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

Femtosecond Titanium:sapphire lasers can deliver high average power broadband spectra in a high quality beam, being therefore an optical source of choice for high-resolution optical coherence tomography (OCT) at high acquisition rates. We present a brief tutorial on the basic physics behind the operation and design of Kerr-lens modelocked lasers, where the high peak powers associated with femtosecond pulses give rise to nonlinear optical effects that play a major role in the laser operation itself and strongly influence the output spectrum. Additional nonlinear devices, in particular photonic crystal fibers (PCFs), can also be directly pumped with the generated femtosecond pulses to further extend the spectral range of the laser output, both in terms of bandwidth and center wavelength. Two specific laser systems employing different technologies for intracavity dispersion compensation (intracavity prisms in one case, and octave-spanning double-chirped mirrors in the other) will be described, and the corresponding advantages for OCT, namely the maximum achievable resolution and the applicability of spectral tuning and shaping techniques, will be briefly discussed.

An overview of the different type of fibre broadband sources and some fiber laser sources that operate as incoherent sources, are briefly discussed and some practical applications are presented. The optical performance and characteristics of several of these fiber sources are reviewed, including emission spectra profiles, autocorrelation functions, wavelength and power stabilities, and polarization behavior.

The prototypes of high-efficiency SLDs with COD threshold of more than 5•10⁶ W/cm² were investigated. Single spatial mode samples with 4 μm-wide active channel exhibited CW output power of more than 200 mW. Preliminary reliability tests at 100 mW level were successful. It was shown that in double-pass operation mode achieved using SM fiber reflector, external efficiency can be increased significantly. The estimations show that multimode SLD with 20-30 μm active channel width based on the same QW heterostructure may ensure reliable enough operation at output power level of more than 0.5W.

The results of recent studies of superluminescent diodes (SLDs) based on new quantum-well (QW) (GaAl)As and (InGa)As heterostructures of spectral range 800 - 900 nm with spectral bandwidths of up to 80 nm and output power ex SM fiber of up to 50 mW are presented.

Recent developments on broadband optical sources emitting at 1050 nm wavelength for medical applications, in particular optical coherence tomography (OCT), have revealed enhanced depth penetration into the choroid, reduced scattering losses and improved image performances in eyes with turbid media, when compared to the most commercial used semiconductor optical source technology at 820 nm. In this paper, we present our study of fibre optic broadband sources (BBS) at 1 micron region, based on the amplified spontaneous emission (ASE) from rare-earth doped silica fibres for the integration into OCT systems. The target specifications for this type of sources are: 1050 nm central emission wavelength, with spectral width of ~70 nm, tens of miliwatts of output power and smoothly shaped output spectra. Several combinations of rare-earth doped optical fibres integrated into different fibre optic configurations have been tested. Optical bandwidth optimization and spectral shaping using different fibre optic techniques are presented and their autocorrelation function compared.

We used the offset launch and the near field imaging technique to analyse the modal content of large mode area (LMA) fibres in different launch conditions. The coiling technique was applied to suppress higher order mode contents in order to estimate the modal power distribution and to verify the loss factor for the single modes. Based on this analysis, an optimised coiling for LMA fibres will be developed, to suppress the higher order mode contents while maintaining the highest possible fundamental mode content.

The lateral resolution of Fourier domain optical coherence tomography (FD-OCT) systems is limited by the depth of focus that can be achieved over the desired imaging depth at the chosen wavelength. I present a solution in which multiple beams focused at different depths are scanned together, so that a mosaic image can be produced, with at least double the resolution possible from a single beam system. Side-benefits also arise from the ability to combine data from each beam to improve signal-to-noise. The theory of this approach is discussed, advantages, and also the practical realisation in a variety of ex-vivo and in-vivo OCT imaging probes, together with results from a number of applications.

A detection method based on 7 spectral windows at the photodetection stage in an optical coherence tomography system was tested. We investigated its utility in two directions: spectroscopic optical coherence tomography and signal to noise ratio improvement. A diffraction grating was used in the photodetection unit to diffract light over a 16 photodetector array. Currently, this array has been configured to deliver 7 channels only by binning two adjacent photodetectors. The improvement of the signal to noise ratio has been investigated. Preliminary results of spectroscopy analysis which will be shown are B-scan OCT imaging of paint layers. The ultimate aim of the project is to perform spectroscopic analysis of the retina.

Full-field Optical Coherence Tomography (FF-OCT) is a parallel detection OCT technique using a 2D detector array. This technique avoids mechanical scanning in imaging optics. Therefore, it can speed up the imaging process and enhance the imaging quality. We present a FF-OCT instrument to be used in conjunction with the principle of multiple delays (MD) OCT to evaluate the topography of curved objects in a single-shot imaging. We evaluate the optimum combination of the MD principle with the FF-OCT method and measure the radius of a metal ball with this method. We managed to obtain 2n-1 contour lines using an MDE with n delays in a single en-face OCT image to evaluate the curvature of the object surface.

A highly efficient power optical coherence tomography configuration is implemented using a Multiwave Photonics broadband source centred at 1060 nm wavelength, FWHM = 50 nm and a Mach Zehnder interferometer. The interferometer contains a fibre acousto-optic modulator in each arm. One is driven at a fixed frequency of 40 MHz while the other via an RF Function Generation. In this way, the en-face OCT signal is modulated on a carrier frequency adjustable in the range 0 kHz to 1.5 MHz. A circulator is placed in the sample arm. Light retroreflected from the sample is sent via the circulator to a balanced coupler where it interferes with the reference beam. A translation stage is used in the reference arm to adjust the optical path difference in the interferometer. The result is photodetected using two InGaAs photodetectors followed by a differential amplifier in a balance detection configuration The system has been used to acquire en-face images as well as cross section optical coherence tomography images from skin and embryos based on T-scans (transversal reflectivity profiles).

Tissue engineering, rapidly developing branch of bioscience, is widely adopted for the purposes of the tissue growing using the substrate materials. Three-dimensional porous scaffolds possess a great opportunity for the directional growth of the cells and for the supplying them with nutrients. However, the complex porous structure of the scaffolds creates difficulties for the measurements and control of nutrients flow. We applied optical coherence tomography (OCT) for imaging of the scaffold structure. We also investigated the possibility of using Doppler OCT to monitor the flow velocity distribution within the scaffold. The average scaffold's pore diameter has been estimated using electron microscopy. We show that with Doppler OCT it is possible to monitor complex micro-flow and estimate the shear stress (i.e. enhancing factor of cell growing) acting on the cells within the scaffold and to find the optimal input flow rate, consequently.

The paper explores the possibilities of achieving a galvanometric scanner with an enhanced, as close as possible to 100%, duty cycle (η) even for high scan, i.e. high oscillation, frequencies. Nowadays solutions provide high η, but up to certain frequencies. The study of this limit frequency, of its relationship with the duty cycle, and the ascertainment of the scanning and command functions that may produce better results, is the final scope of this work. The scanning device is considered in a setup characteristic to the dimensional, usually on-line, industrial measurements. A detailed theoretical study is performed, starting with the equation of the mobile element of the galvoscanner. The expressions of the active torque and of the necessary command function that has to be used are obtained, with regard to the desired scanning function. This is considered linear and symmetrical on its active portions and with non-linear returning portions that have to be performed as fast as possible. Two such functions for the returning portions are considered and studied: parabolic and sinusoidal. The best scanning function, with regard to achieving the objectives of the device (high duty cycle for high frequencies), is obtained and the way the necessary command function has to be deduced is discussed.

This paper presents a neural network based technique to denoise speckled images in optical coherence tomography (OCT). Speckle noise is modeled as Rayleigh distribution, and the neural network estimates the noise parameter, sigma. Twenty features from each image are used as input for training the neural network, and the sigma value is the single output of the network. The certainty of the trained network was more than 91 percent. The promising image results were assessed with three No-Reference metrics, with the Signal-to-Noise ratio of the denoised image being considerably increased.

Optical Coherence Microscopy (OCM) is an emerging technology capable of depth sectioning of biological tissue at the micrometer scale. In this paper, we propose a developing technology we call Gabor Domain Optical Coherence Microscopy (GD-OCM), whose innovation is two folds: (1) A high lateral resolution optical design of a dynamic-focusing optical probe with no moving parts, which provides an invariant resolution of currently 3 μm across a 2mm full-field of view and 2mm imaging depth by design; (2) An acquisition scheme (using the probe) that is capable of performing automatic data fusion to render an in-focus high resolution image throughout the depth of sample at in vivo speeds.

In-vivo Optical Coherence Tomography (OCT) imaging of the fruit fly Drosophila Melanogaster larval heart allows non invasive visualizations and assessment of its cardiac function. In order to image Drosophila heart, we have developed a dedicated imaging instrument able to provide simultaneous OCT and Laser Scanning Confocal Microscopy (LSCM) images. With this dual imaging system, the heart can easily be located and visualised within the specimen and the change of the heart shape in a cardiac cycle monitored. Here we have used targeted gene expression to knockdown the myospheroid (mys) gene in the larval heart using a specific RNAi construct. By knocking down a β integrin subunit encoded by mys we have recorded an enlarged heart chamber in both diastolic and systolic states. Also, the fraction of reduction of the chamber diameter was smaller in the knockdown heart. These phenotypic differences indicate that impaired cardiac contractility occurs in the heart where the integrin gene express level is reduced. At our knowledge, this is for the first time when it is shown that integrins have a direct relationship to a dilated heart defect.

Zebrafish (Danio rerio), a vertebrate, is a good model system in medical research to understand a variety of human biological processes. These studies often require measurements of the morphological and physiological parameters of Zebrafish. Therefore, development of noninvasive imaging techniques for this purpose is of considerable interest. In this article, we present a brief overview of the use of OCT for noninvasive in-vivo imaging of adult Zebrafish.

The study of flow dynamics in complex geometry vessels is highly important in many biomedical applications where the knowledge of the mechanic interactions between the moving fluid and the housing media plays a key role for the determination of the parameters of interest, including the effect of blood flow on the possible rupture of atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT), as a functional extension of Optical Coherence Tomography (OCT), is an optic, non-contact, non-invasive technique able to achieve detailed analysis of the flow/vessel interactions. It allows simultaneous high resolution imaging (10 μm typical) of the morphology and composition of the vessel and determination of the flow velocity distribution along the measured cross-section. We applied DOCT system to image high-resolution one-dimensional and multi-dimensional velocity distribution profiles of Newtonian and non-Newtonian fluids flowing in vessels with complex geometry, including Y-shaped and T-shaped vessels, vessels with aneurism, bifurcated vessels with deployed stent and scaffolds. The phantoms were built to mimic typical shapes of human blood vessels, enabling preliminary analysis of the interaction between flow dynamics and the (complex) geometry of the vessels and also to map the related velocity profiles at several inlet volume flow rates. Feasibility studies for quantitative observation of the turbulence of flows arising within the complex geometry vessels are discussed. In addition, DOCT technique was also applied for monitoring cerebral mouse blood flow in vivo. Two-dimensional DOCT images of complex flow velocity profiles in blood vessel phantoms and in vivo sub-cranial mouse blood flow velocities distributions are presented.

We have investigated the applicability of en-face OCT in imaging freshly excised biopsies of Basal Cell Carcinoma. Encouraging results have been obtained in identifying tumor features and abnormal skin architecture.

Assessment of lymph node involvement is a key prognostic marker in early breast cancer. This paper demonstrates the ability of optical coherence tomography (OCT) to characterise the micro-architecture of healthy, non-cancerous lymph nodes. OCT is shown to differentiate stroma, cortex and adipose tissue. Characteristic patterns are also identified for germinal centres and blood vessels within the node. Results are correlated against a histopathological gold standard.

In this work we use the optical coherence tomography (OCT) technique to produce in vitro transversal section images of human hair. It was possible to identify in the A-scan protocol its principal structures: cuticle, cortex and medulla. The mean diameter of medulla was 29 ± 7 μm and hair diameter was 122 ± 16 μm in our samples of standard Afro-ethnic hair. We also compared the OCT signal before and after chemical treatment with 18% w/w ammonium thioglycolate solution. After chemical treatment, it was not possible to identify the main structures of hair fiber, due the index matching promoted by deleterious action of chemical agent. A tridimensional image was built starting from 601 cross-sectional images (slices). Each slice was taken in steps of 6.0 μm at 8 frames per second, and the whole 3D image was built in 60 seconds.

Purpose: To investigate using en-face Optical Coherence Tomography (OCT) the microleakage after Er:YAG laser cavity preparation. Material and Methods: Thirty single- and multi-rooted freshly extracted human teeth divided into two study groups, group I (laser) and group II (control), were used in this study. In group I, Class V cavities were prepared using laser on the buccal surface of each tooth. The laser device used was an Er:YAG laser (2940 nm, VSP, 250-320 mJ, 10-20 Hz). In group II, cavities were prepared conventionally and acid etched on the oral surface of the same tooth. All cavities were filled with composite resin. The cavity microleakage was investigated using en-face Optical Coherence Tomography prototype, based on transverse scanning and operating at 1300 nm. Results: The investigation demonstrated qualitatively the reduction of microleakage in cavities prepared with Er:YAG laser as compared to the control group, in which cavities were prepared conventionally. Conclusion: The en-face OCT method provided a superior non-invasive and real time investigation method, thus reducing the occurrence of secondary caries by early detection. Moreover, based on the results of this investigation, it may be concluded that Er:YAG laser-assisted cavity preparation leads to reduction of microleakage.

Dental prostheses are very complex systems, heterogenous in structure, made up from various materials, with different physical properties. An essential question mark is on the physical, chemical and mechanical compatibility between these materials. They have to satisfy high stress requirements as well as esthetic challenges. The masticatory stress may induce fractures of the prostheses, which may be triggered by initial materials defects or by alterations of the technological process. The failures of dental prostheses lead to functional, esthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. The purpose of this study is to evaluate the capability of en-face optical coherence tomography as a possible non-invasive high resolution method in supplying the necessary information on the material defects of dental prostheses and microleakage at prosthetic interfaces. C-scan and B-scan OCT images as well as confocal images are acquired from a large range of samples. Gaps between the dental interfaces and material defects are clearly exposed. We conclude that OCT can successfully be used as a noninvasive analysis method.

Bonding has become a routine procedure in several dental specialties - from prosthodontics to conservative dentistry and even orthodontics. In many of these fields it is important to be able to investigate the bonded interfaces to assess their quality. All currently employed investigative methods are invasive, meaning that samples are destroyed in the testing procedure and cannot be used again. We have investigated the interface between human enamel and bonded ceramic brackets non-invasively, introducing a combination of new investigative methods - optical coherence tomography (OCT) and confocal microscopy (CM). Brackets were conventionally bonded on conditioned buccal surfaces of teeth The bonding was assessed using these methods. Three dimensional reconstructions of the detected material defects were developed using manual and semi-automatic segmentation. The results clearly prove that OCT and CM are useful in orthodontic bonding investigations.

Transversal scanning (or en-face) optical coherence tomography (TS-OCT) represents an imaging modality that is capable to record high isotropic resolution images of the human retina in vivo. However, axial eye motion still remains a challenging problem of this technique. In this paper we introduce an improved method of our previously published axial eye motion correction technique. To measure accurately the position of the cornea an auxiliary spectral domain partial coherence interferometer (SD-PCI) operating at 1310nm that is integrated into a TS-OCT system is used. The recorded corneal position is used to drive a rapid scanning optical delay line in the reference arm of the TS-OCT system to correct for axial eye motion. Currently, the correction can be performed with a rate of ~1kHz which is approximately 20 times faster than our previous system and practically eliminates axial eye motion artifacts. The TS-OCT instrument is operated with a line scan rate of 8000 transversal lines per second which enables simultaneous scanning laser ophthalmoscope (SLO) and OCT imaging at a frame rate of 40fps (650x200pixels).)

Ultra-high speed optical coherence tomography employing an ultra-broadband light source has been combined with adaptive optics utilizing a single high stroke deformable mirror and chromatic aberration compensation. The reduction of motion artefacts, geometric and chromatic aberrations (pancorrection) permits to achieve an isotropic resolution of 2-3 μm in the human eye. The performance of this non-invasive imaging modality enables to resolve cellular structures including cone photoreceptors, nerve fibre bundles and collagenous plates of the lamina cribrosa, and retinal pigment epithelial (RPE) cells in the human retina in vivo with superior detail. Alterations of cellular morphology due to cone degeneration in a colour-blind subject are investigated in ultra-high resolution with selective depth sectioning for the first time.

Two high speed systems for spectrometer based frequency domain optical coherence tomography are presented. A device operating at 800 nm, based on the Basler Sprint CMOS camera with linerates of up to 312,000 lps and a device based on the Goodrich SUI LHD 1024 px camera at 1060 nm with 47,000 lps are applied in a clinical environment to normal subjects. The feasibility of clinical high and ultra high-resolution optical coherence tomography (OCT) devices for retinal imaging at different wavelengths, capable of isotropic sampling with 70 to 600 frames per second at 512 depth scans/frame for widefield imaging and high density sampling at 1 Gvoxel are demostrated.

The amount of light backscattered from neural tissues changes as a function of activation and is the basis of intrinsic optical signal (IOS). Typically IOS is observed by looking at darkfield scatter with a CCD camera. The retina is a calculating portion of the central nervous grey matter with an optical quality window, and is likewise easily stimulated optically. Therefore the retina makes a natural model for observing neural interactions with optical tools. Optical coherence tomography (OCT) is an imaging modality that provides depth resolved maps of the amount of light backscattered from tissue that has wide clinical use for observing structural defects associated with ophthalmic disease. It is therefore also natural to use OCT as means to observe intrinsic optical signal in the retina. Indeed, OCT has recently been used to observe an increase in backscatter at the level of the outer photoreceptor segment after bleaching light stimulation in an excised rabbit retina. We are currently attempting to translate this result towards a diagnostic technique for photoreceptor dysfunction in human patients. Currently patient motion and physiological noise present barriers that must be overcome with increases in technological and experimental sophistication. This proceeding reviews current understanding of retinal intrinsic optical signal and discusses its measurement challenge.

A new variety of nanoparticles showing unique and characteristic optical properties, appeals for its use as contrast agents in medical imaging. Gold nanospheres, nanorods and nanoshells with a silica core are new forms of promising contrast agents which can be tuned to specific absorption or scattering characteristics within the near-infrared (NIR) spectrum ranging from 650 - 1300 nm. They have the ability to be used for both image enhancement and as photosensitive markers due to their well designable scattering and absorption properties. Furthermore, their strong optical absorption permits treatment of malignant cells by photoablation processes, induced when heating them with a matched light source. Differential absorption optical coherence tomography (DA-OCT) allows for the detection and depth resolved concentration measurement of such markers. So far, reports on DA-OCT systems used A-scan based imaging systems to assess depth resolved information about the absorption properties and the concentration of a chemical compound. Enface OCT (B(T) or C(T) scan based) images allow for better depth localization and a depth resolved concentration measurement of the compound under investigation. For this aim, we evaluate the suitability of a multiscan time-domain OCT set-up, compatible with different light sources providing different wavelengths and bandwidths in the NIR, to perform differential absorption OCT measurements, using gold nanorods as the contrast agent.

Optical elastography is aimed at using the visco-elastic properties of soft tissue as a contrast mechanism, and could be particularly suitable for high-resolution differentiation of tumour from surrounding normal tissue. We present a new approach to measure the effect of an applied stimulus in the kilohertz frequency range that is based on optical coherence tomography. We describe the approach and present the first in vivo optical coherence elastography measurements in human skin at audio excitation frequencies.

Recently the area of bioimaging has benefited from new types of image enhancing agents such as quantum dots, carbon nanotubes and other nanoparticles. Cellular or even molecular level resolution has been achieved with different techniques during these last years (i.a. Fluorescence microscopy, PET/CT scan, AFM). Optical Coherence Tomography (OCT) as an imaging technique should also profit from newly developed probes. In this work we explored the tunable properties of different types of nanoparticles as contrast enhancers in OCT applications. We mainly studied the development and characteristics of metallic nanoparticles with tunable properties: gold nanoshells made of a silica core coated with a gold shell. Nanoshell and nanoparticles processing techniques are discussed, as well as their optimization for designing particles with specific absorption and scattering characteristics, and its use in OCT imaging.

We present results of OCT and polarization-OCT applied to various ex vivo tissue samples and discuss related issues of image contrast, comparing in vivo and ex vivo preparations. Time-domain and frequency-domain OCT at 835nm and 1300nm have been applied to ex vivo skin and rabbit cornea. We can distinguish rabbit cornea epithelium for up to a month after excision. However, the skin loses all contrast upon excision and despite numerous experiments we cannot distinguish epidermis, which is clearly visible in vivo. Using a time-domain system, birefringence is clearly visible for decalcified tissue but can also be detected more weakly on fully mineralised tissue. Analysis suggests that demineralization increases the birefringence value.

Recent developments in adaptive optics - optical coherence tomography (AO-OCT) allow for ultra-high isotropic resolution imaging of the in-vivo retina, offering unprecedented insight into its volumetric microscopic and cellular structures. In addition to this promising achievement, the clinical impact and application of this technology still needs to be explored. This includes assessment of limitations and challenges for existing as well as future AO-OCT systems, especially in the context of potential transfer of this technology from an optical bench to a portable imaging system. To address these issues we will describe our current AO-UHR-OCT focusing on its sub-components, as well as application for clinical imaging. Additionally, we describe some directions for future development of our AO-OCT instrument that would improve its clinical utility including: new compact AO-OCT design, new improved AO sub-system (extreme AO), and new generations of Fourier-domain-OCT.

The applications of three-dimensional Fourier domain optical coherence tomography (FD-OCT) to ophthalmology are demonstrated. The fundamentals of two types of FD-OCT, i.e., spectral domain OCT (SD-OCT) and swept source OCT (SS-OCT) are described. The 3D investigation of age-related macular degeneration and keratoconus are presented.

The combination of adaptive optics (AO) and optical coherence tomography (OCT) has been successfully applied to in vivo retinal imaging, motivated by the potential of unprecedented 3D resolution. The eye, however, not only suffers from monochromatic aberrations, which are corrected by AO, but also substantial chromatic aberrations, which are not. To correct chromatic aberrations, achromatizing lenses have been recently employed in ultrahigh resolution AO-OCT instruments. These lenses, like their earlier predecessors for vision improvement, effectively correct the eye's longitudinal chromatic aberration (LCA), but make no attempt at the complementary transverse chromatic aberration (TCA). This raises an important concern as to the degrading impact of TCA on the 3D resolution of AO-OCT and OCT retina cameras. To address this, we undertook a theoretical analysis of TCA for high-resolution retinal imaging. The theoretical analysis included the two primary contributors of TCA for retinal imaging: (1) errors in the lateral positioning of the eye and (2) off-axis imaging. The analysis predicted the extent to which TCA impacts retinal imaging and the conditions under which it can be held at acceptable levels for AO-OCT and OCT. Several near-infrared bands were chosen that correspond to common OCT light sources.

The capabilities of a novel deformable mirror and wave-front sensor combination to correct aberrations in microscopy are analyzed. The deformable mirror, (Mirao52-D, Imagine Eyes) is incorporated with a Shack-Hartmann sensor (HASO, Imagine Optic) within a complex imaging system able to produce simultaneous en-face Optical Coherence Tomography and Laser Scanning Confocal Microscopy images as well as B-scan OCT images. A large angle imaging along one of the scanning directions is demonstrated using the AO loop to correct for the interface optics aberration. The image is split into three panels, and each panel is imaged using its own set of corrections. The three images are subsequently collaged into a final image and preliminary promising results are presented.

Adaptive Optics (AO) is particularly suitable for correction of aberrations that change over time - a necessity for high resolution imaging of the retina. The rapidly changing aberrations originating from eye movements require wavefront sensors (WFS) with high repetition rates. Our approach is enhancing aberration correction by integrating a Pupil Tracking System (PTS) into the AO loop of the retinal imaging system. In this study we assessed the performance of the PTS developed for this purpose. Tests have demonstrated that the device achieves an accuracy of <15 μm in a ±2 mm range of eye movements with a standard deviation <10 μm. PTS can tolerate ±5 mm defocus with an increase of 4 μm in mean standard deviation. In vivo measurements done with temporarily paralyzed pupils have resulted in a precision of approximately 13 μm.

Adaptive optics (AO) is used to correct wavefront aberrations in light in real-time. An AO system is principally made up of three parts; a wavefront measuring device, a correction device, and a control algorithm to compute the residuals between the measured and a reference wavefront. Deformable mirrors (DM) are commonly used as the correction devices in such a system. This paper presents a method to improve a DM's temporal performance by attenuating parasite oscillations of its reflective membrane when applying high-frequency signals to the mirror actuators. The method consists of implementing low-pass filtering into the software driving the mirror. Different filtering functions were studied both when stimulating one single actuator, and when applying voltages to the complete array of actuators. A linear decomposition in 41 substeps showed the best performance for all considered configurations. The obtained results represented an important reduction of the settling time as well as the overshoot of the signal response.

We describe here two parts of our future 3D fundus camera coupling Adaptive Optics and full-field Optical Coherence Tomography. The first part is an Adaptive Optics flood imager installed at the Quinze-Vingts Hospital, regularly used on healthy and pathological eyes. A posteriori image reconstruction is performed, increasing the final image quality and field of view. The instrument lateral resolution is better than 2 microns. The second part is a full-field Optical Coherence Tomograph, which has demonstrated capability of performing a simple kind of "4 phases" image reconstruction of non biological samples and ex situ retinas. Final aim is to couple both parts in order to achieve 3D high resolution mapping of in vivo retinas.

High-speed, high-resolution full-range 1 μm spectral-domain optical coherence tomography has been demonstrated. The axial resolution of 7 μm and the depth range of 2.6 mm in tissue are achieved with the line rate of 46,900 Hz. The sensitivity of 98 dB is obtained with full-range imaging. These parameters are comparable or superior than those of commercially available ophthalmic instruments. Three dimensional structures of the retina and the choroid are visualized with the high axial resolution. High penetration property of 1 μm wavelength band in the deeper region of the posterior human eye enable high-contrast imaging of the choroid. In addition to that, vessels outer the choroid are visualized.

There has been a long tradition of applying biomedical imaging techniques to the examination of historical artefacts, owing to similar demands for non-invasive methods in both fields. Optical Coherence Tomography (OCT) is no exception. We review the achievements on OCT applications to art conservation and archaeology since the publication of the first papers in 2004. Historical artefacts include a much broader range of materials than biological tissues, hence presenting a greater and somewhat different challenge to the field of OCT. New results will be presented to illustrate the various applications of OCT including both qualitative and quantitative analysis.

In this contribution the application of Optical Coherence Tomography (OCT) for non-invasive structural imaging of easel paintings will be presented. Since the technique permits imaging semi-transparent layers accessible for infrared light, the varnish and glaze layers are usually under investigation. The major emphasis will be laid on application of OCT to resolving specific conservation problems, arising during the restoration process. The examples of imaging multilayer varnishes and subsequent alterations will be given and the application of these images for authentication of inscriptions will be discussed. Since the thickness of imaged layers may be directly measured with OCT in completely non-destructive, quick and convenient way as many times as necessary, the application of the technique to generation of varnish thickness maps will be presented.

We have assembled a swept source optical coherence tomography (OCT) system for use in Art & Archaeological Conservation. The system is illuminated by an in-house swept source with a central wavelength of 1300 nm. This system includes dedicated optics to allow for angular averaging for speckle noise reduction. We demonstrate that the averaging produces significant improvements in speckle SNR in art and archaeological type objects and allows easier identification of features. We further demonstrate that there is practically no loss of axial resolution.