Caustic surface produced by a plane wavefront refracted through positive bi-conic lenses

2016 ◽  
Author(s):  
Osvaldo Ponce-Hernández ◽  
Maximino Avendaño-Alejo ◽  
Edwin Román-Hernández ◽  
Iván Moreno-Oliva
Keyword(s):  
Caustic Surface ◽  
Plane Wavefront

Caustic surface of a plane wavefront refracted by a smooth arbitrary surface

2014 ◽  
Author(s):  
Maximino Avendaño-Alejo
Keyword(s):  
Caustic Surface ◽  
Plane Wavefront

CBED Shadow Images and Cs:Aberration Measurement

1982 ◽  
Vol 40 ◽  
pp. 696-697
Author(s):  
R. W. Carpenter ◽  
I.Y.T. Chan ◽  
J. M. Cowley
Keyword(s):  
Focal Point ◽  
Spherical Aberration ◽  
Optic Axis ◽  
Wide Angle ◽  
Caustic Surface ◽  
Convergent Beam

Wide-angle convergent beam shadow images(CBSI) exhibit several characteristic distortions resulting from spherical aberration. The most prominent is a circle of infinite magnification resulting from rays having equal values of a forming a cross-over on the optic axis at some distance before reaching the paraxial focal point. This distortion is called the tangential circle of infinite magnification; it can be used to align and stigmate a STEM and to determine Cs for the probe forming lens. A second distortion, the radial circle of infinite magnification, results from a cross-over on the lens caustic surface of rays with differing values of ∝a, also before the paraxial focal point of the lens.

scholarly journals Calibration of the island effect: Experimental validation of closed-loop focal plane wavefront control on Subaru/SCExAO

2018 ◽  
Vol 610 ◽  
pp. A18 ◽  
Author(s):  
M. N’Diaye ◽  
F. Martinache ◽  
N. Jovanovic ◽  
J. Lozi ◽  
O. Guyon ◽  
...  
Keyword(s):  
Image Quality ◽  
Focal Plane ◽  
Closed Loop ◽  
Near Infrared ◽  
Experimental Tests ◽  
Relative Increase ◽  
Visible Range ◽  
Wavefront Control ◽  
Island Effect ◽  
Plane Wavefront

Context. Island effect (IE) aberrations are induced by differential pistons, tips, and tilts between neighboring pupil segments on ground-based telescopes, which severely limit the observations of circumstellar environments on the recently deployed exoplanet imagers (e.g., VLT/SPHERE, Gemini/GPI, Subaru/SCExAO) during the best observing conditions. Caused by air temperature gradients at the level of the telescope spiders, these aberrations were recently diagnosed with success on VLT/SPHERE, but so far no complete calibration has been performed to overcome this issue. Aims. We propose closed-loop focal plane wavefront control based on the asymmetric Fourier pupil wavefront sensor (APF-WFS) to calibrate these aberrations and improve the image quality of exoplanet high-contrast instruments in the presence of the IE. Methods. Assuming the archetypal four-quadrant aperture geometry in 8 m class telescopes, we describe these aberrations as a sum of the independent modes of piston, tip, and tilt that are distributed in each quadrant of the telescope pupil. We calibrate these modes with the APF-WFS before introducing our wavefront control for closed-loop operation. We perform numerical simulations and then experimental tests on a real system using Subaru/SCExAO to validate our control loop in the laboratory and on-sky. Results. Closed-loop operation with the APF-WFS enables the compensation for the IE in simulations and in the laboratory for the small aberration regime. Based on a calibration in the near infrared, we observe an improvement of the image quality in the visible range on the SCExAO/VAMPIRES module with a relative increase in the image Strehl ratio of 37%. Conclusions. Our first IE calibration paves the way for maximizing the science operations of the current exoplanet imagers. Such an approach and its results prove also very promising in light of the Extremely Large Telescopes (ELTs) and the presence of similar artifacts with their complex aperture geometry.

Wavefronts, light rays and caustic associated with the refraction of a plane wavefront by a conospherical lens

2021 ◽  
Author(s):  
José Israel Galindo-Rodríguez ◽  
Gilberto Silva-Ortigoza
Keyword(s):  
Optical Axis ◽  
Spherical Surface ◽  
Bessel Beam ◽  
Optical Element ◽  
The Other ◽  
Two Dimensional ◽  
Light Rays ◽  
Plane Wavefront ◽  
The Relationship ◽  
Dimensional Surface

Abstract The aim of the present work is to introduce a lens whose faces are a conical surface and a spherical surface. We illuminate this lens by a plane wavefront and its associated refracted wavefronts, light rays and caustic are computed. We find that the caustic region has two branches and can be virtual, real or one part virtual and the other real, depending on the values of the parameters characterizing the lens. Furthermore, we present a particular example where one of the branches of the caustic region is constituted by two segments of a line, one part is real and the other one virtual. The second branch is a two-dimensional surface with a singularity of the cusp ridge type such that its Gaussian curvature is different from zero. It is important to remark that for this example, the two branches of the caustic are disconnected. Because of this property and the result obtained by Berry and Balazs on the relationship between the acceleration of an Airy beam and the curvature of its corresponding caustic, we believe that using this optical element one could generate a scalar optical accelerating beam in the region where the caustic is a two-dimensional surface of revolution, and at the same time a scalar optical beam with similar properties to the Bessel beam of zero order in the region were the real caustic is a segment of a line along the optical axis.

scholarly journals Focal Plane Wavefront Sensing with the FAST TGV Coronagraph

2020 ◽  
Vol 132 (1012) ◽  
pp. 064401
Author(s):  
Benjamin L. Gerard ◽  
Christian Marois
Keyword(s):  
Focal Plane ◽  
Wavefront Sensing ◽  
Plane Wavefront

Caustic surfaces produced by a plane wavefront refracted through cemented doublet lenses

2018 ◽  
Author(s):  
Maximino Avendaño Alejo ◽  
M. Carmen López-Bautista ◽  
Luis Castañeda
Keyword(s):  
Plane Wavefront

On-sky results of focal-plane wavefront sensing and control with the asymmetric pupil vector-apodizing phase plate coronagraph

2020 ◽  
Author(s):  
Steven P. Bos ◽  
Kelsey L. Miller ◽  
Julien Lozi ◽  
Olivier Guyon ◽  
Vikram Mark Radhakrishnan ◽  
...  
Keyword(s):  
Focal Plane ◽  
Phase Plate ◽  
Wavefront Sensing ◽  
Plane Wavefront ◽  
And Control

Laboratory demonstration of focal plane wavefront sensing using phase diversity: a way to tackle the problem of NCPA in SHARK-NIR

2020 ◽  
Author(s):  
Daniele Vassallo ◽  
Maria Bergomi ◽  
Federico Biondi ◽  
Elena Carolo ◽  
Davide Greggio ◽  
...  
Keyword(s):  
Focal Plane ◽  
Wavefront Sensing ◽  
Phase Diversity ◽  
Plane Wavefront

A formula for the ray density over a caustic surface for variable index media

1982 ◽  
Vol 72 (S1) ◽  
pp. S58-S58
Author(s):  
Donald G. Burkhard
Keyword(s):  
Caustic Surface ◽  
Ray Density
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