side-lobe cancellation in the array operation. The utilized PIN-diode-based modulators are capable of operation with time constants under 1 nanosecond, thereby enabling very rapid response.
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