| Many applications require a LADAR system smaller in size and more power efficient than those using a polygon, galvo, or Risley-prism beam scanner. A fiber-coupled, monostatic LADAR system which transmits and receives through the same aperture has many advantages. These advantages include low cost, easy optical alignment, small size, and low weight. Optical alignment of the system is greatly simplified since there is no parallax between transmitted and received beam paths. The direction of the received light is inherently aligned with that of the transmitted beam. Multiple alignment steps of bulk optical components are one of the major reasons many laser systems are expensive. Using an all-fiber approach the optical alignment is simplified by automated splicing of the fibers. A 1-D LADAR consisting of a stationary monostatic rangefinder with real-time pulse processing is first demonstrated. Then a 3-D scanning LADAR is demonstrated. A vibrating fiber cantilever tip that is used to scan the laser beam is mounted on a resonant piezo-electric lead zirconium titanate (PZT) stripe actuator that requires very little power. A position sensing detector (PSD) is needed to sense the fiber position since the motion of the scanned fiber may not be fully predictable. The PSD operates in a two-photon absorption mode to accurately measure the fiber tip position for each laser pulse, with very low insertion loss. |
