Laser scanning system employing an optics module capable of forming a laser beam having an extended depth of focus (DOF) over the laser scanning field

摘要

A laser scanning system having a laser scanning field, and a laser beam optics module with an optical axis and including: an aperture stop disposed after a laser source for shaping the laser beam to a predetermined beam diameter; a collimating lens for collimating the laser beam produced from the aperture stop; an apodization element having a first and second optical surfaces for extending the depth of focus of the laser beam from the collimating lens; and a negative bi-prism, disposed after the apodization element, along the optical axis, to transform the energy distribution of the laser beam and cause the laser beam to converge to substantially a single beam spot along the far-field portion of the laser scanning field, and extend the depth of focus of the laser beam along the far-field portion of the laser scanning field.

主权项

1. A laser scanning code symbol reading system for reading code symbols comprising:
a housing with a light transmission window; a laser scanning module, disposed in said housing, for scanning a laser beam across a laser scanning field having a near portion and a far portion defined external to said light transmission window, wherein said laser scanning module is responsive to one or more control signals generated by a system controller and includes
(i) a laser drive module for driving a far-field laser source and a far-field laser beam optics module to produce a far-field laser beam in response to receiving said one or more control signals from said system controller, and(ii) a laser scanning mechanism for scanning said far-field laser beam across said laser scanning field and a code symbol on an object in said laser scanning field; wherein said far field laser beam optics module having an optical axis and including: an aperture stop for shaping the beam to a predetermined diameter; a collimating lens for collimating said laser beam produced from said aperture stop; an apodization element having a first and second optical surfaces for extending the depth of focus of said laser beam from said collimating lens; and a negative bi-prism, disposed immediately after said apodization element, along said optical axis, to transform the energy distribution of said laser beam and cause the laser beam to converge to substantially a single beam spot along said far-field portion of said laser scanning field, so as to extend the depth of focus of said laser beam along said far-field portion of said laser scanning field; light collection optics, disposed in said housing, for collecting light reflected/scattered from scanned object in said laser scanning field; a photo-detector, disposed in said housing, for detecting the intensity of collected light from said code symbols, and generating an analog scan data signal corresponding to said detected light intensity during laser scanning operations; an analog scan data signal processor, disposed in said housing, for processing said analog scan data signals and converting the processed analog scan data signals into digitized data signals; a programmed decode processor, disposed in said housing, for decode processing said digitized data signals, and generating symbol character data representative of each code symbol scanned by said far-field laser beam; and an input/output (I/O) communication interface, disposed in said housing, for interfacing with a host system and transmitting symbol character data to said host system, via a communication link, supported by said laser scanning code symbol reading system and said host system; said system controller for controlling operations within said laser scanning bar code symbol reading system.