Beam focusing through a tapered subwavelength aperture surrounded by dielectric surface gratings

2009 ◽  
Vol 282 (20) ◽  
pp. 4146-4151 ◽  
Author(s):  
Gai-Ge Zheng ◽  
Lin-Xing Shi ◽  
Hai-Lin Wang ◽  
Xiang-Yin Li
Keyword(s):  
Dielectric Surface ◽  
Subwavelength Aperture ◽  
Beam Focusing

Subwavelength beam focusing by multiple-metal slits surrounded by chirped dielectric surface gratings

2012 ◽  
Vol 285 (6) ◽  
pp. 1519-1522 ◽  
Author(s):  
Sen Jia ◽  
Lihe Yan ◽  
Jinhai Si ◽  
Wenhui Yi ◽  
Feng Chen ◽  
...  
Keyword(s):  
Dielectric Surface ◽  
Beam Focusing

Optical beam focusing by a single subwavelength metal slit surrounded by chirped dielectric surface gratings

2008 ◽  
Vol 92 (1) ◽  
pp. 013103 ◽  
Author(s):  
Seyoon Kim ◽  
Yongjun Lim ◽  
Hwi Kim ◽  
Junghyun Park ◽  
Byoungho Lee
Keyword(s):  
Dielectric Surface ◽  
Optical Beam ◽  
Beam Focusing

Point-Cathode Electron Gun Using Electron-Beam Bombardment for Cathode Tip Heating

1990 ◽  
Vol 48 (1) ◽  
pp. 198-199
Author(s):  
Ryo Iiyoshi ◽  
Susumu Maruse ◽  
Hideo Takematsu
Keyword(s):  
Electron Beam ◽  
Tungsten Wire ◽  
Local Heating ◽  
Electron Gun ◽  
Original Position ◽  
Beam Power ◽  
Radius Of Curvature ◽  
High Brightness ◽  
Beam Focusing ◽  
Time Operation

Point cathode electron gun with high brightness and long cathode life has been developed. In this gun, a straightened tungsten wire is used as the point cathode, and the tip is locally heated to higher temperatures by electron beam bombardment. The high brightness operation and some findings on the local heating are presented.Gun construction is shown in Fig.l. Small heater assembly (annular electron gun: 5 keV, 1 mA) is set inside the Wehnelt electrode. The heater provides a disk-shaped bombarding electron beam focusing onto the cathode tip. The cathode is the tungsten wire of 0.1 mm in diameter. The tip temperature is raised to the melting point (3,650 K) at the beam power of 5 W, without any serious problem of secondary electrons for the gun operation. Figure 2 shows the cathode after a long time operation at high temperatures, or high brightnesses. Evaporation occurs at the tip, and the tip part retains a conical shape. The cathode can be used for a long period of time. The tip apex keeps the radius of curvature of 0.4 μm at 3,000 K and 0.3 μm at 3,200 K. The gun provides the stable beam up to the brightness of 6.4×106 A/cm2sr (3,150 K) at the accelerating voltage of 50 kV. At 3.4×l06 A/cm2sr (3,040 K), the tip recedes at a slow rate (26 μm/h), so that the effect can be offset by adjusting the Wehnelt bias voltage. The tip temperature is decreased as the tip moves out from the original position, but it can be kept at constant by increasing the bombarding beam power. This way of operation is possible for 10 h. A stepwise movement of the cathode is enough for the subsequent operation. Higher brightness operations with the rapid receding rates of the tip may be improved by a continuous movement of the wire cathode during the operations. Figure 3 shows the relation between the beam brightness, the tip receding rate by evaporation (αis the half-angle of the tip cone), and the cathode life per unit length, as a function of the cathode temperature. The working life of the point cathode is greatly improved by the local heating.

Spark Discharge over the Solid Dielectric Surface in Vacuum

2018 ◽  
Vol 7 (7) ◽  
pp. 31-36
Author(s):  
Vyacheslav I. ASYUNIN ◽  
◽  
Sergei G. DAVYDOV ◽  
Alexander N. DOLGOV ◽  
Andrei V. KORNEYEV ◽  
...  
Keyword(s):  
Dielectric Surface ◽  
Spark Discharge ◽  
Solid Dielectric

Laser Failure Isolation Techniques Demonstrated On Test Structures

2008 ◽  
Author(s):  
Frank S. Arnold
Keyword(s):  
Integrated Circuits ◽  
Laser Beam ◽  
Case Studies ◽  
Induced Resistance ◽  
Simple Test ◽  
Resistance Change ◽  
Cross Sectional ◽  
Beam Focusing ◽  
Isolation Techniques ◽  
Heating Effects

Abstract To be better prepared to use laser based failure isolation techniques on field failures of complex integrated circuits, simple test structures without any failures can be used to study Optical Beam Induced Resistance Change (OBIRCH) results. In this article, four case studies are presented on the following test structures: metal strap, contact string, VIA string, and comb test structure. Several experiments were done to investigate why an OBIRCH image was seen in certain areas of a VIA string and not in others. One experiment showed the OBRICH variation was not related to the cooling and heating effects of the topology, or laser beam focusing. A 4 point probe resistance measurement and cross-sectional views correlated with the OBIRCH results and proved OBIRCH was able to detect a variation in VIA fabrication.

scholarly journals Achromatic terahertz Airy beam generation with dielectric metasurfaces

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Qingqing Cheng ◽  
Juncheng Wang ◽  
Ling Ma ◽  
Zhixiong Shen ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Biomedical Imaging ◽  
Frequency Dispersion ◽  
Light Sheet ◽  
Photonic Devices ◽  
Self Healing ◽  
Beam Focusing ◽  
Light Sheet Microscopy ◽  
Airy Beam ◽  
Potential Applications ◽  
Airy Beams

AbstractAiry beams exhibit intriguing properties such as nonspreading, self-bending, and self-healing and have attracted considerable recent interest because of their many potential applications in photonics, such as to beam focusing, light-sheet microscopy, and biomedical imaging. However, previous approaches to generate Airy beams using photonic structures have suffered from severe chromatic problems arising from strong frequency dispersion of the scatterers. Here, we design and fabricate a metasurface composed of silicon posts for the frequency range 0.4–0.8 THz in transmission mode, and we experimentally demonstrate achromatic Airy beams exhibiting autofocusing properties. We further show numerically that a generated achromatic Airy-beam-based metalens exhibits self-healing properties that are immune to scattering by particles and that it also possesses a larger depth of focus than a traditional metalens. Our results pave the way to the realization of flat photonic devices for applications to noninvasive biomedical imaging and light-sheet microscopy, and we provide a numerical demonstration of a device protocol.

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