scholarly journals High-contrast Imaging with a Small, Well-corrected Subaperture and a Phase-mask Coronagraph

2009 ◽  
Author(s):  
D. Mawet ◽  
E. Serabyn ◽  
Tomonori Usuda ◽  
Motohide Tamura ◽  
Miki Ishii
Keyword(s):  
Phase Mask ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging

In-lab testing of six-level phase mask coronagraphs onto the high-contrast imaging THD2 bench

2018 ◽  
Author(s):  
Fabien Patru ◽  
Pierre Baudoz ◽  
Raphaël Galicher ◽  
Qing Cao ◽  
Kai Wang ◽  
...  
Keyword(s):  
Phase Mask ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging

scholarly journals Laboratory validation of the dual-zone phase mask coronagraph in broadband light at the high-contrast imaging THD testbed

2016 ◽  
Vol 592 ◽  
pp. A119 ◽  
Author(s):  
J. R. Delorme ◽  
M. N’Diaye ◽  
R. Galicher ◽  
K. Dohlen ◽  
P. Baudoz ◽  
...  
Keyword(s):  
Phase Mask ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging

scholarly journals Search for cool extrasolar giant planets combining coronagraphy, spectral and angular differential imaging

2013 ◽  
Vol 8 (S299) ◽  
pp. 21-25
Author(s):  
Anne-Lise Maire ◽  
Anthony Boccaletti ◽  
Julien Rameau ◽  
Gaël Chauvin ◽  
Anne-Marie Lagrange ◽  
...  
Keyword(s):  
Spectral Properties ◽  
Point Sources ◽  
Giant Planets ◽  
Phase Mask ◽  
Evolutionary Models ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Nearby Stars ◽  
Differential Imaging

AbstractSpectral differential imaging (SDI) is part of the observing strategy of current and on-going high-contrast imaging instruments on ground-based telescopes. Although it improves the star light rejection, SDI attenuates the signature of off-axis companions to the star, just like angular differential imaging (ADI). However, the attenuation due to SDI has the peculiarity of being dependent on the spectral properties of the companions. To date, no study has investigated these effects. Our team is addressing this problem based on data from a direct imaging survey of 16 stars combining the phase-mask coronagraph, the SDI and the ADI modes of VLT/NaCo. The objective of the survey is to search for cool (Teff<1000-1300 K) giant planets at separations of 5-10 AU orbiting young, nearby stars (<200 Myr, <25 pc). The data analysis did not yield any detections. As for the estimation of the sensivity limits of SDI-processed images, we show that it requires a different analysis than that used in ADI-based surveys. Based on a method using the flux predictions of evolutionary models and avoiding the estimation of contrast, we determine directly the mass sensivity limits of the survey for the ADI processing alone and with the combination of SDI and ADI. We show that SDI does not systematically improve the sensitivity due to the spectral properties and self-subtraction of point sources.

scholarly journals PCA-based approach for subtracting thermal background emission in high-contrast imaging data

2018 ◽  
Vol 611 ◽  
pp. A23 ◽  
Author(s):  
S. Hunziker ◽  
S. P. Quanz ◽  
A. Amara ◽  
M. R. Meyer
Keyword(s):  
Background Subtraction ◽  
Complete Data ◽  
Phase Mask ◽  
High Contrast ◽  
Imaging Data ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Background Emission ◽  
Data Reductions ◽  
Thermal Background

Aims.Ground-based observations at thermal infrared wavelengths suffer from large background radiation due to the sky, telescope and warm surfaces in the instrument. This significantly limits the sensitivity of ground-based observations at wavelengths longer than ~3 μm. The main purpose of this work is to analyse this background emission in infrared high-contrast imaging data as illustrative of the problem, show how it can be modelled and subtracted and demonstrate that it can improve the detection of faint sources, such as exoplanets. Methods. We used principal component analysis (PCA) to model and subtract the thermal background emission in three archival high-contrast angular differential imaging datasets in the M′ and L′ filter. We used an M′ dataset of β Pic to describe in detail how the algorithm works and explain how it can be applied. The results of the background subtraction are compared to the results from a conventional mean background subtraction scheme applied to the same dataset. Finally, both methods for background subtraction are compared by performing complete data reductions. We analysed the results from the M′ dataset of HD 100546 only qualitatively. For the M′ band dataset of β Pic and the L′ band dataset of HD 169142, which was obtained with an angular groove phase mask vortex vector coronagraph, we also calculated and analysed the achieved signal-to-noise ratio (S/N). Results. We show that applying PCA is an effective way to remove spatially and temporarily varying thermal background emission down to close to the background limit. The procedure also proves to be very successful at reconstructing the background that is hidden behind the point spread function. In the complete data reductions, we find at least qualitative improvements for HD 100546 and HD 169142, however, we fail to find a significant increase in S/N of β Pic b. We discuss these findings and argue that in particular datasets with strongly varying observing conditions or infrequently sampled sky background will benefit from the new approach.

Lab results of the circular phase mask concepts for high-contrast imaging of exoplanets

2012 ◽  
Author(s):  
Mamadou N'Diaye ◽  
Kjetil Dohlen ◽  
Thierry Fusco ◽  
Kacem El Hadi ◽  
Rémi Soummer ◽  
...  
Keyword(s):  
Phase Mask ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging

scholarly journals Companion search around β Pictoris with the newly commissioned L'-band vector vortex coronagraph on VLT/NACO

2013 ◽  
Vol 8 (S299) ◽  
pp. 50-51
Author(s):  
D. Mawet ◽  
O. Absil ◽  
J. Milli ◽  
P. Baudoz ◽  
A. Boccaletti ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Diffraction Limit ◽  
Phase Mask ◽  
Circumstellar Disk ◽  
High Contrast ◽  
Contrast Imaging ◽  
Subwavelength Gratings ◽  
High Contrast Imaging ◽  
Wide Range ◽  
L Band

AbstractHere we present the installation and successful commissioning of an L'-band Annular Groove Phase Mask (AGPM) coronagraph on VLT/NACO. The AGPM is a vector vortex coronagraph made from diamond subwavelength gratings tuned to the L' band. The vector vortex coronagraph enables high contrast imaging at very small inner working angle (here 0″.09, the diffraction limit of the VLT at L'), potentially being the key to a new parameter space. During technical and science verification runs, we discovered a late-type companion at two beamwidths from an F0V star (Mawet et al. 2013), and imaged the inner regions of β Pictoris down to the previously unexplored projected radius of 1.75 AU. The circumstellar disk was also resolved from ≃ 1″ to 5″ (see J. Milli et al., these proceedings). These results showcase the potential of the NACO L-band AGPM over a wide range of spatial scales.

The CM120 Biotwin: a high-contrast objective lens, optimum cryo-vacuum and improved EDX performance

1995 ◽  
Vol 53 ◽  
pp. 584-585
Author(s):  
Uwe Lücken ◽  
Michael Felsmann ◽  
Wim M. Busing ◽  
Frank de Jong
Keyword(s):  
Life Science ◽  
Focal Length ◽  
Objective Lens ◽  
High Contrast ◽  
Contrast Imaging ◽  
X Ray ◽  
Forming Mechanism ◽  
Similar Image ◽  
High Contrast Imaging ◽  
Low Concentrations

A new microscope for the study of life science specimen has been developed. Special attention has been given to the problems of unstained samples, cryo-specimens and x-ray analysis at low concentrations.A new objective lens with a Cs of 6.2 mm and a focal length of 5.9 mm for high-contrast imaging has been developed. The contrast of a TWIN lens (f = 2.8 mm, Cs = 2 mm) and the BioTWTN are compared at the level of mean and SD of slow scan CCD images. Figure 1a shows 500 +/- 150 and Fig. 1b only 500 +/- 40 counts/pixel. The contrast-forming mechanism for amplitude contrast is dependent on the wavelength, the objective aperture and the focal length. For similar image conditions (same voltage, same objective aperture) the BioTWIN shows more than double the contrast of the TWIN lens. For phasecontrast specimens (like thin frozen-hydrated films) the contrast at Scherzer focus is approximately proportional to the √ Cs.

scholarly journals Anti-quenching NIR-II molecular fluorophores for in vivo high-contrast imaging and pH sensing

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Shangfeng Wang ◽  
Yong Fan ◽  
Dandan Li ◽  
Caixia Sun ◽  
Zuhai Lei ◽  
...  
Keyword(s):  
Ph Sensing ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging
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