This PDF file contains the front matter associated with SPIE Proceedings volume 7064, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

In this study we focus on the aluminium nitride (AlN). This material shows a large number of advantages associated with good piezoelectric properties. Therefore, AlN is an excellent candidate for MEMS actuation where low dielectric loss, low thermal drift and high signal-to-noise ratios are required. In this paper, the case of AlN driven cantilevers composed of three thin layers deposited on the silicon substrate will be considered. Precise knowledge of physical and material parameters of AlN applied in these simple elements are necessary for their further applications. However, up to now, AlN still represents a technological challenge and many of its micromechanical and piezoelectric properties are not precisely described. That is why, our study has been concentrated on determination of such parameters like the residual thin film stresses, thermal expansion coefficient α and piezoelectric coefficient d₃₁. In this paper the interactions between the theoretical solution, the numerical FEM simulations and experimental results were performed. This hybrid methodology allows to identify the main source of behaviors discrepancy between the physical and numerical model of tested cantilevers. Obtained knowledge leads to optimization of the technological process and required parameters of actuator functionality achievement by better understanding of the tested microdevices properties. In experimental procedure, it was used nanoindentation tests for obtaining an elastic properties of AlN, interferometric techniques for performing the static and dynamic measurements of cantilevers and scanning electron microscope for measuring topography.

In the context of this article we demonstrate a novel Fizeau interferometric system that copes with the presence of vibrations. Besides the conventional high spatial, but low temporal resolution detector system (the CCD camera) used in phase shifting interferometry, an additional high temporal, but low spatial resolution detector system was integrated, in order to measure the random phase shifts that are induced under the influence of the vibrations. The additional sensor consists of three photodiodes. The acquired analog signals enable the measurement of the occurring phase shifts at three non-collinear locations on the test surface. The resulting phase shifts at the three individual locations enable the determination of the random phase shifts over the entire image aperture. To avoid the smear phenomenon at very short exposure time, a beam shutter was integrated. Another alternative is to integrate a pulsed laser diode, for this purpose the concept of a wavelength meter is proposed. While the random oscillations of the test object are continuously measured, the CCD camera acquires several interferograms. In consequence, a phase shifting algorithm for random phase shifts was applied. In order to proof the validity of the new interferometer, a test surface of known topography was measured. The results of the measurements in presence of vibrations show very good concordance with the surface data given by the supplier. The analysis of the root mean square (RMS) over ten different measurement show a measurement repeatability of about 0.004 waves (approximately 2.5 nm for 632.8 nm laser wavelength).

In recent years a wide variety of liquid based optical elements have been conceived, designed and fabricated even for commercial products like digital cameras. The impressive development of microfluidic systems in conjunction with optics has led to the creation of a completely new field of investigation named optofludics. Among other things, the optofluidic area deals with the investigation and the realization of liquid micro-lenses. Different methods and configurations have been proposed in literature to achieve liquid variable micro-lenses. This paper reports about the possibility to achieve lensing effect by a relatively easy to accomplish technique based on an open microfluidic system consisting of a tiny amount of appropriate liquid manipulated by the pyroelectric effect onto a periodically poled LiNbO₃ substrate. Basically, an electrowetting process is performed to actuate the liquid film by using the surface charges generated pyroelectrically under temperature variation. The configuration is electrode-less compared to standard electrowetting systems, thus improving the device flexibility and easiness of fabrication. The curvature of the liquid lenses has been characterized by interferometric techniques based on the evaluation of the phase map through digital holography. The results showing the evolution of the lens curvature with the temperature variation will be presented and discussed.

The measurement accuracy in non contact profilometric techniques is generally limited by mechanical vibrations and by geometrical defaults of the micro-scanning table. In order to free the measurement from these environnemental perturbations, we describe a novel type of interferometric microscopy based on the well-known Spectroscopic Analysis of White Light Interferograms (SAWLI). The originality of the presented set-up lies in the fixation of the reference plate on the inspected object. As reference plate and sample are fixed together, the mechanical vibrations do not affect the measurements. As a result the potential nanometric accuracy of interferometric microscopy is effective. This method consists in measuring the air gap thickness between the reference plate and the sample. At the output of the spectral interferometric microscope a channelled spectrum is observed. From this signal, the spectral phase is calculated using a numerical seven points phase shifting algorithm allowing the measurement of the local height of the analyzed surface. These preliminary results demonstrate the ability of this method as a point sensor. Then this technique will be implemented in a high frequency scanning STIL technology named MPLS 180.

The lateral shearing interferometer was applied to in vivo investigate the stability of the tear film surface covering the contact lenses. The 8 mW HeNe laser was used as the light source. The sequences of interferograms were recorded by CCD camera in real time during the inter-blink intervals at 25 fps, stored in a computer memory and numerically processed. Every frame illustrates the pattern of interference fringes that corresponds to temporal stage of prelens tear film surface. Fast Fourier Transform was used to quantitative evaluate tear film surface irregularities and the numerical measure M2 was used to obtain quantitative description of the tear film smoothness. The M2 index is the lowest for the smooth and regular surface of the tear film and its values increase if the prelens tear film begins to be unstable. The proposed way of analysis of each interferogram gives opportunity to calculate the credibility of given M2 index and automatically reject a part of a frame, that is not covered by interference fringes with an appropriate contrast due to eye movement. The tear film smoothness has been measured on different types of soft contact lenses of 4 companies. The significance differences in tear film stability have been noticed between low and high water content materials of contact lenses. The tear film was less stable on low water content materials.

Based on the discovery that cutting signals contain fractal patterns, a recurrence plot based methodology called recurrence quantification analysis (RQA) is applied to the time series constructed using information contained in speckle images of machined surface for chatter detection in turning operation. Variations in the roughness of machined surface created by virtue of chatter, manifests as changes in the statistical properties of speckle images of the surface when examined frame by frame along the axis of the machined part. A significant parameter of such images, the frame wise average intensity value is extracted separately and arranged in sequence for constructing the time series. Since this time series is found to be non-stationary in nature and due to the fact that the turning operation is low dimensional chaotic, the nonlinear time series analysis methodology of RQA is used for analyzing the time series. The present study ascertains that the derived time series do have a deterministic origin and it further investigates the sensitivity of the different RQA variables to chatter cutting by analyzing this time series and demonstrates that this methodology is capable of capturing the transition from regular cutting to the chatter cutting.

Machine tool chatter is an unfavorable phenomenon during metal cutting, which results in heavy vibration of cutting tool. With increase in depth of cut the cutting regime changes from chatter- free cutting to one with chatter. In this paper, we propose the use of permutation entropy (PE), a conceptually simple and computationally fast measure to detect the onset of chatter from the time series generated using laser speckle pattern recorded using Charge Couple Device (CCD) camera. Laser speckle is an interference pattern produced by light reflected or scattered from different parts of the illuminated surface. It is the superposition of many wave fronts with random phases, scattered from different parts of the rough surface. If a speckle pattern is produced by coherent light incident on a rough surface, then surely the speckle pattern, or at least the statistics of the speckle pattern, must depend upon the detailed surface properties. Therefore we propose PE as an ideal measure, which can efficiently distinguish regular and complex nature of any signal, to extract information about the roughness of the reflecting surface. In the present study two work pieces, one taper cut and one step cut are machined to form cylindrical pieces, by continuously varying the depth of cut. As the depth of cut increases the surface finish is expected to deteriorate, mainly due to the onset of chatter vibrations. To analyze the surface texture characteristics, the speckle pattern is obtained by illuminating this curved surface using a collimated laser beam (5mW Diode Laser at 676nm wavelength.). The laser beam is made to incident obliquely to the curved surface of the work piece, and the speckle pattern is recorded using a CCD camera. The beam is scanned along the axis of the work-piece and the speckle pattern is recorded at different regions at constant intervals. A time series is generated from the speckle data and analyzed using PE. Permutation entropy is a complexity measure suitable for regular, chaotic, noisy or reality-based signals. PE work efficiently well even in the presence of dynamical and/or observational noise. Unlike other nonlinear techniques PE is easier and faster to calculate as the reconstruction of the state space from time series is not required. Increasing value of PE indicates increase in complexity of the system dynamics. PE of the time series is calculated using a one-sample shift sliding window technique. PE of order n>=2 is calculated from Shanon entropy where the sum runs over all n! permutations of order n. PE gives the information contained in comparing n consecutive values of the time series. The calculation of PE is fast and robust in nature. Under situations where the data sets are huge and there is no time for preprocessing and fine-tuning, PE can effectively detect dynamical changes of the system. This makes PE an ideal choice for online detection of chatter, which is not possible with other conventional methods.

We report application of phase shifting interferometric measurements to study of the spatially resolved quantum efficiency (QE) of the semiconductor solar-cells. In our method solar-cell is illuminated by two sets of mutually spatially orthogonal fringe patterns of known frequency, and varying phase (shifted phase). We report theoretical results obtained using simple analytical model describing properties of small spot size defects, and preliminary experimental results validating this method. The new method and new apparatus can be also used for studies of spectrally resolved QE.

The authors have been working on the development of a white light interferometer to measure both inner and external cylindrical surfaces. High precision diamond turned conical mirrors were used to shape the light beam appropriately. Collimated light from a Michelson-like white light interferometer was directed to the conical mirror. The reflected light was radially directed to the cylindrical part to be measured. A telecentric lens system captured the image of the measured cylindrical part reflected on the conical mirror surface. Scanning of the measured volume was performed in cylindrical coordinates by linear displacement of a flat mirror in the reference arm of the interferometer. A cloud of points was directly built in cylindrical coordinates. The present paper focus on two main topics of recent development: wear measurement of cylinders and cylindrical part alignment. An appropriate mathematical model was developed to fit the cylindrical cloud of points to the experimental data. The use of the least absolute method instead of the least squares method for fitting the model is presented and discussed. This model is used to align two measured cloud of points to a same reference coordinate system, one acquired before and the other after a wearing test. Direct comparison between both clouds of points allowed computing the volume of the removed material by wearing. Results are presented and discussed for both cases.

In characterizing the performance of a phase-shifting interferometer, the dependence of the measured height on the spatial frequency is rarely considered. We describe a test mirror with a special height relief that can be used to measure the height transfer function for the interferometer in a fashion analogous to the measurement of the modulation transfer function for the optical imaging system. We fabricated the test mirror at the National Institute of Standards and Technology (NIST) using a lithography-based process. The test mirror has several patterns (reminiscent of moth antennae) with variable spacing in radial direction. We describe the fabrication of the test mirror and its application to test the performance of the interferometer.

In previous work, wavefront coding technology has been applied on an off-axis three mirror anastigmatic optical system. The secondary mirror is selected as the wavefront coded element. After redesigned the surface of secondary mirror becomes an unusual unrotational-symmetric surface with cubic term, which can not be tested by traditional null testing with compensator. For preparing for manufacturing and testing this kind of elements, a simple cubic surface whose equation is z=3λ(x³ + y³) (where x, y is normalized coordinate, λ=0.6328 μm) is polished. The final surface figure is 0.327λ(PV) and 0.023λ(RMS). The manufacture of this surface is introduced in this paper. The tilt component is subtracted to minimize the material removal. Also a non-null method is described for testing the experimental element. The deviation from a reference plane of the cubic surface is regarded as system error. In another words, the ideal cubic surface is set as the reference artificially. A special system error file for interferometer can be created so that the cubic term can be extracted during the testing process automatically. The residual error is just the departure from the ideal figure of the surface under machining by this way. The error and effective range is also presented. But the method may not be practical for the secondary mirror as wavefront coded element because the surface of that kind is convex asphere added cubic term. An improved non-null method is discussed for testing this kind of surface.

CSIRO's Australian Centre for Precision Optics has recently finished the production of a high-precision concave spherical mirror. The specifications were very ambitious: numerical aperture 0.75; asphericity below 5.5 nm rms and 27.3 nm P-V. The available reference transmission sphere had to be calibrated to enable adequate accuracy. Due to the high numerical aperture of the mirror, sub-aperture measurements had to be stitched together to form a complete surface map of the mirror. Phase-shifting interferometry at high numerical aperture suffers from phase-step non-uniformity because of the large off-axis angles. We present what we believe to be a new interpretation of this phenomenon as a focus error, which clarifies where in the interferometer the phase-shift error occurs. We discuss the ball-averaging method for calibrating the reference transmission sphere and present results from the averaging process to ensure an uncertainty commensurate with the certification requirement. For carrying out the sub-aperture measurements, we constructed a two-axis gimbal mount to swivel the mirror around the focus of the test wavefront. If the centers of curvature of the transmission sphere and the mirror coincide, the mirror can be tilted without losing the interferogram. We present a simple and effective alignment method, which can be generally applied to optical tests where the wavefront comes to a focus. The mirror was coated with protected aluminum and tested in its mount. No effect on the sphericity error from the coating was found, and the specifications were exceeded by approximately 30%. We discuss subtleties of the stitching process on curved surfaces and report final results.

Wavefront curvature sensing with phase error correction system is carried out using phase retrieval based on a partially-developed volume speckle field. Various wavefronts are reconstructed: planar, spherical, cylindrical, and a wavefront passing through the side of a bare optical fiber. Spurious fringe pattern in the reconstructions due to a small tilt in the plane illumination wave is detected and numerically corrected for. Difference in the curvatures of two spherical wavefronts is also evaluated. Possible applications include angular displacement and range measurements.

The Space Interferometry Mission - Planet Quest Lite (SIM-PQL) Guide 2 telescope system is currently being developed at JPL. The SIM-PQL is a new mission concept to perform micro-arcsecond narrow-angle astrometry to search approximately 50 nearby stars for Earth-like planets, and to perform global astrometry with an accuracy of six micro-arcseconds in position and parallax. The novel cost and mass reducing "Lite" concept includes reduction in interferometer baselines and replacing the second guide interferometer (Guide 2) with a telescopic system. The resulting simplification still allows meeting most science goals without significant performance degradation. The Guide 2 telescope employs a nulling pointing control system that utilizes a Fast Steering Mirror (FSM) as an actuator and a star tracking CCD camera as a control sensor. Under the nulling closed loop control, the modulated attitude motion of the instrument is picked off by a metrology FSM tip-tilt sensor (AMET). The Guide 2 pointing control system requires mili-arcsecond class fine pointing, maintenance of low jitter and thermal stability and a sub-nanometer class metrology system that ties the sensor bench to rest of the instrument. This paper presents the Guide 2 telescope pointing control system design and resulting performance estimates. The pointing control requirements are first stated followed by the descriptions of the system architecture, algorithm design and simulation results. Concept and algorithm validation is conducted on a workstation-based simulation testbed, specifically developed to capture critical sensor/actuator behavior and environmental disturbances.

The technology path to produce low cost microinterferometric heads in plastic and the optical methods for quality investigations of these elements are presented. Specifically the interferometric and photoelastic tomography methods, applied for the 3D studies of refractive index (n) and birefringence (B) in photonics components replicated by means of hot embossing (HE) technology, are investigated. The enhanced automated measurement and data analysis procedures are described and the experimental results obtained for micro-objects working in transmission are given. Also the methodology to combine the tomographic data for full characterization of internal structure of 3D photonics elements is provided. The samples under test are massive waveguide microinterferometerers in the form of cuboids produced by hot embossing process characterized by a variety of parameters. The systematic tomographic studies of 3D distribution of n and B provided important information for extending knowledge about the process and optimization hot embossing technology. The tomographic measurements are supported by measurements of top and side walls profile and roughness.

A white-light interferometer with new signal analysis techniques provides 3D top surface and thickness profiles of transparent films. With an additional change from conventional object imaging to pupil-plane imaging, the same instrument platform provides detailed properties of multilayer film stacks, including material optical properties. These capabilities complement conventional surface-topography measurements on the same platform, resulting in a highly flexible tool.

We present a numerical technique for automatic extended focused imaging and three-dimensional analysis of microparticle field observed in a digital holographic microscope working in transmission. We use Fourier method for the extraction of complex amplitude from the single exposition digital holograms. We create a synthetic extended focused image (EFI) using the focus plane determination method based on the integrated amplitude modulus. We apply the refocusing criterion locally for each pixel, using small overlapping windows, in order to obtain a depth map and a synthetic image in which all objects are refocused independent from their refocusing distance. The obtained synthetic EFI allows us to perform image segmentation and object detection. We improve the accuracy of vertical localization using an additional refining procedure in which each particle is treated separately. A successful application of this technique in the analysis of microgravity particle flow experiment is presented.

The paper deals with the analysis of the uncertainty of high precision long range three-dimensional Nanopositioning and Nanomeasuring Machines (NPMM). Those high-tech instruments consisting of precision 3d-guides, interferometers, a 3d-reference-mirror and nanoprobes, connected by a stabile frame are subject of research. Especially the interferometer mirror system characterizes the precision of such machines. Therefore a new vectorial metrological model will be described to characterize this machine part. Its properties and advantages are shown and the model is used to analyze the uncertainty budget of a concrete Nanopositioning and Nanomeasuring Machine.

Spatial light modulators (SLM) are used in different microscopy setups. Examples are optical tweezers, programmable phase contrast imaging, confocal imaging, and aberration correction. We report on a method that measures and corrects specimen-induced aberrations in wide-field microscopy without additional optical components (e.g. Shack-Hartmann sensors) by taking advantage of the SLM that is already used in the setup. Different local gratings are written into the SLM which is positioned in a plane conjugate to the pupil of the imaging system. Multiple images are recorded and based on the shift of subimages we deduce the wavefront. We demonstrate first experimental results of this method for a system using a high resolution LCoS modulator.

In the paper the multiwavelength interferometer with automatic data analysis based on phase fraction method is described. It is used to extend measurement range without losing sensitivity, especially to calibrate long gauge blocks. Numerical simulations and experimental work results have been shown to confirm proper functioning of this method. However, stabilization of environmental conditions and light sources has significant influence on correctness of measurement results. To match those requirements measurement system, which will be built for Polish Central Office of Measures, has been designed. This design is based on Twyman-Green interferometer and assumes usage of two highly stabilized laser sources. Optical and mechanical design of this system has been shown. Moreover, system for monitoring and stabilization of environmental conditions is required.

Deep Proton Writing (DPW) is a rapid prototyping technology allowing for the fabrication of micro-optical and micro-mechanical components in PMMA, which are compatible with low-cost replication technologies. Using DPW, a high-precision 2D fiber connector featuring conically-shaped micro-holes for easy fiber insertion, was realized. When populating these fiber connectors by fiber insertion and fixation, a critical issue is the accurate control of the fiber protrusion. The use of laser interferometry to measure the fiber's facet position with respect to the connector surface to within a few micrometers, is inconvenient in view of the measurement range as compared to the fiber dimensions. In this paper, we propose an interferometric method for in-situ monitoring of the fiber insertion depth, based on the phenomenon of low temporal coherence light interference in a Twyman - Green setup. In addition, achieving a few micrometers measurement range with low coherence light requires vertical scanning of the sample under test. The design of the experimental setup and the achieved measurement results are shown and discussed.

By using a CGH test plate fabricated with our equipment and techniques, we measured a perfect sphere surface. The measurement result is quantified into four parts: the figure error from the spherical surface under test; the figure error from the spherical reference surface; the error from hologram and the adjustment error from misalignment. The measurement result removed from the later three errors, shown excellent agreement with Zygo test of the same sphere surface. This verified that the measurement accuracy by using this kind of CGH could be very high.

An interesting problem that has concerned forensic scientist for many years, is their need for accurate, reliable and objective methods for performing fracture matching examinations. The aim of these fracture matching methods is to determine if two broken object halves can be matched together, e.g., when one half is recovered at a crime scene, while the other half is found in the possession of a suspect. In this paper we discuss the use of a commercial white-light profilometer system for obtaining 2D/3D image surface scans of multiple fractured objects. More specifically, we explain the use of this system for digitizing the fracture surface of multiple facing halves of several snap-off blade knives. Next, we discuss the realization and evaluation of several image processing methods for trying to match the obtained image scans corresponding to each of the broken off blade elements used in our experiments. The algorithms that were tested and evaluated include: global template matching based on image correlation and multiple template matching based on local image correlation, using so-called "vote-map" computation. Although many avenues for further research still remain possible, we show that the second method yields very good results for allowing automated searching and matching of the imaged fracture surfaces for each of the examined blade elements.

In order to determine the properties of thin films with the required performance and reliability, a sensing system for dynamic monitoring is proposed to measure the thickness of thin films. The system is based on the principle of white-light interference, and is combination of spectrum analysis and optical fiber techniques. When two reflected lights interfere within white-light coherent length range, relationship of between interference intensity and the wavelength of incident light is achieved according to the equation of interference light's intensity. According to different thickness of film, the relevant method is selected to calculate the thickness of thin film. So the interference can be analyzed in spectral domain. The scheme of the system is set up including white-light source, multi-mode optical fiber, beam splitter, spectrometer. With the help of optical fiber, the interference pattern is captured by spectrometer. When thickness of thin film is varying, spectra curve will shift. The original spectra curve is processed in the computer. In order to determine accurate extreme points, many methods of curve processing are used to decrease the noise. The spectra curve is smoothed by signal processing method called empirical mode decomposition (EMD). This method is suitable for non-linear and non-stationary data processing. The experimental data is contrast to the calibrated value. The results show that the relative error of this method is lower 1%. This method has advantages over other measuring methods, such as higher accuracy, low-cost instrument, extensive measurement range, simple structure and non-destructive.

The design and system performance of a far-infrared interferometer with which to test rough aspheric surfaces are presented. It is based on the optical configuration of classical Fizeau interferometer. A CO2 laser is used as a light source operating at a 10.6μm wavelength. A He-Ne laser is introduced into the interferometer to solve problems concerning with alignment. The measuring error(RMS) of the interferometer is less than λ/200(λ=10.6μm), this accuracy is able to fulfill the need of grinding primary mirror.

In this study, a simple method for measuring the small displacements is presented. When a circularly polarized heterodyne light beam reflected from a mirror is incident into a hemi-spherical prism and is reflected at the base of the prism. Then the reflected light beam passes through an analyzer for interference. With properly chosen azimuth angles of transmission axis of the analyzer, the phase difference between s- and p- polarized light is sensitive to the incident angle near the internal reflection polarization angle. The phase difference can be accurately measured with the heterodyne interferometry. The small displacement of the mirror causes a small variation of incident angle and a phase change. Therefore, substituting the phase difference into special derived equations; the small displacement can be determined. The proposed method has advantages of common-path configuration and heterodyne interferometry.

In ophthalmology, the laser excimer corneal surface ablation used to correct the refractive eye defects, such as myopia, astigmatism and hyperopia and, more recently, presbyopia is known as refractive surgery. Typically, the characterization of the corresponding technique, as well as the laser accuracy, is performed by analyzing standard ablation profiles made on PMMA (polymethylmethacrylate) plates. A drawback of this technique is that those plates do not necessarily represent the dimensions of the cornea during the ablation. On the other hand, due to the time varying process of the eye aberrations, the direct eye refractometric measurements can produce some errors. We report in this work the interferometric analysis of the ablation profile obtained with refractive surgery, applied directly on a contact lens. In this case, the resultant ablation profile might be closer to the real profile as well as time invariant. We use, as a reference, a similar contact lens without ablation. The preliminary results of the characterization of the corresponding ablation profile are also presented.

The concept of spatial coherence wavelet has been introduced some years ago with very productive results. It has given new insight on the fundamental optical phenomena, and has predicted novel light characteristics like polarizations domain and transverse energy transference. The concept of marginal power spectrum emerges as the amplitude of the wavelet and provides a phase-space representation of the optical field in any state of spatial coherence. Its values have energy units and are carried by the spatial coherence wavelets along specific paths or rays. Some of them, called carrier rays, are corresponding to the radiant energy of the field, but the rest, called dark (or tamasic) rays, do not contribute to the radiant energy, i.e. they take on positive and negative values, symmetrically distributed, which are responsible for the constructive and destructive interference after redistributing the radiant energy of the field. This description of interference is illustrated by analyzing the Young experiment, gratings and one-dimensional apertures. Furthermore, the principle of spatial coherence modulation is introduced, showing its feasibility for practical applications in beam shaping.