This PDF file contains the front matter associated with SPIE Proceedings volume 7558, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

An ultrathin scanning fiber endoscope (SFE) has been developed for high resolution imaging of regions in the body that are commonly inaccessible. The SFE produces 500 line color images at 30 Hz frame rate while maintaining a 1.2-1.7 mm outer diameter. The distal tip of the SFE houses a 9 mm rigid scan engine attached to a highly flexible tether (minimum bend radius < 8 mm) comprised of optical fibers and electrical wires within a protective sheath. Unlike other ultrathin technologies, the unique characteristics of this system have allowed the SFE to navigate narrow passages without sacrificing image quality. To date, the SFE has been used for in vivo imaging of the bile duct, esophagus and peripheral airways. In this study, the standard SFE operation was tailored to capture wide field fluorescence images and spectra. Green (523 nm) and blue (440 nm) lasers were used as illumination sources, while the white balance gain values were adjusted to accentuate red fluorescence signal. To demonstrate wide field fluorescence imaging of small lumens, the SFE was inserted into a phantom model of a human pancreatobiliary tract and navigated to a custom fluorescent target. Both wide field fluorescence and standard color images of the target were captured to demonstrate multimodal imaging.

To reduce the number of invasive tissue biopsies and needle aspirations performed during cancer screenings, endomicroscopes can be used to image tissue in vivo. However, when optical fiber bundles are used to transmit the image, the resolution of such systems is limited by undersampling due to the spacing of the bundle's individual fibers for a given field of view. We propose a method to increase the sampling of an optical biopsy system and thereby improve the system's resolution. The method involves taking several images, shifting the object and fiber bundle slightly relative to each other from one image to the next. Multiple shifting patterns were evaluated to determine which provided the greatest increase in resolution. The shifted images are later realigned and recombined by a custom algorithm. By combining four shifted images of a USAF resolution target, we were able to measure an improvement in the resolution of the system from approximately 3.9 μm to 2.2 μm. When tested on cultured cells, a visible increase in detail was detectable. This technique can provide the basis for improving the diagnostic abilities of optical biopsy systems.

There is always a tradeoff between resolution and Field of View (FOV) in an imaging system. This limit can be due to the number of pixels in the detector, however a fundamental limit also exists in any optical system called the Space Bandwidth Product (SBP) which scales as the FOV area divided by the area of the diffraction limited spot. The SBP can only be increased by increasing the size of the optical system. In applications where the size of the optical system is constrained such as endoscopes, the SBC will ultimately limit the resolution or FOV. However, there is a way to provide both high resolution and a wide FOV without changing the total number of pixels in the image. The technique is called foveated imaging because is mimics this characteristic of the human eye in which the fovea has a higher resolution at the center of the FOV than the surrounding retina. A similar effect can be achieved optically by introducing a large amount of barrel distortion in the lens design. The result is an effective increase in the magnification at the center of the FOV, and reduced resolution but larger angular sampling at the edge. The stretching effect of the distortion can be compensated for computationally to provide an onscreen display that is not distorted, but merely appears blurred at the edges. Such an objective will enable for endomicroscopy while still providing "peripheral vision" to allow endoscopists to navigate and locate regions of interest.

Slit-scanning geometries for confocal microendoscopy represent a compromise between acquisition rate and optical performance. Such systems provide high frame rates that freeze motion but recent Monte Carlo simulations show that scattered light severely limits the practical imaging depth for in vivo applications. A new multi-point scanning architecture for confocal microendoscopy has been developed. The new scanner is based on a relatively simple modification to the slit-scanning geometry that results in a parallelized point-scanning confocal microendoscope that maintains the high frame rate of a slit-scanning system while providing optical performance close to that of a single point scanning system. The multi-point scanner has been incorporated into an existing multi-spectral slit-scanning confocal microendoscope. The new confocal aperture consists of a slit and a rotating low duty cycle binary transmission grating, which effectively produces a set of continuously moving widely spaced illumination points along the slit. The design maintains the ability to rapidly switch between grayscale and multi-spectral imaging modes. The improved axial resolution of the multi-point scanning confocal microendoscope leads to significantly better confocal sectioning and deeper imaging, which greatly improves the diagnostic potential of the instrument.

An endoscope capable of Coherent Anti-Stokes Raman scattering (CARS) imaging would be of significant clinical value for improving early detection of endoluminal cancers. However, developing this technology is challenging for many reasons. First, nonlinear imaging techniques such as CARS are single point measurements thus requiring fast scanning in a small footprint if video rate is to be achieved. Moreover, the intrinsic nonlinearity of this modality imposes several technical constraints and limitations, mainly related to pulse and beam distortions that occur within the optical fiber and the focusing objective. Here, we describe the design and report modeling results of a new CARS endoscope. The miniature microscope objective design and its anticipated performance are presented, along with its compatibility with a new spiral scanningfiber imaging technology developed at the University of Washington. This technology has ideal attributes for clinical use, with its small footprint, adjustable field-of-view and high spatial-resolution. This compact hybrid fiber-based endoscopic CARS imaging design is anticipated to have a wide clinical applicability.

The use of white or color tunable LEDs (light-emitting diodes), which can replace a large light source apparatus and light-guiding fiber bundle, enable the miniaturization of the whole endoscope system and remove constraints on the design of its shape. We have developed a novel white LED for a new experimental prototype LED-illuminated gastrointestinal endoscope having the color rendering in the clinically important red range at around 600 nm.­

We demonstrate the implementation of a Fourier domain optical coherence tomography (OCT) imaging system incorporated into the optical train of a fluorescence confocal microendoscope. The slit-scanning confocal system has been presented previously and achieves 3μm lateral resolution and 25μm axial resolution over a field of view of 430μm. Its multi-spectral mode of operation captures images with 6nm average spectral resolution. To incorporate OCT imaging, a common-path interferometer is made with a super luminescent diode and a reference coverslip located at the distal end of the fiber bundle catheter. The infrared diode spectral width allows a theoretical OCT axial resolution of 12.9μm. Light from the reference and sample combine, and a diffraction grating produces a spectral interferogram on the same 2D CCD camera used for confocal microendoscopic imaging. OCT depth information is recovered by a Fourier transform along the spectral dispersion direction. Proper operation of the system scan mirrors allows rapid switching between confocal and OCT imaging modes. The OCT extension takes advantage of the slit geometry, so that a 2D image is acquired without scanning. Combining confocal and OCT imaging modalities provides a more comprehensive view of tissue and the potential to improve disease diagnosis. A preliminary bench-top system design and imaging results are presented.

Barrett's esophagus (BE) with high-grade dysplasia is generally treated by endoscopic mucosal resection or esophagectomy. Radiofrequency ablation (RFA) is a recent treatment that allows broad and superficial ablation for BE. Endoscopic three-dimensional optical coherence tomography (3D-OCT) is a volumetric imaging technique that is uniquely suited for follow-up surveillance of RFA treatment. 3D-OCT uses a thin fiberoptic imaging catheter placed down the working channel of a conventional endoscope. 3D-OCT enables en face and cross-sectional evaluation of the esophagus for detection of residual BE, neo-squamous mucosa, or buried BE glands. Patients who had undergone RFA treatment with the BARRX HALO90 system were recruited and imaged with endoscopic 3D-OCT before and after (3-25 months) RFA treatment. 3D-OCT findings were compared to pinch biopsy to confirm the presence or absence of squamous epithelium or buried BE glands following RFA. Gastric, BE, and squamous epithelium were readily distinguished from 3D-OCT over a large volumetric field of view (8mmx20mmx1.6 mm) with ~5μm axial resolution. In all patients, neosquamous epithelium (NSE) was observed in regions previously treated with RFA. A small number of isolated glands were found buried beneath the regenerated NSE and lamina propria. NSE is a marker of successful ablative therapy, while buried glands may have malignant potential and are difficult to detect using conventional video endoscopy and random biopsy. Buried glands were not observed with pinch biopsy due to their extremely sparse distribution. These results indicate a potential benefit of endoscopic 3D-OCT for follow-up assessment of ablative treatments for BE.

The long-term purpose of this project is to build inexpensive endomicroscope systems from optical plastics that operate over a wide spectral range. We report on a design of a plastic achromatic doublet using PMMA and optical grade polystyrene, as well as a design of an achromatized endomicroscope system using the same materials. The fabrication of such optical elements and systems is feasible using methods such as diamond turning or diamond milling. Finally, a multispectral Shack-Hartmann test bed has been created that can measure the chromatic focal shift of a lens over a broad spectral band (from 400 nm to 1,000 nm) and detect shifts in focal length down to 90 nanometers. The multispectral Shack-Hartmann test bed has been used to characterize the chromatic focal shift of a glass singlet lens and a glass achromat triplet lens. The lenses were tested from 500 nm to 700 nm in 5 nm and 10 nm steps, respectively. In both cases, we found close agreement between test results obtained from a ZEMAX model of the test bed and those obtained by experiment.

A new focused OCT-LIF endoscope has been constructed for high resolution imaging between 325 nm and 1300 nm. This endoscope is 2 mm in diameter for non-destructive imaging in vivo. A reflective design ball lens is employed that eliminates the difficulty of operating achromatically over a large range, while taking advantage of TIR at two faces and coating a third mirror face internally to focus the beams downwards. It is a 1:1 imaging system that obtains a theoretical diffraction-limited resolution for both the OCT (800-1300 nm) and LIF (greater than 325 nm) channels.

Endoscopic imaging in tubular structures, such as the tracheobronchial tree, could benefit from imaging optics with an extended depth of focus (DOF). This optics could accommodate for varying sizes of tubular structures across patients and along the tree within a single patient. In the paper, we demonstrate an extended DOF without sacrificing resolution showing rotational images in biological tubular samples with 2.5 μm axial resolution, 10 ìm lateral resolution, and > 4 mm depth range using a custom designed probe.

Recently, optical imaging system is widely used in medical purpose. By using optical imaging system specific diseases can be easily diagnosed at early stage because optical imaging system has high resolution performance and various imaging method. These methods are used to get high resolution image of human body and can be used to verify whether the cell is infected by virus. Confocal microscope is one of the famous imaging systems which is used for in-vivo imaging. Because most of diseases are accompanied with cellular level changes, doctors can diagnosis at early stage by observing the cellular image of human organ. Current research is focused in the development of endo-microscope that has great advantage in accessibility to human body. In this research, I designed small probe that is connected to confocal microscope through optical fiber bundle and work as endo-microscope. And this small probe is mainly designed to correct chromatic aberration to use various laser sources for both fluorescence type and reflection type confocal images. By using two kinds of laser sources at the same time we demonstrated multi-modality confocal endo-microscope.

Minimally invasive surgical procedures or examinations require increasingly sophisticated devices to explore the interior of the patient's body. The new generation of medical scopes takes advantage of the recent progresses in optic miniaturization and high resolution imaging sensors (1.3MP). Even with such high resolution, the endoscopic vision remains quite different than human vision, especially regarding the field of view. Several optical systems have been developed to meet large field of view requirements. However most of these optical systems suffer from low resolution or poor quality. This paper presents the results of our investigation of a new innovative approach based on a wide angle panomorph lens designed for endoscopes and its dedicated visualisation software. This lens is based on human vision which increases the resolution in the field of view of interest to meet the image quality requirement specific to endoscopic applications. We show how the wide angle field of view, augmented resolution, close focus and distortion-free multi-visualisation software can improve laparoscopic and other endoscopic procedures.