The work is devoted to the analysis of the accuracy characteristics of rotation angle sensors using angular scales from nanostructured metasurfaces. The principle of their operation is based on the dependence of the frequency response of metasurfaces on the orientation of the incident light polarization plane. The influence of the noise characteristic of angle sensors on the measurement result is considered. It is shown that for the sensors considered in the work, it might be on the order of units of arc seconds. The influence on the accuracy characteristics of misalignments of the angular scale and thermal effects that the sensor may experience during operation is analyzed. Recommendations to reduce the influence of parasitic effects and further improve the accuracy characteristics are given.
A sample of an optical monoblock ring confocal resonator is analyzed. It is a reflective prism made of S-TIH optical glass with four working surfaces located at the vertices of a square. One of the reflective surfaces is used to input and output radiation from the resonator by violating the effect of total internal reflection with the help of an auxiliary reflective prism. The spectral and other optical characteristics of a sample of an optical monoblock ring confocal resonator are studied. Its advantages over other types of optical ring resonators and the prospects for its application in optical sensors, in particular, in optical gyroscopes, are also considered.
A sample of a ring confocal resonator designed to operate as a sensitive element of an optical resonator gyroscope is studied. The sample has a monoblock design - the resonator is a single block (prism) with reflective surfaces operating on the effect of total internal reflection. The optical contour of the resonator has the shape of a square with a side length of 10 mm and is formed by four reflective surfaces. Three reflecting surfaces are flat, and one is toroidal with curvature radii in the meridional and sagittal planes that satisfy the confocality condition. The resonator is designed to operate at wavelengths of about 1.55 μm. The advantages of using a of a ring confocal resonator as a sensitive element of an optical resonator gyroscope are analyzed. In particular, it is shown that the reduction of the angular velocity measurement error caused by the optical Kerr effect becomes possible (compared to the use of a waveguide cavity and a whispering gallery mode cavity). The resistance of the system to external influences also improves.
The principle of operation of all resonator micro-optical gyroscope prototypes developed to date involves frequency scanning of the ring resonator. In previous works on this topic, we proposed and considered an optical resonator gyroscope scheme that does not require frequency scanning of the ring resonator. There two counterpropagating waves pass along the same optical path. It reduces the parasitic nonreciprocity, which leads to additional errors in measuring the angular velocity in most of the known schemes. In addition, this scheme allows further reduction of gyro prototypes dimensions. In this work, we simulate a resonator gyroscope made according to the described scheme. In this case, we simulate both the optical path of the proposed resonator gyroscope and the system for generating the output signal. Using the model, we evaluate its characteristics, including limiting sensitivity, operating range, etc.
The most promising type of micro-optical gyro is a resonator gyroscope. At the same time, the principle of operation of all prototypes of resonator micro-optical gyroscopes developed to date involves scanning a passive ring resonator in frequency. We devoted this work to a new approach to the construction and operation principle of a resonator micro-optical gyroscope. This approach does not require scanning a passive ring resonator in frequency and is realized through the use of a Mach–Zehnder modulator with a passive ring resonator connected to one of its arms. It was shown that, with this approach, the angular velocity can be determined, first, by the difference between the maxima and minima of the radiation power at the output of the Mach–Zehnder modulator when the optical length of one of its arms is modulated and, second, by the displacement of these maxima and minima. A common drawback of all considered angular velocity measurement methods utilizing the Mach–Zehnder modulator is the limited measurement range. For the resonator considered in this paper, the measurement range is of the order of ±1500 rad / s.
In the modern world there is a pronounced tendency for miniaturization. It applies to navigation systems and sensors used in them. Due to this, micromechanical gyroscopes in particular, became widespread, which made it possible to measure the angular velocity of miniature objects. But their sensitivity to accelerations and vibrations limits the range of their application. Currently, research in the direction of minimizing the size of general and precise optical gyroscopes is relevant, i.e. the development of micro-optical gyros. The most promising type of micro-optical gyro is a resonator one. Wherein the principle of operation of all prototype resonator micro-optical gyroscopes developed to date involves the scanning of a passive ring resonator in frequency. This work is devoted to a new approach to the construction and principle of operation of a resonator micro-optical gyroscope. This approach does not require scanning the passive ring resonator in frequency and is achieved through the use of a Mach-Zehnder modulator, one of whose arms is connected to a passive ring resonator. This allows to simplify the design of a micro-optical gyroscope, to obtain a mutual configuration, and to drop the tunable laser (required in most schemes) in favor of a laser with a constant generation frequency. The paper also discusses the limitations of the new approach and ways to overcome them.
Resonators with an equidistant spectrum are often required in optics. One of the ways to obtain it is the frequency degeneracy of the resonator mode, which is observed, for example, in the well-known classical (linear) confocal resonator. At the same time, there exist configurations of ring resonators similar to it in terms of their properties—ring confocal resonators. In the first approximation, they can be obtained using several reflecting surfaces in the cavity, at least one of which is concave toroid with radii of curvature in the two main meridional sections ensuring the confocal condition and the degeneracy of the spectrum. Such resonators can be used, in particular, as sensitive elements of miniature optical gyroscopes. We consider the specifics and properties of ring confocal resonators and the conditions necessary to obtain them. Using the modified Fox and Li method to calculate open-ring resonators with astigmatic reflective surfaces, the field of the ring confocal resonator is simulated.
Often, optical devices require resonators with a limited set of natural frequencies and an equidistant spectrum. These requirements are satisfied by ring confocal resonators. Such resonators can be manufactured as a single monolithic element (prism) and used, in particular, as sensitive elements of miniature optical gyroscopes. As a result of external mechanical and thermal effects and imperfection of manufacturing technology, the reflecting surfaces of ring confocal resonators can be misaligned. This paper is devoted to the analysis of the effect of these misalignments on the optical properties of resonators. OOFELIEMultiphysics software is used to calculate the deformations arising in the resonator as a result of external effects. The influence of the deformation of the resonator on its optical properties is estimated using the modified method of Fox and Lee.
In recent years, the optical resonators of whispering gallery modes (WGMs) have attracted increasing interest in the scientific community. These are the axially symmetric dielectric resonators (spherical, disk, torus, bottle-shaped, etc.) with smooth edges that support the existence of WGMs due to the total internal reflection from the surface of the resonator. The rotation of the WGM resonators with respect to the inertial space causes changes in their radii. This, in turn, leads to the reciprocal (the same for light beams travelling in opposite directions) spectral shift of the WGMs. Thus, the rotation of such resonators causes a spectral shift, by which it is possible to calculate the motion parameters. Earlier the prospects of creation of the angular velocity sensor on the basis of this effect were discussed. Spherical, torus, and disk-shaped resonators were considered as possible sensitive elements. This work is devoted to the analysis of the influence of rotation on the mutual shift of the WGM of bottle-shaped resonators. An important part of the work is the study of cross-sensitivity of bottle resonators to rotation.
Resonators with an equidistant spectrum are required in optics quite often. One of ways to obtain them is to use degeneracy of the frequencies of the resonator modes, which is observed, for example, in well-known confocal resonators. At the same time it is possible to find configuration of the ring resonator with a similar properties – confocal ring resonator. In the first approximation, the ring confocal resonator can be obtained using several (at least three) reflecting surfaces: flat and concave toroidal with the radii of curvature in the two main meridional sections ensuring the fulfillment of the confocality condition and the degeneration of the spectrum. Such resonators can be manufactured as a single monolithic element (prism) and used, in particular, as sensing elements of miniature optical gyroscopes. This work is devoted to the study of the properties of ring confocal resonator with the use of multiphysical modeling.
Today micromechanical gyroscopes are very popular in different areas. Solid-state micromechanical gyroscopes based on surface acoustic waves (SAW) have good vibration and shock resistance because of absence of elastic suspensions, ability to work at 50 000 g loads, small dimensions, cheap in mass production, etc. Unfortunately, there are some limits for further development of such gyroscopes because it requires prototype production in small series. In this study we are investigating laser ablation method. Earlier existing bidirectional delay line produced by photolithography method was modeled in OOFELIEMultiphysics. Frequency response of modeled bidirectional line was at the same level as for existing prototype which can be a confirmation of correct modeling process. As the next step one more prototype was produced by laser ablation method. For this prototype operational characteristics were examined and compared with photolithography bidirectional delay line and with results of finite element modeling. Results of tests and its comparison with modeling and photolithography method are discussed.
In recent years, whispering gallery mode optical resonators are attracting ever-growing interest of the scientific community. They are axially symmetric dielectric resonators (spherical, disk-like, toroidal, bottlelike etc) with smooth edges that support the existence of whispering gallery modes by total internal reflection on the surface of the resonator. The rotation of the whispering gallery modes resonators with respect to the inertial space causes changes of their radiuses. This, in turn, leads to mutual (same for the opposite directions of the resonator bypass) spectral shift of whispering gallery modes. Thus, the rotation of such resonators causes a spectral shift, registering which one can calculate the motion parameters. Earlier, the prospects of creating an angular velocity sensor based on this effect were considered. Аt the same time the spherical, disk-like and toroidal resonators were considered as sensitive elements of this sensor. This paper is devoted to the analysis of the effect of rotation on the mutual frequency shift of the whispering gallery modes of bottle-shaped resonators. An important aspect of this work is the investigation of the cross-sensitivity to rotation of bottle resonators. The study is based on the results of the simulation in OOFELIEMultiphysics software.
The optical whispering-gallery mode (WGM) resonators are axially symmetrical resonators with smooth edges, supporting the existence of the WGMs by the total internal reflection on the surface of the resonator. As of today, various types of such resonators have been developed, namely the ball shaped, tor shaped, bottle shaped, disk shaped, etc. The movement of WGM resonators in inertial space causes the changes in their shape. The result is a spectral shift of the WGMs. Optical methods allow to register this shift with high precision. It can be used in particular for the measurement of angular velocities in inertial orientation and navigation systems. However, different types of resonators react to the movement in different manners. In addition, their sensitivity to movement can be changed when changing the geometric parameters of these resonators. The work is devoted to investigation of these aspects.
The influence of centrifugal forces on angular velocity sensors that measure a spectral shift of whispering-gallery modes (WGMs) is investigated. Spherical WGM resonators of different materials are considered the sensing elements. The study is based on the results of the simulation in OOFELIE::Multiphysics software.
The optical whispering gallery modes resonators are axially symmetrical resonators with smooth edges, supporting the existence of the whispering gallery modes by the total internal reflection on the surface of the resonator. For today various types of such resonators were developed, namely the ball-shaped, tor-shaped, bottle-shaped, disk-shaped etc. The movement of whispering gallery modes resonators in inertial space causes the changes of their shape. The result is a spectral shift of the whispering gallery modes. Optical methods allow to register this shift with high precision. It can be used in particular for the measurement of angular velocities in inertial orientation and navigation systems. However, different types of resonators react to the movement on a miscellaneous. In addition, their sensitivity to movement can be changed when changing the geometric parameters of these resonators. This work is devoted to a research of these aspects.
Laser ablation technique is promising for production of surface acoustic wave (SAW) sensors complicated topologies. Its main advantages in comparison to a photolithography method are: simplicity in pattern creation, no need in photomasks, possible to work with thick metallization (up to 20 μm), possibility to correct topology after the sensor sealing and others. This work discusses possible error sources, including side heating of metal films, and presents results of first characteristics evaluation for experimental delay lines produced by laser technology.
Influence of the centrifugal forces on angular velocity sensors that measure a spectral shift of whispering gallery modes is investigated. Spherical whispering gallery mode resonators of different materials are considered as sensing elements. The study is based on the results of the simulation in OOFELIE::Multiphysics software.
Nowadays surface acoustic wave sensors are produced using a photolithography method. It is expensive in small series production and do not allow further topology correction, which is important for inertial sensors. In this case, a laser ablation method seems promising. It does not require a photomask and can achieve a good matching of topologies produced on opposite sides of the wafer. Several delay lines were produced using a proposed technique. Its characteristics were explored and discussed.
Influence of the centrifugal forces on angular velocity sensors that measure a spectral shift of whispering gallery modes is investigated. Spherical whispering gallery mode resonators of different materials are considered as sensing elements. The study is based on the results of the simulation in OOFELIEMultiphysics software.
Nowadays surface acoustic wave (SAW) sensors are produced using a photolithography method. In case of inertial sensors it suffers several disadvantages, such as difficulty in matching topologies produced on opposite sides of the wafer, expensive in small series production, not allowing further topology correction. In this case a laser ablation method seems promising. Details of a proposed technique are described in the paper along with results of its experimental test and discussion.
The article is devoted to assessing the impact of various external factors on the characteristics of microoptical gyroscope sensing elements. The rating is based on the results of a m ultiphysical modeling using software OOFELIE: Multiphysics.
A great number of design concepts of surface acoustic wave (SAW)-based gyroscopes was proposed through the last decade mainly due to their unique robustness and ability to survive extremely high shocks. At the same time, these devices are small, cheap and easy to produce. Later publications offered a novel idea of constructing a fully passive and wireless gyroscope using SAW-based elements. Although this idea is very attractive, proposed design concepts rise a number of questions. This paper is dedicated to give a short overview of existing design concepts, focusing on details of its operation. Moreover, a new design concept utilizing a single delay line and a phase detector is proposed.
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