Point Spread Function

The point spread function (PSF) describes the response of an imaging system to a point source or point object. A more general term for the PSF is a system's impulse response, the PSF being the impulse response of a focused optical system. The PSF in many contexts can be thought of as the extended blob in an image that represents an unresolved object. In functional terms it is the spatial domain version of the modulation transfer function. It is a useful concept in Fourier optics, astronomical imaging, electron microscopy and other imaging techniques such as 3D microscopy (like in Confocal laser scanning microscopy) and fluorescence microscopy. The degree of spreading (blurring) of the point object is a measure for the quality of an imaging system. In incoherent imaging systems such as fluorescent microscopes, telescopes or optical microscopes, the image formation process is linear in power and described by linear system theory. This means that when two objects A and B are imaged simultaneously, the result is equal to the sum of the independently imaged objects. In other words: the imaging of A is unaffected by the imaging of B and vice versa, owing to the non-interacting property of photons. The image of a complex object can then be seen as a convolution of the true object and the PSF. However, when the detected light is coherent, image formation is linear in the complex field. Recording the intensity image then can lead to cancellations or other non-linear effects.

Read more about Point Spread Function:  Introduction, Theory, History and Methods, PSF in Microscopy, The PSF in Astronomy, Point Spread Functions in Ophthalmology

Other articles related to "point spread function, spreads, point":

Multiphoton Fluorescence Microscope - Description
... The optical sectioning produced by multiphoton microscopes is a result of the point spread function formed where the pulsed laser beams coincide ... The multiphoton point spread function is typically dumbbell-shaped (longer in the x-y plane), compared to the upright rugby-ball shaped point spread function of confocal microscopes ...
Microscopist - Optical Microscopy - Techniques - Deconvolution
... spot), light coming from this spot spreads out the further out of focus one is ... Under ideal conditions, this produces an "hourglass" shape of this point source in the third (axial) dimension ... This shape is called the point spread function (PSF) of the microscope imaging system ...
Richardson–Lucy Deconvolution
... for recovering a latent image that has been blurred by a known point spread function ... Pixels in the observed image can be represented in terms of the point spread function and the latent image as where is the point spread function (the fraction of light coming from true location ... are element wise, and is the flipped point spread function, such that In problems where the point spread function is dependent on one or more unknown parameters, the Richardson–Lucy algorithm cannot be used ...
The Dark Energy Survey - Weak Lensing - Systematics
... primary systematics of the telescope are described by the point spread function of the telescope ... Distortions in the point spread function caused by the mirror, optics, or geometry of the various telescope components will act to produce a false cosmic shear image ... most of these effects can be corrected for by actively measuring the point spread function of the telescope ...

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