This PDF file contains the front matter associated with SPIE Proceedings Volume 8172, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

The suitability of a corneal graft for transplant surgery is based on different criteria. It may be rejected in particular due to a loss of transparency, directly linked to its scattering properties. Then, these become an important parameter. The aim of this paper is to quantify the influence of the cornea thickness and of the epithelial layer on scattering properties. The origin of scattering is discussed based on polarimetric analysis of scattered field (surface and/or bulk) and on full-field optical coherence tomography imaging (structural information).

We present a technique for monitoring alien substances in foods and blood vessels in the human body. A prototype of the system using near-infrared rays is developed, and its applicability to food is analyzed in detail. The system developed is basically composed of an optical source and a CMOS sensor. Some optical components adjusted at 850-nm band are also set in the system. The system can monitor organic alien substances intentionally added to foods and blood vessels. The clarity of the image increased with decreasing water content and homogeneous material density. The resolving power of the images was confirmed to be about 100 μm. This technique will be useful for our safety and health in our daily lives.

Depth selectivity is crucial for accurate depth volume probing in vivo in a large number of medical applications such as brain monitoring. Polarization gating has been widely used to analyze biological tissues. It is shown that using polarized light allows probing tissues on a specific depth depending on the polarization illumination type (linearly, circularly) and the tissues properties. However, accurate depth investigation of the tissue requires a high selectivity of the probed depth. We propose and simulate the use of different elliptically polarized illuminations for continuous depth examination between linearly and circularly polarized illumination. Monte Carlo simulations verify that circularly polarized illumination penetrates deeper than linearly polarized illumination in biological scattering media. Furthermore, we show that elliptically polarized light can be tuned in its penetration depth continuously between the penetration depth of linearly polarized light and circularly polarized light. Experimental results obtained on phantoms mimicking in vivo situations are presented.

Human liver biopsy samples, consisting into a 16 μm thickness biomaterial chemically fixed into a formaldehyde matrix, and stained by red picrosirius dye, are analysed for different states of fibrosis degeneration. Polarimetric methods, and specially Mueller polarimetry based on wavelength coding, have been qualified as an efficient tool to describe many different biological aspects. The polarimetric characteristics of the media, extracted from a Lu and Chipman decomposition^{1, 2} of their Mueller Matrix (MM), are correlated with the degeneracy level of tissue. Different works and results linked to the clinical analysis will be presented and compared to previous performed works.³ Polarimetric imaging will be presented and compared with SHG measurements. A statistical analysis of the distribution of polarimetric parameters (such as the retardance R and depolarisation P_d) will be presented too, in order to characterise the liver fibrosis level into the biomaterial under study.

Imagistic investigation of the metal-ceramic crowns and fixed partial prostheses represent a very important issue in nowadays dentistry. At this time, in dental office, it is difficult or even impossible to evaluate a metal ceramic crown or bridge before setting it in the oral cavity. The possibilities of ceramic fractures are due to small fracture lines or material defects inside the esthetic layers. Material and methods: In this study 25 metal ceramic crowns and fixed partial prostheses were investigated by radiographic method (Rx), micro computer tomography (MicroCT) and optical coherence tomography (OCT) working in Time Domain, at 1300 nm. The OCT system contains two interferometers and one scanner. For each incident analysis a stuck made of 100 slices was obtain. These slices were used in order to obtain a 3D model of the ceramic interface. After detecting the presence and the positions of the ceramic defects the numerical simulation method was used to estimate the biomechanical effect of the masticatory forces on fractures propagations in ceramic materials. Results: For all the dental ceramic defects numerical simulation analysis was performed. The simulation of crack propagation shows that the crack could initiate from the upper, lower or both parts of the defect and propagates through the ceramic material where tensile stress field is present. RX and MicroCT are very powerful instruments that provide a good characterization of the dental construct. It is important to observe the reflections due to the metal infrastructure that could affect the evaluation of the metal ceramic crowns and bridges. The OCT investigations could complete the imagistic evaluation of the dental construct by offering important information when it is need it.

Dental onlays are restorations used to repair rear teeth that have a mild to moderate amount of decay. They can also be used to restore teeth that are cracked or fractured if the damage is not severe enough to require a dental crown. The use of onlays requires less tooth reduction than does the use of metal fillings. This allows dentists to conserve more of a patient's natural tooth structure in the treatment process. The aims of this study are to evaluate the biomechanical comportment of the dental onlays, by using the 3D photo elasticity method and to investigate the integrity of the structures and their fitting to the dental support. For this optical coherence tomography and micro-computed tomography were employed. Both methods were used to investigate 37 dental onlays, 17 integral polymeric and 20 integral ceramic. The results permit to observe materials defects inside the ceramic or polymeric onlays situate in the biomechanically tensioned areas that could lead to fracture of the prosthetic structure. Marginal fitting problems of the onlays related to the teeth preparations were presented in order to observe the possibility of secondary cavities. The resulted images from the optical coherence tomography were verified by the micro-computed tomography. In conclusion, the optical coherence tomography can be used as a clinical method in order to evaluate the integrity of the dental ceramic and polymeric onlays and to investigate the quality of the marginal fitting to the teeth preparations.

We present results, obtained by rigorous computational approaches, for light of p- and s-polarization scattered from two-dimensional, randomly rough, perfectly conducting, lossy metallic, and dielectric surfaces. The perfectly conducting surfaces we study are characterized by an isotropic power spectrum of the surface roughness and by an anisotropic power spectrum. The mean differential reflection coefficient and the full angular distribution of the intensity of the scattered light are calculated for the perfectly conducting and metal surfaces. From the latter calculations it is found that the computational approach used in these calculations conserves energy in the scattering from a perfectly conducting and from a lossless metal surface with an error that is smaller than 0.5%. Finally, we presents results obtained by a numerical, nonperturbative, solution of the reduced Rayleigh equation for the scattering of p- and s-polarized light from two-dimensional randomly rough, metallic and dielectric surfaces. We show that the results for the metallic surface are in good agreement with results for the same metallic surface obtained by the rigorous computational approach.

A universal approach to modeling the refraction of a monochromatic plane wave incident on an optical metamaterial arranged of arbitrary (passive, active, or plasmonic) layers of linear or feebly non-linear elemental materials is examined. The approach is built on an alternative formulation of the method of single expression, which works well upon different combinations (non-linear lossy dielectric, graded-index Kerr medium, and gain medium with metal) upon either ppolarized or s-polarized light. We show that although the formulation for s-polarized light is straightforward, the ppolarization case is more complicated, since solving an implicit material equation is required. Numerical validation of the proposed method indicates good agreement with the results taken from other numerical solvers (based on finite element and mode matching methods).

The paper addresses numerical time-domain methods for modeling of active and passive dispersive media, needed for simulations of plasmonic metamaterials. The proposed algorithms differ from published results, as our models employ more general formalisms and are more computationally efficient. The frequency dispersion of the permittivity is considered as an arbitrary Pade approximant, its numerical implementation is more universal and effective for all known ADE and RC methods. The gain model is implemented for an arbitrary topology of transitions with the ADE method. The proposed dispersion models are in a good fit with spectroscopic data and are included into a database of optical materials at nanohub.org.

Amplitude - phase spectra of IR waves tunneling through a gradient dielectric nanophotonic barrier, found in the framework of an exactly solvable model of this medium, are used for optimization of superluminal reshaping of tunneling pulses. This barrier, characterized by a cut-off frequency Ω, determined by the shape of distribution of refractive index across the barrier, provides a tunneling regime for waves whose frequencies are less than Ω. In a spectral range located nearby this cut-off frequency Ω, an almost reflectionless tunneling of these waves occurs, accompanied by large strongly dispersive phase shifts. These shifts outstrip in some spectral range the phase shifts accumulated by the same harmonics along the same way in free space. Depending on the detuning between the pulse carrier frequency ω₀ and Ω the interplay between superluminal (tunneling) and subluminal (transparent) harmonics results in an ultrafast reshaping of the transmitted waveform, yielding a pulse spatial broadening, formation of superluminal precursors at the front edge of transmitted pulse and the splitting of pulse's maximum, while the displacement of the centre of gravity of reshaped pulse as well as the velocity of energy transfer stay subluminal.

Experimental results concerning the influence of plasmon effect from silver nanoparticles on the organic photovoltaic device performance are presented. The metallic nanoparticles (NPs) are placed on top of ITO layer using a physical vapor deposition technique. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) followed by an interpenetrated poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) blend layer are then spin-coated. The aluminum electrode is finally evaporated on. Photovoltaic properties compared to devices without NPs are shown. A spectrophotometric characterization is carried on. Moreover, a ToF-SIMS measurement is performed in order to obtain the depth chemical profiles of solar cell containing such NPs. Silver NPs diffusion inside other layers of the cell is investigated.

Random rough surfaces are of primary interest for their optical properties: reducing reflection at the interface or obtaining specific scattering diagram for example. Thus controlling surface statistics during the fabrication process paves the way to original and specific behaviors of reflected optical waves. We detail an experimental method allowing the fabrication of random rough surfaces showing tuned statistical properties. A two-step photoresist exposure process was developed. In order to initiate photoresist polymerization, an energy threshold needs to be reached by light exposure. This energy is brought by a uniform exposure equipment comprising UV-LEDs. This pre-exposure is studied by varying parameters such as optical power and exposure time. The second step consists in an exposure based on the Gray method.¹ The speckle pattern of an enlarged scattered laser beam is used to insolate the photoresist. A specific photofabrication bench using an argon ion laser was implemented. Parameters such as exposure time and distances between optical components are discussed. Then, we describe how we modify the speckle-based exposure bench to include a spatial light modulator (SLM). The SLM used is a micromirror matrix known as Digital Micromirror Device (DMD) which allows spatial modulation by displaying binary images. Thus, the spatial beam shape can be tuned and so the speckle pattern on the photoresist is modified. As the photoresist photofabricated surface is correlated to the speckle pattern used to insolate, the roughness parameters can be adjusted.

The m-lines guided mode technique is demonstrated as a powerful tool for the measurement of wavelength and temperature refractive index dispersion in thin films. The proper treatment of results reveals measurement uncertainties of the order of 10^-3 for the refractive index, and a sensitivity to changes in this quantity of the order 10^-6. Furthermore, the thickness of the films can be established to a precision of 1nm. Using an optical stack consisting of a silicon wafer substrate, a low index buffer layer (index 1.52), topped with a polymer blend guiding film, The wavelength dispersion of the change of refractive index of the guiding film with temperature has been successfully measured. The temperature dispersion of the refractive index of the guiding layer is of ~ -6.7×10^-5 /K.

Propagation and tunneling of polarized light through gradient nanophotonic barriers, formed by continuous distributions of dielectric susceptibility ε(z) across the films, fabricated from dielectrics without free carriers, are considered. The decisive influence of giant artificial heterogeneity - induced non -local dispersion, both normal and abnormal, stipulated by the gradient and curvature of distribution ε(z), is shown to provide the polarization - dependent tunneling of radiation in any spectral range in need. New trends in technology of sputtering of gradient silicon films of controlled distribution of ε(z) on the substrate are developed, and the parameters of films, fabricated by means of these technologies, are measured. Special methods for polarimetric testing of gradient dielectric nanofilms, based on new exact analytical solutions of Maxwell equations for inclined incidence of polarized waves, are presented. New types of dispersive elements for photonic crystals, based on polarization effects in gradient dielectric nanofilms, including, e.g., mode selectors, miniaturized phase shifters and large angle polarizers, are discussed.

Periodically poled lithium niobate waveguides (PPLN/W) are considered to be one of the most useful toolboxes for enabling quantum communication experiments. Thanks to the high optical confinement over longer lengths than in bulk configurations (a few cm in our case), such structures provide highly efficient non-linear interactions, i.e., in parametric downconversion, or sum and difference frequency generation regimes. Within the framework of long-distance quantum communication at telecom wavelengths, PPLN/Ws have therefore been proved to be a key ingredient for building ultrabright sources of time-bin, as well as polarization entangled photons, and for photonic quantum interfaces providing coherent wavelength conversions from telecom to visible wavelength range, and conversely. During the presentation, we will discuss some recent experimental advances regarding polarization entanglement sources and quantum interfaces.

The implementation of single-photon detectors in waveguide photonic circuits will open the possibility of experiments in quantum regime that would otherwise be impossible to be implemented using bulk optics. Nanowire superconducting single-photon detectors (SSPDs) are good candidates for integration due to their relative ease of fabrication on top of GaAs heterostructures. In this paper we show the experimental demonstration of single-photon detectors, based on superconducting nanowires, fully integrated with GaAs/AlGaAs ridge waveguides. We will discuss all the major challenges surmounted and all the steps necessary to achieve these results.

The Mercator Advanced Imager for Asteroseismology (MAIA) is being designed particularly for asteroseismology of hot subdwarf stars on the 1.2m Mercator Telescope. In order to achieve the required precision on the pulsation amplitude ratios, the photometric variations must be measured simultaneously in several bands with respect to constant reference stars in the field. MAIA is an optical imager to observe simultaneously in three color bands, corresponding approximately with an SDSS u, g, r+i+z photometric system. The fully dioptric design uses a common collimator, two dichroic beam splitters (cut-offs at 390nm and 550nm) and three cameras. Each camera holds a fast frame-transfer CCD cooled down to -90°C with a compact Stirling cryocooler. All lenses are axially and radially constrained by a calibrated spring load, with radial adjustment mechanisms to calibrate the centering of each lens. The differential thermal expansion of the optical system is compensated by the thermal expansion of the different materials in the mechanical mountings, resulting in a design that is insensitive to thermal variations. Specific care has been taken to reduce the effect of manufacturing tolerances on the performance of the instrument. The tilt angle of two of the beam splitters is adjustable in two dimensions to compensate for remaining misalignment in the optical system. Finite element models have been constructed to verify that the structural flexure and structural dynamics are within the requirements. A tool has been developed to estimate the performance of the instrument based on the design parameters. Various commercial software tools have been used to optimize the workflow in this complex system design.

Fourier transform spectrometry allows us to detect small Doppler velocity shifts of spectral lines by measuring phase shifts of their associated interference patterns. In this paper, we present the project of space-borne Doppler Spectro Imager (DSI), Echoes, dedicated to Jovian seismology and aeronomy, which is proposed as payload to the JUICE mission project (ex-EJSM/Laplace), which competes in the Cosmic Vision program of the European Space Agency (ESA). The instrumental principle inherits from the ground based experiment SYMPA (Schmider et al, 2007, Gaulme et al, 2008): it is a Mach-Zehnder interferometer working in the visible domain that is sensitive to Doppler shifts of solar spectral lines reflected on the planetary atmosphere. It aims to detect small periodic movements of Jupiter's upper troposphere generated by internal acoustic modes, and to measure their temporal frequencies and spatial geometry. Such measurement would bring unprecedented knowledge on the internal structure of Jupiter, especially on the central region, and would provide unique constraints on giant planet formation models. We are currently realizing a prototype to measure the real instrumental performance in laboratory and to demonstrate the capacity to reach the Technology Readiness Level 5. We describe the experimental set-up and the expected results.

Dense Aperture Masking (DAM) is a new interferometric technique allowing high-angular resolution over a narrow field of view (FOV) imaged by the present class of mono-pupil telescopes equipped with adaptive optics (AO). DAM is realized by a suited afocal double lenslet array (BIGRE), remapping the entrance aperture (telescope pupil) into coherent sub-apertures (sub-pupils), and adopted as sub-pupils spatial filter and re-imager.We focus our attention on the point spread function (PSF) properties of DAM, highlighting those related to spatial sampling and filtering of the frequency coverage of the entrance pupil.We stress why the high spatial frequency sampling of the pupil and the low spatial frequency filtering of the sub-pupils are consistent with both a mono-pupil (telescope) and an array of sub-pupils (hypertelescope). We explain how DAM provides high Strehl and high-angular resolution images, first by filtering the low frequencies, which in turn are not so well corrected with a standard AO, second by preserving an object-image convolution relation over a narrow FOV. Finally, we make a comparison with the imaging properties of a telescope and a hypertelescope with the aim to show the complementary of DAM with other techniques adopted in high-contrast imaging.

Dense Aperture Masking (DAM) is a high-contrast imaging technique which enhances the capabilities of the current direct imaging instrumentation, mainly to detect low bright companions at small separation from their parent star. DAM benefits from the experience achieved with the integral field unit installed on SPHERE spectrograph at the VLT (BIGRE, Antichi et al. 2009) with a very similar optical design. More in detail, it is obtained by exploiting the BIGRE integral field unit - composed of two consecutive micro-lens arrays - to subdivide the telescope pupil in many sub-pupils, preserving their relative position and providing the same amount of spatial filtering to each one. We present here results of a system study we pursued for a proficient implementation of BIGRE-DAM. We focus on the case of an 8 m class telescope coupled with the instrument NACO at the VLT. We detail on how the optical design and the related mechanical implementation of a DAM unit could be successfully achieved within NACO thanks to a wise optimization of the BIGRE micro-lenses array, adopted as sub-pupils re-imager instead of integral field unit. Diffraction limit is achieved by optical design and good apochromatic performances are proven for a narrow-band filter around 2.18 micron.

point. This monitoring method is derived from a traditional optical monitor structure. The corresponding error compensations were applied to get good output. Another optical monitoring system is also demonstrated to extract the temporal phase change of the reflection coefficient of the growing film stack. A vibration and air turbulence insensitive polarization interferometers was used in this system to directly detect fluctuating phase and magnitude of the reflection coefficient of a growing film stack as well as the real time optical admittance at normal incidence.

There is a considerable interest in the development of new optical imaging systems that are able to give threedimensional images. Potential applications range across medical imaging, surveillance and robotic vision. Identifying targets or objects concealed by foliage or camouflage is a critical requirement for operations in public safety, law enforcement and defense. The most promising techniques for these tasks are 3D laser imaging techniques. Their principles are to use movable light sources and detectors to collect information on laser scattering and to reconstruct the 3D objects of interest. 3D reconstruction algorithm is a major component in these optical systems for identification of camouflaged objects. But 3D reconstruction must take into account sparse collected data i.e. concealed objects and reconstruction algorithms must solve a complex multi-parameter inverse problem. Therefore the inverse problem of recovering the surface three-dimensional shape function from intensity data is more challenging. The objective of our paper is to present a new algorithmic approach for the generation of 3D surface data from 3D point clouds corresponding to reconstruction algorithm. This algorithmic approach is based on research of automatic minimization of an energy function associated with a sparse structure of 3D points. The role of this type of algorithmic data-driving process is to complete the incomplete 3D image at satisfactory levels for reliable identification of concealed objects.

In many aerial and close-range photogrammetry applications, the near infrared (NIR) spectral range is required in addition to the visible (VIS) spectral range. Currently, many especially aerial photogrammetric systems use particularly optimized camera systems for each spectral band. Using separate cameras or lenses can introduce parallaxes and timedelays between the acquired images, and thus complicate the data fusion process. Furthermore, it adds additional weight to the entire system. With an image acquisition through a single objective, the complexity of the data fusion and the weight can be significantly reduced. However, to be able to only use one objective for different spectral bands, the optical system has to be free of chromatic aberrations. For photogrammetric applications, a wide field-of-view and a high resolution are frequent additional requirements. Therefore, we will present a design and an adapted photogrammetric calibration method of an all-reflective unobscured optical system optimized for full-frame imaging sensors. All-reflective unobscured optical systems may also be a very efficient imaging tool in combination with unmanned aerial vehicles (UAVs). Due to the limited payload capacity, many currently available UAVs can only be used with one spectrally limited camera system at the same time. With miniaturized all-reflective camera systems, the image data could be acquired in the visible and e.g. the NIR spectral range simultaneously.

A new optical design inclusive of Blue-Ray Pickup head system and liquid crystal optics is proposed in this paper. With electrode pattern and the differential biased circuit, the gradient of the electric field distribution inside the liquid crystal sample cell are able to vary through the adjustment of driving voltage. Optical power of liquid crystal lens can be determined by changing the polarity of gradient within the sample cell which posses the homogeneous alignment, then deliver convergence or divergence of specific light beams. This design is capable of correcting aberrations fast with liquid crystal optics scheme when any misalignment errors occur. According to specification from Blue-ray Disc White paper, there are several kinds of pick up head system with LC liquid optics are designed and discussed in this paper. Different tolerance such as de-focus, tilt, de-center and their related compensation are further analyzed in this research. The simulation results show that optical design using liquid crystal optics with aperture stop setup as a compensation device can eliminate up to 46% compared to traditional ones.

Today, waste recycling, (bottles, papers...), is a mechanical operation: the waste are crushed, fused and agglomerated in order to obtain new manufactured products (e.g. new bottles, clothes ...). The plastics recycling is the main application in the color sorting process. The colorless plastics recovered are more valuable than the colored plastics. Other emergent applications are in the paper sorting, where the main goal is to sort dyed paper from white papers. Up to now, Pellenc Selective Technologies has manufactured color sorting machines based on RGB cameras. Three dimensions (red, green and blue) are no longer sufficient to detect low quantities of dye in the considered waste. In order to increase the efficiency of the color detection, a new sorting machine, based on visible spectroscopy, has been developed. This paper presents the principles of the two approaches and their difference in terms of sorting performance, making visible spectroscopy a clear winner.

Objective: Study's objectives are focused on non-invasive OCT and RX investigations, of interfaces obtained after repairing a metal-ceramic crown with ceramic materials. Material and method: In this study 40 metal-ceramic crowns were involved. Each crown is restoring the first central incisor 1.1. Metallic infrastructure was performed from nickel-chrome WIRON 99 BEGO alloy, and Kiss Ceramic. The defects of 3×3mm were created into ceramic material in the buccal-incisal area with a grinding instrument. The samples were divided into two groups and the defects were reconstructed with two different types of ceramic materials: Kiss and Vita Omega. The interfaces between crown and ceramic material used for reparation were Rx and OCT investigated which are both non-invasive, imagistic investigation techniques. For better investigation three-dimensional reconstructions were performed. Results: The interfaces showed defects for both systems used. Major defects such as gaps could be identified at the ceramic-ceramic interface. Also material defects could be observed at the areas of congruence between the two ceramic materials and smaller defects along the interfaces. The defects were present into the deep and superficial layers of interface. The OCT system used a length wave of 1300nm and worked in B-scan mode along the interfaces to be studied while the C-scan mode was only used at the defect areas. Rx investigation detected the macro defects. Conclusions: Time Domain OCT and RX systems were identifying the faulty areas after repairing artificially created defects, of metal-ceramic crowns with ceramic material, hereby enabling us to establish recommendations for the clinical use.

Orthodontic bonding is a simple yet important procedure that can influence the outcome of treatment in case it is performed incorrectly. An orthodontic treatment shadowed by repeated bonding failures can become unduly long and will decrease patient trust and compliance. Optical coherence tomography has been widely used in ophtalmology but is relatively new to dentistry. Using OCT one can detect aerial inclusions within the orthodontic adhesive or even identify incongruence between the bracket base and the tooth surface. The aim of our study was to identify bonding defects and reconstruct them three-dimensionally in order to be able to characterize them more accurately. We bonded 30 sound human permanent teeth with ceramic orthodontic brackets using a no-mix self-curing orthodontic adhesive. Prior to bonding all teeth were stored in tap water at 4°C and then professionally cleaned with rotary brushes and pumice. The samples were processed by the same person and the rotary brushes were changed after every fifth tooth. All interfaces were investigated by means of OCT and 4 defects were found. Subsequently, the defects were reconstructed threedimensionally using an open-source program. By identifying and reconstructing bonding defects we could assess the quality of the bonding procedure. Since bonding tends to be more accurate in vitro where the environmental conditions are close to ideal, it is probable that defects found in vivo be even greater in number, which leads to the conclusion that this type of investigation is potentially valuable.

Dental prosthetic restorations have to satisfy high stress as well as aesthetic requirements. In order to avoid deficiencies of dental prostheses, several alternative systems and procedures were imagined, directly related to the material used and also to the manufacturing technology. Increasing the biomechanical comportment of polymeric materials implies fiber reinforcing. The different fibers reinforcing products made very difficult the evaluation of their performances and biomechanical properties analysis. There are several known methods which are used to assess the quality of dental prostheses, but most are invasive. These lead to the destruction of the samples and often no conclusion could be drawn in the investigated areas of interest. Using a time domain en-face OCT system, we have recently demonstrated real time thorough evaluation of quality of various dental treatments. The aim of this study was to assess the quality of various polymeric materials used in dental technology and to validate the en face OCT imagistic evaluation of polymeric dental prostheses by using scanning electron microscopy (SEM) and microcomputer tomography (μCT). SEM investigations evidenced the nonlinear aspect of the interface between the polymeric material and the fiber reinforcement and materials defects in some samples. The results obtained by microCT revealed also some defects inside the polymeric materials and at the interfaces with the fiber reinforcement. The advantages of the OCT method consist in non-invasiveness and high resolution. In addition, en face OCT investigations permit visualization of the more complex stratified structure at the interface between the polymeric material and the fiber reinforcement.

Off-axis highly aspheric optical surfaces modeling needs a new mathematical formalism in order to implement it into ray-tracing optimization codes. This new description must be able to take into account different kinds of deformations: from low order to medium and high order deformations. This paper presents a new basis of polynomials (based on Bernstein polynomials) for a new analytical definition of such optical surfaces. A general definition of Bernstein polynomials and some of the mathematical properties will be first introduced. Then, we will briefly review some straightforward tools which can be very useful for optical design and optimization in the use of this specific basis.

Work covers design and optimization of optical systems for observation of transient events and moving targets in space, such as gamma-ray bursts, asteroids, comets, meteors, satellites, space debris etc. Several all-spherical full-aperture catadioptric designs with focal ratios within f/3-f/0.8 range optimized for large format CCD detectors are presented. Analyzed systems may be grouped in following families: a) Prime-focus/folded Newtonian systems: 1. Hamilton. 2. Sonnefeld. 3. Richter-Slevogt. b) Cassegrain systems: 1. Richter-Slevogt-Cassegrain. 2. Hamilton-Cassegrain. 3. Shenker. Principal results of the work are: 1. Development of several optical designs suitable for realization. 2. Comparison of systems of different design families with comparable performance. 3.. Atmospheric dispersion correction in large-aperture systems is analyzed, with proposal of compensation by motion of principal optical elements. 4. Historical survey and comparison of all-spherical full-aperture catadioptric systems is performed.

In designing the optics of an imaging classic mount multi-étalon spectro-polarimeter as a post-focus instrument for the next generation of ground-based solar telescopes (Advanced Technology Solar Telescope, European Solar Telescope), many constraints must be considered. The large entrance pupil diameter of the telescope (4 m), the demanded large field of view (≥ 90 arcsec), high spectral resolving power (≥ 200000), and limited field-dependent blue-shift of the instrumental profile (≤ 3 FWHM) require Fabry-Pérot interferometers of large diameter (≥ 200 mm), lighted by highly collimated beams. This implies large optical elements and long optical paths. Moreover, to use interference pre-filters, placed between the interferometers to reduce the inter-reflections in axial-mount, with a relatively small diameter (≤ 70 mm), a "pupil adapter" should be included, with a further increase of the optical path length. Although a multi-étalon spectro-polarimeter works in quasi-monochromatic light, the Fraunhofer lines of interest cover a wide range of wavelengths (850 nm - 1650 nm), demanding a good chromatic aberration control. Finally, a low instrumental polarization (≤ 0.5 %) is required to allow a high polarimetric precision. In this paper a diffraction limited optical solution is described, fulfilling all the above requirements in a relative small volume.

The future generation of Extremely Large Telescopes will require a complex combination of technologies for adaptive optics (AO) systems assisted by laser guide stars (LGS). In this context, the distance from the LGS spot to the telescope pupil ranges from about 80 to 200 km, depending on the Sodium layer altitude and the elevation of the telescope. This variation leads to a defocusing effect on the LGS wave-front sensor which needs to be compensated. We propose an active mirror able to compensate for this variation, based on an original optical design including this active optics component. This LGS Variable Curvature Mirror (LGS-VCM) is a 120 mm spherical active mirror able to achieve 820 μm deflection sag with an optical quality better than 150 nm RMS, allowing the radius of curvature variation from F/12 to F/2. Based on elasticity theory, the deformation of the metallic mirror is provided by an air pressure applied on a thin meniscus with a variable thickness distribution. In this article, we detail the analytical development leading to the specific geometry of the active component, the results of finite element analysis and the expected performances in terms of surface error versus the range of refocalisation. Three prototypes have been manufactured to compare the real behavior of the mirror and the simulations data. Results obtained on the prototypes are detailed, showing that the deformation of the VCM is very close to the simulation, and leads to a realistic active concept.

Compact spectrometers are of interest for space applications for both Earth observation and analysis of planet soil. The spectrometer here described is dedicated to Land imaging and is based on the use of linear variable filters for wavelength selection. This kind of filter is able to transmit the radiation in a narrow band (<20 nm) centered on a wavelength that changes along its surface, and to operate in a wide spectrum (visible-infrared). Both the variable filter characteristics and the results of the breadboard spectrometer operation will be reported.

In this paper we analyze the performance of an LQG based controller for an adaptive optics (AO) system. The optimal control uses the state-feedback of the disturbance predictions. Such predictions (Kalman filter estimates) are based on a disturbance model of the atmospheric distortion wavefront. In many AO applications wind velocities and the strength of the distortion of the wavefront can change rapidly, rendering the disturbance prediction far from optimal and degrading the disturbance rejection property of the AO loop. Special attention is given to the choice of the disturbance model to ensure satisfactory disturbance rejection performance despite turbulence variation. The proposed approach also serves the trade-off between the accuracy of the prediction and the model complexity to limit the computational cost of the LQG control. The achieved performances are evaluated through numerical experiments using the Software Package CAOS.

An optical system to extract the reflection coefficient and optical admittance of film stack is presented. Both reflection phase and reflection magnitude intensity from the tested film stack were measured under normal incidence of the light. Two dimensional refractive index and thickness distribution of each layer in multilayer thin films can be obtained by the analysis of the reflection coefficients or optical admittance of multi-wavelengths. A novel monitoring method for the thin film deposition using the reflection coefficient and optical admittance loci as the thickness grows is also proposed to achieve better performance in this article.