A lens system which forms image of a point source object is called as point spread function (or) PSF. Point spread function is also called as Fraunhofer diffraction pattern, impulse response and Green’s function.
Figure: Above figure was generated by Zemax
|Eip – Image irradiance, J1 – Bessel function, λ – Wavelength|
Properties of point spread function (PSF):
- PSF can be computed from pupil function by squaring its fourier transform.
- Peak irradiance of PSF strongly depends on wavelength λ.
- PSF forms depends upon the shape of the pupil boundaries.
Robert R. Shannon and James C. Wyant, “Applied optics and Optical engineering”, Academic press, Inc. Vol. 7, ISBN 0-12-408608-X (v. 8), 1980.