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The present document describes a compact, multiple input, multiple output (MIMO) radar system mounted on an industrial conveyor. The aim of this radar is the detection of small foreign particles within different types of products, including packed food. The radar system is composed of a Stepped-Frequency Continuous-Wave (SFCW) radar, eight ultra-wide band customized Vivaldi antennas configured in a semicircular geometry, and a switching system that allows configuring each antenna as either transmitter or receiver. By using this radar setup it is possible to detect and generate 2D images of small particles. As an example the detection of a metallic sphere with diameter $D=5.0\ \text{mm}$ is shown. The radar cross-section of metal spheres of this sizes lies within the Rayleigh scattering region, which generates reduced amount of reflected radar signals.

The industry of the agave-derived bacanora, in the northern Mexican state of Sonora, has been growing substantially in recent years. However, this higher demand still lies under the influences of a variety of social, legal, cultural, ecological and economic elements. The governmental institutions of the state have tried to encourage a sustainable development and certain levels of standardization in the production of bacanora by applying different economical and legal strategies. However, a large portion of this alcoholic beverage is still produced in a traditional and rudimentary fashion. Beyond the quality of the beverage, the lack of proper control, by using adequate instrumental methods, might represent a health risk, as in several cases traditional-distilled beverages can contain elevated levels of harmful materials. The present article describes the qualitative spectral analysis of samples of the traditional-produced distilled beverage bacanora in the range from 0 cm −1 to 3500 cm −1 by using a Fourier Transform Raman spectrometer. This particular technique has not been previously explored for the analysis of bacanora, as in the case of other beverages, including tequila. The proposed instrumental arrangement for the spectral analysis has been built by combining conventional hardware parts (Michelson interferometer, photo-diodes, visible laser, etc.) and a set of self-developed evaluation algorithms. The resulting spectral information has been compared to those of pure samples of ethanol and to the spectra from different samples of the alcoholic beverage tequila. The proposed instrumental arrangement can be used the analysis of bacanora.

We report the use of the Raman spectral information of the chemical compound toluene C 7 H 8 as a reference on the analysis of laboratory-prepared and commercially acquired gasoline-ethanol blends. The rate behavior of the characteristic Raman lines of toluene and gasoline has enabled the approximated quantification of this additive in commercial gasoline-ethanol mixtures. This rate behavior has been obtained from the Raman spectra of gasoline-ethanol blends with different proportions of toluene. All these Raman spectra have been collected by using a self-designed, frequency precise and low-cost Fourier-transform Raman spectrometer (FT-Raman spectrometer) prototype. This FT-Raman prototype has helped to accurately confirm the frequency position of the main characteristic Raman lines of toluene present on the different gasoline-ethanol samples analyzed at smaller proportions than those commonly found in commercial gasoline-ethanol blends. The frequency accuracy validation has been performed by analyzing the same set of toluene samples with two additional state-of-the-art commercial FT-Raman devices. Additionally, the spectral information has been contrasted, with highly-correlated coefficients as a result, with the values of the standard Raman spectrum of toluene.

In order to reduce some of the toxic emissions produced by internal combustion engines, the fossil-based fuels have been combined with less harmful materials in recent years. However, the fuels used in the automotive industry generally contain different additives, such as toluene, as anti-shock agents and as octane number enhancers. These materials can cause certain negative impact, besides the high volatility implied, on public health or environment due to its chemical composition. Toluene, among several other chemical compounds, is an additive widely used in the commercially-available gasoline-ethanol blends. Despite the negative aspects in terms of toxicity that this material might have, the Raman spectral information of toluene can be used to achieve certain level of frequency calibration without using any additional chemical marker in the sample or any other external device. Moreover, the characteristic and well-defined Raman line of this chemical compound at 1003 cm −1 (even at low v/v content) can be used to quantitatively determine certain aspects of the gasoline-ethanol blend under observation. By using an own-designed Fourier-Transform Raman spectrometer (FT-Raman), we have collected and analyzed different commercially-available and laboratory-prepared gasoline-ethanol blends. By carefully observing the main Raman peaks of toluene in these fuel blends, we have determined the frequency accuracy of the Raman spectra obtained. The spectral information has been obtained in the range of 0 cm −1 to 3500 cm −1 with a spectral resolution of 1.66 cm −1 . The Raman spectra obtained presented only reduced frequency deviations in comparison to the standard Raman spectrum of toluene provided by the American Society for Testing and Materials (ASTM).

The determination of the physical state of the lubricant materials in complex mechanical systems is highly critical from different points of view: operative, economical, environmental, etc. Furthermore, there are several parameters that a lubricant oil must meet for a proper performance inside a machine. The monitoring of these lubricants can represent a serious issue depending on the analytical approach applied. The molecular change of aging lubricant oils have been analyzed using an all-standard-components and self-designed FT-Raman spectrometer. This analytical tool allows the direct and clean study of the vibrational changes in the molecular structure of the oils without having direct contact with the samples and without extracting the sample from the machine in operation. The FT-Raman spectrometer prototype used in the analysis of the oil samples consist of a Michelson interferometer and a self-designed photon counter cooled down on a Peltier element arrangement. The light coupling has been accomplished by using a conventional 62.5/125μm multi-mode fiber coupler. The FT-Raman arrangement has been able to extract high resolution and frequency precise Raman spectra, comparable to those obtained with commercial FT-Raman systems, from the lubricant oil samples analyzed. The spectral information has helped to determine certain molecular changes in the initial phases of wearing of the oil samples. The proposed instrument prototype has no additional complex hardware components or costly software modules. The mechanical and thermal irregularities influencing the FT-Raman spectrometer have been removed mathematically by accurately evaluating the optical path difference of the Michelson interferometer. This has been achieved by producing an additional interference pattern signal with a λ= 632.8 nm helium-neon laser, which differs from the conventional zero-crossing sampling (also known as Connes advantage) commonly used by FT-devices. It enables the FT-Raman system to perform reliable and clean spectral measurements from the analyzed oil samples.

The combination of fossil fuels with bio-fuels, specially ethanol and methanol, has acquired relevance and attention in several countries in recent years. A variety of factors have induced this trend: market prices, constant geopolitical events, new sustainability policies and laws, etc. The fuels used in the automotive industry, including bio-fuels, normally contain additives as anti-shock agents and as octane booster. These additives may endanger (beside the high volatility implied) public health or environment due to the nature of its chemical composition. Raman spectral information from different additives, specially toluene, contained in E10 gasoline-ethanol blends has been obtained by using an own-design Fourier-Transform Raman spectrometer (FT-Raman). This information has been also compared with Raman spectra from pure additives and with standard Raman lines in order to validate its accuracy in frequency. The spectral information is presented in the range of 0 cm −1 to 3500 cm −1 with a resolution of 1.66 cm −1 . The Raman spectra obtained shows a reduced frequency deviation (less than 0.4 cm −1 when compared to standard Raman spectra from different calibration materials, e.g. cyclohexane and toluene, without compensation for instrumental response). The Fourier-Transform Raman spectrometer prototype used for the spectral analysis, consisting of a Michelson interferometer and a self-designed photon counter cooled down on a three stage Peltier element arrangement, is able to extract high resolution and precise Raman spectra from the additives in the fuels analyzed. The proposed FT-Raman prototype has no additional complex hardware or software control. The mechanical and thermal disturbances affecting the FT-Raman system are mathematically compensated by extracting the optical path information from the generated interference pattern of λ = 632.8nm Helium-Neon laser (HeNe laser), which is used at the spectrum evaluation. This allows the device to be used in complicated environments where certain level of security is required (e.g. fuel production, storage, transportation, etc.).

The combination of fossil-derived fuels with ethanol and methanol has acquired relevance and attention in several countries in recent years. This trend is strongly affected by market prices, constant geopolitical events, new sustainability policies, new laws and regulations, etc. Besides bio-fuels these materials also include different additives as anti-shock agents and as octane enhancer. Some of the chemical compounds in these additives may have harmful properties for both environment and public health (besides the inherent properties, like volatility). We present detailed Raman spectral information from toluene (C 7 H 8 ) and ethanol (C 2 H 6 O) contained in samples of ElO gasoline-ethanol blends. The spectral information has been extracted by using a robust, high resolution Fourier-Transform Raman spectrometer (FT-Raman) prototype. This spectral information has been also compared with Raman spectra from pure additives and with standard Raman lines in order to validate its accuracy in frequency. The spectral information is presented in the range of 0 cm -1 to 3500 cm -1 with a resolution of 1.66cm -1 . This allows resolving tight adjacent Raman lines like the ones observed around 1003cm -1 and 1030cm -1 (characteristic lines of toluene). The Raman spectra obtained show a reduced frequency deviation when compared to standard Raman spectra from different calibration materials. The FT-Raman spectrometer prototype used for the analysis consist basically of a Michelson interferometer and a self-designed photon counter cooled down on a Peltier element arrangement. The light coupling is achieved with conventional62.5/125μm multi-mode fibers. This FT-Raman setup is able to extract high resolution and frequency precise Raman spectra from the additives in the fuels analyzed. The proposed prototype has no additional complex hardware components or costly software modules. The mechanical and thermal disturbances affecting the FT-Raman system are mathematically compensated by accurately extracting the optical path information of the Michelson interferometer. This is accomplished by generating an additional interference pattern with a λ = 632.8 nm Helium-Neon laser (HeNe laser). It enables the FT-Raman system to perform reliable and clean spectral measurements from the materials under observation.

The use of bio-fuels and fuel blends, specially in automotive industry, has been increasing substantially in recent years due to market prices and trends on sustainable development policies. Different spectral analysis techniques for quality control, production, purity, and counterfeit detection have been reported as non-invasive, fast, and price accessible. Raman spectra from three different commercial binary E10 fuel-ethanol blends has been obtained by using a low-cost Fourier-Transform Raman spectrometer (FT-Raman). Qualitative comparison between the commercial fuel blends and a laboratory-prepared fuel blend have been performed. The characteristic Raman lines from some additives contained in the commercial gasoline have been also observed. The spectral information is presented in the range of 0 cm-1 to 3500 cm-1 with a resolution of 1.66 cm-1. These Raman spectra shows reduced frequency deviation (less than 0.4 cm-1 when compared to standard Raman spectra from cyclohexane and toluene without compensation for instrumental response). Higher resolution values are possible, since the greater optical path lengths of the FT-Raman are achievable before the instrumental physical effects appear. The robust and highly flexible FT-Raman prototype proposed for the spectral analysis, consisting mainly of a Michelson interferometer and a self-designed photon counter, is able to deliver high resolution and precise Raman spectra with no additional complex hardware or software control. The mechanical and thermal disturbances affecting the FT-Raman system are mathematically compensated by extracting the optical path information from the generated interference pattern of a l=632.8 nm Helium-Neon laser (HeNe laser), which is used at the spectrum evaluation.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

In different study fields the manipulation and imaging of micro-sized particles is essential. The use of holographic optical tweezers (HOT) and digital holographic microscopy (DHM) facilitates this task in a non-mechanical way by providing the proper computer generated hologram and the required amount of light. Electrically addressed spatial light modulators (EASLM) found in holographic optical tweezers are typically of the reflective liquid crystal on silicon (LCoS) type which can achieve a phase shift of more than 2π but they are expensive. Similar components like transmissive twisted nematic liquid crystal displays (TN-LCD) are produced in large quantities, their optical characteristics improve rapidly and they are inexpensive. Under certain circumstances these devices can be used instead of expensive spatial light modulators. Consumer grade objectives are not always well corrected for spherical aberration. In that case conventional liquid crystal displays can also compensate these undesired optical effects. For this purpose software-corrected computer generated holograms are calculated. Procedures to analyze and compensate different parameters of a conventional low-cost liquid crystal display, e.g. phase shift evaluation and aberration correction of objectives by Zernike polynomials approximation are explained. The applied software compensation of the computer generated hologram has shown significant improvement of the focus quality. An important price reduction of holographic devices could be achieved by replacing special optical elements if correction algorithms for conventional liquid crystal displays are provided.

A robust, flexible Fourier transform Raman spectrometer (FT-Raman) based on a Michelson interferometer and a self-made photon counter is presented. The proposed inexpensive setup has no complex hardware or control systems for optical path compensation. The mechanical and thermal induced errors are mathematically compensated by extracting the optical path information from the generated interference pattern of a λ = 632.8nm Helium-Neon laser (HeNe laser). This information also permits high frequency precision of the calculated Raman spectrum. This system is flexible and allows the user having complete access to hardware and software. It enables a variety of experimental changes in the system, which are difficult to achieve with commercial devices. Precise, high resolution Raman spectra of cyclohexane with a resolution of 1.66 cm -1 to 5.0cm -1 have been measured with this device. Higher resolution values can be achieved since longer scanning distances at the Michelson interferometer are possible and its calculated ´etendue (throughput) does not substantially corrupt the obtained interferograms. Other chemical compounds have been also monitored. Additionally, a detailed spectral analysis of different precision optical components and light sources has been performed.

The microscopic three-dimensional imaging of cells is a key method in biological and medical research. Conventional high-resolution scanning methods e.g. laser scanning microscopes are limited or require some form of compensation in monitoring of living cells. The proposed method uses a low-cost twisted nematic liquid crystal display (TN-LCD) which is used as phase modulating electrically addressed spatial light modulator (EASLM) to holographically generate a reference wave which can be translated and shift in phase. Wavefront distortions caused by aberrations are determined by scanning the system with the EASLM, approximating them with Zernike polynomials and calculating a phase correction function which can be superposed with the hologram. The interference pattern of the object and shifted reference wave is captured with a CMOS camera and subsequently the object wave is reconstructed from the taken images. With this procedure it was already possible to reconstruct a diatom in different layers.