Lyot Coronagraphy at the Palomar and Phase-Mask Coronagraphy at the VLT

2005 ◽  
pp. 25-30
Author(s):  
Anthony Boccaletti ◽  
Jean-Charles Augereau ◽  
Gaël Chauvin ◽  
Pierre Riaud ◽  
Jacques Baudrand ◽  
...  
Keyword(s):  
Phase Mask

Fabrication of two-layer integrated phase mask and single-beam, single exposure fabrication of 3D photonic crystal template using the mask

2008 ◽  
Author(s):  
Yuankun Lin ◽  
Ahmad Harb ◽  
Daniel Rodriguez ◽  
Karen Lozano ◽  
Di Xu ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Phase Mask ◽  
Single Exposure ◽  
Single Beam

scholarly journals Partial aperture imaging system based on sparse point spread holograms and nonlinear cross-correlations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Angika Bulbul ◽  
Joseph Rosen
Keyword(s):  
Structural Changes ◽  
Imaging System ◽  
Current System ◽  
Three Dimensional ◽  
Phase Mask ◽  
Coded Aperture ◽  
Space Telescopes ◽  
Reconstruction Process ◽  
Cross Correlations ◽  
Equivalent Systems

AbstractPartial aperture imaging system (PAIS) is a recently developed concept in which the traditional disc-shaped aperture is replaced by an aperture with a much smaller area and yet its imaging capabilities are comparable to the full aperture systems. Recently PAIS was demonstrated as an indirect incoherent digital three-dimensional imaging technique. Later it was successfully implemented in the study of the synthetic marginal aperture with revolving telescopes (SMART) to provide superresolution with subaperture area that was less than one percent of the area of the full synthetic disc-shaped aperture. In the study of SMART, the concept of PAIS was tested by placing eight coded phase reflectors along the boundary of the full synthetic aperture. In the current study, various improvements of PAIS are tested and its performance is compared with the other equivalent systems. Among the structural changes, we test ring-shaped eight coded phase subapertures with the same area as of the previous circular subapertures, distributed along the boundary of the full disc-shaped aperture. Another change in the current system is the use of coded phase mask with a point response of a sparse dot pattern. The third change is in the reconstruction process in which a nonlinear correlation with optimal parameters is implemented. With the improved image quality, the modified-PAIS can save weight and cost of imaging devices in general and of space telescopes in particular. Experimental results with reflective objects show that the concept of coded aperture extends the limits of classical imaging.

scholarly journals Review of Femtosecond-Laser-Inscribed Fiber Bragg Gratings: Fabrication Technologies and Sensing Applications

2021 ◽  
Author(s):  
Jun He ◽  
Baijie Xu ◽  
Xizhen Xu ◽  
Changrui Liao ◽  
Yiping Wang
Keyword(s):  
Femtosecond Laser ◽  
Optical Fiber ◽  
Oil And Gas ◽  
Optical Fiber Sensor ◽  
Phase Mask ◽  
Fiber Types ◽  
Direct Writing ◽  
Excellent Thermal Stability ◽  
Sensing Applications ◽  
Compact Size

AbstractFiber Bragg grating (FBG) is the most widely used optical fiber sensor due to its compact size, high sensitivity, and easiness for multiplexing. Conventional FBGs fabricated by using an ultraviolet (UV) laser phase-mask method require the sensitization of the optical fiber and could not be used at high temperatures. Recently, the fabrication of FBGs by using a femtosecond laser has attracted extensive interests due to its excellent flexibility in creating FBGs array or special FBGs with complex spectra. The femtosecond laser could also be used for inscribing various FBGs on almost all fiber types, even fibers without any photosensitivity. Such femtosecond-laser-induced FBGs exhibit excellent thermal stability, which is suitable for sensing in harsh environment. In this review, we present the historical developments and recent advances in the fabrication technologies and sensing applications of femtosecond-laser-inscribed FBGs. Firstly, the mechanism of femtosecond-laser-induced material modification is introduced. And then, three different fabrication technologies, i.e., femtosecond laser phase mask technology, femtosecond laser holographic interferometry, and femtosecond laser direct writing technology, are discussed. Finally, the advances in high-temperature sensing applications and vector bending sensing applications of various femtosecond-laser-inscribed FBGs are summarized. Such femtosecond-laser-inscribed FBGs are promising in many industrial areas, such as aerospace vehicles, nuclear plants, oil and gas explorations, and advanced robotics in harsh environments.

Optimization of chromeless phase mask by comparing scattering bars with zebra patterns

2006 ◽  
Author(s):  
Hye-Young Kang ◽  
Ji-Eun Lee ◽  
Eun-A Kwak ◽  
Eun-Jin Kim ◽  
Seung-Wook Park ◽  
...  
Keyword(s):  
Phase Mask

Generation of optical vortices using light-induced phase mask in a V-type system

2004 ◽  
Vol 242 (1-3) ◽  
pp. 199-207
Author(s):  
Jin-Ho Jeon ◽  
Wonshik Choi ◽  
Myoung-Kyu Oh ◽  
Kyungwon An ◽  
Jai-Hyung Lee
Keyword(s):  
Type System ◽  
Phase Mask ◽  
Optical Vortices

scholarly journals Manufacturing of four-quadrant phase mask for nulling interferometry in the thermal infrared

2004 ◽  
Author(s):  
Frederic Lemarquis ◽  
Michel Lequime ◽  
Gerard Albrand ◽  
Ludovic Escoubas ◽  
Jean-Jacques Simon ◽  
...  
Keyword(s):  
Thermal Infrared ◽  
Phase Mask ◽  
Nulling Interferometry ◽  
Four Quadrant
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