A miniaturized laser beam transmitter, in which a visible laser module at λ=650 nm is precisely stacked upon an infrared (IR) module at λ=905 nm, has been proposed and constructed to provide an IR collimated beam in conjunction with a collinear monitoring visible beam. In particular, the IR beam is selectively dispersed through a perforated sheet diffuser, so as to create a rapidly diverging close-range beam in addition to a highly defined long-range beam simultaneously. The complementary close-range beam plays a role in mitigating the blind region in the vicinity of the transmitter, which is inevitably missed by the main long-range beam, thereby uniformly extending the transmitter's effective trajectory that is sensed by a receiver. The proposed transmitter was designed through numerical simulations and then fabricated by incorporating a diffuser sheet, perforated with an aperture of 2 mm. For the manufactured transmitter, the IR long-range beam was observed to have divergences of ~2.3 and 1.6 mrad in the fast and slow axes, respectively, while the short-range beam yielded a divergence of ~24 mrad. The angular alignment between the long-range IR and visible beams was as accurate as ~0.5 mrad. According to an outdoor feasibility test involving a receiver, the combination of the IR long- and short-range beams was proven to achieve a nearly uniform trajectory over a distance ranging up to ~600 m, with an average detectable cross-section of ~60×80cm<sup>2</sup>.
© 2012 Optical Society of Korea
(120.1680) Instrumentation, measurement, and metrology : Collimation
(140.3300) Lasers and laser optics : Laser beam shaping
(230.1980) Optical devices : Diffusers
(060.2605) Fiber optics and optical communications : Free-space optical communication
Original Manuscript: September 6, 2012
Revised Manuscript: October 19, 2012
Manuscript Accepted: October 19, 2012
Published: December 25, 2012
Haeng-In Kim, Hong-Shik Lee, and Sang-Shin Lee, "Compact Infrared/Visible Laser Transmitter Featuring an Extended Detectable Trajectory," J. Opt. Soc. Korea 16, 331-335 (2012)
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