Passive autofocus systems, articles and methods

An image acquisition system, comprising:

• an aimer subsystem operable to emit an aimer beam outward of the image acquisition system to produce an aimer pointer in a field of view of the image acquisition system,
• at least one image sensor that captures image information representative of one or more characteristics of the aimer pointer returned to the image acquisition system and image information representative of targets in the field of view of the image acquisition system, at least one optic;
• and
• a control system comprising at least one processor, the control system operable to:
• for each of a plurality of focus settings,
• adjust a focal point of the at least one optic according to a current one of the focus settings of the plurality of focus settings;
• and
• determine at least one of the one or more characteristics of the aimer pointer at the current one of the focus settings of the plurality of focus settings;
• identify the one of the plurality of focus settings that results in an optimized focus of the aimer pointer based at least in part on the determined at least one of the one or more characteristics of the aimer pointer;
• and
• configure the image acquisition system based on the identified one of the plurality of focus settings that results in the optimized focus of the aimer pointer to at least one of:
• capture images and processor the captured images by the at least one processor.

A data reader for reading machine-readable symbols, comprising:

• a camera subsystem operable to capture image frames, and including an image sensor and an adjustable focus lens system;
• an aimer subsystem operable to project a visible aimer beam;
• storage media storing passive autofocus executable instructions;
• at least one processor operably coupled with the storage media and configured to execute the passive autofocus executable instructions to:
• access focus step specifications that specify a set of focus positions for the adjustable focus lens system;
• cause the aimer subsystem to project the aimer beam outward of the data reader;
• set an exposure time and/or an analog gain for the at least one image sensor;
• set a region of interest less than a full image area for the image sensor to acquire an image of the aimer beam;
• perform a focus sweep according to the focus step specifications and process the corresponding images;
• select the image during the focus sweep with the aimer beam determined to have a smallest characteristic dimension, shape, or best edge sharpness to be a selected focus position;
• and
• adjusting the aimer subsystem to the selected focus position for subsequent image capture and decoding of a machine-readable symbol.