This PDF file contains the front matter associated with SPIE Proceedings Volume 7791, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

High precision optical metrology may be viewed from the perspective of the relevant object properties for optical measurement such as microstructure, surface gradient and geometrical complexity. We discuss high precision measurement methods and compare their suitability with respect to these object properties. We emphasize reflectometry and shearography as examples of two interesting techniques particularly suited for high precision optical metrology and extend the discussion to optical non destructive testing (NDT). In this context, reflectometry and shearography appear to be interesting techniques suitable for both optical metrology and NDT. We finally discuss the unique features of laser ultrasonic for NDT.

The paper introduces different approaches to overcome the large ratio between wafer size and feature size in micro production. The EU-project SMARTIEHS develops a new concept for high volume M(O)EMS testing. The design of the test station is presented and the advancements compared to the state of the art are introduced within the following fields: micro-optical laser interferometer (LI) design, DOE-based microinterferometer production, smart-pixel camera and signal processing for resonance frequency and vibration amplitude distribution determination. The first experiments performed at LI demonstrator are also reported.

Microelectromechanical systems (MEMS) are exposed to a variety of environmental conditions, making the prediction of operational reliability difficult. In this contribution, we investigate the environmental effects on the static and dynamic properties of piezoelectrically actuated MEMS microcantilevers where aluminium nitride (AlN) is used as actuation material. The environmental effects to be considered include thermal and humid cycling, as well as harsh electrical loading performed under standard weather conditions. Investigated properties are defined for the static behaviour (i.e. determined initial deflection, out-of-plane displacement vs. constant voltage) and dynamic behaviour (i.e. determined 1st resonance frequency, vibration amplitude at 1st resonance mode) of AlN-based microcantilevers. The metrology tool is a Twyman Green interferometer, operating in both stroboscopic regime and time-average interferometry mode. The initial deflection and the frequency changes of the first resonance mode of microcantilevers are monitored during the accelerated thermal aging, the humidity tests, as well as harsh electrical loading and fatigue tests. Finally, the resonant fatigue tests, accelerated by application of a high voltage are accomplished to evaluate the lifetime of microcantilevers. For constant values of voltage higher than 15 V, a delamination of top electrode of AlN transducer is observed.

Grating interferometers overcome the diffraction limit of optical waves. They can provide nano-scale displacement resolution, and will have great potential for nano-metrology applications. The optical configurations of used grating interferometers are Michelson's type with different paths between the measurement beam and reference beam. Environmental disturbance can directly enter the measured signals and cannot be essentially slashed. Thus the accuracy of the used grating interferometers becomes dramatically worse. In this paper, a homodyne common-path grating interferometer is proposed, that can reduce the environmental disturbance at its lowest level. It has promising potential for nanotechnology applications. The measurement principle and experimental verifications are done in the work.

A universal, extended dynamic range novel optical inspection system for aspheric optical components and optics that are not easily inspected with conventional interferometry is presented. Modern optical design and manufacturing procedures have begun using such components more and more in routine applications to improve optical system capability. Inspection tools required for these types of optical components have lagged the capability to manufacture them. In this paper unique measurement procedures employing digital holography combined with a spatial light modulator are discussed for complex shapes such as aspheres and mandrels.

Non-contact optical measurement methods are essential tools in many industrial and research domains. A family of new non-contact optical measurement methods based on the polarization states splitting technique and monochromatic light projection as a way to overcome ambient lighting for in-situ measurement has been developed^1,2. Recent works³ on a birefringent element, a Savart plate, allow to build a more flexible and robust interferometer. This interferometer is a multipurpose metrological device. On one hand, the interferometer can be set in front of a CCD camera. This optical measurement system is called a shearography interferometer and allows to measure micro displacement between two states of the studied object under coherent lighting. On the other hand, by producing and shifting multiple sinusoidal Young's interference patterns with this interferometer, and using a CCD camera, it is possible to build a 3D structured light profilometer. After giving the behavior of the Savart plate, an overview of the two devices will be given as well as their specifications and some applications.

Electret-based electrostatic devices have been used in the electro-acoustic field for decades. Recently, the improvement of its charge retention has been of interest for application to the field of smart materials. Hence, the flexible electret-based loudspeaker has become an important research topic for futuristic applications such as 3C (computers, communications and consumer electronics) and smart curtains. The volume velocity and the on-axis sound pressure level (SPL) of an electret loudspeaker are the key parameters of interest. To study the vibration characteristics of an electret diaphragm, a finite element analysis (FEA) was introduced to facilitate the design. To validate the finite element analysis (FEA) model, an out-of plane full-field non-destructive optical detection method which incorporates electronic speckle pattern interferometry (ESPI), was applied to determine the vibration mode shape of thin film. By driving the electret loudspeaker at different frequencies, a corresponding vibration mode of interest was detected with the ESPI set-up. Both the simulations and the experimental results obtained on the measurement platform are detailed in this paper.

Based on the Fresnel's equations and the phase-shifting method, an alternative method for measuring the refractive index distribution of a GRIN lens is presented. A linearly/circularly polarized light in order enters a modified Twyman-Green interferometer, in which an electro-optical modulator is used as a phase shifter. In the interferometer, the light beam is divided by a beam-splitter into two beams, a reference beam and a test beam. After they are reflected by a plane mirror and the tested GRIN lens, respectively, they are combined together and pass through an analyzer. The analyzer extracts the same polarized components to interfere each other, and the full-field interference signals produced by the components of the s- and the p-polarizations can be obtained. The full-field interference signals are taken by a CMOS camera. The phase differences can be obtained by using the four-step phase-shifting interferometric method. Substituting these two groups of data into special equations derived from Fresnel equations, and the two-dimensional refractive index distribution of the GRIN lens can be calculated. Its validity is demonstrated and has some merits such as simple optical configuration, easy operation and high resolution.

We describe a unique high-speed Doppler imaging vibrometer configured for rapid full-field measurement of arbitrary solid body vibrations without temporal or spatial measurement multiplexing. The instrument design employs a staring 16×16 measurement beam matrix and passive fiber-optic focal plane array, remotely coupled to distributed parallel receivers and digital processors. High-speed data captured by the instrument indicate the rich dynamic complexity to be found even in comparatively simple coupled mechanical systems with transient features that are otherwise difficult to observe. The system provides a new tool for instantaneous non-contact full-field vibration measurement of structural dynamics, including, but not limited to, transient or non-repeatable phenomenon.

Quantitative analyses of the tympanic membrane mechanical properties are needed for better understanding of its role in detailed clinical evaluation. Optical methods like Digital Holographic Interferometry (DHI), time averaged holography and ESPI are quite promising for the investigation of biological tissues. Their demonstrated ability to detect displacement changes in quasi and real time and without contacting the sample surface under study provides relevant features, such as clinical and mechanical properties. In this research time averaged vibrations patterns are shown for fresh tympanic membrane specimens taken from post-mortem cats, and subject to acoustic stimuli in the frequency range of 485 Hz up to 10 kHz. The results may provide information about sample mechanical characteristics such as its elasticity coefficient. An important feature of this approach over other techniques previously used to study the vibrations of the tympanic membrane is that it only requires an image and less equipment to carry out the measurements. Good agreement was found between the present and past measurements from previous research work. Results show the usefulness of the method in the medical field in providing relevant data about key mechanical characteristics of biological samples.

Current ear examination procedures provide mostly qualitative information which results in insufficient or erroneous description of the patient's hearing. Much more quantitative and accurate results can be achieved with a holographic otoscope system currently under development. Various ways of accurate positioning and stabilization of the system in real-life conditions are being investigated by this project in an attempt to bring this new technology to the hospitals and clinics, in order to improve the quality of the treatments and operations of the human ear. The project is focused at developing a mechatronic system capable of positioning the holographic otoscope to the patient's ear and maintaining its relative orientation during the examination. The system will be able to be guided by the examiner, but it will maintain the chosen position automatically. To achieve that, various trajectories are being measured for existing otoscopes being guided by doctors in real medical conditions. Based on that, various kinematic configurations are to be synthesized and their stability and accuracy will be simulated and optimized with FEA. For simplification, the mechanism will contain no actuators, but only adjustable friction elements in a haptic feedback control system. This renders the positioning system safe and easily applicable to current examination rooms. Other means of stabilization of the system are being investigated such as custom designed packaging of all of the otoscope subsystems, interferometrically compensating for the heartbeat induced vibration of the tympanic membrane as well as methods for monitoring and active response to the motion of the patient's head.

The number of cells is commonly employed to describe the cell viability and the status of cell culture in a certain extent. An automatic and non-invasive detecting method for the status analysis of cell culture is developed based on digital holography microscopy (DHM) technology. Digital holographic imaging can retrieve quantitative information of object wavefront by the numerical reconstruction from a single digital hologram recorded by a detector such as CCD or CMOS camera, which is especially suitable for the morphology detection of the transparent or semi-transparent cells. In this contribution, the lensless Fourier transform (LFT) based holography configuration is designed for cell imaging without prestaining, and the amplitude and phase of living cells can be reconstructed by digital reconstruction and phase unwrapped algorithms. Then the image filtering and segmentation are combined for the automatic evaluation of the level of confluency. In imaging experiments, the culture status of the cervical cancer cell TZMbl is detected, and the results demonstrate that digital holography microscopy provides a feasible non-invasive method for monitoring the living cell culture.

The characterization of streambed topography is crucial to approach problems in fluvial hydraulics, river engineering and geomorphology. In most steep alpine environments measurement apparatus like terrestrial laser scanners or airborne Lidar systems are difficult to successfully apply, because they need free sight, elevated positions and good aerial or road access. In mountain streams this is generally not the case. We describe a novel technology to acquire 3D models of nonsubmerged parts of such streambeds. The core of our range imaging system is a commercial time-of-flight video camera. The camera produces a per-pixel distance measurement using an integrated near-infrared modulated light source and an image sensor that measures the phase-shift between modulated and reflected light at each pixel. If mounted on a lightweight crane vertical above the stream, the camera can observe the streambed topography with a 3D resolution of down to 0.5 cm. However, the distance measurements degrade in accuracy under direct sunlight and when strong illumination contrasts occur. With the collected data detailed digital terrain models can be computed.

A digital speckle pattern (DSP) interferometer using a special diffractive optical element (DOE) was developed by the authors. A collimated laser beam is diffracted by the DOE in such a way that the first diffraction orders produce a circular double illuminated measurement area. Due to natural symmetry of the illumination scheme, the interferometer reaches pure radial in-plane sensitivity. It is demonstrated and verified that the resulting interferometer is not sensitive to laser wavelength variations at all. Its configuration is presented as well as its performance evaluation for residual stress measurements using the blind hole-drilling method.

This paper presents a new method for measuring vibration based on interference from two spherical waves. By integrating the two interference arms into a beamsplitter cube by reflective film and the probe beam being divided into two parts, the interferometer can distinguish that the vibrations are from the monitored optical components or from laser interferometer system itself. At the same time, because the two interference waves are spherical, it can realize monitoring the three-dimensional vibrations. The experimental setup has advantages of being stable and reliable with an integrated structure. Theoretical analysis and experimental demonstration are performed. The experiment results indicate that the method can monitor three-dimensional vibration sensitively.

Optical inspection using multi-sensor multi-scale systems requires the selection of proper sensors, their parameters (e.g. resolution, N.A, lighting conditions), and measurement strategies. We propose an assistance system that automatically selects the suitable sensors and their parameters for an inspection specification. The specimen and the defects are described based on their properties (e.g. geometry, material etc) to the assistance system. The system then uses different "sub-assistants", each designed for a specific measurement technique, to recommend the most suitable measurement setups. The system and initial results for fringe projection techniques are presented.

In this paper, we present advances on our development of an optoelectronic holographic computing platform with the ability to quantitatively measure full-field-of-view nanometer-scale movements of the tympanic membrane (TM). These measurements can facilitate otologists' ability to study and diagnose hearing disorders in humans. The holographic platform consists of a laser delivery system and an otoscope. The control software, called LaserView, is written in Visual C++ and handles communication and synchronization between hardware components. It provides a user-friendly interface to allow viewing of holographic images with several tools to automate holography-related tasks and facilitate hardware communication. The software uses a series of concurrent threads to acquire images, control the hardware, and display quantitative holographic data at video rates and in two modes of operation: optoelectronic holography and lensless digital holography. The holographic platform has been used to perform experiments on several live and post-mortem specimens, and is to be deployed in a medical research environment with future developments leading to its eventual clinical use.

In this paper, we present a metrology system to characterize the refractive index profile of intraocular lenses (IOLs). Our system is based on interferometric optical phase computed tomography. We believe this metrology system to be a key enabling technology in the development of the next generation of IOLs. We propose a Fizeau-based optical configuration and present a simulation study on the application of computed tomography to IOL characterization.

Gap uniformity between two plates is an important parameter in many optical devices or instruments. The proposed method combines low coherence tandem interferometry and the concept of distributed fiber sensors for in-situ multipoint gap measurement. No gratins or special marks are required on the surfaces of the plates. A superluminescent diode (SLD) is used as the light source because of its low temporal coherence, high spatial coherence, and high optical power. Therefore, the proposed technique can also be easily implemented in free space. A collimated light beam from the SLD first passes through a scanning Michelson interferometer. The output of the interferometer is split into several separate beams, and then each beam is normally incident to the test sample at different positions. Gap distribution measurement is performed by sequentially opening the shutter behind each incident beam. A detector is employed to receive the reflected lights from the sample. The interferometric signal is recorded as a function of the arm-length difference of the scanning interferometer. The gap is eventually derived from the separation of the two side fringe packets, whose peak positions are determined by the centroid algorithm. Preliminary experimental results validate the feasibility of the presented method.

It briefly introduces the international development status of the high resolution for air-to-ground remote sensing satellite. High resolution for the air-to-ground observation is also the civil and martial pursuing target. Because of the rising cost along with the large-diameter telescope, the weight, cubage will also become large. Nowadays, how to get high resolution with light weight, small cubage launch and large diameter is one of the important research directions in many countries. We raise a method of large field-of-view and high resolution optical synthesis telescope which can solve this problem. It is a co-phased segment mirrors which synthetic aperture diameter is about 1 m. Four 50cm diameter segment mirrors can fulfill the requirement. It is folded during its launch and is spread after it reaches to its working spot. In this way, it can reach the requirement of low launch weight, small launch cubage and can get high resolution observation. This method contains the key technologies of real-time UV coverage, optics design optimization, co-phase measurement and adjustment, micro-displacement sensor technology, the optics design and structure design. We explore the technology which can fulfill field-of-view of 1.86° and the resolution of 0.4m. We will discuss the UV-coverage method which includes the aperture arrangement, the relationship between the aperture number and the synthetic aperture diameter. There are much more detail calculation and analysis to it. Something is discussed about its structure design and optics design in the paper.

Presented work deals with the description of a novel interferometric nanocomparator intended for calibrating displacement sensors with nanometer resolution used in precision engineering. The nanocomparator is based on a 633 nm laser homodyne interferometer with 2-pass measuring arm. Digital signal filtering increases the SNR and allows achieving sub-nanometer resolution of interferometric measurements. High dynamic range of the measuring mirror displacement is achieved using a two-stage positioning system formed of a linear guide way and piezoelectric actuators. A linear guide way is used for positioning over a 100 mm range with 50 nm resolution. Piezoelectric actuators linked in a closed loop locked to the interferometer value are used for fine positioning with better than 1 nm resolution over a 5 um range. Two alternative versions of the mechanical design of the coarse positioning stage were tested and compared: a design utilizing a linear guide way with ball carrier bearings and a positioning system formed of a parallelogram frame with flexible junctions. Wearing out of linear guide ways may cause angular deviations of the mirror from the ideally perpendicular position to the laser beam. Active stabilization of the mirror using piezoelectric actuators linked to a 4-quadrant light detector was developed to eliminate these deviations and other angular errors. A set of experimental calibrations of inductive and incremental rule precision displacement sensors was conducted.

Irradiating the HeNe laser on a disc rotating at low speed, the speed of each location on the rotating surface was measured by analyzing images captured by a high speed camera. The Doppler shift, which was generated when the laser light was mixed with the Doppler-shifted light scattering signal generated at each position when the laser light was irradiated on the rotating surface, was acquired by a high-speed camera to store in a memory. After performing FFT for stored measurements of each location, the Doppler-shifted value was converted to the rotational speed. The maximum measurable rotational speed was determined depending on a frame speed of the camera, and the speed distribution of the rotating surface was measured.

A novel double Sagnac distributed fiber-optic sensor based on Sagnac interferometer for determining the position of disturbance along an optical fiber is presented. The configuration and operating principle of the system is illustrated, the location principle and method for the detection system are analyzed. The system realizes the location of the disturbance using the adaptive time delay estimation with the LMS (least mean square) algorithm in the time domain. Theory analysis and experiment result show that the proposed technology can realize the detection and location of the disturb signal rapidly and effectively, this method is simply and can be obtained easily, and it has high measurement sensitivity and location precision.

Based on the theory of Michelson optical fiber interferometer and Doppler frequency shift equations, author proposed a new optical fiber non-contact velocity measurement technique. And the new method was successfully used in flyer velocity measuring test. In the test, the optic fiber interferometer system not only measured the velocity which was around 3km/s but also acquired the full explosion progress of flyer plates. System adopts large pupil optical transceiver devices to improve the anti-deflection capability compared with the traditional self-focusing lens. Optical fiber noncontact velocity measurement equipment which was simple structure, high sensitivity and adaptability could be widely used velocity parameter measurement.

We present the integration of an optical fiber interferometer with a MEMS probe station for measuring the out-of-plane displacement of MEMS structures. The interferometric system presented uses a phase generated carrier demodulation scheme. Digital signal processing techniques provide a theoretical measurement dynamic range greater than 10⁸. Experimental results characterizing a novel vertical-lift electro-thermal actuator are presented. These results are in good agreement with modeling data based on finite element analysis.