Signal beam

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

Improvements in apparatus for the positional detection of objects

Abstract: Apparatus for the positional detection of objects in which a holographic image of the sample object is recorded on a photographic plate, which includes a laser source (40), a double convex lens (42) a collimating mirror (44), a holographic recording plate (46) and an object support (48). The lens (42) directs both the reference and signals onto the collimating mirror (44) and the object support (48) respectively. The signal beam by interference with the reference beam produces a three dimensional holographic image of the object on the recording plate (46).

Propagation of transient quantum coherence

Abstract: We perform a time-resolved quantum interference experiment based on the effect of induced coherence without induced emission using two pulsed parametric down-conversion sources. We periodically vary the transmission of the first source's idler beam and measure the time-dependent visibility of fringes in the interference between the two signal beams. The visibility is found to be correlated with the transmissivity with a time delay corresponding to a combined path of the first idler and the second signal beam. The experiment is discussed in the context of the delayed choice experiments.

Holographic rom system

Abstract: A holographic ROM system includes a light source (200) for emitting a laser beam; an expanding unit (204) for expanding the laser beam; and a mask (206) for modulating a certain portion of the expanded laser beam to thereby generate a signal beam which is directly provided to a holographic medium (208) and sifting the remainder portion of the expanded laser beam to thereby generate a reference beam which is provided to a conical mirror (210) reflecting the reference beam toward the holographic medium. The holographic medium is composed of a recording region onto which both the reference beam and the signal beam are projected; and a transparent region which passes through the reference beam sifted by the mask, to thereby provide the reference beam to the conical mirror.

Transversal structure of a sum-frequency beam generated from the surface of a chiral medium

Abstract: In this work we study sum-frequency generation from the surface of an isotropic chiral medium in arbitrary interaction geometry of the paraxial light beams at fundamental frequencies. The analytical formulae have been deduced completely describing the transversal spatial distribution of the electric field in the light beam at sum-frequency. Even in a zero-order approximation on the divergence angles of the beams the transversal spatial intensity distribution in the signal beam is elliptic Gaussian, and its shape depends only on the geometry of incidence, the transversal dimensions and the frequencies of the fundamental beams. Within the first-order approximation approach, generally, the polarization state of light is distributed inhomogeneously in the reflected signal beam cross section, and the transversal intensity distribution is not Gaussian. But when the fundamental beams are not focused tightly enough, the non-Gaussian part of the field is negligibly small, compared to the Gaussian part with uniform polarization distribution. However, at larger angles of incidence the non-Gaussian contribution becomes comparable with the Gaussian zero-order part of the field (or exceeds it) even in the case of slightly focused fundamental beams. In this case the transversal distributions of intensity and polarization of light become very sophisticated.

Optical Information Recording and Reproducing Device

Abstract: The optical information recording and reproducing device utilizing holography requires the optical system to generate the signal beam and the reference beam to be irradiated to the holographic storage medium as well as another optical system to generate the curing light beam to be irradiated to the holographic storage medium. Furthermore, from the viewpoint of backward compatibility, if the same device is used for recording or reproduction on the conventional optical discs represented by Blu-ray Disc, another optical system adaptable to recording and reproduction on these optical disks is required. This means the optical system configurations become complicated and larger in size. One solution for downsizing is to use the reference beam also as the curing light beam. Another way is sharing of optical path for curing light beam and for the reference beam. Furthermore, it is possible to share the light source for generating the curing light beam and for generating the recording or reproducing light beam. In such way, optical system configurations become simple.