RF photonic instantaneous frequency measurement using DC photo-detection

A microwave photonic instantaneous frequency measurement (IFM) system based on a photonic transversal approach and DC-detection is proposed and practically demonstrated. This system is able to measure the RF frequency and power level independently

Two output RF hybrid coupler using photonic transversal approach

A novel technique to implement a two output broad band RF hybrid coupler based on transversal signal processing is proposed and practically demonstrated. It features broadband frequency range, stable phase difference at outputs, 50 ohm input/output impedance, and low noise characteristics. This technique is suitable for non-coherent optic implementation

Amplitude independent RF instantaneous frequency measurement system using photonic Hilbert transform

A photonic instantaneous frequency measurement system capable of measuring both RF frequency and power simultaneously, is conceived and practically demonstrated. This system employs an RF photonic Hilbert transformer together with low-cost, low-frequency photo-detectors to obtain two orthogonal DC measurements. This system exhibits a frequency range of 1-10 GHz. Wider frequency range can be achieved through integration

Wideband RF photonic in-phase and quadrature-phase generation

A photonic implementation of a practical broadband RF Hilbert transformer is demonstrated by using a four-tap transversal system. An almost ideal 90° phase shift with less than 3 dB of amplitude ripple has been achieved from 2.4 to 17.6 GHz. An efficient method to realize both transformed (quadrature-phase) and reference (in-phase) signal has been achieved by using a coarse wavelength division multiplexing coupler. Extension of the transformer bandwidth and further improvements of its implementation are discussed

Reduced cost photonic instantaneous frequency measurement system

A wideband photonic instantaneous frequency measurement system is proposed and practically demonstrated. This system employs only a low-frequency inexpensive photodetector and thus the system cost is reduced

Photonic instantaneous frequency measurement using non-linear optical mixing

In this paper we propose and demonstrate a photonically implemented instantaneous frequency measurement system. This system uses two differentially delayed modulated optical carriers that are mixed using a semiconductor optical amplifier. The output of the system includes a DC component that varies as a function of frequency. This can be used for frequency measurement using a low-cost DC photo-detector. Operation is demonstrated from 2-20 GHz

Low-cost RF frequency measurement using photonic approach

A technique to implement frequency measurement photonically using only low-cost DC photodetectors is proposed and a proof of concept implementation is practically demonstrated. Techniques to further reduce cost and extend bandwidth are proposed

Software Design for Smile Analysis

Introduction: Esthetics and attractiveness of the smile is one of the major demands in contemporary orthodontic treatment. In order to improve a smile design, it is necessary to record “posed smile” as an intentional, non-pressure, static, natural and reproduciblesmile. The record then should be analyzed to determine its characteristics. In this study,we intended to design and introduce a software to analyze the smile rapidly and precisely in order to produce an attractive smile for the patients.Materials and Methods: For this purpose, a practical study was performed to design multimedia software “Smile Analysis” which can receive patients’ photographs and videographs. After giving records to the software, the operator should mark the points and lines which are displayed on the system’s guide and also define the correct scale for each image. Thirty-three variables are measured by the software and displayed on the report page. Reliability of measurements in both image and video was significantly high(=0.7-1).Results: In order to evaluate intra- operator and inter-operator reliability, five cases were selected randomly. Statistical analysis showed that calculations performed in smile analysis software were both valid and highly reliable (for both video and photo).Conclusion: The results obtained from smile analysis could be used in diagnosis,treatment planning and evaluation of the treatment progress

Instantaneous frequency measurement system using optical mixing in highly nonlinear fiber

A broadband photonic instantaneous frequency measurement system utilizing four-wave mixing in highly nonlinear fiber is demonstrated. This new approach is highly stable and does not require any high-speed electronics or photodetectors. A first principles model accurately predicts the system response. Frequency measurement responses from 1 to 40 GHz are demonstrated and simple reconfiguration allows the system to operate over multiple bands

Investigation on braze joint strength and microstructure of Ti-CP with Ag and Ti base filler alloys

This research investigates influences of brazing parameters (brazing alloy, temperature and time) on microstructures and mechanical properties of a commercially pure (CP) titanium sheet which is brazed with CBS 34 (Ag-based) and STEMET 1228 (Ti-based) braze-filler foils. Brazing was performed in a conventional inert furnace at temperature ranges of 800-870°C and 10-30 minutes for holding times. Qualities of the brazed joints were evaluated by ultrasonic testing, and then, microstructure and phase constitution of the bonded joints were analyzed by means of metallography, scanning electron microscope (SEM), and X-ray diffraction (XRD). Mechanical properties of brazed joints were evaluated by shear testing. Diffusion of titanium from substrate to filler alloy developed a strong reaction between them. A number of phases such as TiCu, Ti 2Cu, TiAg, Ag-Zn solid solution matrix (for Ag-based brazed samples) and Ti 2Cu, (Ti,Zr) 2Ni, Zr 2Cu (for Ti-based brazed samples) have been identified. The optimum brazing parameters were achieved at a temperature of 870 °C-20 min for CBS 34 and 870 °C-30 min for STEMET 1228. The specimen using STEMET 1228 braze alloy demonstrates best bonding strength (equal to Ti-CP tensile strength). Copyright 2012 ASM International® All rights reserved