Demonstration of 3-dimensional wide angle laser beam scanner using liquid crystals

Design and demonstration of a versatile liquid crystal-based scanner is shown for steering a laser beam in three dimensions. The scanner consists of a unique combination of digital and analog control polarization-based beamforming optics resulting in both continuous and random fashion beam steering. The design features a novel device biasing method, large aperture beamforming optics, low electrical power consumption, and ultrafine as well as wide angle coarse beam steering. Demonstrations include one, two and three dimensional beam steering with a maximum of 40.92degrees continuous scan, all at 1550 nm. The minimum scanner aperture is 1 cm diameter and uses a combination of ferroelectric and nematic liquid crystals in addition to Rutile crystal birefringent prisms

Wavelength tunable and broadband variable fiber-optic attenuators using liquid crystals

Fiber-Optic Variable Optical Attenuators (VOAs) are demonstrated using Liquid Crystals (LC) for broadband as well as wavelength tunable applications. Attenuation is achieved by using a beam spoiling approach implemented via electrically reconfigurable non-pixelated no moving parts Nematic LC deflectors. The VOAs feature in-line architecture and polarization insensitive design without the use of bulky polarization splitting and combining optics. The proof-of-concept VOAs in the 1550 nm band demonstrate >30 dB attenuation ranges, low polarization dependent losses and low power consumption. Applications for these VOAs include agile wavelength tunable secure data communications networks and RF sensor systems

Patterns of abnormal glucose metabolism in acromegaly and impact of treatment modalities on glucose metabolism

Background: Chronic exposure to high levels of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) leads to metabolic complications, most importantly dysglycemia in the form of diabetes mellitus and pre-diabetes. Dysglycemia if diagnosed early in the course of the disease can decrease complications. Treatment modalities in the form of surgery and medical therapy have varied impacts on glucose metabolism.Objective: To determine the frequency of diabetes mellitus, impaired glucose tolerance, and impaired fasting glucose in Pakistani patients with acromegaly and to establish the impact of the intervention (surgery/medical) on glucose metabolism.Methods: This study was a retrospective review of patient records. Eighty-nine patients fulfilling the Endocrine Society criteria for acromegaly diagnosis were included. A data of baseline, GH, IGF-1 level, hemoglobin A1C (HbA1C), fasting blood glucose (FBG), and random blood glucose (RBS) levels were reviewed before and after the intervention (surgery/medical therapy). Normal glucose tolerance (NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and diabetes mellitus (DM) were defined based on the American Diabetes Association (ADA) criteria. Patients were grouped into normoglycemic (NGT) and dysglycemic (IFG, IGT, and DM) based on FBG, RBS, and HbA1C.Results: Major risk factors for dysglycemia included age (15-45 years), male sex (33.70%), obesity (45.7%), and macroadenoma (77.52%). Both mean GH levels (58.29 vs. 54.36 ng/dl) and IGF-1 levels (862.98 vs. 824.32 ng/dl) were higher among the normoglycemic than dysglycemia. Pre-surgery NGT, IFG, IGT, IFG, and IGT/DM combined were found in 48.31%, 5.61%, 1.1%, 5.61%, and 39.32% of the subjects respectively. Post-surgery, HbA1C improved in 79.5%, deteriorated in 6.8%, and remained the same in 13.6%. Similarly, it improved in 67% post-medical therapy. Both FBG and RBS improved post-surgery and medical therapy. Further, the number of anti-diabetic drugs used also decreased post-surgery.Conclusion: Dysglycemia is more common among patients with acromegaly as compared to the general population and tends to be poorly controlled in untreated acromegaly. Glycemic control improves significantly after surgery and medical therapy

Noncontact no-moving parts surface height measurement sensor using liquid crystal-based axial scanning confocal optical microscopy

An analog liquid crystal lens-based axial scanning confocal microscope is demonstrated as a 48 &mgr;m continuous range optical height measurement sensor used to characterize a 2.3 &mgr;m height Indium Phosphide twin square optical waveguide chip

Electrohydrodynamic Processes and Their Affecting Parameters

Electrohydrodynamic processes such as electrospinning and electrospraying are simple, flexible, and cost-effective. Both processes use electrically charged jet of polymer solution for the fabrication of micro- or nanofibers and micro- or nanoparticle. Both of these electrodynamic techniques have been receiving increasing attention not only in the scientific community but also in industry. These fibers and particles offer several morphological and functional features that are suitable for tissue engineering in biomedical applications. The main apparatus used for both of these processes is almost the same. Both need electric voltage to induce charge on the droplet, which at optimized electric field leads to micro- or nanofibers and micro- or nanoparticles. Rayleigh in 1882, for the first time, theoretically estimated the maximum amount of charge that a liquid droplet could carry to change in a jet. This theory is now known as the “Rayleigh limit.” He predicted that a droplet on reaching Rayleigh limit would move as fine jets of liquid. More than 100 years later, Rayleigh limit theory was confirmed experimentally. Beside electric field there are other operating and solution parameters that need to be optimized before we obtain a desire product

High-speed polarization multiplexed optical scanner for three-dimensional scanning applications

A versatile high speed 3-D scanner design is proposed and demonstrated for optical beamforming applications such as free-space laser communications, 3-D displays, scanning 3-D optical microscopy, data retrieval, and vision applications. The scanner consists of fast digital-analog control polarization-based optical beamforming cells resulting in complete three-dimensional beamforming programmability. Features include low electrical power consumption and large aperture beamforming optics, digital repeatability, and time multiplexed accurate analog beamforming. Analog frequency and amplitude control of the nematic liquid crystal beamformer cells allows continuous fine scan programmability over a 0.66 mrad horizontal-deflection, 0.75 mrad vertical deflection, and an infinity to 1.84 m focal length longitudinal scan, all at 1310nm. For the first time is demonstrated a coarse angular deflection of an 8-point linear 1-D scan at 1550 nm with a 35 mus random-access time.A versatile high speed 3-D scanner design is proposed and demonstrated for optical beamforming applications such as free-space laser communications, 3-D displays, scanning 3-D optical microscopy, data retrieval, and vision applications. The scanner consists of fast digital-analog control polarization-based optical beamforming cells resulting in complete three-dimensional beamforming programmability. Features include low electrical power consumption and large aperture beamforming optics, digital repeatability, and time multiplexed accurate analog beamforming. Analog frequency and amplitude control of the nematic liquid crystal beamformer cells allows continuous fine scan programmability over a 0.66 mrad horizontal-deflection, 0.75 mrad vertical deflection, and an infinity to 1.84 m focal length longitudinal scan, all at 1310nm. For the first time is demonstrated a coarse angular deflection of an 8-point linear 1-D scan at 1550 nm with a 35 mus random-access time

Demonstration of 3-dimensional wide angle laser beam scanner using liquid crystals

Design and demonstration of a versatile liquid crystal-based scanner is shown for steering a laser beam in three dimensions. The scanner consists of a unique combination of digital and analog control polarization-based beamforming optics resulting in both continuous and random fashion beam steering. The design features a novel device biasing method, large aperture beamforming optics, low electrical power consumption, and ultra-fine as well as wide angle coarse beam steering. Demonstrations include one, two and three dimensional beam steering with a maximum of 40.92° continuous scan, all at 1550 nm. The minimum scanner aperture is 1 cm diameter and uses a combination of ferroelectric and nematic liquid crystals in addition to Rutile crystal birefringent prisms

Experimental Study on the Structural Behavior of Cast in-situ Hollow Core Concrete Slabs

An experimental work has been carried out to study the flexural behavior of cast in-situ hollow core reinforced concrete (HCRC) slabs constructed by using easy, cost effective and implementable techniques in field. The precast elements made of different easily available affordable material i.e. concrete, polyvinyl chloride (PVC) and plaster of paris having voided cross- sections of circular, rectangular and triangular shapes were incorporated in one direction during pouring of concrete with minimum flexural reinforcement to construct HCRC slabs. A total of 14 slab specimens including 02 specimens per specification were tested with third point loading for the assessment of flexural behavior as per ASTM standards C78/C78M. The flexural behavior of HCRC slabs with polyvinyl and plaster of paris elements having hollow cross-sections was comparable with the control solid slabs, however, HCRC slab with concrete pipes showed 7 to 8 percent reduction in flexural strength with 19 to 20 percent reduction in self-weight. All the tested specimens performed well in shear as no shear failure was observed. This study reveals that HCRC slabs with locally available material having hollow cross section elements can be used for the construction of cast in-situ monolithic construction of one-way slabs with ordinary construction techniques. Doi: 10.28991/cej-2020-03091597 Full Text: PD