Signal beam

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

Narrow linewidth BBO optical parametric oscillator utilizing extraordinary resonance

Abstract: Optical parametric oscillators using non-linear crystals cut for the type I interaction have an extraordinary pump beam which generates ordinary signal and idler beams. The use of an optical element to rotate the signal beam before sending this signal beam to a grating element allows for the grating element to have its dispersion plane oriented coplanar with the extraordinary crystal plane of the non-linear crystal. In this manner, for non-linear crystals which have relatively narrow acceptance angles, such as BBO crystals, the reduction in angular aperture of the parametric gain in the extraordinary plane will produce a reduction in the linewidth of the produced output. The grating translates the angular variations into variations in wavelength. If no rotator was used in the optical parametric oscillator, then in order to get the maximum efficiency out of the grating, the dispersion plane of the grating should be orthogonal to the extraordinary plane of the crystal, and therefore the narrow angular acceptance of the crystal would not result in a narrow output linewidth.

Second harmonic generation in isotropic chiral medium with nonlocality of nonlinear optical response by heterogeneously polarized pulsed beams.

Abstract: The second harmonic generation in the bulk of an isotropic chiral liquid with spatial or temporal nonlocality of its quadratic response is studied analytically. The fundamental pulsed beam has Gaussian time envelope and carries a polarization singularity at its axis. The influence of the topological charge and the handedness of the polarization singularity on the polarization state of the signal beam is revealed.

Variable reference phase holocamera to compensate for object motion

Abstract: A variable reference phased holographic system for recording holograms of objects having some movement with respect to the photographic plate which has the conventional signal beam and reference beam provided by a beam splitter having a phase shifter in the reference beam path to adjust the phase of the reference beam to correspond to phase shifts in the signal beam at the center of the hologram recording plate due to the movement of the object. The reference beam is brought to a focus and passed through an aperture between the phase shifter and hologram recording plate. The aperture is moved to adjust the reference beam for phase shifts in the signal beam at points not at the center of the hologram recording plate. In one embodiment the phase corrections are made by sensing means which sense movement of interference fringes at the center and one edge of the hologram recording plate with the output of the sensing means being applied to phase shifters in the reference beam.

Electronic perimeter warning system

Abstract: Apparatus and method are disclosed to provide an electronic perimeter warning system to prevent the ingress or egress of persons or machines from a selected area such as in an area along the perimeter of a roof under construction. Battery powered signal transmitters and receivers establish a signal beam between two locations. When the continuity of the signal beam is broken, an alarm is sounded to warn the person who is crossing the signal beam of imminent danger.

Holographic recording and reconstructing apparatus and holographic recording and reconstructing method

Abstract: A holographic recording and reconstructing apparatus includes a laser light source for emitting a laser beam, a beam splitting element for splitting the emitted laser beam into a signal beam and a reference beam, a light modulating element for modulating the signal beam, an optical system for collecting the modulated signal beam and the reference beam onto a reflection hologram recording medium at substantially the same location, a light detection element for detecting a reconstructed light beam from the hologram recording medium, and wavelength shifting means for shifting the wavelength of the laser beam used during reconstruction from the wavelength used during recording.