Higher density optical disk system of super parallel optical heads using a two dimensional VCSEL array are described for the higher data transfer rate and technological capability. Optical heads of the VCSEL array and microlens array play a key role to get higher evanescent light from a small aperture for the optical disk system, of which disk surface is coated with a lubricant and protective film on the flat recording medium in order to keep the gap between the super-parallel optical head and the disk surface within 20 nm. Higher throughput efficiency has been obtained in the near-field semiconductor optical probe array head. However, the obtained evanescent light power is about 10μW from the 100nm probe aperture using a VCSEL 1mW laser output power, which is still not enough to write bits on the phase change optical disk medium. One solution for improvement of the writing power is to develop a special nano-fabricated corrugated thin metal film for higher throughput efficiency by surface plasmon polariton enhancement. A metal fine grating fabrication method to get evanescent light wave resonantly enhancement has been studied with a FDTD simulation result.

In this paper, a novel repulsive force based rotary micromirror is proposed. A repulsive force is produced in the rotary micromirror and the mirror plate is pushed up and away from the substrate. Therefore the rotation angle of the micromirror is not limited to the space underneath the mirror plate and thus the "pull-in" effect is completely circumvented. The novel rotary micromirror can achieve a large rotation angle with a large mirror plate. In addition the novel micromirror has a very simple structure and can be fabricated by standard surface micromachining technology. Numerical simulation is used to verify the working principle of the novel micromirror. A prototype of the novel rotary micromirror is fabricated by a commercially available surface microfabrication process called MUMPs. The prototype has a mirror size of 300μm x 300μm. The experimental measurements show that the prototype can achieve a mechanical rotation of 2.25 degrees (an optical angle of 4.5 degrees) at a driving voltage of 170 volts. A conventional surface micromachined attractive force based rotary micromirror of the same size can only achieve an angle of 0.1~0.2 degree.

We present a novel micro optical waveguide (MOW) on micro actuating platform (MAP) structure that is used for a variable optical attenuator. The device is consists of a fused biconical taper (FBT) coupler mounted on an electromechanical system where an axial stress over the waist of FBT coupler is precisely controlled. Its operation is based on change of coupling constant by compressive stress induced photoelastic effects on the waist zone. We use two FBT couplers to implement an enhanced performance of variable optical attenuator. The couplers are made from a standard single mode fiber and have a circular cross-section in their waist with an enough heating temperature. Each FBT coupler is optimized at 1450nm where total insertion loss is 0.75dB. π phase shifts in the coupling constant have been observed at an axial displacement of 9.5μm. The spectral response between two output ports of the coupler is reciprocal. This allows the proposed device to achieve a high attenuation of >72dB and for 20dB attenuation a flat bandwidth of <1dB over 100nm. Both a low polarization dependent loss (PDL) of <0.07dB and a low operating voltage of 15.3V have been demonstrated with a micro-order actuation.

An optimized KOH micromachining process is presented, which offers perfectly flat sidewalls and a homogenous etching rate. We investigate the influence of ultrasound to the KOH wet etching process for different frequencies and operational modes. Especially small and deep grooves with a high aspect ratio cause difficulties in conventional etching because the time controlled etching process is often not reproducible. Rough bottoms of etched cavities are also found. The main reason for these problems is hydrogen, which is a byproduct of the chemical reaction. It settles down to the surface of the wafer until the hydrogen bubble is big enough to turn up into the solution. During that retention period, the silicon is micro-masked and the reaction in that area, consequentially, is interrupted for some time. To drive hydrogen out of small gaps is even more difficult, so that the etching rate decreases with the depth of the groove. Without any ultrasound, anisotropic KOH etching of deep trenches always leads to insufficient results, e.g. rough surfaces. Using common ultrasonic frequencies such as 35 kHz or 130 kHz reduces the effect of masking bubbles, but the risk of partial damage is much higher in comparison to a 1 MHz excitation frequency. Wafers etched with additional megasound show flat and homogeneous planes. Aspect ratios up to 60 have successfully been fabricated in {110} silicon.

An optical actuator has some interesting characteristics, such as no generation of magnetic noise and receiving the energy remotely. A novel two-dimensional actuator using temperature-sensitive ferrite is proposed. It consists of a moving object made by magnet and a base with temperature-sensitive ferrites that are aligned as a matrix. When the temperature-sensitive ferrites are irradiated by the light beam, their magnetic susceptibility is decreased. The moving part moves along opposite side of irradiation light because of balance of magnetic force. The moving effect irradiated by light beam is simulated and measureed. The two dimensional moving of a magnet with 2.4 mm of squire is demonstrated by using 10 x 8 sets of ferrite with 1.5 mm of diameter.

Bacteriorhodopsin (bR) thin films have been investigated in recent years as a viable biomaterial for constructing micro- or nanoscale optical devices. During illumination, the bR molecules in the thin film undergo a photocycle that is followed by a proton transport from the cytoplasmatic side to the extracellular side of the cell membrane. The photoelectric response induced by the charge displacement can be influenced by both the wavelength and intensity of the impinging light sources. A photocell based on the photoelectric properties of a thin bR film is described in this paper. The bR-based photocell is built as a sandwich-structural device with an ITO (Indium Tin Oxide) electrode/bR film/ITO electrode configuration. The photocell is fabricated by depositing the oriented bR film onto the grounded ITO electrode. The cytoplasmic side of the bR membrane is attached to the ITO conductive surface and the extracelluar side is placed in contact with the second ITO electrode that provides the signal input to the instrumentation circuit. A polyester thin film was used as the spacer separating the two ITO electrodes. The size of the active area of the photocell is about 10×10 mm. A HeNe laser coupled with an acoustic-optical scanning system is used as the light source. Experimental results confirm that the photoelectric response generated by the bR-photocell prototype is durable, stable, and highly sensitive to changes in light intensity. The sensitivity of the proposed signal transducer is 10.25mV/mW. The wavelength dependence of the photoelectric responses is similar to the optical absorption spectrum of bR membrane.

We describe new light-driven actuator based on films of the polymer polyvinylidene fluoride known as PVDF. The actuator employs the photomechanic effect of bending of the polymer film caused by low power (10 mW and less) laser radiation. The photomechanic effect combines various physical mechanisms, such as thermal expansion, converse piezoelectric along with photogalvanic and pyrolelectric, while the thermal mechanism is prevailing. The force applied by the actuator to external objects was measured with a torsion balance. It is proportional to the power of laser beam and could be as high as 10-4 N for a 50-micron film illuminated with a 10-mW beam. We demonstrated mechanical oscillations of a 1-mm by 10-mm actuator at a frequency of 0.3 kHz. The frequency could reach 1 MHz and higher for actuators of micron size. The actuators could be easily made of various shapes. Illumination could be in multiple regions of the actuator body with various time delays between laser pulses in different regions. All this can provide a lot of flexibility in terms of the trajectory of mechanical motion. As an example, we demonstrated an actuator with elliptical motion that could drive inner workings of a conventional mechanical alarm clock. The proposed actuator has a potential of being used as a core element of future optical micro- and nanomotors.

A micromanipulator based on the photo-thermal bending effect experienced by a beveled optical fiber is described in this paper. The micromanipulator design incorporates four fingers, two bendable fibers for actively grasping small objects and two stationary fibers to provide structural support while holding the object. Each finger is a 1mm diameter acrylic optic fiber with a 25mm beveled edge near the tip. The beveled edge is coated with a thin layer of black paint where the thickness has a measurable impact on the amount of tip deflection. A light beam, from a 150W halogen illuminator, is directed into the fixed end of the sculpted optic fiber causing the tip at the free end to deflect by approximately 50 microns. Several experiments are conducted to demonstrate that this simple microgripper is able to grasp, hold, and release a variety of small metal screws and ball bearings. Finite element analysis is used to further investigate the physical properties of the optical actuator. The theoretical deflections are slightly greater than the experimentally observed values. The FEM analysis is also used to estimate the maximum force (~ 0.7mN) generated at the actuator tip during deflection.

I propose a high-speed vertical scanning profilometry which has nanometric height resolution. The proposed profilometry is equipped with two short-coherent-light sources, which are made of extremely-high-power light emitting diodes ( LED) and whose center wavelengths are 503 and 591 nm. In 3-D profile measurements, this profilometry acquires many interferograms while vertically-scanning a Mirau-type microscope objective with 0.415-mm step/interferogram and alternately-flashing LED. Odd-numbered interferograms are acquired with 503-nm LED and even-numbered interferograms are with 591-nm LED. Regarding the acquired interferograms, a computer calculates phase and modulation contrast using a phase-shifting technique. As two step movements are repeated between acquirements of interferograms flashed with the same LED, phase step corresponds to approximately 6 p + p/2 with 503 nm and approximately 6 p - p/2 with 591 nm, respectively. After searching the interferogram having a contrast peak, the computer extracts optical path difference of the searched interferogram with nanometric resolution from the phase information. From the vertical step length of 0.415 mm and a frame rate of 110 Hz, a vertical scanning speed is given as 46 mm/s. Height resolution of the profilometry is confirmed from measured data of a step height standard.

Impact response of an impact hammer is evaluated by means of an optical method. In the method, an object levitated with sufficiently small friction using a pneumatic linear bearing is collided with the impact hammer under test. The inertial force, that is the product of the mass and the acceleration, is measured highly accurately by means of measuring the Doppler frequency shift of the laser light beam reflected on the mass. The velocity, the position, the acceleration and the inertial force of the mass are then numerically calculated from the time-varying frequency. The output signal of a force transducer embedded in the hammer and the inertial force measured by the method are compared. The present status and the future prospects of the proposed method are discussed.

We propose a new method for measuring vibration frequency with electronic speckle pattern interferometry. In this method, laser beam wavelength is modulated with an independent frequency. In accordance with a frequency difference between the modulation and the vibration, a maximum intensity in a fringe pattern image changes. When the modulation magnitude is reduced, the frequency difference between the vibration and the modulation, in which the fringe pattern diminishes, widens and the maximum intensity in the fringe pattern image alters gently while the modulation frequency is scanned. Then we can search the vibration frequency, in which the maximum intensity in the image has a peak when the modulation frequency equals to the vibration frequency, with a hill-climbing method. It is confirmed in an experiment that the vibration frequency can be measured in a short time sufficient for practical use.

This paper presents a practical shape-from-focus method for measuring three-dimensional shapes on production lines. A focused plane was inclined typically at 45° to an optical axis in an afocal optical system and was imaged on a CCD image sensor, which was also inclined at an angle of 45° to the optical axis. When the focused plane and surface of an object intersect, a contour of the object is defined at each position of the carrier conveying the object. Each contour can be obtained by detecting focused points in an image of the focused plane using a specific focus-measure. To correctly detect the focused points on the right focused-plane image, a sequence of focused-plane images was taken at each position of the carrier moving perpendicular to the optical axis. A focused image point representing a contour point was detected as a specific pixel in a focused-plane image that gave a maximum of focus-measure for the contour point from the focused-plane images taken contiguously while sweeping the object by the focused-plane. Both the detected pixel coordinates and the carrier position producing the focused-plane image, including the detected pixel, could determine the three-dimensional coordinates of the contour point. A minute hemisphere with a diameter of 4.8 mm could be measured with a standard deviation of 16 μm.

In this paper, we present our most recent theory and the experimental setup to verify our research into an advanced automation technique that yields high performance, low cost optoelectronic alignment and packaging through the use of intelligent control theory and system-level modeling. Our approach is to build an a priori knowledge based model, specific to the assembled package's optical power propagation characteristics. From this model, a piece-wise linear inverse model is created and used in the "feed-forward" loop. If accurate models are determined, perfect tracking can be achieved. In addition to this feed-forward model, our controller is designed with feedback components, along with the inclusion of a built-in optical power sensor. We will also introduce the test bed that we have developed to verify our control loop algorithm and present initial results.

In this paper, we report an innovative depth-sensing nanoindenter using a lead zirconium titanate (PZT) stack actuator. The conventional nanoindenter requires two sensors and closed-loop controls for precise loading or positioning due to inherent high hysteresis and creep characteristics of the PZT actuators. On the other hand, we have shown that an open-loop positioning control scheme using a single displacement sensor can be used for nanoindentation. The developed control scheme compensates for the hysteresis and creep errors of PZT actuators. By adopting the single-sensor open-loop control, the overall system structure can be simplified and a robust control environment can be achieved. In addition, a high positioning repeatability was achieved by using a flexure type mainframe with a high preload applied to the PZT actuator. To verify the system performance, we conducted the standard indentation tests on a fused quartz sample, and the results were compared with those from a commercial nanoindenter. Besides the basic nanoindentation functions, the developed system also has the capability for surface imaging through a scanning function. The pre-indentation scanning capability proved to be a very useful method for positioning the tip in the desired indentation location. Similarly, post-indentation scanning allows for visualization of the indentation marks after the tests.

A control system that tunes the resonant frequency of a lightly damped resonator to its excitation frequency in the face of detuning disturbances is investigated. The resonance tuning is achieved by adaptively controlling the resonant frequency of the resonator using the error between the excitation frequency and resonant frequency. Assuming that the parameters of the resonator are slowly time-varying, a nonlinear time-varying model that accurately predicts the tuning performance of the system is developed. This developed model is subsequently linearized to obtain a linear time-invariant model that facilitates both analysis and design of the resonance tuning system. Based on the developed linear time-invariant model, guidelines for designing the resonance tuning system are provided. The results are illustrated by examples.

An experimental set-up to measure the out-of-plane displacement field of surfaces in reflection microscopy is presented. It is derived from a Nomarski shear-interferometer. When the shear is greater than the length of the microcantilever, this interferometer, used with a sinusoidal phase modulation and four integrating buckets, allows one to obtain the displacement field of the observed surface, with a reproductibility in the 10 pm range. Identification techniques derived from the "Equilibrium Gap Method" developed recently to measure local mechanical properties and loading, the displacement field measured by the shear-interferometer may be used to determine simultaneously the "temperature" field and the local elastic properties of the cantilever. The feasibility of the in-situ (in water solution) full-field measurement of displacement fields in MEMS is proved, and preliminary results tends to show that mechanical effets induced by DNA hybridization are heterogeneous.

In this paper, novel piezoelectric microbalance biosensors using single crystal lead zinc niobate-lead titanate (PZN-PT) and lead magnesium niobate-lead titanate (PMN-PT) are presented. The PZN-PT/ PMN-PT materials exhibit extremely high piezoelectric coefficients and other desirable properties for biosensors, supposed to be a superior substitution for the conventional quartz crystal with the improved performance. . These biosensors provide rapid and minute quantitative target detection by monitoring the change in resonance frequency of the crystal probe. With the geometrical variations, various prototypes are compared with conventional quartz crystal microbalances (QCM). The superiority of the materials over conventional quartz crystal is demonstrated experimentally in terms of sensitivity. In addition, we examine the feasibility of ultra miniaturization of the PZN-PT based biosensor by fabricating freestanding single crystal films of the PZN-PT and patterning micro-scale biosensors with ion milling and argon-ion laser-induced etching technique. A fabricated prototype sensor utilizing the material in a thin film form has a size of 300x100x7um³.

To develop the head mounted visual enhancement device (HMVED), we have suggested five methods for visual acuity enhancement such as image magnification, effects of viewing axis control, wavelength control of light source, and effects of power control of light source and focal length control. In addition, the mobility and convenience of the HMVED should be considered. The HMVED consists of a 0.44" high quality TFT Color LCD (active dots: 800(H)×225(V)), a magnifier lens, a TFT color LCD back light, a prism and a diopter lens. The LCD is used to display the magnified image by a magnifying lens. The backlight can be controlled by the intensity and color light source. The prism can refract the viewing axis. The basic clinical experiments of the HMVED have been performed at Low Vision Device Company in Korea. The results show beneficiary effects on people with low vision.

A sensor fusion scheme for mobile robot environment recognition that incorporates range data and contour data is proposed. Ultrasonic sensor provides coarse spatial description but guarantees open space (with no obstacle) within sonic cone with relatively high belief. Laser structured light system provides detailed contour description of environment but prone to light noise and is easily affected by surface reflectivity. We present a sensor fusion scheme that can compensate the disadvantages of both sensors. Line models from laser structured light system play a key role in environment description. Overall fusion process is composed of two stages: Noise elimination and belief updates. Dempster-Shafer's evidential reasoning is applied at each stage. Open space estimation from sonar range measurements brings elimination of noisy lines from laser sensor. Comparing actual sonar data to the simulated sonar data enables data of two disparate sensors be fused at the unified feature space. Experiments have been conducted to recognize a naturally cluttered indoor environment partially surrounded by window glasses. Experimental results demonstrate the effectiveness of the proposed method.

In robot-manipulator teleoperation, vision-based tracking of the human operator motion offers a non-contacting approach that permits unhindered operator motion. To control the robot manipulator, the three-dimensional (3D) position and orientation of the arm of the operator is required. This paper presents a neural-network (NN) based method of determining the orientation of the human hand using non-invasive markerless vision-based tracking. The tracking method uses images of the hand from two fixed cameras to determine three angles of hand orientation. The neural network processing to determine the hand orientation consists of five procedures. First, a preprocessing system performs basic transformations on the input images to prepare them to be interpreted by the neural network. Secondly, an unsupervised neural network extracts relevant local features necessary to recognize the input patterns. Thirdly, a self-organizing neural network combines the local features of the previous network to identify the global pattern. Next, a modified radial-basis function (RBF) neural network calculates the probabilities that a given input pattern corresponds to each basic pattern, for which the RBF NN was trained. Finally, the orientation of the hand is interpolated between these basic patterns by calculating the weighted average of the most probable configurations identified by the RBF NN.

Parallel kinematics machines (PKM) present a promising new formation of machine kinematics. But, their application is limited due to insufficient positioning accuracy, caused by errors of the transformation model and indirect position measurements. The theoretically attainable machining accuracy of machine tools is further decreased by unsolved calibration problems, which are the most important obstacles concerning the introduction of new machine tools with parallel or hybrid kinematics. This paper presents a conceptual improvement based on a direct position measurement in Cartesian coordinates, which overcomes these problems.

A novel design of an atomic force microscope (AFM) with a (1-x)Pb(Mg_1/3Nb_2/3)O_3-xPbTiO₃ (PMN-PT) single crystal scanner and a self-sensing cantilever is presented in this paper. The piezoelectric scanner and the self-sensing cantilever are integrated into a small-sized all-in-one structure with a microscope objective focused on the tip. The Z-scanner consists of two parallel PMN-PT unimorphs. This design can minimize the rotation and the sideways deflection at the sensing tip. The XY-scanner consists of two perpendicular small rods of PMN-PT. In this design, each PMN-PT rod serves as an actuator as well as a flexure because of the elastic property of the single crystal material. Under this configuration, the XY scanner can guarantee a fully decoupled planar scanning motion without positioning sensors and a sophisticated closed-loop control mechanism which is required for a XY scanner with conventional piezoelectric tubes. Furthermore, by adopting a self-sensing MEMS cantilever, the AFM design is simplified by discarding various optical sensing components. The attached objective offers fast visible inspection and rough positioning of the tip for measurement setups. We used a digital signal processor (DSP) based control scheme to achieve fast control speeds of the AFM. We also used LABVIEW for a flexible programming environment. We conducted finite-element analyses to characterize the dynamic performance of the AFM system. The system showed a high frequency band due to the small inertia of the moving part with relatively rigid structure. In addition, various scanning tests were performed to demonstrate that the system is capable of providing near video images.

The small form factor optical data storage devices are developing rapidly nowadays. Since it is designed for portable and compatibility with flesh memory, its components such as disk, head, focusing actuator, and spindle motor should be assembled within 5 mm. The thickness of focusing actuator is within 2 mm and the total working range is +/-100um, with the resolution of less than 1μm. Since the thickness is limited tightly, it is hard to place the yoke that closes the magnetic circuit and hard to make strong flux density without yoke. Therefore, Halbach array is adopted to increase the magnetic flux of one side without yoke. The proposed Halbach array type focusing actuator has the advantage of thin actuation structure with sacrificing less flex density than conventional magnetic array. The optical head unit is moved on the swing arm type tracking actuator. Focusing coil is attached to swing arm, and Halbach magnet array is positioned at the bottom of deck along the tracking line, and focusing actuator exerts force by the Fleming's left hand rule. The dynamics, working range, control resolution of focusing actuator are analyzed and performed.

A smart cantilever structure using single-crystal relaxor ferroelectric material is presented. The smart cantilever possesses both sensing and actuation capabilities, embedded in a monomorph and resulting in a smart structure. Single crystal relaxor ferroelectric materials (1-x)Pb(Zn_1/3Nb_2/3)O_3-xPbTiO₃ (PZN-PT) and (1-x)Pb(Mg_1/3Nb_2/3)O_3-xPbTiO₃ (PMN-PT) are ideal for actuator and sensor applications since they exhibit very high piezoelectric coefficients. We separately pattern interdigitated electrodes on the top and bottom surfaces of a single crystal cantilever beam. The interdigitated electrode design results in an electric field- gradient that after poling not only induces flapping actuation but also, simultaneously, allows us to detect internally or externally induced stresses. As a monolithic actuator integrated with a sensor, it has potential applications in various Micro-Electro-Mechanical Systems (MEMS), Scanning Probe Microscopy (SPM) and Near-field Scanning Optical Microscopy (NSOM). We fabricate monomorph prototypes and characterize their performance in terms of actuation displacement and sensing capabilities, respectively. Finally, an active vibration control experiment was successfully conducted by using the smart cantilever structure.

This paper presents a new design of a Shear Motion Mode (SMM) actuator for ultra-high precision positioning in nanotechnological applications. In the SMM Actuator, a V-shape stage is driven by four parallel polarized piezoelectric plates with shear displacement. Based on its simple mechanism, the SMM actuator can be built very compactly. For fast and precision positioning tasks, we develop three different driving modes to control the SMM actuator. For large stroke, the inertial and frictional driving modes are applied for fast and precision positioning, respectively. The scanning mode enables the adjustment of the scanning distance in highest resolution. Positioning function of the developed SMM actuator may also be brought into applications in the low temperature and Ultra High Vacuum (UHV) environment. These three driving modes are experimentally tested to measure their dynamic performance. The stroke of the SMM actuator is 5mm. By applying the frictional driving mode, the SMM actuator can achieve a positioning resolution of 3nm with a pay load of 500g.

In this letter, we propose the new first light search algorithm using 2 tilting stages in optical fiber component assembly process. The proposed algorithm is theoretically and experimentally investigated. The experimental results for 4 different initial light spot conditions show that the theoretical approach and the experiments of our algorithm are exactly matched and that our proposed algorithm can be a new candidate for the first light search algorithm in the fiber-optic component assembly industrial field.

Novel all-fiber optic temperature sensors based on hollow optical fibers (HOFs) are presented. The HOFs with an air hole diameter of 8um at the center are fabricated through elaborate controls of MCVD and fiber drawing process. Two types of all-fiber temperature sensors are described. One is an all-fiber temperature sensor composed of a short HOF serially concatenated between a pair of long-period fiber gratings using a B/Ge-codoped core single mode fiber (SMF). The broadband pass-band tuning range of 84.3nm, covering both S and C band, is observed in the range from 25 to 215°C. Transmission peak is linearly shifted showing negative slope of -0.44nm/°C at 1500nm region. Its design, fabrication arts, and device integration are explained with characteristics of output filter spectrum and temperature tuning. The other is an in-line fiber etalon temperature sensor using a short HOF segment fusion-spliced between standard SMFs. This device is characterized in terms of wavelength shift according to temperature for HOFs with and without Ge-doped ring core. Temperature sensitivity of 3.38×10^-5/°C and dynamic range of 20dB are observed over the range from 25 to 330°C at 1550nm. It is confirmed that the experimental results for both fiber optical sensors show a good agreement with theoretical analysis.

Small particles are one of the biggest sources that cause loss in semiconductor and flat panel display industry. Therefore, it is important to control them during their manufacturing process. To achieve this goal, exact measurement of particles is first required. Laser light scattering is the most widely used technique for diagnosis of particles because it does not disturb flow field and enables real time and spatially resolved analysis. Measurement of nonspherical aggregates comprised of small primary particles is difficult compared with spherical particles because they have very complex morphology. In addition, most researches on aggregates using light scattering are limited to point measurement, which requires much time to inspect large area and is difficult to observe unsteady phenomenon. Motivated by this, we have developed a laser light scattering method for simultaneous measurement of spatial distributions of aggregate size and morphology. Silica aggregates that were generated in Methane/air premixed flame were used as test particles. Multiangular planar light scattering measurement was carried out using a sheet beam of Ar ion laser and an intensified charge coupled device (ICCD) camera as a light source and a detector, respectively. The result was interpreted based on the Rayleigh-Debye-Gans scattering theory for fractal aggregates to obtain the mean radius of gyration and fractal dimension that are the parameters characterizing aggregate size and morphology. The suitability of our new technique was confirmed by experiment using conventional light scattering.

A simple method for the measurement of angular displacement is proposed. As a laser beam is incident on a planar optical waveguide, the m-lines will be obtained by scanning the angle of incidence. It is found that the m-lines will shift with the variation of the thickness of the guided layer. And interesting measurement approaches which are based on intensity measurement and angle interrogation, respectively, are described. Theoretical results and simulation show that intensity measurement is more sensitive than angle interrogation. And small angle of incidence is more sensitive than large angle of incidence which corresponds to high-order modes and low-order modes, respectively.