This PDF file contains the front matter associated with SPIE Proceedings Volume 7371, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

Three-dimensional imaging assays of anti-cancer drugs applied to tissues are performed using motility contrast imaging (MCI), a speckle holographic imaging technique that detects sub-cellular motion as a fully-endogenous imaging contrast agent.

Optical tomography provides three-dimensional data of the measured specimen, while quantitative phase imaging enables measuring the induced phase-shifts. Combining those two technologies makes possible to get three-dimensional refractive index reconstruction. This can be achieved by introducing a scan in the measurement process, which can be done in several ways. We present and compare results of tomographic measurements, taken either in angle-scanning or wavelength-scanning approach, respectively in transmission or in reflection microscopy, in the framework of digital holographic microscopy.

We have developed a novel turbid polarimetry platform for characterization of biological tissues. Currently, we are exploring the use of this platform for characterization of the extracellular matrix particularly for use in monitoring regenerative treatments of myocardial infarctions. Collagen is a fibrous protein and exhibits birefringence due to different refractive indices parallel and perpendicular to the direction of the fibers. As a result, changes in the collagen content and organization in the tissue lead to changes in birefringence. We demonstrate our ability to measure these extracellular changes in vivo using a mouse dorsal window chamber model. Collagenase was injected into a region of the chamber to denature the extracellular matrix. Birefringence measurements show a large decrease in birefringence associated with the destruction of collagen fibers. Birefringence measurements were also made through ex vivo myocardial tissues from rats with induced myocardial infarctions including a number that had undergone regenerative treatment with mesenchymal stem cells. Results show a decrease in birefringence from normal to infracted myocardium, indicating a decrease in tissue organization associated with scar formation, however, an increase in birefringence was seen in those myocardial tissues that had undergone regenerative treatment indicating reorganization of tissue structure.

Fluorescence diffuse optical tomography (FT) is a promising molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. In this phantom study, we built a photo-multiplier tube (PMT) based single detection system that uses fiber bundles to collect light. Measurements were acquired both with a 1 mm diameter single fiber and a 6 mm diameter fiber bundle using the very same detection unit for comparison purposes. We demonstratethat the fluorescence concentration and lifetime can be well recovered for 6 mm diameter objects deeply embedded in an 80 mm diameter breast-sized phantom when the fiber bundle is utilized.

A novel tomographic approach for photon discrimination in turbid media using a single source-detector distance and exploiting temporal information is presented and validated by numerical simulations and in-vivo measurements.

Continuous wave Near InfraRed Spectroscopy (NIRS) has been used successfully in clinical environments for several years to detect cerebral activation thanks to oxymetry (i.e. absorption of photons by oxy- and deoxy- hemoglobin) measurement. The goal of our group is to build a clinically-adapted time-resolved NIRS setup i.e. a setup that is compact and robust enough to allow bedside measurements and that matches safety requirements with human patients applications. Indeed our group has already shown that time resolution allows spatial resolution and improves sensitivity of cerebral activation detection. The setup is built with four laser diodes (excitation wavelengths: 685, 780, 830 and 870 nm) whose emitted light is injected into four optical fibers; detection of reflected photons is made through an avalanche photodiode and a high resolution timing module used to record Temporal Point Spread Functions (TPSF). Validation of the device was made using cylindrically-chaped phantoms with absorbing and/or scattering inclusions. Results show that recorded TPSF are typical both of scattering and absorbing materials thus demonstrating that our apparatus would detect variation of optical properties (absorption and scattering) deep within a diffusive media just like a cerebral activation represents a rise of absorption in the cortex underneath head surface.

In this work we report a novel technique for obtain thiol capped CdTe colloidal quantum dots in one step. These nanoparticles are compatible for silica capping indicating their possible use as fluorescent markers.

Autofluorescence spectroscopy from brain tissue may help to discriminate cancerous from healthy tissue. The characteristics of our probe are studied on phantoms and confronted to Monte Carlo simulations. Geometrical origins of fluorescence light are evaluated.

We describe the implementation of a non-linear grating-based angular filter for the assessment of turbid media with ballistic photons. A monochromatic source incident on a ruled grating, positioned at grazing diffraction, followed by a narrow slit conform the proposed system. We validate the angular amplification experimentally, with values ranging on the order of 10-20X. In addition, similar values of transversal beam size reduction, provide an efficient ~100X filtering scheme. We address the plausible application of the angular filter to perform ballistic transillumination of turbid media, such as biological tissue. Non-linear angular amplification and beam width reduction are employed to separate ballistic photons from forward-scattered ones. Preliminary experimental results of the technique are encouraging, as compared to those of traditional transillumination.

In the current study we try to optimise the cancerous/normal tissue contrast perception using white light and autofluorescence image processing. We deconvolved the RGB channels of both white light and autofluorescence images pixel by pixel and pointed out the best contrast enhancement technique, manipulating each channel seperately. By using false-color mapping according to a particular Look-Up Table, the borders between normal and cancerous area of the tissue are better delineated. Cancer tissue identification was confirmed by the histological examination that followed our investigation.

In experiments and numerical simulations of pulsed photothermal temperature profiling, we compare three signal binning approaches. In uniform binning n subsequent signal data points are averaged, quadratic binning follows from the characteristic of thermal diffusion, and geometrical binning utilizes geometric progression. Our experiment was performed on collagen gel samples with absorbing layers located at various subsurface depths. From measured PPTR signals laser-induced temperature profiles were reconstructed using spectrally composite kernel. The simulated PPTR signals of temperature profiles resembling experimental temperature profiles contain noise with characteristics consistent with our experimental system. In addition, we simulated PPTR signal of a biopsy-defined port-wine stain skin geometry. In PPTR temperature profiling of collagen gel samples, quadratic binning results in optimal reconstructions for shallow absorbing structures, while uniform binning performs optimally for deeper absorbing structures. Overall, geometric binning yields least accurate reconstructions, especially for deeper absorbing layers.

Exhaled nitric oxide was of high interest in breath analyses in the past few years. After its first detection in human breath in 1991, numerous publications uncovered the role of NO and its relation to different diseases. A strong relationship between an asthmatic eosinophilic airway inflammation and an increased NO level is medically confirmed. In this study a new photoacoustic detection system for nitric oxide based on a pulsed quantum cascade laser is introduced. The laser's single mode emission provides adequate selectivity to differentiate NO from other molecules in the sample. The demonstrated detection sensitivity allows in principle an application of the new system as diagnostic tool for asthma.

Photoacoustic imaging is based on the excitation of ultrasound waves by irradiating objects with short laser pulses. Absorbing laser energy causes thermal expansion, which leads to broadband ultrasonic waves, carrying information about size, location and optical properties of the observed target. Images reveal purely optical contrast, yet the technique is acoustic. Classical ultrasonic imaging generates images with purely acoustical contrast based on the impedance differences of structures in observed samples. For developing a dual mode scanning acoustic microscope, which uses simultaneously both contrast mechanism (acoustic pulse-echo and photoacoustic image contrast) ultrasonic pulses with a large depth of field are advantageous. By illuminating special conically shaped transducers, so called axicons, with short laser pulses, broadband ultrasonic pulses with a large depth of field at small lateral extension can be excited. These special pulses, so called X-waves and their use in a microscope are investigated.

We present a 'hybrid' imaging system, which can image both optical absorption properties and acoustic transmission properties of an object in a two-dimensional slice using a computed tomography photoacoustic imager. The ultrasound transmission measurement method uses a strong absorber of light which is placed in the path of the light illuminating the sample. This acts as a source of ultrasound, whose interaction with the sample can be measured at the far-end of the sample using the same ultrasound detector used for photoacoustics. Such measurements are made at various angles around the sample in a computerized tomography approach. The ultrasound transients at the multi-element detector at all projections are analyzed for both times-of-arrival and amplitude. Using a fan-beam projection reconstruction algorithm we obtain hybrid images of optical absorption, speed-of-sound and acoustic attenuation. We validate the method on an appropriate phantom.

For photoacoustic imaging (PAI) so called integrating detectors are used. We developed two types of fiber-based integrating detectors for photoacoustic tomography (PAT). First images of phantoms with simple structures reconstructed from data collected with fiber-based detectors are presented.

Photoacoustic imaging with a scanning, fixed focus receiver gives images with high resolution, without the need for image reconstruction. For achieving high depth of field, a conically shaped piezoelectric ultrasound detector, the so called axicon-detector, is investigated. It is characterized by a sustained line of focus with a length that depends only on the geometry of the detector but not on the wavelength. Simulated and experimentally taken images of various objects reveal X-shaped artifacts due to the conical surface of the detector. To improve the image quality a frequency domain deconvolution can be applied, as the point spread function (PSF) of the detector is spatially invariant over the depth of field. The reduction of the artifacts works well for simulated images but is not functional for experimental data yet. Nevertheless, the detector gives images with precise shape and position of the investigated samples.

Large optical annular detectors were realized using polymer optical fibers and a Mach-Zehnder interferometer. Photoacoustic measurements were performed and compared to numerical simulations. Furthermore, a simple deconvolution algorithm was developed and applied to reduce artifacts in the images.

We show an optically induced AC electrokinetic technique that rapidly and continuously accumulates colloids on an electrode surface resulting in a crystalline-like monolayer aggregation. We demonstrate colloidal aggregation for particles ranging from 100 nm to 3 μm. Electrothermal hydrodynamics produce a microfluidic vortex that carries particles in suspension towards its center where they are trapped by low-frequency AC electrokinetic forces. We characterize the rate of particle aggregation as a function of the applied AC voltage and hence characterize trapping kinetics of this technique. We show that inter-particle distance varies with frequency and we explain this in the light of available theory.

This paper describes an optofluidic approach for fiber coupling and flexible beam shaping in the central plane of all-glass microfluidic devices. Special microchannels with half circular sidewalls have been integrated into the device in order to create micro lens systems. Focal length of each of these micro-lenses can be controlled by the refractive index of the fluid inside the channel. That way adaptive, microfluidically controllable lens systems can be realized for use in beam shaping and light-section creation. A prototyped chip with five parallel fluidic channels with different distances between them and with free adjustable and combinational fluidic refraction indices inside has been prepared and investigated. A total of six fiber channels on each side are used for light input and output. The developed chip concept has a great potential for application in small biochemical analysis units like lab-on-a-chip or μ-total analysis systems. Simulations of light distribution inside the chip in dependence on fluid refraction indices as well as geometrical parameters are in accordance with realized transmission measurements.

We demonstrate a system for constructing reconfigurable microstructures using multiple, real-time configurable counterpropagating-beam traps. We optically assemble geometrically complementary microstructures with complex three-dimensional (3D) topologies produced by two-photon polymerization. This demonstrates utilization of controllable 3D optical traps for building hierarchical structures from microfabricated building blocks. Optical microassembly with translational and tip-tilt control in 3D achieved by dynamic multiple CB traps can potentially facilitate the construction of functional microdevices and may also lead to the future realization of optically actuated micromachines. Fabricating morphologically complex microstructures and then optically manipulating these archetypal building blocks can also be used to construct reconfigurable microenvironments that can aid in understanding cellular development processes.

Bladder cancer is widely spread in the world. Many adequate diagnosis techniques exist. Video-endoscopy remains the standard clinical procedure for visual exploration of the bladder internal surface. However, video-endoscopy presents the limit that the imaged area for each image is about nearly 1 cm². And, lesions are, typically, spread over several images. The aim of this contribution is to assess the performance of two mosaicing algorithms leading to the construction of panoramic maps (one unique image) of bladder walls. The quantitative comparison study is performed on a set of real endoscopic exam data and on simulated data relative to bladder phantom.

In the light of the bimodal technical innovations put forward in the diagnosis of early stage colorectal cancer, we present a preliminary study based on a first prototype of a high Resolution MRI-Optics probe along with the first tests carried out and the results obtained.

Existing image restoration methods, requiring a referenced image inserted in body, can not apply to endoscope imaging. We therefore propose a method by estimating polluted MTF for the degraded imaging system to restore blurred images.

We present preliminary data from an imaging system based on LED illumination for obtaining sequential multispectral optical images of the human ocular fundus. The system is capable of acquiring images at speeds of up to 20fps and we have demonstrated that the system is fast enough to allow images to be acquired with minimal inter-frame movement. Further improvements have been identified that will improve both imaging speed and image quality. The long-term goal is to use the system in conjunction with novel image analysis algorithms to extract chromophore concentrations from images of the ocular fundus, with a particular emphasis on age-related macular degeneration. The system has also found utility in fluorescence microscopy.

We propose a method for imaging simultaneously blood flow and hemoglobin concentration change in skin tissue using speckle patterns acquired at two wavelengths of 780 and 830 nm. Experimental results demonstrate that the method is useful for time-varying analysis of blood circulation in human forearm skin tissue from one set of sequential speckle images.

A fluorescence-based biochip with an integrated holographic diffractive optical element on its underside is presented. The diffractive element is a thick volume hologram written into a layer of photopolymer recording material. The element acts as a collector of the spatially anisotropic fluorescence light emitted from surface-bound fluorophores and redirects the light to a CCD detector. The holographic lithography setup used to fabricate the diffractive elements is described. The performance of the diffractive elements to enhance the light collection is demonstrated.

Cancer is a leading cause of death worldwide, and about 30% of cancer deaths can be prevented. In the next future, the number of global cancer deaths is projected to increase 45% in the future. A general treatment has not yet been found. The best defense against cancer is early detection, when tumor dimensions are very small. The methods as mammography, ultrasounds, MRI, CT, etc., can detect anatomic or structural changes like tumors and cysts. They are anatomical imaging procedures, consequently, they have the ability to locate the area of the tumor, but they cannot detect a fast-growing cancer in the pre-invasive stage. Thermograms are looking for the physiologic changes in tissue; which may indicate a risk of developing cancer in the future. The results using a new device, operating in infrared band, are described. The paper focuses on thyroid cancer because it allows investigations on larger areas before surgery and on residual, smaller areas following surgery. The experiment results for 24 patients with thyroid nodules are described. Malign tumors have a distinct infrared signature. Only the area affected is thermal registered and that has an irregular shape and a strong nonuniform structure with rapid variations on skin temperature.

Propagation of light in a cubic scattering region containing different concentrations of polystyrene spheres in water was calculated. Therefore an analytical solution of Maxwell theory was applied, as well as a numerical solution of radiative transfer theory. Apart from differences in the calculated differential scattering cross sections at small and large scattering angles, a comparison of both methods showed only small deviations for almost the whole angle range. This indicates the usefulness of radiative transfer theory for concentrations up to 20% as a fast approximative method to describe multisphere scattering.

A novel method for evaluation of bacteria colonies concentration based on optical spectra examination, is proposed. The influence of bacteria colonies number on Fourier spectrum properties is considered in term of scalar diffraction theory and corresponding theoretical model is presented. Computational simulations are performed to confirm the theoretical predictions. Additionally, optical Mellin transform is used to omit the dependence of Fourier spectrum pattern on bacteria colonies size fluctuations and to provide a scale-invariant analysis. Presented results have shown high potential of the proposed approach for comparative study of bacteria colonies grown on solid medium in vitro.

The interconnection between geometry of biological tissue structure with their polarization properties has been studied. It has been shown that for physiologically normal biological tissues polarization properties of radiation scattered on architectonic nets formed by protein fibrils possess the fractal character. Pathological changes of biological tissues architectonics are accompanied with the transformation of self-similar structure of Mueller-matrix images into stochastic and statistic ones.

Monitoring the epithelium vessel capillary density pattern is critically important for preventing rapidly developing life threatening syndromes such as shock or systemic organ failures. The objective of this study is real time monitoring of epithelium vessel density pattern. The fiber sensor will be based on spatially resolved diffuse reflectance spectra. The parameters comprising period and depth of capillary spatial modulation are exploited for shock detection. The preliminary investigations with simulated spectra have shown that the new method can reasonably extracts minor deviations of oxygenation and local volume blood fraction - parameters, directly related to the local vessel density. The original method developed to use these parameters is much less dependent on light scattering in visible range as opposed to the most of the currently used methods.

This work is directed to the investigation of the scope of the technique of laser polarimetry of oncological changes of the human prostate tissue under the conditions of multiple scattering, which presents a more general and real experimental clinical situation. To compare the above mentioned scope of biotissue laser polarimetry on the first stage the research of human prostate tissue in the conditions of single scattering was performed. The analysis of the obtained results showed high diagnostic sensitivity of statistic moments of the 3rd and 4th orders of coordinate distributions of matrix elements of both types of biotissues to the changes of optical-geometric structure.

In this work measurements of the acoustic attenuation coefficient for water in the frequency range of 20-40 Mhz have been performed. These measurements have been conducted with a photoacoustic setup, containing a nano second pulse laser and an integrating line detector. The nanosecond pulse laser is used to generate ultra sound waves in a target. Those waves are transmitted into water and are then detected by the line sensor. In this way the resulting ultra sound field was scanned and the absorption coefficient was evaluated. Different pulse energies, beam diameters and target materials were used. The resulting coefficients are in the range of the reported values found in literature.