K. Kochunarayanan

Bio: K. Kochunarayanan is an academic researcher from University of Kerala. The author has contributed to research in topics: Photonic-crystal fiber & Graded-index fiber. The author has an hindex of 2, co-authored 3 publications receiving 20 citations.

PMMA (polymethyl methacrylate) fiber optic probe as a noncontact liquid level sensor

Abstract: This article reports the principle of operation, design aspects, experimentation, and performance of a noncontact fiber optic liquid level sensor. The sensor is based on the phenomenon of reflective concept. The device consists of fiber optic transmitter, fiber optic probe, floating reflector, photodiode detector, and digital multimeter. The fiber optic probe consists of two 60-cm-long PMMA (polymethyl methacrylate) fibers of diameter 1 mm, numerical aperture 0.5, core refractive index 1.492, and cladding refractive index 1.402. The fiber optic sensor is a promising alternative to other well-established methods for the measurement of liquid level due to its simplicity of design, high precision, long-term stability, linearity, high degree of sensitivity, dynamic range, noncontact sensing, and low cost of the fabrication make it suitable for applications in precise level control in analytical and process chemistry, biochemistry, bioanalytics, and on-line measurement or inspection of liquid level. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2114–2118, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25415

Study of gratings recorded in different holographic recording media for real-time holographic fingerprint sensor

Abstract: Recording holographic gratings in different recording materials and applying these holograms to design a holographic fingerprint sensor. The sensor uses a laser as light source and consists of a glass plate with a plain gratingtype hologram, and a focusing lens system under the hologram.

Watermarking on PCAS compressed images

Abstract: Embedded Image Coding provides a gradual improvement in the reconstruction of image as transmission proceeds. Designing of a successful embedded image compression algorithm involves the method of modeling and ordering in wavelet domain. A new embedded image compression algorithm Pixel Classification and Sorting (PCAS) is employed because of its effective and excellent compression performance. Watermarking of these PCAS compressed images is done to embed secret information for authentication purpose.

Distributed polymer optical fiber sensors: a review and outlook

Abstract: Aging degradation and seismic damage of civil infrastructures have become a serious issue for society, and one promising technology for monitoring their conditions is optical fiber sensing. Glass optical fibers have been predominantly used for the past several decades to develop fiber sensors, but currently polymer or plastic optical fibers (POFs) have also been used extensively to develop advanced fiber sensors because of their unique features, such as high flexibility, large breakage strain, and impact resistance. This review focuses on recently developed distributed and quasi-distributed POF-based sensing techniques based on Rayleigh scattering, Brillouin scattering, and fiber Bragg gratings.

Polymer Optical Fiber Liquid Level Sensor: A Review

Abstract: Polymer optical fiber (POF) level sensors have a lot of potential in liquid level sensing because of their inherent safety, chemical corrosion resistance, anti-electromagnetic interference, electrical isolation, compactness, high coupling efficiency, and flexibility. In this context, a review of POF liquid level sensing is presented. Several POF materials are introduced, including polymethyl methacrylate (PMMA) and perfluorinated polymer (CYTOP). In addition, the operation principles of intensity modulation and wavelength modulation are described in general. Thereafter, contemporary POF liquid level sensing applications are discussed. For intensity modulation, the bending or polishing type and coupling type sensors are introduced. There are also some extrinsic POF level sensors based on intensity modulation. For wavelength modulation, a POF fiber Bragg grating (POFBG) and a special structure grating based POF liquid level sensors are introduced.

Liquid Level Sensor Based on a V-Groove Structure Plastic Optical Fiber

Abstract: A high sensitivity and easily fabricated liquid level sensor based on the V-groove structure plastic optical fiber (POF) was described. In the design, the V-groove structure on the POF is produced by using a die-press-print method, which effectively reduces the complexity of the fabrication process and makes it easier for mass production of liquid level sensors. This greatly enhances the usefulness of the proposed sensor in cost effective liquid level sensing applications. The transmission characteristic of the POF could be changed when the V-groove structure was immerged or emerged by the rising or falling liquid. The liquid level sensing performances for the sensor probes with different structural parameters were investigated, and the sensor performances for the liquids with different refractive indices and the sensor dynamic response were also tested. Experimental results show that the sensor's sensitivity can reach 0.0698 mm-1, with a resolution of 2.5 mm. Results also show that the sensor has a fast response time of 920 ms.

All-fiber, thermo-optic liquid level sensor.

Abstract: This paper proposes an all-optical-fiber sensor for continuous measurements of liquid levels The proposed sensor utilizes an optically absorbing vanadium doped optical fiber, which is configured as a long-gauge, optically-heated, fiber-optic, Fabry-Perot interferometer that is immersed into the measured liquid The sensor is excited cyclically by a medium-power 980 nm optical source, which induces periodic temperature variation and, consequently, optical path length modulation within the vanadium doped fiber The amplitude of this path length variation depends on the liquid level and is measured by an interferometric approach The relation between the liquid level and the amplitude of optical path length modulation caused by the fiber's temperature variation were investigated analytically, and the theoretical model proved to be in good agreement with the experimental results Two versions of level sensors are demonstrated experimentally, the first with single-side optical heating power delivery and 045 m measurement range, and the second with dual-side power delivery and 1 m of operational measurement span Experimental measurement level resolutions achieved for 045 m and 1m operational measurement span were approximately 2 and 3 mm, respectively The simple and efficient design of sensor and signal interrogation system, the latter is based solely on a few widely available telecom components, provides straightforward opportunities for use of the proposed system in a variety of industrial applications

Vibration sensor using 2 × 2 fiber optic coupler

Abstract: A simple fiber optic vibration sensor is designed and demonstrated using fiber optic fused 2×2 coupler that utilized the principle of reflected light intensity modulation. In order to avoid source signal power fluctuations and fiber bending losses, the rational output (RO) technique is adopted. A calibrated 1-mm linear and high sensitivity of 0.36 a.u./mm (2.1 mV/μm ) region of the displacement characteristic curve is considered for vibration measurement. The experimental results show that the sensor is capable of measuring the frequency up to 3500 Hz with ∼ 0.03−μm resolution of vibration amplitude over a dynamic range of 0 to 1 mm. The signal-to-noise ratio of the RO is also improved with respect to the sensing signal. In comparison with dual-fiber and bifurcated-bundle fiber, the designed sensor consists only of a single slope that makes the sensor alignment simple by eliminating the dark region and front slope. Simplicity in design, noncontact measurement, high degree of sensitivity, and economical, along with advantages of fiber optic sensors, are the attractive attributes of the designed sensor that lend support to real-time monitoring and embedded applications.