scholarly journals The Point Spread Function Variations inside Wide-field Astonomical Images

10.14311/1696 ◽  
2013 ◽  
Vol 53 (1) ◽  
Author(s):  
Elena Anisimova ◽  
Jan Bednář ◽  
Petr Páta
Keyword(s):  
Point Spread Function ◽  
Imaging System ◽  
Wide Field ◽  
Optical Aberrations ◽  
Atmospheric Scattering ◽  
Function Fitting ◽  
Astronomical Imaging ◽  
Point Spread ◽  
Spread Function ◽  
Field Imaging

The Point Spread Function (PSF) of the astronomical imaging system is usually approximated by a Gaussian or Moffat function. For simplification, the astronomical imaging system is considered to be time and space invariant. This means that invariable PSF within an exposed image is assumed. If real wide-field imaging systems are considered, this presumption is not fulfilled. In real systems, stronger optical aberrations are expected (especially coma) at greater distances from the center of the captured image. This impacts the efficiency of stellar astrometry and photometry algorithms, so it is necessary to know the PSF variation. In this paper, we perform the first step toward assigning PSF changes: we study the dependence of the Moffat function fitting parameters (FWHM and the atmospheric scattering coefficient ) on the position of a stellar object.

Point spread function degradation model of a polarization imaging system for wide-field subwavelength nanoparticles

2020 ◽  
Vol 59 (23) ◽  
pp. 7114 ◽  
Author(s):  
Wu Qiong ◽  
Kun Gan ◽  
Zizheng Hua ◽  
Zhenzhou Zhang ◽  
Hanwen Zhao ◽  
...  
Keyword(s):  
Point Spread Function ◽  
Imaging System ◽  
Wide Field ◽  
Degradation Model ◽  
Polarization Imaging ◽  
Point Spread ◽  
Spread Function

scholarly journals Fast algorithms to approximate the position-dependent point spread function responses in radio interferometric wide-field imaging

2020 ◽  
Vol 499 (1) ◽  
pp. 292-303
Author(s):  
M Atemkeng ◽  
O Smirnov ◽  
C Tasse ◽  
G Foster ◽  
S Makhathini
Keyword(s):  
Point Spread Function ◽  
Simulated Data ◽  
High Sensitivity ◽  
Image Plane ◽  
Three Dimensions ◽  
Wide Field ◽  
Point Spread ◽  
Spread Function ◽  
Field Imaging ◽  
Wide Field Imaging

ABSTRACT The desire for wide field of view, large fractional bandwidth, high sensitivity, high spectral and temporal resolution has driven radio interferometry to the point of big data revolution where the data are represented in at least three dimensions with an axis for spectral windows, baselines, sources, etc., where each axis has its own set of subdimensions. The cost associated with storing and handling these data is very large, and therefore several techniques to compress interferometric data and/or speed up processing have been investigated. Unfortunately, averaging-based methods for visibility data compression are detrimental to the data fidelity, since the point spread function (PSF) is position-dependent, that is, distorted and attenuated as a function of distance from the phase centre. The position dependence of the PSF becomes more severe, requiring more PSF computations for wide-field imaging. Deconvolution algorithms must take the distortion into account in the major and minor cycles to properly subtract the PSF and recover the fidelity of the image. This approach is expensive in computation since at each deconvolution iteration a distorted PSF must be computed. We present two algorithms that approximate these position-dependent PSFs with fewer computations. The first algorithm approximates the position-dependent PSFs in the uv-plane and the second algorithm approximates the position-dependent PSFs in the image plane. The proposed algorithms are validated using simulated data from the MeerKAT telescope.

Point spread function degradation model of a polarization imaging system for wide-field subwavelength nanoparticles: publisher’s note

2020 ◽  
Vol 59 (27) ◽  
pp. 8118
Author(s):  
Wu Qiong ◽  
Kun Gao ◽  
Zizheng Hua ◽  
Zhenzhou Zhang ◽  
Hanwen Zhao ◽  
...  
Keyword(s):  
Point Spread Function ◽  
Imaging System ◽  
Wide Field ◽  
Degradation Model ◽  
Polarization Imaging ◽  
Point Spread ◽  
Spread Function

Measurement of the Point Spread Function of a Photoacoustic Imaging System using Step Method

2013 ◽  
Vol 33 (4) ◽  
pp. 0411002
Author(s):  
周红仙 Zhou Hongxian ◽  
周有平 Zhou Youping ◽  
王毅 Wang Yi
Keyword(s):  
Point Spread Function ◽  
Imaging System ◽  
Photoacoustic Imaging ◽  
Step Method ◽  
Point Spread ◽  
Spread Function

Point Spread Function Model of Grating Imaging System Based on Boltzmann Function Edge Fitting

2020 ◽  
Vol 40 (14) ◽  
pp. 1405003
Author(s):  
卢泉 Lu Quan ◽  
张泽昊 Zhang Zehao ◽  
张卫平 Zhang Weiping ◽  
刘诣荣 Liu Yirong
Keyword(s):  
Point Spread Function ◽  
Imaging System ◽  
Function Model ◽  
Point Spread ◽  
Boltzmann Function ◽  
Spread Function

Point Spread Function of Pinhole Imaging System for Deviating from Center of Incident γ-Ray

2015 ◽  
Vol 44 (3) ◽  
pp. 311004
Author(s):  
马庆力 MA Qing-li ◽  
唐世彪 TANG Shi-biao ◽  
吴彦华 WU Yan-hua
Keyword(s):  
Point Spread Function ◽  
Imaging System ◽  
Point Spread ◽  
Spread Function ◽  
Pinhole Imaging ◽  
Γ Ray

Improving position accuracy for telescopes with small aperture and wide field of view utilizing point spread function modelling

2020 ◽  
Vol 497 (3) ◽  
pp. 4000-4008
Author(s):  
Rongyu Sun ◽  
Shengxian Yu ◽  
Peng Jia ◽  
Changyin Zhao
Keyword(s):  
Point Spread Function ◽  
Large Scale ◽  
Field Of View ◽  
Wide Field ◽  
Position Measurement ◽  
Small Aperture ◽  
Position Accuracy ◽  
Point Spread ◽  
Wide Field Of View ◽  
Spread Function

ABSTRACT Telescopes with a small aperture and a wide field of view are widely used and play a significant role in large-scale state-of-the-art sky survey applications, such as transient detection and near-Earth object observations. However, owing to the specific defects caused by optical aberrations, the image quality and efficiency of source detection are affected. To achieve high-accuracy position measurements, an innovative technique is proposed. First, a large number of raw images are analysed using principal component analysis. Then, the effective point spread function is reconstructed, which reflects the state of the telescope and reveals the characteristics of the imaging process. Finally, based on the point spread function model, the centroids of star images are estimated iteratively. To test the efficiency and reliability of our algorithm, a large number of simulated images are produced, and a telescope with small aperture and wide field of view is utilized to acquire the raw images. The position measurement of sources is performed using our novel method and two other common methods on these data. Based on a comparison of the results, the improvement is investigated, and it is demonstrated that our proposed technique outperforms the others on position accuracy. We explore the limitations and potential gains that may be achieved by applying this technique to custom systems designed specifically for wide-field astronomical applications.

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