Measurement of Cutting Temperature in Interrupted Machining Using Optical Spectrometry.

This research presents an experimental study focused on measuring temperature at the tool flank during the up-milling process at high cutting speed. The proposed system deals with emissivity compensation through a two-photodetector system and during calibration. A ratio pyrometer composed of two photodetectors and a multimode fiber-optic coupler is employed to capture the radiation emitted by the cutting insert. The pyrometer is calibrated using an innovative calibration system that addresses theoretical discrepancies arising from various factors affecting the measurement of cutting temperature. This calibration system replicates the milling process to generate a calibration curve. Experimentally, AISI 4140 steel is machined with coated tungsten carbide inserts, using cutting speeds of 300 and 400 m/min, and feed rates of 0.08 and 0.16 mm/tooth. The results reveal a maximum recorded cutting temperature of 518 °C and a minimum of 304 °C. The cutting temperature tends to increase with higher cutting speeds and feed rates, with cutting speed being the more influential factor in this increase. Both the pyrometer calibration and experimental outcomes yield satisfactory results. Finally, the results showed that the process and the device prove to be a convenient, effective, and precise method of measuring cutting temperature in machine processes.

Binding Analysis of Functionalized Multimode Optical-Fiber Sandwich-like Structure with Organic Polymer and Its Sensing Application for Humidity and Breath Monitoring.

In recent years, the chemical modification of optical fibers (OFs) has facilitated the manufacture of sensors because OFs can identify several analytes present in aqueous solutions or gas phases. Nevertheless, it is imperative better to understand the chemical interactions in this molecular system to generate low-cost and efficient sensors. This work presents a theoretical and experimental study of organic polymeric functionalized OF structures and proposes a cost-effective alternative to monitor breathing and humidity. The device is based on silicon optical fibers functionalized with (3-Aminopropyl) triethoxysilane (APTES) and alginate. The theoretical analysis is carried out to validate the activation of the silicon dioxide fiber surface; moreover, the APTES-alginate layer is discussed. The computational simulation suggests that water can be absorbed by alginate, specifically by the calcium atom linked to the carboxylic acid group of the alginate. The analysis also demonstrates a higher electrostatic interaction between the water and the OF-APTES-alginate system; this interaction alters the optical fiber activated surface's refractive index, resulting in transmission power variation. The humidity analysis shows a sensitivity of 3.1288 mV/RH, a time response close to 25 s, and a recovery time around 8 s. These results were achieved in the range of 50 to 95% RH. Moreover, the recovery and response time allow the human breath to be studied. The proposed mechanism or device is competitive with prior works, and the components involved made this sensor a cost-effective alternative for medical applications.

All Single-Mode-Fiber Supercontinuum Source Setup for Monitoring of Multiple Gases Applications.

In this paper, a gas sensing system based on a conventional absorption technique using a single-mode-fiber supercontinuum source (SMF-SC) is presented. The SC source was implemented by channeling pulses from a microchip laser into a one kilometer long single-mode fiber (SMF), obtaining a flat high-spectrum with a bandwidth of up to 350 nm in the region from 1350 to 1700 nm, and high stability in power and wavelength. The supercontinuum radiation was used for simultaneously sensing water vapor and acetylene gas in the regions from 1350 to 1420 nm and 1510 to 1540 nm, respectively. The experimental results show that the absorption peaks of acetylene have a maximum depth of approximately 30 dB and contain about 60 strong lines in the R and P branches, demonstrating a high sensitivity of the sensing setup to acetylene. Finally, to verify the experimental results, the experimental spectra are compared to simulations obtained from the Hitran database. This shows that the implemented system can be used to develop sensors for applications in broadband absorption spectroscopy and as a low-cost absorption spectrophotometer of multiple gases.

Optical Methods Based on Ultraviolet, Visible, and Near-Infrared Spectra to Estimate Fat and Protein in Raw Milk: A Review.

The present manuscript focuses on reviewing the optical techniques proposed to monitor milk quality in dairy farms to increase productivity and reduce costs. As is well known, the quality is linked to the fat and protein concentration; in addition, this issue is crucial to maintaining a healthy herd and preventing illnesses such as mastitis and ketosis. Usually, the quality of the milk is carried out with invasive methods employing chemical reagents that increase the time analysis. As a solution, several spectroscopy optical methods have been proposed, here, the benefits such as non-invasive measurement, online implementation, rapid estimation, and cost-effective execution. The most attractive optical methods to estimate fat and protein in cow's milk are compared and discussed considering their performance. The analysis is divided considering the wavelength operation (ultraviolet, visible, and infrared). Moreover, the weaknesses and strengths of the methods are fully analyzed. Finally, we provide the trends and a recent technique based on spectroscopy in the visible wavelength.

A New Method for Total Fat Detection in Raw Milk Based on Dual Low-Coherence Interferometer.

The present work experimentally demonstrates a multimode fiber optic sensing setup for total fat detection in raw milk samples. The optical fiber arrangement incorporates a low-coherence Fabry-Perot cavity operating in dual response. The system provides a phase modulation for a total fat range from 0.97% to 4.36%. Here, the protein remains constant at 3%. The data indicate that maximum sensitivity close to 616 pm/%fat could be achieved at optimal wavelength operation (500 nm). In addition, the system presented a minimal repeatability error measurement of 0.08%, cross-sensitivity between protein and fat of 0.134, and a regression coefficient of r2=0.9763. A thermal analysis was also performed, which indicate the temperature immunity of the system. The proposed method represents a low-cost alternative to detect minimal fat variations in raw cow milk.

Magnetic Field Sensing Based on Bi-Tapered Optical Fibers Using Spectral Phase Analysis.

A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material.

A Core-Offset Mach Zehnder Interferometer Based on A Non-Zero Dispersion-Shifted Fiber and Its Torsion Sensing Application.

In this paper, an all-fiber Mach-Zehnder interferometer (MZI) based on a non-zero dispersion-shifted fiber (NZ-DSF) is presented. The MZI was implemented by core-offset fusion splicing one section of a NZ-DSF fiber between two pieces of single mode fibers (SMFs). Here, the NZ-DSF core and cladding were used as the arms of the MZI, while the core-offset sections acted as optical fiber couplers. Thus, a MZI interference spectrum with a fringe contrast (FC) of about 20 dB was observed. Moreover, its response spectrum was experimentally characterized to the torsion parameter and a sensitivity of 0.070 nm/° was achieved. Finally, these MZIs can be implemented in a compact size and low cost.

Analytical modelling of a refractive index sensor based on an intrinsic micro Fabry-Perot interferometer.

In this work a refractive index sensor based on a combination of the non-dispersive sensing (NDS) and the Tunable Laser Spectroscopy (TLS) principles is presented. Here, in order to have one reference and one measurement channel a single-beam dual-path configuration is used for implementing the NDS principle. These channels are monitored with a couple of identical optical detectors which are correlated to calculate the overall sensor response, called here the depth of modulation. It is shown that this is useful to minimize drifting errors due to source power variations. Furthermore, a comprehensive analysis of a refractive index sensing setup, based on an intrinsic micro Fabry-Perot Interferometer (FPI) is described. Here, the changes over the FPI pattern as the exit refractive index is varied are analytically modelled by using the characteristic matrix method. Additionally, our simulated results are supported by experimental measurements which are also provided. Finally it is shown that by using this principle a simple refractive index sensor with a resolution in the order of 2.15 × 10(-4) RIU can be implemented by using a couple of standard and low cost photodetectors.

An all fiber intrinsic Fabry-Perot Interferometer based on an air-microcavity.

In this work an Intrinsic Fabry-Perot Interferometer (IFPI) based on an air-microcavity is presented. Here the air microcavity, with silica walls, is formed at a segment of a hollow core photonic crystal fiber (HCPCF), which is fusion spliced with a single mode fiber (SMF). Moreover, the spectral response of the IFPI is experimentally characterized and some results are provided. Finally, the viability to use the IFPI to implement a simple, compact size, and low cost refractive index sensor is briefly analyzed.