create_Exponential

pyspeckle.pyspeckle.create_Exponential(M, pix_per_speckle, alpha=1, shape='ellipse', polarization=1)[source]

Generate an M x M polarized, fully-developed speckle irradiance pattern.

The speckle pattern will have an exponential probability distribution function that is spatially bandwidth-limited by the specified pixels per speckle.

The resolution is specified by the parameter pix_per_speckle and refers to the smallest speckle size. Thus pix_per_speckle=2 means sampling is at the Nyquist limit and pix_per_speckle=4 will have four pixels across the smallest speckle.

Non-circular speckle is supported using alpha. This is defined as the ratio of horizontal speckle size to vertical speckle size. alpha=1 is circular and alpha=2 will have speckles that are twice as tall as they are wide.

see Duncan & Kirkpatrick, “Algorithms for simulation of speckle,” in SPIE Vol. 6855 (2008)

Parameters:

  • M – dimension of desired square speckle image

  • pix_per_speckle – number of pixels per smallest speckle.

  • alpha – ratio of horizontal to vertical speckle size

  • shape – ‘ellipse’, ‘rectangle’, or ‘annulus’

  • polarization – degree of polarization

Returns:

M x M speckle image