NIR Spectroscopy and Imaging Techniques for Evaluation of Fish Quality—A Review

Abstract

Fish is a highly perishable product and it is particularly important to pay attention to its quality changes. Maintenance of the high quality of fish and fishery products necessitates development of means for precise and rapid quality evaluation. Near-infrared (NIR) spectroscopy and imaging techniques are proven technologies that can provide useful information for the estimation of quality attributes in fish and fishery products due to fast speed, noninvasiveness, ease of use, and minimal sample preparation. The aim of this review is to communicate perspectives and aspects relating to NIR spectroscopy and imaging techniques with regard to evaluation of chemical composition (fat, protein, and moisture), microbiological (freshness, spoilage, and nematodes), and sensory (flavor, texture, and color) attributes of fish and fishery products. Moreover, the usefulness of NIR spectroscopy and imaging techniques for fish authentication and classification are presented. Finally, some viewpoints on the current situation and suggestions for future research directions are proposed.     

Grating-Stabilized External Cavity Diode Lasers for Raman Spectroscopy—A Review

Abstract: Conventional Raman techniques require a continuous-wave laser with stabilized wavelength, narrow line width, and sufficient output power. Due to their miniature size and low cost, diode lasers are good choice as light sources for Raman spectroscopy, especially when compact and portable instruments are needed. However, a solitary multimode diode laser has certain drawbacks that limit its use for Raman application. To circumvent these drawbacks, an external cavity can be coupled to the active gain medium of the diode to enhance the laser performance. A grating-based external cavity allows the laser to operate in a single longitudinal mode with greatly reduced line width and stabilized wavelength. This article examines the fundamentals of semiconductor lasers to show the necessity of operating diode lasers in an external cavity for Raman applications. Two feedback grating-based external cavity diode laser (ECDL) designs, viz. Littrow and Littman-Metcalf configurations, are explained. Historic and recent progress in the development of ECDL devices is reported. An updated summary of ECDL-equipped Raman systems applied to fields such as in vivo biomedical studies and in situ process/quality control is provided. Topics on mode-hop-free continuous scanning, wavelength stabilization, and dealing with ambient conditions are discussed.     

A Simple Method for Designing Diffractive Optical Elements

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A Novel Fiber Taper for Efficient Optical Interconnection

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Coumarin-Rhodamine Hybrids—Novel Probes for the Optical Measurement of Viscosity and Polarity

A comprehensive systematic study of absorption and fluorescence properties in solvents of varying viscosity and polarity of three novel and red-emitting coumarin-rhodamine hybrid derivatives with differences in the rigidity of their substituents is presented. This includes ethanol-polyethylene glycol, toluene-polyethylene glycol, and toluene-paraffin mixtures. Moreover, protonation-induced effects on the spectroscopic properties are studied. A viscosity-induced emission enhancement was observed for all coumarin-rhodamine hybrid derivatives. MCR2 bearing a julolidine donor showed the expected low sensitivity to viscosity whereas MCR3 with its freely rotatable diphenylamino substituent revealed a particularly pronounced sensitivity to this parameter. Moreover, MCR2 shows an enhancement in emission in the open, i.e., protonated form in conjunction with a largely Stokes shift fluorescence in the deep red spectral region. This enables the application of these dyes as viscosity sensors and as far red emitting pH-sensitive probes.     

A Simple Configuration for Discontinuous Wavelength-tuning Optical Pulse Source

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An Exact Solution and the Pancharatnam Phase for the Generalized Two—Mode Optical System

Using the algebraic dynamical method,we obtain the exact solution for the generalized two-mode optical system.From the solution,the Pancharatnam phase and the mean values of the number operators of the system are calculated.It is emphasized that the system can be used as a quantum memory.     

Optical system and lens design for Blu-ray disc optical pick-up

During the design process of Blu-ray disc optical pick-up(BD OPU),the optical system and the collimator lens design is especially important.This paper designs an optical system and some lenses for'the BD OPU, including collimator lens,beam shaping lens for laser beam shaping,and cylinder lens for signal detecting. In this OPU,we use a triplet lens to collimate the laser beam.At the same time,we build a series of assembly jigs to make sure that each lens can be put into the OPU basement properly.At last,we get the reading spot image and S-curve photo of OPU,which can be used to read Blu-ray disc(BD).     

A Condition in Ln‐Doped Materials for Flat Optical Gain

Fundamental conditions that rule gain flatness in Er‐doped glass optical amplifiers are investigated using few parameters obtained by drastic simplifications for level positions and widths. The obtained general gain flatness condition for rare‐earth–doped glasses contains two parts: a general one valid in any material and a slight modulation of it valid only for glasses when “0–0” transitions are involved. Essentially, the electron–phonon coupling for the considered materials has to be larger than 2/3. In order to exemplify these conditions, they are calculated for fluoride and silicate glasses, which are known to display respectively flat and non‐flat gain behavior.     

A Novel Analytical Approach for Multi-Layer Diaphragm-Based Optical Microelectromechanical-System Pressure Sensors

An optical microelectromechanical-system （MEMS） pressure sensor based on multi-layer circular diaphragm is described and analysed by using the proposed novel analytical approach and the traditional transfer matrix method. The analytical expressions of the deflection of multi-layer diaphragm and absolute optical reflectance are derived respectively. The influence of residual stress on the deflection of diaphragm is also analysed. Simulation results given by the finite element method are consistent with the ones which are analysed by using the analytical approach. The analytical approach will be helpful to design and fabricate the optical MEMS pressure sensors with multi-layer diaphragm based on Fabry-Perot interferometry.     

An Advanced Dynamic Model for Semiconductor Optical Amplifiers and Laser Diodes

We propose a unified time-domain dynamic model for both semiconductor optical amplifiers and laser diodes by employing a set of multi-longitudinal-mode coupled wave rate equations. A novel split-step method has been developed for the numerical solution of the equation set. To demonstrate the capabilities of the model, some calculation results for conventional and distribute feedback-type gain-clamped semiconductor optical amplifiers are presented.     

Optical and Thermal Properties of Nickel-Azo Dyes for Digital Versatile Disc-Recordable

We investigate the absorption spectra, optical constants and thermal decomposition as well as red-light (650nm) static recording properties of three novel nickel-azo dye films based on 4-methylthiazole, beuzothiazole and 6-methylbenzothiazole. Particularly, we obtain the nickel-azo complex film based on 4-methylthiazole, peaking at 562nm and 613nm, with higher refractive index (n = 2.46) and lower extinction coefficient (k = 0.18) at the wavelength 650nm and a sharp threshold of thermal decomposition at 330℃. The results of the static optical recording test of this dye film indicate that high reflectivity contrast of 51% can be observed at a laser writing power of 5.9mW and pulse width of 350ns. These results imply that the nickel-azo complex based on 4-methvlthiazole is a uromising candidate for a recordinz medium of digital versatile disc-recordable.     

A Tapping—Mode Tuning Fork with a Short Fibre Probe Sensor for a Near—Field Scanning Optical Microscope

We report on a tapping-mode tuning fork with a short fibre probe sensor for a near-field scanning optical microscope.The method demonstrates how to fabricate the short fibre probe.This tapping-mode tuning fork with a short fibre probe can provide stable and high Q at the tapping frequency of the tuning fork,and can give high-quality near-field scanning optical microscope and atomic force microscope images of samples.We present the results of using the tapping-mode tuning fork with a short fibre probe sensor for a near-field scanning optical microscope performed on an eight-channel silica waveguide.     

Editorial for Focus Issue on Optical3D Display and Imaging

正With the impressive progress of flat panel display technologies,the three-dimensional(3D)display and imaging technologies have attracted much attention in recent years as they can provide ultimate realistic views to us.Hence we designed a focus issue intended to introduce recent optical researches in this field,especially the works by some distinguished research groups.     

Current Status of Direct Solid Sampling for Electrothermal Atomic Absorption Spectrometry—A Critical Review of the Development between 1995 and 2005

Abstract

The literature about direct solid sampling (SS) and slurry sampling atomic absorption spectrometry (AAS) over the past decade has been surveyed critically. It became apparent that a very significant change had occurred, particularly in the relation between the two major techniques used for that purpose. In the 1990s, slurry sampling was typically considered the technique of choice, combining the significant advantages of the solid and the liquid sampling methods, at least in part because of the availability of a commercial accessory for automatic slurry sampling. The situation is completely inverted now, as the above accessory has been discontinued and rugged and reliable accessories for direct SS became available. Direct SS electrothermal (ET) AAS has been shown to provide the best limits of detection because of the absence of any dilution and a minimal risk of contamination. Calibration against aqueous standards appears to be feasible after careful program optimization. The absence of any significant sample handling makes SS ET AAS ideally suited for fast screening analyses. The introduction of high‐resolution continuum source AAS appears to open additional attractive features for SS ET AAS because of the significantly simplified optimization of furnace programs and the visibility of the spectral environment, which makes it easy to avoid spectral interferences. New calibration strategies make a “dilution” of samples unnecessary, which used to be one of the major limitations of SS ET AAS. Finally, direct SS analysis is an important contribution to clean chemistry, as practically no reagents are used.     

Sample Preparation for the Determination of Metals in Food Samples Using Spectroanalytical Methods—A Review

Abstract

The present article gives an overview of recent publications and modern techniques of sample preparation for food analysis employing atomic and inorganic mass spectrometric techniques, such as flame atomic absorption spectrometry, chemical vapor generation atomic absorption and atomic fluorescence spectrometry, graphite furnace atomic absorption spectrometry, inductively coupled plasma optical emission spectrometry, and inductively coupled plasma mass spectrometry. Among the most frequently applied sample preparation techniques for food analysis are dry ashing, usually with the addition of an ashing aid, and acid digestion, preferably with the assistance of microwave energy. Slurry preparation, particularly with the assistance of ultrasound, is increasingly used to reduce acid consumption and sample preparation time. Direct analysis of solid samples is gaining importance in the field of food analysis as it offers the highest sensitivity, avoids the use of acids and other aggressive reagents, makes possible the analysis of micro‐samples, and can be applied for fast screening analysis, e.g., of fresh meat.     

A Theoretical Scheme for Multi—user Quantum Key Distribution with N Einstein—Podolsky—Rosen Pairs on a Passive Optical Network

We propose a theoretical scheme for any-to-any multi-user quantum key distribution on a passive optical network with ordered N Einstein-Podolsky-Rosen Pairs.This scheme is safe and more efficient than those with single photons.Its efficiency approaches 100% in the limit that the number of pairs used in the eavesdropping check becomes negligible.It also has high capacity and is convenient for users.     

Procedures of Separation and Pre‐concentration for Molybdenum Determination Using Atomic Spectrometry—a Review

Abstract

The literature concerning the improvement of atomic and ionic procedures for molybdenum determination through separation and pre‐concentration were updated. Analytical procedures based on flame atomic absorption spectrometry (AAAS), electrothermal or graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled plasma optical emission spectrometry (ICP‐OES), and inductively coupled plasma mass spectrometry were reviewed taking into consideration the preliminary steps, which can enhance the selectivity and sensitivity based on co‐precipitation, solvent extraction, and solid‐phase extraction. Both in‐batch and on‐line procedures were considered.     

Optical and structural properties of Au-Ag islands films for plasmonic applications

Bimetallic islands films consisting of composite Au-Ag nanoparticles are deposited on glass substrates by electron beam evaporation. Broad tuning of the surface-plasmon resonance (SPR) characteristics can be achieved by controlling film composition, deposition temperature and post-deposition thermal annealing. Optical and structural characterization of the samples enable one to establish the link between the SPR and the morphological and compositional characteristics of nanoparticles.