|
|
Fiber-optic liquid level sensor
Ondra, Dominik ; Beneš, Petr (referee) ; Skalský, Michal (advisor)
This text summarizes scientific principles that are used in fiber optics field, and could be used to design liquid level sensor. Different types of optic fibers and advanced optic structures are analyzed for liquid level sensor usage. Mechanisms of already existing types of optic fiber liquid level sensors and other mechanism liquid level sensors are characterized. Three sensor designs are proposed. One working with different levels of auttenaution when bending the fiber. The other meassuring different refraction indexs of the environment and the last one based on phase delay of light. Viabillity of these principle has been tested. Text also describes optic fiber splicer Fujikura FSM 100P+ and optic fiber sturctures that it is able to produce. Sensor based on refraction index of environment has been calibrated.
|
|
|
Double-Beam Mach-Zehnder Interferometer Forthin Piezoelectric Films Measurement
Skalský, Michal
This paper describes a Mach-Zehnder double-beam interferometer for measurement of piezoelectric films thickness displacement. The measurement of the sample from both sides with probing beam leads to suppression of bending effect, which can otherwise strongly degrade the results acquired by other methods. The performances of the setup were tested on a reference PZT sample. The measured piezoelectric coefficient was in agreement with its theoretical value. The described setup utilizes minimal number of the optical components which are necessary for controlled phase drift compensation. Further techniques for performance enhancement are also proposed.
|
|
|
Compact Fiber-Optic Current Sensor Utilizing Multiple Modes
Skalský, Michal
In this paper, a simple and compact fiber-optic current sensor utilizing a standard telecom fiber is demonstrated. The sensor employs a Faraday effect introducing a circular birefringence, which is added to a birefringence induced by fiber coiling. The experiments revealed that multi-mode propagation of light with wavelength of 633 nm may exhibited much better sensitivity to the Faraday effect and is less harmed by the parasitic birefringence compared to single-mode beam with 1550 nm.
|
|
|
Measurement of sound fields using non-contact optical methods
Karásek, David ; Skalský, Michal (referee) ; Havránek, Zdeněk (advisor)
The purpose of this paper is to assemble measurement chain dedicated to contactless measuring of acoustic fields emitted by test sources and to validate its results. At first author discusses possible optic methods which can be used to measure acoustic fields, then he talks about theoretical foundations which are needed to measure data and to reconstruct final data. The last two chapters are dedicated to cover basics about created program and to analyse various aspects which influence measured and reconstructed data. Created measurement chain is fully functional, at the end of this thesis are proposed some ways of improving
|
|
|
Fiber-Optic Displacement Sensor Based On
Fabry-Pérot Interferometer
Skalský, Michal
This paper describes a simple and inexpensive fiber-optic sensor for dynamic displacement measurement with sub-nanometer resolution. The principle is based on creating a resonator cavity between measured surface and a single-mode fiber, working as a Fabry-Pérot interferometer. The fundamental principles like diffraction, spatial filtration or the role of reflectivity are analyzed theoretically and their effect on the sensitivity is explained. The sensor is then tested experimentally with
an uncoated fiber tip and a gold mirror. Based on the spectral analysis, the effect of working distance on interference visibility is explained.
|
|
|
Closed-Loop Interferometric Fiber-Optic Gyroscope with Unpolarized Light
Skalský, Michal
This article deals with utilizing special techniques to improve parameters of interferometric fiber-optic gyroscope (I-FOG) using unexpensive single-mode (SM) fiber and based on all-fiber components. Firstly, it was shown that polarizer must be used to compensate for depolarizing unperfections. Optimization of Er-doped superfluorescent fiber source (SFS) greatly increased SNR of the sensor. Finally, solution for closed-loop operation with slow piezoelectric phase modulator was found yielding significant extension of measurement range as well as its linearity.
|
|
|
Angular velocity measurement with fiber optic interferometer
Skalský, Michal ; Šedivá, Soňa (referee) ; Havránek, Zdeněk (advisor)
This thesis deals with general theoretical description, design and construction of sensor of angular velocity based on Sagnac interferometer, or interferometric fiber-optic gyroscope. The theoretical part is focused firstly on explanation of basic principles and finding important formulas. Secondly, some state-of-the-art configurations of the fiber-optic gyroscope and their differences are analysed. Limiting factors and parasitic effects are also described. Attention is also paid to properties and suitability of particular optical components. The practical part especially deals with an utilization of common low-birefringent optical fiber in an fiber-optic gyroscope. Firstly, some basic properties of components and the simplest configurations of gyroscope were tested. They provided an important knowledge for design of final solution working in an open loop configuration with phase modulation. Further, specific components used in this demonstration sensor and its construction are described in more detail. Designed gyroscope utilizes all-fiber components made of common low-birefringent fiber so this solution is unexpensive. It uses an unpolarized light and depolarizer to ensure stability. Another specificity is a light source using spontaneous emission of erbium-doped fiber. Finally, some basic parameters of designed gyroscope acquired by measurement as well as record of calibration are stated.
|
|
|
Angular velocity sensor with Sagnac interferometer
Skalský, Michal ; Beneš, Petr (referee) ; Havránek, Zdeněk (advisor)
This thesis deals with theoretical description of fiber-optic angular velocity sensors, or gyroscopes, and further with design and construction of own sensor of this type. The theoretical part describes problematics of interferometric and resonant fiber-optic gyroscopes. Basic principles and physical limits are described for both types. The main focus is then put on analysis of possible conceptions of these sensors. Solutions using different optical configurations as well as various modulation and signal processing schemes are discussed. The practical part deals with design and construction of own interferometric fiber-optic gyroscope in closed-loop configuration. The gyroscope utilizes all-fiber components including piezoelectric phase modulator and unexpensive single-mode fiber, which are commonly used only for open-loop configurations. To realize closed-loop operation, special modulation scheme based on fully harmonic signal was develeped, which yields linear output within wide dynamic range. This type of modulation requires high level of synchronization achieved by using a field-programmable gate array module. The gyroscope utilizes powerful broadband fiber source, polarizer and Lyot depolarizer which ensure good reciprocity of whole architecture. The parameters of the sensor, obtained by measurement, are even comparable to some sensors using PM fiber, which is much more expensive.
|
guest ::
RSS feed.