While RGB imaging is reaching its limits, Hyperspectral Imaging (HSI) is being widely used especially for medical applications. This study points out the ability of HSI technique to help in planning the surgical procedure in orthopedic surgery by automatically identifying anatomical structures and surgical instruments thanks to their spectral signatures. Four segmentation methods have been explored: (i) average spectra method that uses the Euclidean distance between the spectrum of each pixel and the average spectrum of each specific structure, (ii) segmentation using kmeans, (iii) segmentation based on indices in which we identify reflectances ratios at specific wavelengths that allow materials to be correctly classified, (iv) and finally a pixel-based classification method based on neural networks. Experiments on anatomical objects whose physical characteristics are known to have been carried out. Selecting specific wavelengths to reduce the cost of the final device was also discussed.
Polarization-resolved extension of Second Harmonic Generation microscopy (PSHG) exhibits proven efficiency in cancer diagnosis. Contrary to the case of white light microscopy, PSHG can reveal small structural collagen changes, during tumorigenesis, for a broad range of organs such as breast, thyroid, lung, pancreas, and ovary. However, despite its effectiveness for cancer diagnosis, PSHG is not yet fully exploited. One way of improvement consists in taking better advantage of polarization-resolved measurements which are performed by acquiring multiple images (usually between three to 20) of the same sample under different input beam polarization conditions. Each image of the resulting stacked raw images set can contain relevant information not found in the other images of the set. In the literature, information extraction from stacked raw images is performed using methods such as averaging of all images, collagen structural parameters modeling or PSHG polarimetric parameters extraction. If the two latter methods provide a richer information than the first one, they may, however, suffer from a loss of information from the stacked raw images. To examine this potential loss of information, AI methods can be used for extracting information from the stacked raw images. Using recently available images of the public SHG-TIFF database, dealing with breast and thyroid PSHG measurements of both normal and tumor tissues, we test available AI methods for information extraction and benchmark these methods to the state-of-the-art, in terms of automatic cancer diagnosis efficiency.
We demonstrate, for the first time to our knowledge, a SiN-assisted in-plane adiabatic coupler between SiPh and onboard glass waveguides. Our numerical study is founded on an actual graded index glass waveguide developed by Fraunhofer-IZM. The Silicon taper profile and the optimal length are extracted employing the supermode theory and the adiabatic theorem. Fabrication and assembly issues are investigated, resulting to an optimized coupler design that exhibits a theoretical Si-to-glass loss below 0.1dB over the entire C-band. The proposed solution can be realized utilizing standard passive flip-chip assembly equipment and is, therefore, cost-effective, easy to be fabricated, and well-suited for compact packaging.
Large mode area fibers are imperative for scaling up the peak and average power of fiber lasers. Single-mode behavior
and low FM loss are the crucial functionalities for these fibers. While rod-type Photonic Crystal Fibers (PCFs) have
been very successful in offering large mode areas, the typical device length requirement (~1m) and rigid configuration
limits their attractiveness for practical applications. LMA fibers offering a degree of bend tolerance are thus highly
desired. Leakage channel fibers (LCFs) have shown a great potential for offering substantial bend tolerance along with
large mode areas. However, the proposed use of Fluorine-doped rods in the all-solid version limits their practical design space. Here, we propose a novel design concept to attain single-material, large mode area fibers (mode area >~1000μm2) with effectively single mode operation coupled with bending characteristics comparable to all-solid LCFs and, at the same time, greater design flexibility and easier splicing relative to rod-type PCFs.
KEYWORDS: Silica, Lithium, Fiber lasers, Laser applications, Laser systems engineering, Current controlled current source, Resistance, Step index fibers, Cladding, Mirrors
Fibers used for high power delivery are designed to ensure single-mode operation (in order to guarantee good output beam quality), large effective areas (Aeff) and resistance to bend-induced distortions (in order to avoid non-linear effects). For simple step index fibers, the maximum Aeff of the fundamental mode that can practically be achieved at 1.06μm is ~350μm2. All-solid-silica Bragg fibers with large cores were proposed as an alternative solution for high power delivery through their fundamental core mode. These fibers consist of a low-refractive index core surrounded by a multilayer cladding that acts as a Bragg mirror. The loss spectrum of such fibers consists of a concatenation of several transmission windows separated by high-loss peaks. Here, we simultaneously study, for the first time (at our knowledge), the bending impact on Bragg fibers for the three critical properties required for high power delivery: large Aeff, single-mode propagation and low bend losses for the fundamental mode. Thanks to their specific guiding mechanism, Aeff as large as ~500μm2 at 1.06μm can be achieved in Bragg fibers, while maintaining single-mode operation and bend losses lower than 0.1dB/m. Our numerical results are validated by experimental measurements on a PCVD Bragg fiber with a 40μm diameter core.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.