Digital Optical Research Articles

Improvement of the performance of optical handwritten digit recognition by incorporating cross-domain autoencoder-based image to image translation technique

The paper represents a novel approach that improves the performance of optical handwritten digit recognition incorporating image to image translation technique in a way - that it translates the input image of handwritten domain to some model domain so that the performance of any specified classier improves. In this paper, we have done image to image translation using two pretrained autoencoders, one of them is an autoencoder of a handwritten domain and other is an autoencoder of a model domain. We have bonded together the encoder of handwritten domain and the decoder of model domain and a neural network for feature translation in between in order to train the whole neural network for the translation of an image from handwritten domain to the image of a model domain. Also, an analysis has been shown regarding how well our method improves the performance of optical handwritten digit recognition for both Bengali and English digits.

Machine learning methods for digital holography and diffractive optics

Abstract With active advancements in computer and computational technologies, deep learning has found its way into many fields. Recently it has become an active topic of research in diffractive optics and holography. Deep leaning techniques have been shown to benefit greatly from abundant information offered by using both amplitude and phase of the optical field. These techniques can be applied for image reconstruction, zero-order suppression, hologram generation, etc. In this paper various learning based methods for enhancing digital and computer-generated holography are analysed. We demonstrate a deep learning model for generating diffractive optical elements from an arbitrary intensity-only image. Numerical evaluation of model’s performance has shown that generated diffractive optical elements are of acceptable quality.

Application of the ORBEYE three-dimensional exoscope for microsurgical procedures.

Advances in digital imaging, screen technology, and optics have led to the development of extracorporeal telescopes, also known as exoscopes, as alternatives to surgical loupes (SLs) and traditional operating microscopes (OMs) for surgical magnification. Theoretical advantages of the exoscope over conventional devices include improved surgeon ergonomics; superior three-dimensional, high-definition optics; and greater ease-of-use. The ORBEYE exoscope, in particular, has demonstrated early efficacy in the surgical arena. The purpose of this study was to compare the ORBEYE with conventional microscopy. In this case-control pilot study, we compared the ORBEYE (n = 22) with conventional microscopy (n = 27) across 49 consecutive microsurgical cases during a 6-week period. Both visualization methods consisted of breast, and head and neck cases, while the ORBEYE was also used for extremity and lymphedema microsurgical cases. The ORBEYE was utilized during flap dissection and microvascular anastomosis. Baseline demographics, operative time, ischemia time, and intra- and postoperative microvascular complications were examined and compared. Attending surgeons completed an ergonomics and performance survey postoperatively comparing the ORBEYE with their previous use of SL/OM using a 5-point Likert scale. There was no difference in operative time (507 ± 132 min vs. 522 ± 139, p = .714), ischemia time (77.9 ± 31.4 min vs. 77.5 ± 36.0, p = .972), or microsurgical complications (0% vs. 4%, p = 1) between the ORBEYE and conventional microscopy groups. In a survey administered immediately postoperatively, surgeons reported favorable ergonomics, excellent image quality, and ease of equipment manipulation using the exoscope. The ORBEYE is an effective microsurgical tool and may be considered as an alternative to conventional optical magnification technology.

Adaptive process control implementation of wire arc additive manufacturing for thin-walled components with overhang features

The ability to fabricate overhang structures in WAAM (wire arc additive manufacturing) is vital in ensuring that a wide variety of designs can be realised. Unlike other additive manufacturing techniques that leverage on the addition of support structures, WAAM utilises a support-free approach for overhang fabrication to ensure components achieve a minimal buy-to-fly ratio. Currently, turntables are employed to achieve features with overhangs, but this does not scale well for large parts, in which the substrate’s position is fixed. This paper presents an alternative approach to overcome this limitation by implementing adaptive process control for the fabrication of thin-walled components with overhang features under flat-position deposition conditions. An overhang slicer algorithm was developed to generate the toolpath based on the sliced computer-aided design model and tag the toolpath with overhang angle information. A data-driven interpolation model was then used to determine the torch speed for each path segment based its overhang angle that would result in uniform layer height. A thin-walled part with a complex overhang feature that varies from 0° to 37.5° was fabricated using the proposed approach. The result is a near-net shape part, as verified using an industrial optical three-dimensional digitiser.

Effect of digital zone optics® design contact lenses in symptoms, vision and clinical variables

Effect of digital zone optics® design contact lenses in symptoms, vision and clinical variables

Principle of Coherence Optical Systems-Current Applications and Future Challenges

This paper reviews the concept of coherent optical systems as future digital optical communication systems having capacity of achieving 100Gbps speed. While the transmission capacity increases in wavelength-division multiplexed (WDM) system, coherent technologies have been in large interest in recent years. The interest lies in finding methods of increasing the bandwidth demand with multilevel modulation formats based on coherent technologies. We also discuss about requirements and challenges in implementation of respective digital receivers and associated signal processing.

Lateral and axial resolution criteria in incoherent and coherent optics and holography, near- and far-field regimes.

This work presents an overview of spatial resolution criteria in classical optics, digital optics, and holography. Although the classical Abbe and Rayleigh resolution criteria have been thoroughly discussed in the literature, there are a few issues that still need to be addressed, e.g.,the axial resolution criteria for coherent and incoherent radiation (which is a crucial parameter in 3D imaging), the resolution criteria in the Fresnel regime, and the lateral and the axial resolution criteria in digital optics and holography. This work discusses these issues and provides a simple guide on which resolution criteria should be applied for a particular imaging scheme: coherent/incoherent, far- and near-field, lateral and axial resolution. Different resolution criteria such as two-points resolution and the resolution obtained from the image spectrum (diffraction pattern) are compared and demonstrated with simulated examples. It is shown that, for coherent light, the classical Abbe and Rayleigh resolution criteria do not provide accurate estimation of the lateral and axial resolution. The lateral and axial resolution criteria based on the evaluation of the spectrum of the diffracted wave provide more precise estimation of the resolution for coherent and incoherent light. It is also shown that the resolution criteria derived in approximation of the far-field can be applied for the near-field (Fresnel) imaging regime.

Abstract TP249: Functional MRI Guided Navigated TMS to Pharyngeal Motor Cortex

Introduction: Optimization of the precise pharyngeal TMS target within the largest-scale central swallowing networks has been complicated. We addressed this by using state-of-the art fMRI and DTI combined with navigated transcranial magnetic stimulation(nTMS). Hypothesis: We hypothesized that by recording sEMG of lip orbicularis oris (OO) muscles with fMRI-guided nTMS will allow us readily to detect submental complex (SMC) muscles MEP to localize swallowing hotspot in M1. Methods: 8 healthy volunteer subjects (age = 25.714 ± 4.35, males: 2) conduced a voluntary saliva swallowing task modified from our previous study and a similarly sequenced lips pursing task. MEMPRAGE, HARDI as well as standard rsfMRI were performed to assess structural and functional connectivity. The motor cortices of the SMC and OO muscles in each hemisphere were targeted with a TMS neuronavigation that used a graphic user interface and a 3D optical digitizer to precisely position the coil over the cortical site based on individual swallowing/lips-task fMRI target. SMC and lip OO sEMG responses were detected with bipolar electrodes. Results: The fMRI-guided navigated (Figure 1 A and B) lips target was identified by the resting motor threshold compared with a traditionally measured hotspot (Figure 1 C and D). The simultaneous SMC response was detected to further clarify the estimate of the swallowing hotspot (Figure 1 E). The functional patterns of swallowing and connectivity in each hemisphere are demonstrated using resting fMRI combined fiber tractography (Figure 1 F, G, H and I). Conclusions: We provide evidence for the more precise and reliable targeting of pharyngeal motor cortex with the combination of fMRI and DTI and the assistance of fMRI-guided TMS on lips. This multimodal neuroimaging approach will enable visualization of a precise neuronal biomarker of central swallowing and thus allow the development of effective direct clinical treatment strategies for neurogenic swallowing disorders.

Multi-Rate Multi-Format CFP/CFP2 Digital Coherent Interfaces for Data Center Interconnects, Metro, and Long-Haul Optical Communications

New customer usages, such as high-definition videos, business analytics, and cloud services, stress more and more optical transport networks. This demand for ever-increasing capacity combined with the hard competition between telcos results in requests for lower costs in wavelength division multiplexing (WDM) transport. As WDM transceivers operating at 100G and beyond represent a large part of transmission system cost, a strong pressure is applied on vendors so that they lower the price of line-side interfaces. For the past 6–7 years, some equipment suppliers have focused their efforts on the development of pluggable optics adapted to 100G and beyond WDM transport. Thanks to photonic integrated circuits, they develop multisource agreement form factors that are able to generate/detect 100G at a very efficient cost, with notably reduced power consumption and high port density. Two flavors are used for pluggable optics that integrate or not the digital signal processing circuitry into the form factor, i.e., digital coherent optics (DCO) and analog coherent optics, that are supported by two kinds of form factors, i.e., CFP and CFP2. The corresponding cost decrease involved by pluggable optics is really impressive: over the 2014–2018 period the WDM 100G port price has been divided by a factor of ∼6, while the power consumption per 100G port oscillates today between 10 and 30 W (depending on vendors). In addition, CFP-DCO and CFP2-DCO are now able to generate 100G and 200G data rates with multiple modulation formats (i.e., QPSK, 8QAM, and 16QAM) resulting in a very high level of flexibility for these interfaces making them suitable for a wide range of applications. In this invited paper, we present the work performed since 2015 on both 100G CFP-DCO and 100G/200G CFP2-DCO interfaces used in various contexts: short-reach and data center interconnects, metro/regional, long-haul and ultra long-haul optical communications.

Optical Fiber Submarine Cable Deployment and Digital Vulnerability in Sub-Saharan Africa

The recent deployment of fibre-optic submarine cables (SMCs) in sub-Saharan Africa (SSA) raised the prospects for the digital economy expansion and the whole sub-continent take-off, but also exposed countries and populations to new sources of vulnerability. This paper provides empirical evidence on the ambivalent effect of SMC deployment on the digital divide in 46 SSA countries. On the one hand, results show that the laying of SEACOM, MainOne and EASSy cables in 2009-2010 has yielded a three percentage points increase in internet penetration rates. This is a huge increase, meaning that the deployment of these cables has almost doubled the penetration of Internet in the sub-continent’s population. On the other hand, exogenous sources of telecommunication disruptions related to SMC laying – the country’s exposure to SMC outages and digital isolation – are found to reduce internet and mobile penetration rates, to lower investments in ICTs, and to increase mobile-cellular tariffs and the wireline network instability. Therefore, while SMC arrival in SSA has reduced the digital divide, this divide would be lower if SSA countries were less digitally vulnerable.

Three-Dimensional Analysis of Internal Adaptations of Crowns Cast from Resin Patterns Fabricated Using Computer-Aided Design/Computer-Assisted Manufacturing Technologies.

To evaluate the internal adaptations of cast crowns made from resin patterns produced using three different computer-aided design/computer-assisted manufacturing technologies. A full-crown abutment made of zirconia was digitized using an intraoral scanner, and the design of the crown was finished on the digital model. Resin patterns were fabricated using a fused deposition modeling (FDM) 3D printer (LT group), a digital light projection (DLP) 3D printer (EV group), or a five-axis milling machine (ZT group). All patterns were cast in cobalt-chromium alloy crowns. Crowns made from traditional handmade wax patterns (HM group) were used as controls. Each group contained 10 samples. The internal gaps of the patterns were analyzed using a 3D replica method and optical digitization. The results were compared using Kruskal-Wallis analysis of variance (ANOVA), a one-sample t test, and signed rank test (α = .05). For the LT group, the marginal and axial gaps were significantly larger than in the other three groups (P < .05), but the occlusal adaptation did not reveal a significant difference (P > .05). In the ZT group, the axial gap was slightly smaller than in the HM group (P < .0083). All the means of gaps in all areas in the four groups were less than 150 μm. Casting crowns using casting patterns made from all three CAD/CAM systems could not produce the prescribed parameters, but the crowns showed clinically acceptable internal adaptations.

Holographic line field en-face OCT with digital adaptive optics in the retina in vivo.

We demonstrate a high-resolution line field en-face time domain optical coherence tomography (OCT) system using an off-axis holography configuration. Line field en-face OCT produces high speed en-face images at rates of up to 100 Hz. The high frame rate favors good phase stability across the lateral field-of-view which is indispensable for digital adaptive optics (DAO). Human retinal structures are acquired in-vivo with a broadband light source at 840 nm, and line rates of 10 kHz to 100 kHz. Structures of different retinal layers, such as photoreceptors, capillaries, and nerve fibers are visualized with high resolution of 2.8 µm and 5.5 µm in lateral directions. Subaperture based DAO is successfully applied to increase the visibility of cone-photoreceptors and nerve fibers. Furthermore, en-face Doppler OCT maps are generated based on calculating the differential phase shifts between recorded lines.

Case study research: Optical digitization, reverse engineering and rapid prototyping as a solution in pedal car development process

The motivation of this work was to find an appropriate manufacturing method for pedal car accessories. This study describes the application of optical digitization, reverse engineering and rapid prototyping in manufacturing process of accessories for handmade pedal car, which imitates an unique historic Czech car, a Škoda 1000 MB, type 990 Roadster. Two well-known design elements, rear light and front indicator, were digitized by non-contact 3D scanner. The digitized 3D models were used as an inputs for reverse engineering. Their shapes were modified due to technological limits of vacuum forming, scaled and used to design of the 3D printed vacuum forming moulds. The final parts were made of transparent foil, trimmed around the perimeter and airbrushed from the inside. The described process served to verify the manufacturability of these accessories before commencing works on a mass-produced pedal cars intended for sale to customers.

Spectrally encoded coherence tomography and reflectometry: Simultaneous en face and cross-sectional imaging at 2 gigapixels per second.

Non-invasive biological imaging is crucial for understanding in vivo structure and function. Optical coherence tomography (OCT) and reflectance confocal microscopy are two of the most widely used optical modalities for exogenous contrast-free, high-resolution, three-dimensional imaging in non-fluorescent scattering tissues. However, sample motion remains a critical barrier to raster-scanned acquisition and reconstruction of wide-field anatomically accurate volumetric datasets. We introduce spectrally encoded coherence tomography and reflectometry (SECTR), a high-speed, multimodality system for simultaneous OCT and spectrally encoded reflectance (SER) imaging. SECTR utilizes a robust system design consisting of shared optical relays, scanning mirrors, swept laser and digitizer to achieve the fastest reported in vivo multimodal imaging rate of 2 gigapixels per second. Our optical design and acquisition scheme enable spatiotemporally co-registered acquisition of OCT cross-sections simultaneously with en face SER images for multivolumetric mosaicking. Complementary axial and lateral translation and rotation are extracted from OCT and SER data, respectively, for full volumetric estimation of sample motion with micron spatial and millisecond temporal resolution.

Digital signals processing using non-linear orthogonal transformation in frequency domain

The rapid progress of computer technology in recent decades led to a wide introduction of methods of digital information processing practically in all fields of scientific research. In this case, among various applications of computing one of the most important places is occupied by digital processing systems signals (DSP) that are used in data processing remote solution tasks of navigation of aerospace and marine objects, communications, radiophysics, digital optics and in a number of other applications. Digital Signal Processing (DSP) is a dynamically developing an area that covers both technical and software tools. Related areas for digital signal processing are theory information, in particular, the theory of optimal signal reception and theory pattern recognition. In the first case, the main problem is signal extraction against a background of noise and interference of a different physical nature, and in the second - automatic recognition, i.e. classification and signal identification. In the digital processing of signals under a signal, we mean its mathematical description, i.e. a certain real function, containing information on the state or behavior of a physical system under an event that can be defined on a continuous or discrete space of time variation or spatial coordinates. In the broad sense, DSP systems mean a complex algorithmic, hardware and software. As a rule, systems contain specialized technical means of preliminary (or primary) signal processing and special technical means for secondary processing of signals. Means of pretreatment are designed to process the original signals observed in general case against a background of random noise and interference of a different physical nature and represented in the form of discrete digital samples, for the purpose of detecting and selection (selection) of the useful signal and evaluation characteristics of the detected signal. A new method of digital signal processing in the frequency domain is proposed, using some properties of nonlinear orthogonal transformations. The theoretical bases of this method and the results of the statistical modeling, proving its efficacy in suppressing concentrated interference in the communication channels.

Accuracy and eligibility of CBCT to digitize dental plaster casts.

Software-based dental planning requires digital casts and oftentimes cone-beam computed tomography (CBCT) radiography. However, buying a dedicated model digitizing device can be expensive and might not be required. The present study aimed to assess whether digital models derived from CBCT and models digitized using a dedicated optical device are of comparable accuracy. A total of 20 plaster casts were digitized with eight CBCT and five optical model digitizers. Corresponding models were superimposed using six control points and subsequent iterative closest point matching. Median distances were calculated among all registered models. Data were pooled per scanner and model. Boxplots were generated, and the paired t test, a Friedman test, and a post-hoc Nemenyi test were employed for statistical comparison. Results were found significant at p < 0.05. All CBCT devices allowed the digitization of plaster casts, but failed to reach the accuracy of the dedicated model digitizers (p < 0.001). Median distances between CBCT and optically digitized casts were 0.064 + - 0.005mm. Qualitative differences among the CBCT systems were detected (χ 2 = 78.07, p < 0.001), and one CBCT providing a special plaster cast digitization mode was found superior to the competitors (p < 0.05). CBCT systems failed to reach the accuracy from optical digitizers, but within the limits of the study, accuracy appeared to be sufficient for digital planning and forensic purposes. Most CBCT systems enabled digitization of plaster casts, and accuracy was found sufficient for digital planning and storage purposes.

In-vivo digital wavefront sensing using swept source OCT.

Sub-aperture based digital adaptive optics is demonstrated in a fiber based point scanning optical coherence tomography system using a 1060 nm swept source laser. To detect optical aberrations in-vivo, a small lateral field of view of ~[Formula: see text] is scanned on the sample at a high volume rate of 17 Hz (~1.3 kHz B-scan rate) to avoid any significant lateral and axial motion of the sample, and is used as a "guide star" for the sub-aperture based DAO. The proof of principle is demonstrated using a micro-beads phantom sample, wherein a significant root mean square wavefront error (RMS WFE) of 1.48 waves (> 1[Formula: see text]) is detected. In-vivo aberration measurement with a RMS WFE of 0.33 waves, which is ~5 times higher than the Marechal's criterion of [Formula: see text] waves for the diffraction limited performance, is shown for a human retinal OCT. Attempt has been made to validate the experimental results with the conventional Shack-Hartmann wavefront sensor within reasonable limitations.

Scalable Electro-Optic Control of Localized Bistable Switching in Broad-Area VCSELs Using Reconfigurable Funnel Waveguides

A basic challenge in photonics is to reproduce the key functions of electronics, while adding the parallelism and simplified circuitry of optics. One major hurdle is the lack of a generic, diode-like optical element. To address this difficulty, the authors offer proof of principle for a miniaturized optical device capable of being only ``on'' or ``off''. Combining photoinduced optical circuitry in quadratic electro-optic crystals with localized structures in broad-area semiconductor cavities, they create a possible building block for future digital optics.

MP50-09 ROBOTIC FLEXIBLE URETEROSCOPIC TREATMENT OF RENAL AND URETERAL CALCULI: FIRST-IN-MAN EXPERIENCE WITH A NOVEL ROBOTIC SYSTEM

You have accessJournal of UrologyStone Disease: Surgical Therapy V1 Apr 2017MP50-09 ROBOTIC FLEXIBLE URETEROSCOPIC TREATMENT OF RENAL AND URETERAL CALCULI: FIRST-IN-MAN EXPERIENCE WITH A NOVEL ROBOTIC SYSTEM Mihir Desai, Shashikant Mishra, Abhishek Singh, Ravindra Sabnis, Arvind Ganpule, and Mahesh Desai Mihir DesaiMihir Desai More articles by this author , Shashikant MishraShashikant Mishra More articles by this author , Abhishek SinghAbhishek Singh More articles by this author , Ravindra SabnisRavindra Sabnis More articles by this author , Arvind GanpuleArvind Ganpule More articles by this author , and Mahesh DesaiMahesh Desai More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.1597AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES To present the first in man experience with the Robotic Endoscopy System (RES) for the treatment of renal and ureteral calculi. METHODS The RES is a novel system comprised of a remote-driven robotic flexible ureteroscope and robotic access sheath. The robotic ureteroscope incorporates digital optics and the system has the ability to control the laser fiber and irrigation inflow-outflow remotely. The system has a stroke length to navigate the collecting system from the urethra to the kidney. The primary performance endpoint was completion of the intended procedure; the primary safety endpoint was incidence of perioperative complication. The RES performance was graded on a visual analog scale of 1 (worst) to 10 (best) for stability, ease of locating stones, ability to fragment, control and visualization. P values were calculated using the Mann-Whitney U test or Fisher's exact test. RESULTS Of 18 screened adult patients, 16 underwent flexible robotic ureteroscopy (11 with 1; 4 with 2 and 1 with 3 stones). Two patients were excluded intraoperatively due to ureteral strictures. The twenty-two treated stones were distributed throughout the collecting system (n = 7 lower pole, n = 5 renal pelvis, n = 5 interpolar, n = 3 upper ureter, n = 1 upper pole and n = 1 distal ureter). Median stone size was 10 (6 to 20) mm. All procedures were completed successfully using robotic control. One patient experienced fever (101°F) that resolved without intervention. Overall, median total procedure time (TPT) was 73.5 (range = 21 to 131) minutes; median total robot time (TRT) was 42 (6 to 99) minutes. In patients with a single stone only, median TPT decreased from 98 (50 to 131) minutes (first 5 cases) to 40 (21 to 77) minutes (last 6 cases), P = 0.036; median TRT also decreased from 44 (20 to 89) minutes (first 5 cases) to 19.5 (6 to 43) minutes (last 6 cases), P = 0.055. In 5 patients with lower pole stones, median TPT was 50 (21 to 131) minutes; median TRT was 20 (16 to 76) minutes. Stability, ease of locating stone and control, as evaluated by number of scores greater than 9, improved significantly in the last 6 cases(P = 0.035). CONCLUSIONS The robotic ureteroscopy with calculi lithotripsy is safe and feasible using the RES. Future comparative studies to manual ureteroscopy are warranted. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e687 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Mihir Desai More articles by this author Shashikant Mishra More articles by this author Abhishek Singh More articles by this author Ravindra Sabnis More articles by this author Arvind Ganpule More articles by this author Mahesh Desai More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Digital adaptive optics confocal microscopy based on iterative retrieval of optical aberration from a guidestar hologram

Guidestar hologram based digital adaptive optics (DAO) is one recently emerging active imaging modality. It records each complex distorted line field reflected or scattered from the sample by an off-axis digital hologram, measures the optical aberration from a separate off-axis digital guidestar hologram, and removes the optical aberration from the distorted line fields by numerical processing. In previously demonstrated DAO systems, the optical aberration was directly retrieved from the guidestar hologram by taking its Fourier transform and extracting the phase term. For the direct retrieval method (DRM), when the sample is not coincident with the guidestar focal plane, the accuracy of the optical aberration retrieved by DRM undergoes a fast decay, leading to quality deterioration of corrected images. To tackle this problem, we explore here an image metrics-based iterative method (MIM) to retrieve the optical aberration from the guidestar hologram. Using an aberrated objective lens and scattering samples, we demonstrate that MIM can improve the accuracy of the retrieved aberrations from both focused and defocused guidestar holograms, compared to DRM, to improve the robustness of the DAO.