Different Types Of Optical Sensors Research Articles

Study the Dispersion and Losses in Fiber Optics Communication

This paper presents the dispersion of optical fiber in terms of mode of dispersion, attenuation, and losses, etc including optical fiber in terms of introduction, which gives an overview of the optical fiber, including the classifications, type, attenuation losses, etc. Some basic optical fiber sensor technologies are also reviewed .under this study the different types of sensors that introduced the principle and different types of optical sensors based on sensing location i.e. extrinsic and intrinsic sensors, based on operating principles i.e.ProcessinvolvingDemodulation, Sensor based on Intensity Modulation, SensorsbasedonPhase Modulation, Sensors based on Polarization Modulation, Sensors based on Wavelength Modulation, which are constructedonapplicationthatcanmeasure temperature, stress, pH, blood flow along with glucose content.

Optical sensor network interrogation system based on nonuniform microwave photonic filters.

Based on the nonuniformly spaced microwave photonic delay-line filter technology, a new design of a generic optical fiber sensor network interrogation platform is proposed and demonstrated. Sensing information from different types of optical sensors embedded in filter taps is converted into the variations of delay time and amplitude of each filter tap individually. Information to be measured can be decoded from the complex temporal impulse response of the microwave photonic filter. As proof-of-concept, our proposed approach is verified by simulations and experimental demonstrations successfully. Four optical sensors of different types are simultaneously interrogated via inverse Fourier transform of the filter frequency response. The experiment results show good linearity between the variation of temporal impulse response and the variations of the twist, the lateral pressure, the transversal loading and the temperature. The sensitivity of the sensors in the proposed platform is -2.130×10-5 a.u/degree, 6.1039 ps/kPa, -1.9146×10-5 a.u/gram, and 5.1497 ps/°C, respectively. Compared to the conventional optical sensors interrogation system, the presented approach provides a centralized solution that works for different types of optical sensors and can be easily expanded to cover larger optical sensor networks.

Femtosecond Laser Written Plane-by-Plane Bragg Grating Sensors in Bioresorbable Phosphate Optical Fibres

We report on the realization of different types of optical sensors in a bioresorbable phosphate glass optical fiber using a femtosecond laser operating at 517 nm. We inscribed fiber Bragg grating-based optical filters such as uniform Bragg gratings, chirped gratings, and Fabry–Perot cavities, using the plane-by-plane direct write inscription. The gratings were characterized in reflection and tested as sensors for temperature and relative humidity. We studied the stability and resilience of the gratings when inserted in high humidity environments (>95%) for 52 h and observed the evolution of the grating characteristics during this period.

Configuration optimization of multi-optical sensors with complex pointing constraints

This paper investigates the pointing direction optimization problem of multi-optical sensors with complex pointing constraints. In the spacecraft design area, this problem is characterized as the optical-sensor configuration optimization. The complex pointing requirements and avoidance constraints of different types of optical sensors are taken into account, and a new optimization method is presented. The proposed combinatorial optimization algorithm is divided into three steps. First, an initial guess solution is generated by coordinate projection. The relative directions between all constraint objects and the spacecraft are projected into the spacecraft body-fixed coordinate system. Second, the density-of-presence analysis is conducted for relative directions by introducing the image processing concept into the optimization process. The morphological dilation approach is adopted with a new filter, and the high and low density regions are defined to reduce the dimension of the candidate solution group. Finally, the mathematical model of the optimization problem is developed and solved by the Genetic Algorithm (GA). The computer simulations show that the new method can properly handle the configuration optimization problem with complex requirements and constraints in a relatively short calculation time.

Optical Sensing to Determine Tomato Plant Spacing for Precise Agrochemical Application: Two Scenarios

The feasibility of automated individual crop plant care in vegetable crop fields has increased, resulting in improved efficiency and economic benefits. A systems-based approach is a key feature in the engineering design of mechanization that incorporates precision sensing techniques. The objective of this study was to design new sensing capabilities to measure crop plant spacing under different test conditions (California, USA and Andalucía, Spain). For this study, three different types of optical sensors were used: an optical light-beam sensor (880 nm), a Light Detection and Ranging (LiDAR) sensor (905 nm), and an RGB camera. Field trials were conducted on newly transplanted tomato plants, using an encoder as a local reference system. Test results achieved a 98% accuracy in detection using light-beam sensors while a 96% accuracy on plant detections was achieved in the best of replications using LiDAR. These results can contribute to the decision-making regarding the use of these sensors by machinery manufacturers. This could lead to an advance in the physical or chemical weed control on row crops, allowing significant reductions or even elimination of hand-weeding tasks.

Structural peculiarities of single crystal diamond needles of nanometer thickness

Diamond is attractive for various applications due to its unique mechanical and optical properties. In particular, single crystal diamond needles with high aspect ratios and sharp apexes of nanometer size are demanded for different types of optical sensors including optically sensing tip probes for scanning microscopy. This paper reports on electron microscopy and Raman spectroscopy characterization of the diamond needles having geometrically perfect pyramidal shapes with rectangular atomically flat bases with (001) crystallography orientation, 2–200 nm sharp apexes, and with lengths from about 10–160 μm. The needles were produced by selective oxidation of (001) textured polycrystalline diamond films grown by chemical vapor deposition. Here we study the types and distribution of defects inside and on the surface of the single crystal diamond needles. We show that sp3 type point defects are incorporated into the volume of the diamond crystal during growth, while the surface of the lateral facets is enriched by multiple extended defects. Nitrogen addition to the reaction mixture results in increase of the growth rate on {001} facets correlated with the rise in the concentration of sp3 type defects.

New three-dimensional fiber probe for multisensor coordinate measurement

Increasing manufacturing accuracy requirements enforce the development of innovative and highly sensitive measuring tools. Especially for measurement with submicrometer accuracy, the sensor principle has to be chosen appropriately for each measurement surface. Modern multisensor coordinate measurement systems allow automatic selection of different sensor heads to measure different areas or properties of a sample. As an example, different types of optical sensors as well as tactile sensors can be used within the same measuring system. I describe different principles of optical sensors used in multisensor coordinate measurement systems as well as a new approach for tactile measurement with submicrometer accuracy. A special fiber probe has been developed. The tip of the fiber probe is formed as a sphere. The lateral position of this sphere is observed by a microscope objective and can be determined within a fraction of a micrometer. Additionally, a novel optical setup now allows the determination of the z-position of the fiber tip with submicrometer accuracy. For this purpose, an interferometer setup is used. The laser light is coupled into the optical fiber. The light exiting the fiber tip is collected by the microscope objective and superposed with a reference wave, generated directly from the laser. The result is an interference signal that is recorded by the camera and processed by a computer. With this setup, the z-displacement of the fiber sphere can be measured with an accuracy of a fraction of the laser wavelength used.

A novel in situ probe for oxygen uptake rate measurement in mammalian cell cultures

The newly developed in situ oxygen uptake rate (in situ OUR) probe presented in this article is based on the in situ microscope technology platform. It is designed to measure the oxygen uptake rate (OUR) of mammalian cells, an important parameter for metabolic flux analysis, inside a reactor (in situ) and in real-time. The system isolates a known volume of cell culture from the bulk inside the bioreactor, monitors the oxygen consumption over time, and releases the sample again. The sample is mixed during the measurement with a new agitation system to keep the cells in suspension and prevent oxygen concentration gradients. The OUR measurement system also doubles as a standard dissolved oxygen (DO) probe for process monitoring when it is not performing OUR measurements. It can be equipped with two different types of optical sensors (i.e., DO, pH) simultaneously or a conventional polarographic DO-probe (Clark type). This new probe was successfully tested in baby hamster kidney perfusion cell cultures.