Spectral Fingerprint Investigation in the near Infra-Red to Distinguish Harmful Ethylene Glycol from Isopropanol in a Microchannel

Ethylene glycol (EG) and isopropanol (ISO) are among the major toxic alcohols that pose a risk to human health. However, it is important to distinguish them, since EG is more prone to cause renal failure, and can thus be more dangerous when ingested than ISO. Analysis of alcohols such as isopropanol and ethylene glycol generally can be performed with a complex chromatographic method. Here, we present an optical method based on absorption spectroscopy, performed remotely on EG-ISO mixtures filling a microchannel. Mixtures of ethylene glycol in isopropanol at different volume concentrations were analyzed in a contactless manner in a rectangular-section glass micro-capillary provided with integrated reflectors. Fiber-coupled broadband light in the wavelength range 1.3–1.7 µm crossed the microchannel multiple times before being directed towards an optical spectrum analyzer. The induced zig-zag path increased the fluid–light interaction length and enhanced the effect of optical absorption. A sophisticated theoretical model was developed and the results of our simulations were in very good agreement with the results of the experimental spectral measurements. Moreover, from the acquired data, we retrieved a responsivity parameter, defined as power ratio at two wavelengths, that is linearly related to the EG concentration in the alcoholic mixtures.

Microfluidic Devices with Selectable Optical Pathlength for Quality Control of Alcoholic Solutions

In this work, we present a micro-opto-fluidic platform for the analytical testing of alcoholic solutions (isopropyl alcohol, also known as isopropanol, and ethylene glycol) based on their absorption properties in the wavelength region 1.0–1.7 μm. The investigated fluidic channel is a rectangular glass microcapillary externally coated with aluminum layers, to create a zig-zag guiding effect for the radiation provided by a tungsten lamp. Light crosses the capillary multiple times before being directed towards an optical spectrum analyzer; thanks to the enhanced optical path-length inside the sample, the measurement sensitivity is strongly increased. Preliminary experimental results are reported to show sensing performances.

Algorithm of FBG Spectrum Distortion Correction for Optical Spectra Analyzers with CCD Elements

Nonlinear spectrum distortions are caused by the peculiarities of the operation of charge-coupled device elements (CCD), in which the signal exposition time (Time of INTegration–TINT) is one of the significant parameters. A change of TINT on a CCD leads to a nonlinear distortion of the resulting spectrum. A nonlinear distortion of the spectrum, in turn, leads to errors in determining the central wavelength of fiber Bragg gratings (FBGs) and spectrally sensitive sensors, which, in general, negatively affects the accuracy of the measuring systems. This paper proposes an algorithm for correcting the nonlinear distortions of the spectrum obtained on a spectrum analyzer using CCD as a receiver. It is shown that preliminary calibration of the optical spectrum analyzer with subsequent mathematical processing of the signal makes it possible to make corrections in the resulting spectrum, thereby leveling the errors caused by measurements at different TINT.

Pengaruh Perubahan Suhu terhadap Nilai Panjang Gelombang Fiber Optik yang Difungsikan Sebagai Sensor Suhu

Dalam penelitian ini dapat diketahui pengaruh suhu terhadap Panjang gelombang dan frekuensi pada media fiber optic dengan menggunakan splitter dengan melihat panjang gelombang yang terukur ketika serat optic di panaskan menggunakan perantara alumunium sebagai sensor panas. Dengan suhu yang akan digunakan mulai dari suhu 270?C hingga 400?C.Pengukurn dilakukan dengan menggunakan perangkat Optical Spectrum Analyzer (OSA). Dari Variasi suhu yang diberikan menghasilkan kesimpulan bahwa semakin besar suhu yang diberikan, semakin jauh pergeseran panjang gelombang dan semakin kecil juga frekuensi yang dihasilkan. Panjang gelombang yang dihasilkan pada kabel fiber optic splitter 1 sampai dengan kabel fiber optic splitter 4 mempunyai nilai Panjang gelombang yang hampir sama mulai dari suhu 270°C- 400°C. perbedaan terjadi saat kabel sebelum di splitter dan setelah di seplitter. Tingkat kevalidan di setiap splitter mempunyai nilai persesn yang berbeda seperti pada splitter mempunyai nilai kevaildan 99.80%, splitter 2 dengan kevalida 99.72%, Splitter 3 dengan kevalidan 99.72% dan pada splitter 4 dengan kevalidan 99.70%

Algorithm of FBG Spectrum Distortion Correction for Optical Spectra Analyzers with CCD Elements

Nonlinear spectrum distortions are caused by the peculiarities of the operation of charge-coupled device elements (CCD), in which the signal exposition time (TINT) is one of the significant parameters. A change of TINT on a CCD leads to a nonlinear distortion of the resulting spectrum. Nonlinear distortion of the spectrum, in its turn, leads to errors in determining the central wavelength of Fiber Bragg Gratings (FBG) and spectrally sensitive sensors, which, in general, negatively affects the accuracy of measuring systems. The paper proposes an algorithm for correcting nonlinear distortions of the spectrum obtained on a spectrum analyzer using CCD as a receiver. It is shown that preliminary calibration of the optical spectrum analyzer with subsequent mathematical processing of the signal makes it possible to make corrections in the resulting spectrum, thereby leveling the errors caused by measurements at different TINT.

Angle sensitivity testing of equal-period plane diffraction grating fabricated through electron beam lithography line-by-line method

An equal-period plane diffraction grating fabricated through electron beam lithography line-by-line method was designed and applied to the experiment of angle sensitivity testing. The size of the fabricated grating region was [Formula: see text] mm and the period was 1526 nm. The incident light was transmitted via the Y-type fiber to collimator lens fixed on the angle disc, which can be adjusted to change the incident light angle. The diffraction spectra generated by the incident light irradiating the grating surface were collected by the optical spectrum analyzer. In this experiment, the incident light angle was fixed at 25[Formula: see text]. When the spot moved horizontally by 50 mm, the diffraction wavelength was basically unchanged. When the incident light angle was adjusted from 15[Formula: see text] to 31[Formula: see text], the diffraction wavelength was changed from 834.03 nm to 1589.80 nm, the angular sensitivity was 47.508 nm/[Formula: see text], and the linearity was 0.9998.

MULTISENSOR OPTICAL SYSTEM FOR NON-INVASIVE MONITORING OF THE HUMAN OXYGEN BODY DURING FUNC-TIONAL STRESS

This work was performed using optical spectroscopy methods. The proposed method is based on the differences in the absorption spectra of oxyhemoglobin and reduced hemoglobin, as well as on the analysis of the response of the system using mathematical methods for processing multidimensional data. In the course of the work, a prototype of the diagnostic optical system for non-invasive monitoring of the oxygen supply of human tissues was created, which is based on a multi-channel optical spectrum analyzer. As a result of experimental studies, it was shown that each subject has his own individual, reproducible "image". The results of the study confirm the effectiveness of the proposed method for assessing the functional state of a person and the prospects for its use in practical medicine.

A Novel Method of Measuring Instantaneous Frequency of an Ultrafast Frequency Modulated Continuous-Wave Laser

Ultrafast linear frequency modulated continuous-wave (FMCW) lasers are a special category of CW lasers. The linear FMCW laser is the light source for many sensing applications, especially for light detection and ranging (LiDAR). However, systems for the generation of high quality linear FMCW light are limited and diverse in terms of technical approaches and mechanisms. Due to a lack of characterization methods for linear FMCW lasers, it is difficult to compare and judge the generation systems in the same category. We propose a novel scheme for measuring the mapping relationship between instantaneous frequency and time of a FMCW laser based on a modified coherent optical spectrum analyzer (COSA) and digital signal processing (DSP) method. Our method has the potential to measure the instantaneous frequency of a FMCW laser at an unlimited sweep rate. In this paper, we demonstrate how to use this new method to precisely measure a FMCW laser at a large fast sweep rate of 5000 THz/s by both simulation and experiments. We find experimentally that the uncertainty of this method is less than 100 kHz and can be improved further if a frequency feedback servo system is introduced to stabilize the local CW laser.