This PDF file contains the front matter associated with SPIE Proceedings Volume 6852, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Autonomic Dysreflexia (AD) is an inappropriate response of the sympathetic nervous system that often occurs in individuals with spinal cord injury (SCI ) at or above the sixth thoracic vertebrae (T6) level when a noxius stimulus is applied below the level of injury. An AD event can be put into motion by something as simple as an ingrown toenail or a full bladder, with symptoms such as headache, elevated blood pressure, reduced heart rate, decreases in blood flow below the level of injury, and in extreme cases, stroke. We have developed a quantitative method of measuring skin oxygen levels during AD using a fiber optics based probe. Two such probes were located above and below the injury level (on the patient forearm and thigh respectively) and were connected to a dual channel spectrophotometer. Oxygen saturation was calculated using the reflectance spectra and an algorithm based on melanin and hemoglobin absorption. We found that during an AD event, the amount of oxygen in the skin below the injury level drops by as much as 40%, while above the injury level skin oxygenation remains constant. Additionally, we observed elevated persperation levels below the injury level. We hypothesize that the combination of AD-related ischemia with pressure related ischemia and increased perspiration places individuals with injury level at T6 or above at significant risk for developing a pressure sore below the injury site.

In this paper we are reporting the development of a highly sensitive evanescent wave combination tapered fiber optic fluorosensor. We have demonstrated detection of 5 pM Bovine Serum Albumin (BSA) protein using these fiber optic sensors. The sensor can be easily adopted for detection of other proteins. Six identical probes were prepared and affinity pure Goat anti-BSA antibodies were immobilized on the probe surface. We could detect signal from all the probes kept in 5 pM to 1 nM BSA solution while no signal was detected from the probes kept in 20 nM labeled ESA solution.

This work demonstrates the use of a highly sensitive Liquid Core Photonic Crystal Fiber (LCPCF) Surface Enhanced Raman Scattering (SERS) sensor in detecting biological and biochemical molecules. The Photonic Crystal Fiber (PCF) probe was prepared by carefully sealing the cladding holes using a fusion splicer while leaving the central hollow core open, which ensures that the liquid mixture of the analyte and silver nanoparticles only fills in the hollow core of the PCF, therefore preserving the photonic bandgap. The dependence of the SERS signal on the excitation power and sample concentration was fully characterized using Rhodamine 6G (R6G) molecules. The result shows that the LCPCF sensor has significant advantages over flat surface SERS detections at lower concentrations. This is attributed to the lower absorption at lower concentration leading to a longer effective interaction length inside the LCPCF, which in turn, results in a stronger SERS signal. Several biomolecules, such as Prostate Specific Antigen (PSA) and alpha-synuclein, which are indicators of prostate cancer and Parkinson's disease, respectively, and fail to be detected directly, are successfully detected by the LCPCF sensor. Our results demonstrate the potential of the LCPCF SERS sensor for biomedical detection at low concentrations.

Recently, the number of pixels of an image sensor has reached more than one Mega in the field of video endoscopes, while analog signal transmission bands that use existing electric wires will face physical limitations from the perspective of signal bandwidth and EMC (Electro Magnetic Compatibility) noise. In order to solve these problems, we have developed a bi-directional digital optical communication endoscope system that employs both an image sensor and a single line optical fiber. In addition, due to the fiber's high-speed image signal transmission, we have incorporated a digital circuit for serial modulation and deserial demodulation. Consequently, we confirmed that transmission speeds of a 1Gbps downlink image signal and a 110Kbps uplink control signal were achieved as a result of simultaneous communication. We also designed and tested a compact, co-axial bi-directional optical transmitter and receiver module that can be built into the distal side of a scope. The optical communication module size is less than φ4×10mm. It was confirmed that this module could be installed in the distal side of a current endoscope.

Side-polished fiber immunosensor based on surface plasmon resonance (SPR) onto self-assembled protein A layer was proposed for the detection of Legionella pneumophila. A self-assembled protein A layer on gold (Au) surface was fabricated by adsorbing a mixture of 11-mercaptoundecanoic acid (MUA) and activated by N-Ethyl-N'-(3-dimethylaminopropyl) carbodiimide/ N-Hydroxysuccinimide (EDC/NHS). The formation of self-assembled protein A and gold layer on side-polished surface and the binding of antibody and antigen in series were confirmed by SPR response on spectrum. The binding protein A layer can improve the sensitivity, which indirectly supports the configurations that antibody layer is immobilized on the binding protein A layer with a well-ordered orientation. The surface morphology analyses of self-assembled protein A layer on Au substrate and monoclonal antibody against L. pneumophila immobilized on protein A were demonstrated by SPR dip shifts on optical spectrum analyzer. The SPR fiber immunosensor for detection of L. pneumophila was developed and the detection limit was 10 CFU/ml with the SPR dip shift in wavelength from 1070 to 1105nm. The current fabrication technique of a SPR immunosensor using optical fiber for the detection of Legionella pneumophila could be applied to construct other biosensor.

Flexible endoscopes use one sensor element per display pixel. When diameter is reduced to the size of a catheter, there is a significant reduction in the number of pixels within the image. By placing a sub-millimeter microscanner at the tip of a catheter, image quality can be significantly improved. The microscanner consists of a 0.4 mm diameter piezoelectric tube with quadrant electrodes, surrounding a cantilevered singlemode optical fiber. At the distal end, the fiber microscanner is sealed with a 0.9 mm diameter lens assembly, creating a rigid length less than 10 mm at the tip of a highly flexible shaft. The cantilevered fiber is vibrated at the first mode of resonance for bending to generate a circular scan pattern. A spiral scan pattern is generated that constitutes an image frame by modulating the piezoelectric drive signals. By using a custom optical fiber at 80 microns cladding diameter, >10 KHz resonant scanning is achieved, resulting in a 30 Hz frame rate. Red (635 nm), green (532 nm), and blue (442 nm) laser light is scanned by coupling to the fiber scanner. The scanned illumination is detected in a non-confocal arrangement by having one or more optical fibers collecting the backscattered light at MHz pixel rates. Current 1-mm diameter catheterscopes generate 500-line images at maximum fields of view of 100 degrees and spatial resolutions of <20 microns with image zooming. Shaft length of four meters have been fabricated with flexibility of <10 mm bending radius to image previously inaccessible regions of the body.

Infrared-transmitting glass optical fibres are being developed for intended applications in medicine and industry as part of a laser delivery system, giving more flexibility and accuracy of positioning of the laser beam for the User. Chalcogenide glass optical fibre is being designed to transmit light at 10.6 μm, to coincide with the wavelength of the output light from the CO₂ laser. In medicine, ablative surgery performed using the CO₂ laser causes less damage to surrounding tissue than when using shorter wavelength laser sources. The effect of composition of chalcogenide glasses on optical absorption, across the wavelength range 3 μm to > 15 μm, has been investigated using Fourier transform infrared (FTIR) spectroscopy, for a range of binary, ternary and quaternary glasses, in the form of small bulk glass specimens. Glasses containing germanium tended to exhibit higher glass transformation temperatures but a shorter wavelength multiphonon edge. The optical loss of fibre samples has been measured at 10.6 μm using a high power CO₂ laser source and employing the fibre cut-back method. As₂Se and Te₃₀As₂₀Se₅₀ fibres (both unclad) exhibited 7.2, and 2.3, dBm^-1, respectively. Ge₁₇As₁₈Se₆₅ / Ge₁₇As₁₈Se₆₂S₃ core/clad. fibre exhibited an optical loss of 10.3 dBm^-1. After the optical loss measurements, fibres were imaged using scanning electron microscopy and it was found that the high power CO₂ laser caused damage to the launch end of some fibres. In particular, at the launch-end of Te-As-Se fibres the glass appeared to have undergone partial melting and possibly also suffered some vaporisation.

UV solarization resistance of synthetic silica/silica fibers has been researched over many years. Fiber optic probes for applications as diverse as protein analysis, dissolution testing or high pressure liquid chromatography have been developed and successfully commercialized. Although fabrication technology for optical fibers has improved significantly and optical losses due to solarization effects have been minimized in synthetic silica fibers, the generation of UV induced defects in silica fibers due to the generation of E'centers visible in the 215 nm region is still present and can interfere with sensitive spectroscopic absorbance measurements. This work presents methodology to determine the transient response of optical fibers in the 200 nm to 300 nm region during the warm up period and during measurement as a function of light power coupled into the fiber, fiber length and fiber diameter.

Recently, quality factors greater than 100 million were demonstrated using planar arrays of silica microtoroid resonators. These high Q factors allow the toroidal resonators to perform very sensitive detection experiments. By functionalizing the silica surface of the toroid with biotin, the toroidal resonators become both specific and sensitive detectors for Streptavidin. One application of this sensor is performing detection in lysates. To mimic this type of environment, additional solutions of Streptavidin were prepared which also contained high concentrations (nM and μM) of tryptophan.

Hazardous material sensing such as chemical agents, has become an important issue due to terrorist threats. In this work we examine the possibility of using a hollow waveguide as a sensor for chemical material sensing using only one wavelength. We propose to coat the waveguide with a dielectric layer that is sensitive to a certain chemical agent. Once such an agent interacts with the dielectric layer, it changes the index of refraction of the layer and therefore the waveguides transmission at the chosen wavelength. Using our ray model we have conducted a theoretical investigation of the suggested sensor and applied it to three chemical agents; Tabun, Ammonia and Hydrogen Cyanide.

Compared to other transparent infrared fiber materials, ZBLAN fluoride glasses promise to be best suited for laser power delivery in the 3μm wavelength region due to their high transmission and excellent mechanical flexibility. These claims were demonstrated in a series of power handling tests of both straight and coiled fibers using an Er,Cr:YSGG laser emitting a train of pulses of 150 μs duration at a repetition frequency of 20 Hz producing 7.5 W average power. Large core fibers (450/510μm 0,2NA) are characterized by an attenuation of 0.02dB/m at 3μm and stay within 0.5°C from ambient temperature when carrying full laser power. A 2-m fiber length prepared with bare cleaves has been tested for over 23 hours, cumulating 1,140,000 shots of 1530 J/cm² fluence while maintaining 90% transmission without any measurable degradation. Coiling the fiber to 11 cm radius did not have an impact on power handling reliability. These results show the potential of these highly transparent fibers in surgical laser delivery applications.

Laser ablation experiments on hard tissues are performed by guiding combined beam of Ho:YAG and Er:YAG laser light with a hollow optical fiber. An alumina ball is used as a hard-tissue model and ablation phenomenon are observed by an ultra-high-speed camera. The result show that the two laser light give dissimilar ablation effects due to different absorption coefficients in water contained in the tissues. When the two lasers are combined and irradiate on the model, a high ablation rate is observed.

An optical fiber sensor based on evanescent wave sensing and excitation light resonance using a pair of optical reflectors adjacent to two ends of the optical fiber is presented. Excitation light is coupled into the fiber optical sensor through a hole in the first reflector. The excitation light starts to resonate between the reflectors, and results in the amplification of the fluorescent signal, which is generated by the excitation of the analyte binding to the surface of the active fiber sensing area. This device was successfully demonstrated in achieving over 600% amplification in the output signal. This design provides a simple and efficient method in improving the S/N and the sensitivity of the optical fiber evanescent wave sensor over the traditional approach.

Biomedical optical imaging technologies based on optical fibers have been of great interest because of their superiority over conventional bulk-optic counter part in size and integration. Flexible endoscope is a key component to deliver the reflected optical signal from biological tissue to the optical imaging system, such as Optical Coherence Tomography (OCT) and Fiber Confocal Microscopy (FCM). However, conventional optical fibers for the biomedical imaging endoscope have been suffered from a critical wiring problem of a fiber waveguide, which induces additional loss severely. In this work, we have shown excellent properties of holey optical fibers with low bending loss under a minimum bending radius of 10 mm or less, which is almost reaching the wiring limit of endoscope. A curled optical patch cord, like a curled telephone cord, is practically demonstrated for the convenient access of imaging probe to the biological target at the flexible distance. The quality improvement of optical imaging is compared to show the great potential for the endoscopic OCT and endoscopic FCM.

We have developed a single mode fiber-light source at 1.8um band, which composes of thulium (Tm)-doped silica fiber and optical devices used in telecommunication fields. This laser can be operated as a laser and broadband light source selectively. The laser wavelength is tuned from 1765nm to 1812nm by adjusting an angle of a built-in band pass filter (BPF). A maximum output power is 115mW at 1812nm, in the case that pump power is 363mW. The broadband light source has a maximum power of 10mW, the peak wavelength of 1840nm and the full width at half maximum of 50nm. By using these light sources, we have succeeded in obtaining images of test target by observing reflected light through opaque liquid.

Many configurations of fiber optic evanescent wave sensors have recently been explored, with various structural and material modifications applied in attempt to increase their resolution and/or sensitivity. With the aid of long period gratings inscribed within the core of standard single mode fibers, fiber optic evanescent wave sensors with in-fiber interferometric configurations have been realized and have been shown to have excellent resolution due to sharp spectral features. The Michelson interferometer configuration, whereby a single long period grating acts as a beam splitter for the core and cladding modes, is of interest because it operates in reflection mode, which allows for easy signal detection schemes. In this work, it is experimentally demonstrated for the first time that the deposition of a nanoparticle-polymer composite high refractive index overlay film onto the cladding arm surface of such an interferometric sensor greatly increases its sensitivity. Film refractive indices of > 1.7 are achieved and can be further increased to > 2 upon repetition of the nanoparticle synthesis cycle. Sensitivity enhancement factors as large as 16.7 occur in the film index range of 1.9 - 2.1. Experimental data are presented and compared to the theoretical simulation results.

A new approach to virus detection in an aqueous environment has been developed using the electrophoretic deposition of protein and viruses on a charged surface for in situ infrared characterization and identification. In this study, a potential was applied across a germanium ATR crystal, which acted as the anode, and an indium tin oxide (ITO) plate, which acted as the cathode in the electrodeposition setup. Sample aqueous solutions were placed between the germanium and the ITO with different concentrations of the protein bovine serum albumin (BSA) and the virus MS2, in tap water. The pH of the tap water was above the isoelectric point of the virus and the protein, resulting in a net negative charge for both. The negatively charged protein and virus were then driven to the surface of the positively charged germanium ATR crystal, once a potential was applied to the system. FTIR/ATR was used before and throughout electrodeposition to enable the in situ observation of the deposition with time. In this study, we evaluate the capture efficiency, compared to control experiments with no applied voltage, and the feasibility of using this approach for the collection and quantification of proteins and viruses from water samples. This technique resulted in the successful deposition of BSA, and MS2 with an applied voltage of only 1.1V. Furthermore, based on the analysis of the ATR spectra, distinct spectral features were identified for the protein and virus showing the potential for identification and characterization of biological molecules in an aqueous environment.

Radiation doses used in radiation therapy are calculated during the course of treatment planning. Cross-validation of calculated dose versus received dose is performed mostly in-vitro and may not represent actual therapy doses. In vivo measurements are at best typically limited to a few surface points. Presently, dose is measured primarily with diodes, thermoluminescent or MOSFET dosimeters. Their outer sizes are in the range of 3 mm, which are unpractical for in vivo internal use, in particular for interstitial or intracavital brachytherapy. In addition, diode and MOSFET sensors are individually tethered to cables and are therefore inconvenient for making multiple point measurements. Feasibility of multiple point radiation dosimetry using luminescent optical fibers for in vivo dosimetry during radiation therapy is described that overcomes these difficulties. The spectral response of a candidate rare-earth doped optical fiber dosimetric probe is reported, having 0.5 rads/cm sensitivity. This sensor capability would enable continuous radiation monitoring of dose and dose rate during therapy at multiple locations along the sensor fiber.

Infrared-transmissive hollow waveguides (HWGs) are enjoying resurgence as they are now being used in lengths less than 10 m for sensor and power delivery applications. HWGs are routinely fabricated with losses less than 1 dB/m from 2 to 12 μm. Most of the hollow structures involve silica or plastic tubing with an inside thin metallic film followed by a dielectric coating to enhance the reflectivity. In this paper current HWG technologies will be reviewed and several sensor and power delivery applications discussed.

Light delivery and optical monitoring during photodynamic therapy (PDT) is often limited by the need for a physical optical link between the light source and detection devices and the treatment volume. This can be critical when sources need to be implanted within the body for extended periods. We report on the latest developments for a telemetric PDT delivery and monitoring device that can dynamically vary the local illumination parameters based on the in-situ fluence rate within the PDT target volume. Local light delivery and collection is achieved using solid-state optodes, microfabricated on a silicon substrate. Photodiodes have been produced using a standard bipolar process. Chip-form LEDs are then assembled into micro-machined pits adjacent to the light fluence rate detectors. The devices (1.2×1.2mm²) are bonded to a flexible PCB together with the remaining electronics. Power coupling and communications are achieved by means of an inductive link while light delivery and fluence rate monitoring are digitally managed using a microcontroller. These devices are being tested in optical phantoms and in pre-clinical models. Our results show that it is possible to manufacture solid-state optodes of suitable dimensions and that it is feasible to telemetrically deliver and control the local fluence rate using them. It can also be concluded from our work that while the optode is sufficiently small to be useful as a light delivery and monitoring device, digital control, read-out electronics and power coupling can benefit from further optimization and miniaturization.

Damage to optical fiber for medical laser delivery has been observed where the fiber is routinely bent while transmitting high power laser light. In an effort to understand the failure mechanism we measured the temperatures of bent sections of several different types of fibers with different bend diameters. We will discuss our results and some aspects of possible failure mechanisms.

We measured the localized transient temperature of Ho:YAG laser induced bubble in water by infrared radiation measurement with a infrared optical fiber to study heat effect/damage of this bubble for vascular therapeutic applications. Although there have been many reports regarding to the temperature in the Ho:YAG laser induced bubble by both theoretical and experimental approaches, we can not find well-time-response reliable temperature in the laser induced bubble. We constructed the remote temperature measurement system to obtain the temperature of the laser induced bubble with the infrared optical fiber (Optran MIR, CeramOptec) made of AgCl/AgBr with 1mm in core diameter. The flash lamp excited Ho: YAG laser (IH102, NIIC,λ=2.1μm) beam was delivered through a silica optical fiber (core diameter: 600μm) and was irradiated from the fiber tip in water. The tip position of the infrared optical fiber against the silica glass fiber was changed to measure local bubble temperature. The sidewall of the infrared optical fiber tip was covered by a black rubber tube to prevent the collection of the Ho:YAG laser into the infrared fiber. The infrared radiation delivered through the infrared optical fiber was measured by the HgCdTe infrared detector (KMPC12-2-J1, Kolmar Technologies, rise time:500ns). This fiber optic radiation detection system was calibrated before the bubble temperature measurement. Since the bubble boundary location and its shape were changed with time, we corrected influences of these factors. We finally obtained the peak temperature of 61.7±2.8°C at the top surface in the laser induced bubble with 800mJ/pulse. This temperature was 10 degree lower than that of reported. The temperature at the top of the bubble was approximately 9.8 degree higher than that at the bubble side. Obtained temperature distribution with time may be available to study bubble dynamics necessary for our vascular applications.

Extremely flexible hollow fibers with 100 μm-bore size were developed for infrared laser delivery. The hollow fiber was inner coated with silver and a dielectric layer to enhance the reflection rate at an objective wavelength band. The silver layer was plated by using the conventional silver mirror-plating technique. And a thin dielectric layer was coated for low-loss transmission of Nd:YAG and Er:YAG laser light.

Laser spectroscopy in the UV-region below 380 nm is a powerful tool for many biomedical or analytical applications. For such purposes Polymer Optical Fibers (POFs) can be an interesting alternative to silica-based optical fibers if the transmission in the UV-A region is sufficient. In addition to high-power LED-light delivery shown in previous studies, the short and long term performance of PMMA-based POFs under pulsed UV radiation was investigated using a nitrogen laser at 337 nm and the 3rd harmonic of Nd:YAG laser at 355 nm. For thick POFs (core diameter: approx. 1000 μm), the basic (initial) low intensity UV-attenuation is in the order of less than 2 dB/m. However, a typical initial attenuation between 4 and 5 dB/m was determined using the pulsed UV-lasers. At 337 nm, the transmission for these POF is independent of intensity up to 9 MW/cm². No photodegradation was observed, up to 180k pulses if the intensity does not exceed 6 MW/cm². For both wavelengths, the surface damages have been observed, taking into account the differently shaped intensity-profiles.

A theoretical model using ray tracing method is developed. The results predicted by the model were confirmed by experimental results. The model could explain the experimentally observed fact that the maximum signal for a given realistic tapered length is at a probe radius smaller than that expected from V-number matching condition. It is shown that for obtaining maximum fluorescence signal from an evanescent wave fiber optic biosensor a realistic optimum taper length needs to be chosen. We found that different detection environments require different taper lengths at a given taper angle. These facts were confirmed experimentally.

The delivery of the radiation by thin fiber is required for some application, especially in medical internals treatment. Therefore a new 100 μm and 250 μm inner diameter hollow glass waveguides were developed and investigated for the possibility to transport high power near infrared laser radiation without damage of these delivery systems. As laser sources two Nd:YAG laser systems working in Q-switched regime at wavelength 1.06 μm and 1.34 μm were utilized. Delivered radiation characterization was performed. By Alexandrite laser (755 nm) pumped Q-switched Nd:YAG laser has been generating 1.06 μm wavelength radiation with 6 ns length of pulse and maximum output energy 0.7 mJ (116.7 kW). The laser was Q-switched using LiF:F^2- saturable absorber. Second laser system was Nd:YAG/V:YAG microchip pumped by laser diode operating at 808 nm. The radiation at 1.3 μm wavelength has been generated with 250 Hz repetition rate. Pulse length was 6 ns and mean output power 25 mW. Corresponding pulse energy and peak power was 0.1 mJ and 16.7 kW, respectively. Both lasers were operating in fundamental TEM₀₀ mode (M² ~ 1). For delivery a special cyclic olefin polymer-coated silver hollow glass waveguides with the inner/outer diameters 100/190 μm and 250/360 μm were used. The delivery system was consisted of lens, protector, and waveguide. As results the transmission more than 55% and reasonable spatial profile of laser output radiation were found. From these measurements it can be recommended using of this system for near infrared powerful radiation delivery as well as for medical treatment.

Background: High brightness light emitting diodes (LEDs) have become available that appear suitable to replace light sources currently used for illumination through thin light guides, e.g. in endoscopy. We investigated the essential characteristics of a series of commercial single LEDs relevant for direct coupling to a single optical multimode fiber. Methods: LED fiber coupling efficiency was assessed experimentally and theoretically by using a ray tracing software. Results: Surface emitting LEDs proved suitable to be coupled directly into plastic optical fibers (POFs). We have successfully applied a 1 mm core POF-fiber (outer diameter 1.01 mm) in contact with a OSTAR LED (Osram Opto Semiconductors, Regensburg, Germany) to achieve a coupling efficiency of 10-20%, which gave 42 mW, 23.7 mW and 27 mW for blue, green and red LED respectively. Ray tracing simulation revealed a considerable part of photons travelling "out of axis" in spirals along the core-clad interface (non-meridional beams). They account for approximately 30% of the transmitted power.