Planar LED-based illumination array (PLIA) chips

• US 6,959,870 B2
• Filed: 02/04/2002
• Issued: 11/01/2005
• Est. Priority Date: 06/07/1999
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Good, Timothy A., Knowles, C. Harry, Amundsen, Thomas, Tsikos, Constantine J.
• Primary Examiner(s): LE, THIEN MINH
• Application Number:
  US10/067,140
• Publication Number:
  US 20020195496A1
• Time in Patent Office: 1,366 Days
• Field of Search: 235/462, 235/472, 235/454, 235/455, 235/470, 235/494
• US Class Current: 235/462.1
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0057 in the form of a laser diode array, e.g. laser diode bar semiconductor laser arrays with beam combining arrangement H01S5/4012
• CPC Class Codes: G02B 19/0066 in the form of an LED array
• CPC Class Codes: G02B 19/009 for use with infrared radiation
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: G02B 27/0966 Cylindrical lenses cylindrical lenses per se G02B3/06
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G06K 7/10554 Moving beam scanning
• CPC Class Codes: G06K 7/10683 Arrangement of fixed elements
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10861 sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

Abstract

Methods of and systems for illuminating objects using planar laser illumination beams having substantially-planar spatial distribution characteristics that extend through the field of view (FOV) of image formation and detection modules employed in such systems. Each planar laser illumination beam is produced from a planar laser illumination beam array (PLIA) comprising an plurality of planar laser illumination modules (PLIMs). Each PLIM comprises a visible laser diode (VLD, a focusing lens, and a cylindrical optical element arranged therewith. The individual planar laser illumination beam components produced from each PLIM are optically combined to produce a composite substantially planar laser illumination beam having substantially uniform power density characteristics over the entire spatial extend thereof and thus the working range of the system. Preferably, each planar laser illumination beam component is focused so that the minimum beam width thereof occurs at a point or plane which is the farthest or maximum object distance at which the system is designed to acquire images, thereby compensating for decreases in the power density of the incident planar laser illumination beam due to the fact that the width of the planar laser illumination beam increases in length for increasing object distances away from the imaging optics. Advanced high-resolution wavefront control methods and devices are disclosed for use with the PLIIM-based systems in order to reduce the power of speckle-noise patterns observed at the image detections thereof. By virtue of the present invention, it is now possible to use both VLDs and high-speed CCD-type image detectors in conveyor, hand-held and hold-under type imaging applications alike, enjoying the advantages and benefits that each such technology has to offer, while avoiding the shortcomings and drawbacks hitherto associated therewith.

Claims

1. An LED-based planar light illumination (PLIM) chip for use in a planar light illumination and imaging (PLIIM) based system, comprising:

a semiconductor substrate supporting a light emitting diode (LED) array including a linear array of LEDs, each LED having a light emitting source;

a first microlens array having an array of focusing lenslets aligned in spatial registration with said linear array of LEDs;

a second microlens array having an array of collimating lenslets aligned in spatial registration with said linear array of LEDs and said array of focusing lenslets;

an IC package having a light transmission window, for containing said semiconductor substrate, said first microlens array, and said second microlens array,

wherein each focusing lenslet in said first microlens array focuses a reduced-size image of the light emitting source of an LED in said LED array, towards a focal point above said second microlens array;

wherein each collimating lenslet in said second microlens array collimates the light rays associated with the reduced size image of the corresponding light emitting source; and

wherein each cylindrical lenslet diverges the collimated light beam so as to produce a spatially-incoherent planar light illumination beam (PLIB) component, which collectively produce a composite PLIB from the LED-based PLIM.

2. An LED-based planar light illumination module (PLIM) chip for use in a planar light illumination and imaging (PLIIM) based system having a relatively short working distance, comprising:

a light emitting diode (LED) array (A), a first microlens array (B), a second microlens array (C), and a third microlens array (D), wherein each said array is mounted within an IC package of the PLIM chip, for use in object illumination producing a spatially-incoherent planar light illumination beam (PLIB) therefrom.

3. An optical process carried out within an LED-based planar light illumination module (PLIM), wherein (1) a focusing lens element focuses a reduced-size image of a light emitting source of a LED towards a focal point within a barrel structure, (2) a collimating lens element collimates the light rays associated with the reduced-size image of said light emitting source, and (3) a cylindrical lens element diverges the collimated light beam so as to produce a spatially-incoherent planar light illumination beam (PLIB).

4. An optical process carried out within the an LED-based planar light illumination module (PLIM), wherein (1) each focusing lenslet in a focusing lenslet array focuses a reduced-size image of a light emitting source of an LED towards a focal point above a collimating microlens array, (2) each collimating lenslet in said collimating lenslet array collimates the light rays associated with the reduced-size image of the light emitting source, and (3) each cylindrical lenslet in a cylindrical lenslet array diverges the collimated light beam so as to produce a spatially-incoherent planar light illumination beam (PLIB) component, which collectively produce a composite spatially-incoherent PLIB from the LED-based PLIM.

5. A LED-based planar light illumination module (PLIM) is realized as an array of components, contained within a miniature IC package, comprising:

a light emitting diode (LED) array, on a semiconductor substrate, providing a linear array of light emitting sources having the narrowest size and dimension possible;

a first microlens array, mounted above and in spatial registration with the LED array, providing a focusing lenslet above and in registration with each light emitting source, and projecting a reduced image of the light emitting source at its focal point above the LED array;

a second microlens array, mounted above and in spatial registration with the first microlens array, providing each focusing lenslet with a collimating lenslet for collimating the light rays associated with the reduced image of each light emitting device;

a third microlens array, mounted above and in spatial registration with the second microlens array, providing each collimating lenslet with a linear-diverging type lenslet for producing a spatially-incoherent planar light illumination beam (PLIB) component from each light emitting source; and

an IC package containing the above-described components in the stacked order described above, and having a light transmission window through which the spatially-incoherent PLIB is transmitted towards Me a target object being illuminated.

6. A LED-based planar light illumination module (PLIM) realized within an IC package design comprising:

a light emitting diode (LED) providing a light emitting source (having the narrowest size and dimension possible) on a semiconductor substrate;

a focusing lenslet, mounted above and in spatial registration with the light emitting source, for projecting a reduced image of the light emitting source at its focal point, which is preferably set by the further working distance required by the application at hand;

a cylindrical lenslet, mounted above and in spatial registration with a collimating lenslet, for producing a spatially-incoherent planar light illumination beam (PLIB) from the light emitting source; and

an IC package containing the above-described components in the stacked order described above, and having a light transmission window through which the composite spatially-incoherent PLIB is transmitted towards a target object being illuminated.