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This paper presents a new approach to active control of optical jitter with a new transmissive liquid crystal beam steering device, or tilt corrector. The device is driven by a linear time-invariant feedback control loop and an adaptive control loop to maximize the jitter-rejection bandwidth. In contrast to conventional fast steering mirrors, the liquid(More)
Four-wave mixing is studied in a Na-seeded flame in the regime of strong saturation of the Na D-line transitions. The output frequency differs from that of the input lasers so that spectral discrimination can distinguish the mixing signal. Scans of the D2 resonance with another laser set at the D1-line resonance reveals two resonances corresponding to the(More)
Doubly resonant four-wave mixing has been used with two lasers set for resonance with the two Na D-line transitions to perform elemental analysis with a Na-seeded flame. The method is analogous to phase-conjugation methods where all lasers have the same frequency. Strong saturation effects and dynamic Stark splittings are observed and used to optimize the(More)
This paper presents an investigation of adaptive control for a system with control quantization and magnitude and rate saturations. The application is laser beam steering by a liquid crystal device. The effects of using a linear time-invariant feedback loop along with the adaptive controller are discussed, as well as the effects of using nonlinear and(More)
We describe the application of smectic A ͑SmA͒ liquid crystals for beam deflection. SmA materials can be used in digital beam deflec-tors ͑DBDs͒ as fillers for passive birefringent prisms. SmA prisms have high birefringence and can be constructed in a variety of shapes, including single prisms and prismatic blazed gratings of different angles and profiles.(More)
Optical phased arrays using birefringent liquid crystals can efficiently steer a laser communication beam to a small angle. The algorithm presented derives a thickness for the liquid crystal cell and computes a sequence of voltages for the device electrodes that best deflects the beam. Subject terms: optical phased array; beam steering; 2-D optical(More)
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