This PDF file contains the front matter associated with SPIE Proceedings Volume 7372, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

We present the unique ability of polarization-sensitive optical coherence tomography to assess retinal disorders in a quantitative way. Areas of atrophic zones and volumes of subretinal fluids were evaluated.

Novel CMOS detector technology allows for high-speed volumetric tissue imaging with Fourier domain optical coherence tomography. Acquisition speeds of 200kHz reveal comprehensive image details due to the virtual lack of motion artifacts. We applied this system to the retina and achieved high resolution imaging with 5μm x 3μm transverse and axial resolution. Such resolution allows observing microscopic details such as photoreceptor cone mosaic, nerve fiber bundles, and the capillary bed without applying adaptive optics instrumentation. Fast image series reveal perfusion dynamics of full retinal volumes and allow for tracking of individual photoreceptors to study their dynamics. We observed that for in-vivo imaging speed is crucial for reproducible maps of microscopic tissue details.

Extended focus optical coherence microscope (xfOCM) circumvents the compromise between lateral resolution and depth of field by us of a Bessel-like illumination beam. The high sensitivity and parallel depth profiling of Fourier domain optical coherence tomography are preserved, and combined with high isotropic resolution of 1.5 - 2 μm. To comply with the requirements for in vivo measurements, beam scanning had to be implemented. We then performed measurements, first of excised pancreas, validated by standard immunohistochemistry, to investigate the structures that can be observed. For a quantitative analysis, a semi-automatic islet detection algorithm evaluated the islet size, position, contrast and homogeneity. The influence of streptozotocin on the signature of the islets was investigated in a next step. Finally, xfOCM was applied to make measurements of the murine pancreas in situ and in vivo, visualizing pancreatic lobules, ducts, blood vessels and individual islets of Langerhans.

The application of the full-field optical coherence tomography (OCT) microscope to the characterisation of skin morphology is described. An automated procedure for analysis and interpretation of the OCT data has been developed which provides measures of the laterally averaged depth profiles of the skin reflectance. The skin at the dorsal side of the upper arm of 22 patients with Type 1 Diabetes Mellitus has been characterised in a non-contact way. The OCT signal profile was compared with the optical histological data obtained with a commercial confocal microscope (CM). The highest correlation to the epidermal thickness (ET) obtained using CM was found for the distance from the entrance OCT peak to the first minimum of the reflection profile (R²=0.657, p<0.0001). The distance to the second OCT reflection peak was found to be less correlated to ET (R²=0.403, p=0.0009). A further analysis was undertaken to explore the relation between the subjects' demographical data and the OCT reflection profile. The distance to the second OCT peak demonstrated a correlation with a marginal statistical significance for the body-mass index (positive correlation with p=0.01) and age (negative correlation with p=0.062). At the same time the amplitude of the OCT signal, when compensated for signal attenuation with depth, is negatively correlated with age (p<0.0002). We suggest that this may be an effect of photo degradation of the dermal collagen. In the patient population studied, no relation could be determined between the measured skin morphology and the duration of diabetes or concentration of glycated haemoglobin in the blood.

We developed a laryngoscope with an integrated OCT beam path for office-based non-contact imaging of human vocal folds. In combination with conventional videolaryngoscopy superficial and subsurface lesions can be detected. For error-free interpretation of OCT images obtained in office-based examination motion artifacts have to be considered. To demonstrate the implications on OCT images we simulated probe and patient movements for different commercial systems representing the three OCT modalities and analyzed the OCT data. Our results show that time domain and fourier domain OCT with a swept light source are probably better suited for noncontact imaging of awake patients than the current generation of fourier domain OCT engines with spectrometer design.

In this study, we demonstrate that phase-resolved Doppler optical frequency domain imaging (OFDI) is very suitable to quantify the pulsatile blood flow within a vasodynamic measurement in the in vivo mouse model. For this, an OFDI-system with a read-out rate of 20 kHz and a center wavelength of 1320 nm has been used to image the time-resolved murine blood flow in 300 μμm vessels. Because OFDI is less sensitive to fringe washout due to axial sample motion, it is applied to analyze the blood flow velocities and the vascular dynamics in six-week-old C57BL/6 mice compared to one of the LDLR knockout strain kept under sedentary conditions or with access to voluntary wheel running. We have shown that the systolic as well as the diastolic phase of the pulsatile arterial blood flow can be well identified at each vasodynamic state. Furthermore, the changes of the flow velocities after vasoconstriction and -dilation were presented and interpreted in the entire physiological context. With this, the combined measurement of time-resolved blood flow and vessel diameter provides the basis to analyze the vascular function and its influence on the blood flow of small arteries of different mouse strains in response to different life styles.

In this feasibility study we present a method for 4D imaging of healthy and injured subpleural lung tissue in a mouse model. We used triggered swept source optical coherence tomography with an A-scan frequency of 20 kHz to image murine subpleural alveoli during the ventilation cycle. The data acquisition was gated to the pulmonary airway pressure to take one B-scan in each ventilation cycle for different pressure levels. The acquired B-scans were combined offline to one C-scan for each pressure level. Due to the high acquisition rate of the used optical coherence tomography system, we are also able to perform OCT Doppler imaging of the alveolar arterioles. We demonstrated that OCT is a useful tool to investigate the alveolar dynamics in spatial dimensions and to analyze the alveolar blood flow by using Doppler OCT.

1μm light sources are attractive for Fourier domain optical coherence tomography (FD-OCT) applications for ophthalmology. A semiconductor multi-quantum well structure has been designed and grown (based on AlGaAs/GaA material) to reach the 1μm wavelength window. A compact packaged high power (> 30mW) and wide-bandwidth (>100nm) superluminescent light emit diode (SLD) is achieved with catastrophic optical damage (COD) threshold higher than 100mW. The 1μm SLDs are suitable for high-resolution FDOCT and SD-OCT applications. A high gain and high Psat 1050nm semiconductor optical amplifier (SOA) is also achieved. The 1050nm SOA is a suitable gain medium for swept light sources for ultra high resolution OCT and are ideal for in vivo retinal imaging of small choroid blood vessels below the highly reflective and absorbing retinal pigment epithelium (RPE).

A Fourier Domain mode-locked (FDML) laser for polarization sensitive optical coherence tomography (OCT) is presented. The laser generates an alternating sequence of wavelength sweeps with their polarization states 90° separated on the Poincare sphere.

We present a novel wavelength swept light source for Optical Coherence Tomography (OCT). Arbitrary sweep rates up to 2x170kHz are achieved by phase-shifted control of two optical bandpass-filters to compensate light propagation effects.

Modern measurement equipment delivers more detailed data and faster data with each generation. These data can be used for different applications, one of them is doing real time display. Instead of saving all data during the measurements and analyze it afterwards, the data is displayed in real time and only especially selected parts of the data are saved for further work. Moving the screening part of the analysis to the human brain and pattern recognition avoids the saving of vast amounts of data and massive calculation power on computers afterwards and it dramatically improves the level of interaction with the measurement systems. This work starts first with a short look to the question what OCT is and how data is acquired. The different possibilities of volume rendering are presented in their basic ideas. Graphics hardware and algorithms are presented and discussed. Last the results of measurements taken by the system will be presented and discussed.

In OCT imaging the spectra that are used for Fourier transformation are in general not acquired linearly in k-space. Therefore one needs to apply an algorithm to re-sample the data and finally do the Fourier Transformation to gain depth information. We compare three algorithms (Non-Equispaced DFT, interpolated FFT and Non-Equispaced FFT) for this purpose in terms of speed and accuracy. The optimal algorithm depends on the OCT device (speed, SNR) and the object.

We present directional filtering and coherence-enhancing diffusion (CED) as well as two-dimensional quadrature demodulation for analysis of single frame retardation images, acquired with polarisation-sensitive optical coherence tomography (PS-OCT). We compare different denoising techniques applied to stress-induced PS-OCT images and the influence of selected pre-processing methods on the demodulation results.

The early stages of malignant diseases, such as cancer, are characterized by cellular and microstructural changes which define both the diagnosis and the prognosis of the disease. Unfortunately, at the current resolution of Optical Coherence Tomography (OCT), such changes associated with early cancer are not clearly discernible. However, spectral analysis of OCT images has recently shown that additional information can be extracted from those signals, resulting in improved contrast which is directly related to scatterer size changes. Amplitude Modulation - Frequency Modulation (AM-FM) analysis is a fast and accurate technique which can also be applied to the OCT images for estimation of spectral information. It is based on the analytic signal of the real data, obtained using a Hilbert Transform, and provides the instantaneous amplitude, phase, and frequency of an OCT signal. The performance of this method is superior to both FFT-based and parametric (e.g. autoregressive) spectral analysis providing better accuracy and faster convergence when estimating scatterer features. Since disease tissues exhibit variations in scatterer size and thus also exhibit marked differences in spectral and phase characteristics, such advanced analysis techniques can provide more insight into the subtle changes observed in OCT images of malignancy. Therefore, they can make available a tool which could prove extremely valuable for the investigation of disease features which now remain below the resolution of OCT and improved the technology's diagnostic capabilities.

Contrasting of skin forming elements in optical coherence tomography (OCT) images after application of silica/gold nanoshells or titanium dioxide nanoparticles in solution is discussed. The study is performed both by Monte Carlo simulations and in vivo on animals. The result show that application of both types of nanoparticles produces contrast increase in the OCT images of skin. The increase in OCT signal level originates from the higher backscattering on nanoparticles compared to that on skin forming elements. The increase of contrast in the OCT images originates from the difference in nanoparticles concentration within different skin constituents. These experimental results are confirmed qualitatively by Monte Carlo simulations based on multilayer skin model.

Chick embryos are among the most studied species in development biology because they are easily obtained, highly accessible and present a similar development to that of humans. Normally morphological studies are carried out with confocal microscopy, however in-situ imaging is impossible and in- vivo imaging can only be performed with great difficulty. For confocal microscopy the embryo has to be studied outside the egg, what generally also means a short life expectancy of the embryo. Additionally, extracting the embryo of the egg precludes the possibility of studying its development in its natural environment. In this paper it is shown that en-face optical coherence tomography (en-face OCT) is a possible solution to overcome these difficulties allowing for an in-situ and in-vivo study over a timescale of several days. With en-face OCT it is possible to accompany the development of one single embryo over several days and to acquire high resolution and axially resolved images.

Optical coherence tomography (OCT) is performed in the spectral domain simultaneously at two different wavelength bands centered at 800 nm and 1250 nm. A novel commercial supercontinuum laser is applied as a single light source whose emission spectrum is shaped by optical and spatial filtering to obtain an adequate double peak spectrum. After spectral shaping, the wavelength bands 700 - 900 nm and 1100 - 1400 nm are used for OCT imaging. A fiber-coupled setup optimized for both spectral regions facilitates easy and flexible access to the measurement area. Each wavelength band is analyzed with an individual spectrometer at an A-scan rate of about 12 kHz which allows real-time sample examination. The free-space axial resolutions were measured to be less than 4.5 μm and 7 μm at 800 nm and 1250 nm, respectively. This technique combines the high resolution at 800 nm with the enhanced imaging depth at 1250 nm. Furthermore, spatially resolved spectroscopic sample features are extracted by comparing the backscattering properties at the two different wavelength bands, showing the ability of dual-band OCT to enhance image contrast.

In this study, depth resolved measurements of absorption profiles in the wavelength range of 800 nm with a bandwidth of 140 nm are demonstrated using high speed spectroscopic frequency domain OCT (SOCT). With proper calibration, SOCT is able to extract absolute, depth resolved absorption profiles over the whole wavelength range at once without the need of tuning and performing measurements at single wavelengths sequentially. In addition, high acquisition speed in excess of 20 kHz allows to measure absorption dynamics with 50 μs time resolution, which might be useful for the investigation of pharmacokinetics or pharmacodynamics. SOCT of ~600 μm thick single- and multilayered, weakly scattering phantoms with varying absorption in the range of 10-60 cm^-1, equivalent to blood absorption in capillaries, is presented. SOCT measurements are compared with those using a spectrometer in transmission mode. For Indocyanine Green (ICG), a dynamic absorption measurement is demonstrated.

During open brain surgery we acquire perfusion images non-invasively using laser Doppler imaging. The regions of brain activity show a distinct signal in response to stimulation providing intraoperative functional brain maps of remarkably strong contrast.

In this paper we present our improved transversal scanning OCT system that is capable of retinal imaging with cellular resolution. A fast axial eye tracking device was implemented into the system which practically eliminates eye motion artifacts in depth. Together with software based algorithms to correct for transverse eye motion 3D volumes of the human retina with greatly reduced motion artifacts and with isotropic resolution are presented. With this instrument long term changes of single human cone photoreceptors are observed.

We present a novel method to obtain optical angiographies (OAG) on a standard optical coherence tomography (OCT) system. The moving reference arm is simulated by introducing a phase-shift at the post-processing stage. The method can be applied bi-directionally from a single scan, one or more velocity-thresholds can be adjusted during post-processing. First in-vivo results are shown.

Most of the colorectal cancer has grown from the adenomatous polyp. Adenomatous lesions have a well-documented relationship to colorectal cancer in previous studies. Thus, to detect the morphological changes between polyp and tumor can allow early diagnosis of colorectal cancer and simultaneous removal of lesions. In this paper, the various adenoma/carcinoma in-vitro samples are monitored by our swept-source optical coherence tomography (SS-OCT) system. The significant results indicate a great potential for early detection of colorectal adenomas based on the SS-OCT imaging.

Three dimensional alveolar geometry of subpleural lung parenchyma is of high interest for respiratory research exemplary for the development of numerical models of the lung for simulating alveolar mechanics. We present a method for 3D imaging lung tissue up to a depth of 800 μm beneath the pleura by optical coherence tomography with a resolution of less than 10 μm. Isolated and fixated rabbit lungs were perfused with a series of ethanol with increasing concentration (20 % - 50 % - 70 % - 95 % - 100 %; 100 ml of each concentration). The alveolar space, normally air filled, is flooded by the ethanol. The ethanol filling provides an adaptation of the refraction index and therefore imaging artifacts caused by differences in diffraction index between air and tissue are minimized. We improved the penetration depth from 200 μm up to 800 μm for subpleural lung parenchyma and we demonstrated that the acquired 3D data sets are suitable for 3D reconstruction of alveolar tissue.

This study analyzes the adaptation and gap width between fiber posts, adhesive luting cement and root canal wall using optical coherence tomography. The results prove the importance of assessing the quality of the interface after each process of fiber post luting.

Optical coherence tomography (OCT) and micro-computed tomography (μCT) were applied to a bone sample, a 3x4x4mm cube of fixed substantia spongiosa from an arthritic human hip. Three-dimensional image sets (1.0mm x 0.9mm x 1.6mm) were acquired with both imaging systems for the same volume of interest. For better navigation, the sample surface was additionally imaged with microscopy. The resulting OCT images were compared stepwise to the according μCT images, showing a high correlation regarding the visualization of individual trabeculae. System based imaging differences were also found: due to scattering, OCT is limited to an imaging depth of about 1mm, while μCT is capable of imaging the complete trabecular bone architecture. However, OCT images cells and the inner bone structures in contrast to μCT at similar nominal resolutions (5μm respectively 6.5μm).

This pilot study was designed to investigate the quality of endodontic treatment performed with/without Er:YAG laser using en-face Optical Coherence Tomography (OCT) prototype which evinced the presence of voids and microleakage within the root canal.

Using refractive low coherence interferometry (rLCI) technique we determined the concentration of aqueous mixtures of glucose and albumin. The method is based on second-order dispersion derived from spectral phase of time-domain interferogram. A series of 9 mixtures with different concentration ratios in the range of 5mg/ml to 50mg/ml was performed. The results show errors between prepared and measured concentration of a few percent up to 38%.

Multi-band ultrahigh-resolution full-field optical coherence tomography, achieving a detection sensitivity of 90 dB and a micrometer-scale resolution in the three directions, is demonstrated using several detectors or a spectrally adjustable illumination source.

We present how to improve the efficiency and dynamic range for interferometric systems by taking advantage of the finite extinction ratio of a polarizing beam splitter. The technique has been demonstrated on a full-field OCT system by imaging of surfaces as well as transparent and turbid media.

We present a fiber-based spectral-domain optical coherence tomography system, measuring simultaneously at 740 nm and 1300 nm central wavelengths. Real-time imaging is demonstrated with axial resolutions <3 μm and <5 μm, respectively. This technique allows for in vivo functional OCT imaging with high spatial resolution and outstanding spectroscopic imaging contrast.

We evaluate the performance of a cheap ultrasonic stage in setups related to optical coherence tomography. The stage was used in several configurations: 1) optical delay line in optical coherence tomography (OCT) setup; 2) as a delay line measuring coherence function of a low coherence source (e.g. superluminescent diode); 3) as a path length modulator in optical coherence microscopy (OCM) setup and finally 4) in a dynamic focusing arrangement. We evaluate each configuration and point to possible improvements either in setups or ultrasonic stage architecture. The results are as follows: the stage is suitable for coherence function measurement of the light source and, with some limitations, dynamic focusing. We found it unsuitable for OCT due to unstable velocity profile, while smaller step movement is required for OCM imaging.

In this paper, we present a developing technology targeted at clinical imaging, Gabor Domain Optical Coherence Microscopy (GD-OCM), which combines the high resolution imaging of optical coherence microscopy (OCM), high imaging speed of Fourier domain optical coherence tomography (FD-OCT), and invariant lateral resolution of our custom designed dynamic focusing objective. 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, is presented. Furthermore, an acquisition scheme (using the probe) that is capable of performing automatic real time data fusion to render an in-focus high resolution image throughout the depth of sample in real time was implemented. 3D imaging of an African frog tadpole is demonstrated at cellular level resolution.

High-speed and high-sensitive phase-resolved spectral-domain optical coherence tomography has been developed. Two tomograms with a time separation have been acquired with dual beams. High-sensitive Doppler optical coherence angiography of the human eye has been demonstrated.

We demonstrate the capability of spectral domain optical coherence tomography (SD-OCT) with a full range complex (FRC) technique to image the anterior eye segment from the cornea to the back surface of the lens. We improved the spectrometer resolution with an adapted spectrometer design to achieve a single depth range of 7 mm in air. This depth range was doubled to an imaging range of 14 mm with a FRC-technique based on phase modulation introduced by off pivot point illumination of the galvanometer scanner. The performance of our system is demonstrated by recorded 2D and 3D datasets of the whole anterior eye segment of healthy human eyes in vivo. The system is also applicable to demonstrate the changes of the anterior eye segment during the accommodation of the eye.

Ultrahigh speed Spectral/Fourier domain ophthalmic OCT imaging at 70,000-312,500 axial scans per second is demonstrated using a high speed CMOS camera at 800 nm. Comparative imaging results of the fovea illustrate the performance tradeoffs between different imaging speeds and spectrometer configurations. Dense 3D volumetric acquisitions show minimal motion artifacts when acquired at 250,000 axial scans per second. The porous structure of the lamina cribrosa is shown in en face images extracted from a dense volumetric acquisition of the optical nerve head acquired at 106, 382 axial scans per second. Rapid repeated volume imaging (4D-OCT) shows blood flow in retinal capillaries. Boundaries of the capillary network are enhanced by motion contrast. 3D volumetric data acquired at 49,000 axial scans per second using an InGaAs camera at 1050 nm is compared to volumetric data acquired at 101, 010 axial scans per second using a CMOS camera at 800nm. Averaging of adjacent cross sectional scans in the volume is shown to increase contrast in the images and reduce speckle. The enhanced penetration of the 1050 nm compared to the 800 nm OCT imaging system is shown. Dense 2D/3D data sets and 4D-OCT repeated volume imaging promise alternative methods for diagnosis and monitoring of disease.

We report an active tracking device based on white light coherence ranging using a spectrally interrogated Michelson interferometer, which is used to monitor and correct for the axial displacement of the eye and head of the subject in a confocal scanning ophthalmoscope/ en face OCT system (SLO/OCT). The Nyquist limit range of the spectrometer in the tracking interferometer is ~5.4 mm, which is adequate for monitoring the axial position of axially extended layered objects like the human eye fundus. Both the tracking and imaging interferometers share the eye interface optics and the sample and also an optical path (OPD) changing device in the reference (fast voice coil mounted retroreflector), that keeps them locked at constant OPD values. As a consequence, the sensitivity of the tracking interferometer is not affected by the spectrometer sensitivity roll-off with increased OPD and mirror term ambiguity tracking errors close to OPD = 0 are eliminated. Moreover, the axial tracking range is only limited by the voice coil stage travel range. A real time data acquisition processor board is used to digitize the spectrometer signal and calculate the correction signal applied to the voice coil with an update time better than 5 ms. We demonstrate axial motion corrected combined confocal/ en face OCT imaging of the human eye fundus in vivo.

This article studies the combination of the time-domain OCT modality with a dynamically-focusing micro- lens-system. Combining the tunable lens with a fix-focal lens in the sample arm of the OCT setup shows a considerable improvement on the OCT image quality, mainly, the lateral resolution and the signal-to-noise ratio. We present an experimental method and the related first measurements of the lateral resolution of the OCT system using the tunable lens system. Based on this method, the OCT system employing the tunable multi-lens system provides an invariant lateral resolution of 8 μm along ~5mm scan depth. A miniaturized version of the tunable two-lens system utilizes an endoscopic OCT wit a dynamically-focusing functionality. The high lateral resolution endoscopic imaging based on the miniaturized tunable micro-system promises a significant utility in advanced biomedical imaging.

We propose novel spectral domain polarization sensitive optical coherence tomography with single camera spectrometer including a multiplexed custom grating, camera lenses and high-speed multi-line CCD camera. Two polarization beams are measured on different lines of high speed CCD camera. Due to slightly different incident angle of two beam collimators, two orthogonal polarization channel beams are separately measured by different lines of CCD camera each other. After the system is implemented, signal acquisition is performed for polarization-sensitive imaging of various samples.

We explore how histopathology parameters influence OCT imaging of basal cell carcinomas (BCC) and address whether such parameters correlate with the quality of the recorded OCT images. Our results indicate that inflammation impairs OCT imaging and that sun-damaged skin can sometimes provide more clear-cut images of skin cancer lesions using OCT imaging when compared to skin cancer surrounded by skin without sun-damage.

We use variable dispersion compensators to build time (TD-OCT) and spectral (SD-OCT) domain all-fiber optical coherence tomography systems operating in the 800 nm wavelength range. The all-fiber tunable dispersion compensator is based on a pair of fiber stretchers made with different fiber types in which the group delay and the 2nd-order dispersion can be tuned independently. Their abilities are demonstrated in biological tissues with the TD-OCT system reaching a significant sensitivity of 86 dB.

We present a method to separate blood flow information from static tissue in Doppler Fourier domain optical coherence tomograms (D-FDOCT). Histograms of the Doppler tomograms are used to differentiate between pixels containing information about blood flow and pixels representing static tissue. By setting pixels within a certain histogram range to 0 only the blood flow information remains. This approach is demonstrated on different retinal D-FDOCT volume scans taken with a high speed CMOS based FDOCT system. The advantage of the presented approach is the small post processing effort together with the direct availability of quantitative Doppler flow maps.

Blood flow measurement with spectrometer-based Fourier domain optical coherence tomography (FD OCT) is limited by the motion-induced signal fading and the resulting reduction of flow sensitivity. In this study, a combination of the established Doppler OCT and the numerically simulated signal damping due to obliquely moved scatterers is used to estimate the systolic blood flow velocities in the in vivo mouse model at which the standard Doppler OCT does not work any longer.

We introduce Endoscopic Low Coherence Interferometry to obtain topology of upper airways through commonly used rigid endoscopes. Quantitative dimensioning of upper airways pathologies is crucial to provide maximum health recovery chances, for example in order to choose the correct stent to treat endoluminal obstructing pathologies. Our device is fully compatible with procedures used in day-to-day examinations and can potentially be brought to bedside. Besides this, the approach described here can be almost straightforwardly adapted to other endoscopy-related field of interest, such as gastroscopy and arthroscopy. The principle of the method is first exposed, then filtering procedure used to extract the depth information is described. Finally, demonstration of the method ability to operate on biological samples is assessed through measurements on ex-vivo pork bronchi.

Resonant Doppler flow imaging based on optical coherence tomography (OCT) is a recently developed imaging modality that provides, besides the structural information, dynamic blood flow information. We show that this method can be applied to a common path OCT system by mounting the mirror in the reference arm on a small piezo actor leading to a simpler and more stable system design. Besides the known 3 state cycle, we describe other cycles with any number of states leading to higher measurement speed or larger velocity range. The hysteresis of the piezo actor is compensated by applying an optimized electrical signal. Two different approaches, one using a Levenberg-Marquardt optimization, the other using the Prandtl-Ishlinskii model for compensation of hysteresis, are applied to generate the optimized control signal. Besides providing an analytical formula for the calculation of the axial velocity for cycles having certain spacings in the reference velocity, we describe deviations from the signal degradation caused by the transversal part of the motion causing errors in the velocity estimation. The performance of the system with two and three states is first evaluated with a mirror on a loud speaker. Measurements with a flow phantom consisting of 1 % Intralipid dilution flowing through small diameter capillaries show the suitability of the system and the expected deviations at high velocities.

A Line-field Spectral Domain Optical Coherence Tomography method is proposed to enable fast B-Scan imaging. This system was constructed from a combination of a conventional Spectral Domain OCT and a line field imaging system, which directs a line-shaped focus onto a specimen. An array of depth-information-encoded-spectra was collected by a two-dimensinal CCD camera. Numeric frequency resampling was applied to rows collected from the camera, followed by Fourier transformation on each individual spectrum obtained. This lead to B-Scan images generated from a single shot event. The performances of the imaging system are discussed. Images from skin of human fingers in-vivo and osseous tissue of human teeth are presented.

The aim of this study is the early detection and monitoring of occlusal overload in bruxing patients. En-Face Optical coherence tomography (eF-OCT) and fluorescence microscopy (FM) were used for the imaging of several anterior teeth extracted from patients with light active bruxism. We found a characteristic pattern of enamel cracks, that reached the tooth surface. We concluded that the combination of the en-Face OCT and FM is a promising non-invasive alternative technique for reliable monitoring of occlusal overload.

Standardized class V cavities, prepared in human extracted teeth, were filled with Premise (Kerr) composite. The specimens were thermo cycled. The interfaces were examined using a system employing two simultaneous imaging channels, an en-face Optical Coherence Tomography channel and a confocal microscopy channel.

The aim of this study was to analyze the quality of marginal adaptation and gap width of Empress veneers using en-face optical coherence tomography. The results prove the necessity of investigating the marginal adaptation after each veneer bonding process.

In this work, we present clinical images of IVUS and OCT in the evaluation of pharmacological stent endothelization. These preliminary imaging results are analyzed and compared in order to determine the ability of these technologies to visualize relevant intravascular features of interest in interventional cardiology. The results enable to compare the performance of both techniques and to evaluate their potential for clinical purposes.

The application of optical coherence tomography OCT in tissue engineering facilities offers great potential for the automated detection of defects or inhomogeneities in tissue products. This non-invasive and non-destructive measurement technique enables the high speed generation of two dimensional cross sections of tissue with micron resolution. The integration of an OCT device into a tissue production facility allows the monitoring and quality control of tissue engineering products. By the selective exclusion of tissue products with insufficient quality features a high degree in production standard is guaranteed. In a first study, OCT tomograms of artificial skin equivalents were acquired and compared with microscopic images of associated histologies. As a result, a well-defined analogy of the obtained images is presented. The most common defect in terms of hole structures that occurs due to a procedural steps could be detected. Further characteristics like the topography, homogeneity and layer structure was analysed. Hence, OCT provides a powerful measurement technique to monitor the quality of tissue products in automated tissue engineering facilities.