Laser beam generation system employing a laser diode and high-frequency modulation circuitry mounted on a flexible circuit
A laser beam generation system having an integrated coherence reduction mechanism. The system includes: a flexible circuit having a first end portion and a second end portion; a laser diode mounted on the first end portion of the flexible circuit, for producing a laser beam having a central characteristic wavelength; diode current drive circuitry for producing a diode drive current to drive the laser diode and produce said laser beam; and high frequency modulation (HFM) circuitry also mounted on the first end portion of the flexible circuit, for modulating the diode drive current at a sufficiently high frequency to cause the laser diode to produce a laser beam having a spectral side-band components about the central characteristic wavelength, and thereby reducing the coherence as well as coherence length of the laser beam.
1. A laser beam generation system having an integrated coherence length reduction mechanism, comprising:
a flexible circuit having a first end portion and a second end portion;
a laser diode mounted on said first end portion of said flexible circuit, for producing a laser beam having a central characteristic wavelength and a coherence length;
diode current drive circuitry for producing a diode drive current to drive said laser diode and produce said laser beam; and
high frequency modulation (HFM) circuitry, mounted on said first end portion of said flexible circuit, for modulating said diode drive current at a sufficiently high frequency to cause said laser diode to generate spectral side-band components about said central characteristic wavelength, and thereby reducing the coherence length of said laser beam.
2. The laser beam generation system of claim 1 , wherein said diode current drive circuitry is mounted on said flexible circuit.
3. The laser beam generation system of claim 1 , wherein said diode current drive circuitry is mounted on a printed circuit board that is interfaced with said second end portion of said flexible circuit.
4. The laser beam generation system of claim 1 , wherein said diode current drive circuitry is mounted on said second end portion of said flexible circuit.
5. The laser beam generation system of claim 1 , wherein said laser diode is a diode selected from the group consisting of a visible laser diode (VLD) and an IR laser diode (IR-LD).
6. The laser beam generation system of claim 1 , in combination with an optical beam multiplexing (OMUX) module for receiving said laser beam as an input beam, and a generating as an output laser, a plurality of laser beam components that are recombined to produce a composite laser beam having a substantially reduced coherence length for use in illumination applications where a substantial reduction in speckle pattern noise is achieved.
7. The laser beam generation system of claim 6 , wherein said OMUX module comprises:
a single glass plate having an input surface and an output surface, and reflective and semi-reflective coatings provides on said input and output surfaces, so as to optically multiplex said laser beam entering said input surface, into multiple spatial-coherence reduced output laser beams exiting from said output surface.
8. The laser beam generation system of claim 7 , wherein said multiple spatial-coherence reduced output laser beams are planarized into a composite substantially planar laser illumination beam (PLIB) by way of a multi-cylinder planarizing-type illumination lens array disposed in close proximity to said output surface.
9. The laser beam generation system of claim 7 , wherein said OMUX module comprises:
a glass plate bearing mirror and semi-transparent reflective coatings, and deployable in a laser-despeckling PLIM so as to reduce (i) the coherence of the resulting planar/narrow-area illumination beam generated therefrom, and (ii) thus the amount of speckle pattern noise observed at an image detection array in an image formation and detection subsystem.
10. The laser beam generation system of claim 8 , in combination with said OMUX module, and also a digital image detection array for detecting digital images of an object illuminated by said composite substantially planar laser illumination beam;
wherein the power of speckle pattern noise observed in a digital image of an object detected at said digital image detection array is substantially reduced when said digital image is formed using said composite substantially planar laser illumination beam.