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 extended blob in an image that represents a single point object, that is considered as a spatial impulse. In functional terms, it is the spatial domain version (i.e., the inverse Fourier transform) of the optical transfer function (OTF) of an imaging system. It is a useful concept in Fourier optics, astronomical imaging, medical 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) in the image of a point object for an imaging system is a measure of the quality of the imaging system. In non-coherent imaging systems, such as fluorescent microscopes, telescopes or optical microscopes, the image formation process is linear in the image intensity and described by a linear system theory. This...

Scaphella junonia, common names the junonia, or Juno's volute, is a species of large sea snail, a marine gastropod mollusk in the family Volutidae, the volutes. This species lives in water from 29 m to 126 m depth in the tropical Western Atlantic. Because of its deepwater habitat, the shell usually only washes up onto beaches after strong storms, or hurricanes. The species is named after the ancient Roman goddess Juno. Distribution Scaphella junonia is found throughout Florida to Texas and the Gulf of Mexico. A subspecies, Scaphella junonia johnstoneae, is found off of Alabama and is the state shell of that state. It is named for Kathleen Yerger Johnstone, an amateur conchologist from Alabama who published two books on seashell collecting. Another subspecies, Scaphella junonia butleri, is found off of the Yucatan.Shell description The largest recorded shell of Scaphella junonia is 154 mm in length. The shell is cream in color with about 12 spiral rows of...