Flat dielectric grating focusing lens with TE-polarized incident light

2013 ◽  
Author(s):  
Ting Ma ◽  
Xiao-dong Yuan ◽  
Wei-min Ye ◽  
Wei Xu
Keyword(s):  
Incident Light ◽  
Dielectric Grating ◽  
Focusing Lens

A Micro-Focusing Stage Applied to Optical Pick-Up Head

2004 ◽  
Author(s):  
Chia-Wen Lee ◽  
Chung-Feng Lai ◽  
Weileun Fang
Keyword(s):  
Light Beam ◽  
Self Assembly ◽  
Focal Point ◽  
Incident Light ◽  
Disk Surface ◽  
Electrode Layer ◽  
Assembly Mechanism ◽  
Out Of Plane ◽  
Focusing Lens ◽  
Through Hole

Presently, various micromachined actuators have been employed to tune the tracking and focusing of the light beam of optical pick-up head [1–2]. This work demonstrates a novel micro-focusing stage for optical pick-up head application. As in Fig. 1a, the presented micro-focusing stage for optical pick-up head is consisted of four parts: out-of-plane actuator, connecting joint, through hole, and focusing lens plate. The stress-induced beams acted as the self-assembly mechanism to lift up focusing lens plate. In addition, the stress-induced beams also acted as the out-of-plane electrostatic actuator after deposited with an electrode layer. Unlike the design in [3], a through hole underneath the lens plate is allowed in this case for the incident light beam. After properly driving the stress-induced beams, the position of the focusing plate was controlled, as shown in Fig. 1b. The stage had piston motion to adjust the focal point of the lens. Moreover, the stage had tilt motion, so as to ensure that the lens paralleled the disk surface. Thus, the incident laser beam was always orthogonal with the disk surface.

UHV-TEM studies of laser-induced damage

1991 ◽  
Vol 49 ◽  
pp. 632-633
Author(s):  
T.S. Savage ◽  
R. Ai ◽  
D. Dunn ◽  
L.D. Marks
Keyword(s):  
Surface Science ◽  
Rapid Heating ◽  
Local Heating ◽  
Routine Practice ◽  
Transmission Electron ◽  
Northwestern University ◽  
Laser Induced Damage ◽  
Set Up ◽  
Focusing Lens ◽  
Diffusion Of Impurities

The use of lasers for surface annealing, heating and/or damage has become a routine practice in the study of materials. Lasers have been closely looked at as an annealing technique for silicon and other semiconductors. They allow for local heating from a beam which can be focused and tuned to different wavelengths for specific tasks. Pulsed dye lasers allow for short, quick bursts which can allow the sample to be rapidly heated and quenched. This short, rapid heating period may be important for cases where diffusion of impurities or dopants may not be desirable.At Northwestern University, a Candela SLL - 250 pulsed dye laser, with a maximum power of 1 Joule/pulse over 350 - 400 nanoseconds, has been set up in conjunction with a Hitachi UHV-H9000 transmission electron microscope. The laser beam is introduced into the surface science chamber through a series of mirrors, a focusing lens and a six inch quartz window.

Full-parallax 3D display using time-multiplexing projection technology

2020 ◽  
Vol 2020 (2) ◽  
pp. 100-1-100-6
Author(s):  
Takuya Omura ◽  
Hayato Watanabe ◽  
Naoto Okaichi ◽  
Hisayuki Sasaki ◽  
Masahiro Kawakita
Keyword(s):  
Incident Light ◽  
Polarization State ◽  
3D Image ◽  
3D Display ◽  
Time Division Multiplexing ◽  
3D Images ◽  
Polarization Gratings ◽  
Light Rays ◽  
Time Division

We enhanced the resolution characteristics of a threedimensional (3D) image using time-division multiplexing methods in a full-parallax multi-view 3D display. A time-division light-ray shifting (TDLS) method is proposed that uses two polarization gratings (PGs). As PG changes the diffraction direction of light rays according to the polarization state of the incident light, this method can shift light rays approximately 7 mm in a diagonal direction by switching the polarization state of incident light and adjusting the distance between the PGs. We verified the effect on the characteristics of 3D images based on the extent of the shift. As a result, the resolution of a 3D image with depth is improved by shifting half a pitch of a multi-view image using the TDLS method, and the resolution of the image displayed near the screen is improved by shifting half a pixel of each viewpoint image with a wobbling method. These methods can easily enhance 3D characteristics with a small number of projectors.

COLOUR FILTERS APPLICATION FOR DIAGNOSTICS SOME PATHOLOGICAL PROCESS

1970 ◽  
pp. 44-49
Author(s):  
A. G. Belova ◽  
E. V. Zimina ◽  
N. P. Simbirtsev
Keyword(s):  
Visual Analysis ◽  
Color Change ◽  
Incident Light ◽  
Venous Blood ◽  
Subjective Assessment ◽  
Pathological Process ◽  
Dark Spot ◽  
High Reflectivity ◽  
Arterial Blood ◽  
Green Background

During a pathoanatomic autopsy, it is very important to correctly assess the color change of the organs. However, it is not always clear because the color depends on the spectrum of the incident light. There is also a subjective assessment of color. In addition, in animals with large amounts of circulating blood, for example, dogs, early imbibition occurs, which makes it difficult to assess the color of the organ and pathoanatomical diagnosis. We have proposed a simple and visual method of recognition of two pathological processes – inflammation and edema using colored filters. This technique also allows to accurately differentiate inflammation from postmortem imbibition, to recognize fibrin and hemorrhage well. Postmortem examination of different types of animals (predacious families of mustelids, canids, felids) was performed in accordance with Shore’s method in the prosectorium of the Pathonomy Department, K.I. Skryabin Moscow State Academy of Veterinary Medicine and Biotechnology visual analysis – under various artificial lights (fluorescent lamps with banded spectrum and halogen lamps). In the red filter are well identified the pathological processes associated with the venous blood presence in the tissues (venous hyperemia and pulmonary edema). The focus of venous hyperemia or edema in the red filter looks like a dark zone, and tissues, where arterial bloods predominated, aren’t detected in red filter. In the yellow – green filter the inflammation is clearly detected: the zone is brightly red and surrounding tissues become dark. Red colour filters have rather narrow band of transmittance from 600 to 700 nm. Yellow-green have a width zone – from 500 to 700 nm, including both red, and yellow-green part of spectrum. Oxidized hemoglobin in red part of spectrum absorbs ten time weaker, has more high reflectivity and looks red. Surrounding tissues reflect the red rays, which incident on them also red. Therefore, the zone of edema, venous hyperemia and hemorrhaging, containing venous blood, are detected the dark spot, and inflammation zone merges with the red background. Oxidized hemoglobin in the red spectrum part absorbs ten time weaker than reduced hemoglobin, has high reflectivity of the red spectrum part and looks brightly red, surrounding tissues reflect yellow-green spectrum part and look green. Therefore, the zones of inflammation, active hyperemia and hemorrhaging, containing arterial blood, sharp contrast with green background and are clearly visible. Diagnoses made with the help of color filters are confirmed by histological studies.

Stress Whitening in Polypropylene. I. Light Scattering Theory and Model Experiments

1995 ◽  
Vol 60 (11) ◽  
pp. 1875-1887 ◽  
Author(s):  
Jaroslav Holoubek ◽  
Miroslav Raab
Keyword(s):  
Refractive Index ◽  
Light Scattering ◽  
Incident Light ◽  
Polymeric Materials ◽  
Wavelength Dependence ◽  
Theoretical Background ◽  
Surrounding Matrix ◽  
Embedded Particles ◽  
The One ◽  
Stress Whitening

Theoretical background for an optical method is presented which makes it possible to distinguish unambiguously between voids and particles as light scattering sites in polymeric materials. Typical dependences of turbidity as a function of diameter of scattering elements, their volume fractions and also turbidity curves as a function of the wavelength of the incident light were calculated, based both on the Lorenz-Mie theory and the fluctuation theory. Such dependences calculated for polypropylene-containing voids on the one hand and particles, differing only slightly from the surrounding matrix in their refractive index, on the other hand, are markedly different. The most significant results are: (i) Turbidity is at least by two orders of magnitude larger for voids in comparison to embedded particles of ethylene-propylene (EPDM) rubber of the same size, concentration and at the same wavelength. (ii) The wavelength dependence of turbidity for EPDM particles and the inherent refractive index fluctuations in the polypropylene matrix is much steeper as compared to voids for all considered diameters (0.1-10 μm). Thus, the nature of stress whitening in complex polymeric materials can be determined from turbidity measurements.

scholarly journals Laser Lens Size Measurement Using Swept-Source Optical Coherence Tomography

2020 ◽  
Vol 10 (14) ◽  
pp. 4936
Author(s):  
Pingping Jia ◽  
Hong Zhao ◽  
Yuwei Qin
Keyword(s):  
Optical Coherence Tomography ◽  
High Speed ◽  
Wave Number ◽  
Radius Of Curvature ◽  
Optical Coherence ◽  
Swept Source ◽  
Laser Focusing ◽  
Fitting Algorithm ◽  
Laser Confocal Microscope ◽  
Focusing Lens

A high-speed, high-resolution swept-source optical coherence tomography (SS-OCT) is presented for focusing lens imaging and a k-domain uniform algorithm is adopted to find the wave number phase equalization. The radius of curvature of the laser focusing lens was obtained using a curve-fitting algorithm. The experimental results demonstrate that the measuring accuracy of the proposed SS-OCT system is higher than the laser confocal microscope. The SS-OCT system has great potential for surface topography measurement and defect inspection of the focusing lens.

Effective Dielectric Function of Porous Silicon: the Transverse Component

1994 ◽  
Vol 358 ◽  
Author(s):  
G. Gumbs
Keyword(s):  
Absorption Spectrum ◽  
Absorption Coefficient ◽  
Electron Density ◽  
Quantum Wires ◽  
Interband Transition ◽  
Incident Light ◽  
Transverse Component ◽  
Effect Of Temperature ◽  
High Electron ◽  
Confining Potential

ABSTRACTA self-consistent many-body theory is developed to study the effect of temperature and electron density on the interband absorption coefficient and the frequency-dependent refractive index for an array of isolated quantum wires. The peaks in the absorption coefficient correspond to interband transitions resulting in the resonant absorption of light. The oscillations in the derivative spectrum are due to the quantization of the energy levels related to the in-plane confining potential for such reduced dimensional systems. There are appreciable changes in the absorption spectrum when the electron density or temperature is increased. One interband transition peak is suppressed in the high electron density limit and the thermal depopulation effect on the electron subbands can be easily seen when the temperature is high. We also find that the exciton coupling weakens the shoulder features in the absorption spectrum. This study is relevant to optical characterization of the confining potential and the areal density of electrons using photoreflectance. By using incident light with tunable frequencies in the interband excitation regime, contactless photoreflectance measurements may be carried out and the data compared with our calculations. By fitting the numerical results to the peak positions of the photoreflectance spectrum, the number of electrons in each wire may be extracted.

scholarly journals Controlling wave fronts with tunable disordered non-Hermitian multilayers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Denis V. Novitsky ◽  
Dmitry Lyakhov ◽  
Dominik Michels ◽  
Dmitrii Redka ◽  
Alexander A. Pavlov ◽  
...  
Keyword(s):  
Incident Light ◽  
Passage Time ◽  
Photonic Devices ◽  
Gain Saturation ◽  
Wave Fronts ◽  
Optical Effects ◽  
Front Shape ◽  
Optical Applications ◽  
Increasing Demand ◽  
First Time

AbstractUnique and flexible properties of non-Hermitian photonic systems attract ever-increasing attention via delivering a whole bunch of novel optical effects and allowing for efficient tuning light-matter interactions on nano- and microscales. Together with an increasing demand for the fast and spatially compact methods of light governing, this peculiar approach paves a broad avenue to novel optical applications. Here, unifying the approaches of disordered metamaterials and non-Hermitian photonics, we propose a conceptually new and simple architecture driven by disordered loss-gain multilayers and, therefore, providing a powerful tool to control both the passage time and the wave-front shape of incident light with different switching times. For the first time we show the possibility to switch on and off kink formation by changing the level of disorder in the case of adiabatically raising wave fronts. At the same time, we deliver flexible tuning of the output intensity by using the nonlinear effect of loss and gain saturation. Since the disorder strength in our system can be conveniently controlled with the power of the external pump, our approach can be considered as a basis for different active photonic devices.

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