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The point spread function (PSF) describes the response of a focused optical imaging system to a point source or point object. A more general term for the PSF is the system's impulse response; the PSF is the impulse response or impulse response function (IRF) of a focused optical imaging system. The PSF in many contexts can be thought of as the ...
EMPy ("Electromagnetic Python") software. motofit is a program for analysing neutron and X-ray reflectometry data. OpenFilters is a program for designing optical filters. Py_matrix is an open source Python code that implements the transfer-matrix method for multilayers with arbitrary dielectric tensors. It was especially created for plasmonic ...
A perfect lens system will provide a high contrast projection without shifting the periodic pattern, hence the optical transfer function is identical to the modulation transfer function. Typically the contrast will reduce gradually towards zero at a point defined by the resolution of the optics.
Note that, since the multiplication of matrices is non-commutative, this is not the same RTM as that for a lens followed by free space: = [] [] = []. Thus the matrices must be ordered appropriately, with the last matrix premultiplying the second last, and so on until the first matrix is premultiplied by the second.
Due to diffraction, the smallest point to which a lens or mirror can focus a beam of light is the size of the Airy disk. Even if one were able to make a perfect lens, there is still a limit to the resolution of an image created by such a lens.
The envelope function represents the effect of additional aberrations that damp the contrast transfer function, and in turn the phase. The envelope terms comprising the envelope function tend to suppress high spatial frequencies. The exact form of the envelope functions can differ from source to source.
This picture is darker at the edges. This variation is called vignetting, and can be corrected by selectively brightening the perimeter of the image.. Flat-field correction (FFC) is a digital imaging technique to mitigate the image detector pixel-to-pixel sensitivity and distortions in the optical path.
In Python, functions are first-class objects that can be created and passed around dynamically. Python's limited support for anonymous functions is the lambda construct. An example is the anonymous function which squares its input, called with the argument of 5: