Method for designing a passive single-channel imager capable of estimating depth of field

An electro-optical device comprising:

• a depth estimator operating in a distance range;
• an objective comprising a number of lenses;
• a detector positioned in a focal plane of the objective;
• and
• a diaphragm;
• wherein characteristics of said objective are determined according to a performance metric depending on a comparison function that performs a comparison between a local estimate of a distance from a source to a point of arrival of the electro-optical device and an actual distance from the source to the point of arrival;
• wherein said comparison function comprises calculating a probabilistic average of the behavior of the discrepancy between the estimated distance and the actual distance for a catalog of images;
• and
• wherein said discrepancy is characterized by calculating an average curvature of a likelihood function, as regards the depth, for the catalog of images, such likelihood function being calculated according to the following acts:
• recording a library of point-spreading functions (PSFs), with each one of said PSF functions being associated with a depth and with one of a plurality of different electro-optical systems;
• at least one of capturing and modeling at least one image using one of the PSFs of the PSF library;
• dividing said at least one image into at least one thumbnail having a preset size to record a thumbnail collection;
• calculating a likelihood of each PSF, as regards the content of the thumbnails, and estimating the point-spreading function (PSF), which maximizes this likelihood for each one of said thumbnails;
• and
• measuring a local curvature of the likelihood function around the PSF to maximize the likelihood function.

A method of manufacturing an electro-optical device, the method comprising:

• modeling, with a computer, propagation of radiation from a source through a plurality of different hypothetical optical subsystems for the electro-optical device using a spatial model of the source, wherein each hypothetical optical subsystem of the plurality of different hypothetical optical subsystems is associated with a different set of optical parameters;
• modeling detection of the radiation for a hypothetical detector subsystem of the electro-optical device for each hypothetical optical subsystem of the plurality of different hypothetical optical subsystems;
• modeling, for each hypothetical optical subsystem, image processing of data corresponding to the radiation detected by the detector subsystem for a plurality of different hypothetical image processing subsystems for the electro-optical device, wherein each hypothetical image processing subsystem is associated with a different set of processing parameters;
• computing a performance metric of the electro-optical device for each combination of the plurality of different hypothetical optical subsystems and the plurality of different hypothetical image processing subsystems, wherein the performance matrix is determined using a comparison function that compares an actual distance between a point of arrival of the electro-optical device and the source to an estimate of the actual distance, wherein said comparison function comprises calculating a probabilistic average of the behavior of the discrepancy between the estimated distance and the actual distance for a catalog of images, said discrepancy being characterized by calculating an average curvature of a likelihood function, as regards the depth, for the catalog of images, such likelihood function being calculated according to the following acts:
• recording a library of point-spreading functions (PSFs), with each one of said PSF functions being associated with a depth and with one of a plurality of different electro-optical systems;
• at least one of capturing and modeling at least one image using one of the PSFs of the PSF library;
• dividing said at least one image into at least one thumbnail having a preset size to record a thumbnail collection;
• calculating a likelihood of each PSF, as regards the content of the thumbnails, and estimating the point-spreading function (PSF), which maximizes this likelihood for each one of said thumbnails;
• and
• measuring a local curvature of the likelihood function around the PSF to maximize the likelihood function;
• selecting a combination of one of the plurality of different hypothetical optical subsystems and one of the plurality of different hypothetical image processing subsystems based, at least in part, on the performance metric corresponding thereto;
• and
• manufacturing the electro-optical device including:
• an optical subsystem having a same set of optical parameters as the selected one of the plurality of different hypothetical optical subsystems;
• and
• an image processing subsystem having a same set of processing parameters as the selected one of the plurality of different hypothetical image processing subsystems.