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Point spread functions at different field angles and phase deviations of the cubic mask are used for image restoration to
analyze the off-axis performance of a wavefront coded imaging system.
Keywordsdeconvolution-wavefront coding-cubic phase-off axis-shift invariant
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... One more thing to consider is the relation on the variable α in phase units with a variable of distance units, in order to describe the shape of the phase mask. This transfer equation can be expressed as [11] The WFC technology also enables the possibility of taking PSFs at different field angles and phase deviations from a wave-front coded system in order to restore the image and to analyze the off-axis performance. We will take this principle and use it to analyze the different field angles in our telescope design [11]. ...
... This transfer equation can be expressed as [11] The WFC technology also enables the possibility of taking PSFs at different field angles and phase deviations from a wave-front coded system in order to restore the image and to analyze the off-axis performance. We will take this principle and use it to analyze the different field angles in our telescope design [11]. ...
... Increasing the α constant would increase the extension of the depth of field but would imply a trade-off between the extension of the depth of field and the light-gathering capability required by the application at hand. Also, we are trying to maintain the MTF sag as large as possible, since this sag represents a loss of signal-to-noise ratio [5][6][7][8][9][10][11][12]. ...
A wave-front coded imaging system is an optical-digital method for aberration control. Wave-front coding technology incorporates an aspheric element in the optical system in order to capture a coded image and by digital processing decode it to obtain the final image. The WFC system is very insensitive to defocus-like aberrations and thereby becomes a tool in the aberration balancing for telescope systems. We propose WFC technology to be implemented in a two spherical mirror telescope. In this work we present the design and simulation of the proposed telescope, trade-offs encountered in the design process and aspects of the image restoration.
Wavefront coding (WFC) is an imaging technique for enhancing some invariance capabilities of optical instruments (typically invariance against defocus). So far, the procedure has been mostly used in practical environments where the optical aberrations of the optical system correspond to a rotationally symmetrical one, i.e., on-axis imaging. These problems have been extensively tackled in recent years, leading to successful designs like the cubic and petal-shaped phase plates. An interesting aspect of the implementation of the phase plate is the use of a liquid crystal spatial light modulator (SLM) placed at the pupil of the instrument, since it allows enhanced versatility. Under these circumstances, the characteristics of the pupil phase plate, in order to provide invariance, refer only to spherical and defocus aberrations. However, when the optical system is not rotationally symmetrical, like for field imaging, the theoretical framework of the problem is quite different, as one has to deal with more general aberrations. Our aim is to analyze this field imaging invariance problem when using WFC techniques and to try to extend the well known on-axis techniques to this new application.
