Signal beam

About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.

Optical light valve system for providing phase conjugated beam of controllable intensity.

Abstract: An optical light valve system (10) for providing an amplified phase conjugated replica (S1*) of a potentially low intensity phase aberrated optical signal beam (S1) is disclosed herein. The optical light valve system (10) of the present invention includes a reference beam source (17) for providing a coherent reference beam (R) having first and second components of first and second polarization states, respectively. Further included is a signal beam source (15) for providing a coherent signal beam (S) of the first polarization state. An improved optical light valve (20) phase conjugates the second component of the reference beam in response to the aberrated beam (S1*).

Very high-gain two-wave mixing in BaTiO 3 with a self-bent pump beam

Abstract: We propose a two-wave mixing interaction between a self-bent pump beam and a signal beam in a BaTiO3 crystal. This new configuration exhibits two-wave mixing gain values as high as Gsat = 1.5 × 105, corresponding to an enhancement of 40× in comparison with a conventional two-wave mixing geometry. Application to coherent image amplification with such a high gain combined with a very good signal-to-noise ratio is demonstrated.

Efficient dynamic phasefront modulation system for free-space optical communications

Abstract: An optical communications system is disclosed for correcting in real-time the wavefront distortions of a beam from a coherent optical transmitting source The system includes a collimating lens and beam splitter for receiving a distorted wavefront signal beam and splitting the beam into a pump beam and a weaker intensity signal beam The system includes a detector and computer for measuring the beam distortion and specifying a compensatory wavefront The weaker intensity signal beam is modified in a 2-D spatial light modulator according to a compensatory wavefront A photo-refractive material is used to couple energy from the pump beam to the compensated wavefront signal beam thereby producing a corrected and intensity-enhanced communications beam

Transient Grating Spectroscopy in a Hot Turbulent Compressible Free Jet

Abstract: Speed of sound profiles of an unseeded hot, supersonic, axisymmetric free air jet at atmospheric pressure are measured with 2% uncertainty using laser-induced electrostrictive gratings. Signal level and lifetime decay with increasing temperature, and no data are obtained for static temperatures above 540 K. The influence of temperature, turbulence, beam steering, and mechanical vibrations on the signal amplitude and lifetime is examined quantitatively. It is argued that electrostrictive gratings are applicable for thermometry and velocimetry in supersonic combustors by employing a powerful pulsed infrared probe beam. The significantly larger beam power raises the signal level by three orders of magnitude, whereas the longer wavelength reduces the effects of beam steering by increasing the angular separation between probe and signal beam.

Point-diffraction interferometer utilizing separate reference and signal beam paths

Abstract: A split-path point-diffraction interferometer (SPPDI) comprising separate signal and reference beam paths is disclosed. A beamsplitter is used to divide a linearly polarized converging incident signal beam into separate signal and reference beam paths prior to focus. The reference beam path comprises a diffracting aperture located at the focal point of the signal beam. The diffracting aperture in the reference beam path produces an expanding, diffraction-limited reference wavefront. The signal and reference beam paths comprise linear polarizers whose yaw, pitch, and roll orientation may be freely adjusted. Yaw and pitch adjustment of one or more linear polarizers provides for adjustment of fringe spacing and orientation. Roll adjustment of one or more linear polarizers provides for adjustment of fringe contrast and intensity. Beam turning mirrors are used to direct the signal and reference beams to a beam combiner. Polarizing analysers are placed in the combined output beams produced by the beam combiner. A double-pass embodiment of an SPPDI comprising a beam splitter and compact laser source is disclosed.