Spatial filter

About: Spatial filter is a research topic. Over the lifetime, 6170 publications have been published within this topic receiving 100451 citations.

Proposal for phase recovery from a single intensity distribution

Abstract: A method is proposed for the recovery of phase information from a single intensity distribution. The proposal requires the use of a specially designed spatial filter and is analyzed for a one-dimensional case using the theory of entire functions. The only, and unlikely, ambiguity is detectable a posteriori.

Read/write system for optical disc apparatus with fiber optics

Abstract: A read/write system is disclosed for optical disc apparatus. The light source is removed from the head and optically coupled to the disc by a single-mode fiber which acts as a spatial filter. Adverse effects on the light source due to reflection from the disc are avoided by making the fiber length greater than one-half the coherence length of the source. A sparing switch and combiner component may be included in the system. An array of discrete light sources, each coupled to an associated fiber, may also be employed for multiple track accessing.

Highly coherent light at 13 nm generated by use of quasi-phase-matched high-harmonic generation.

Abstract: By measuring the fringe visibility in a Young's double pinhole experiment, we demonstrate that quasi-phase-matched high-harmonic generation produces beams with very high spatial coherence at wavelengths around 13 nm. To our knowledge these are the highest spatial coherence values ever measured at such short wavelengths from any source without spatial filtering. This results in a practical, small-scale, coherent, extreme-ultraviolet source that is useful for applications in metrology, imaging, and microscopy.

Coherent optical production of the Hough transform

Abstract: The Hough transform (HT) is an efficient shape detector that maps straight lines into a two-parameter feature space. Recently it has been pointed out that the forward Radon transform (FRT), well known from the theory of computed tomography, and the HT are equivalent for binary images. In this paper, analog coherent optical implementation of the FRT is discussed. The FRT will not only be of use in implementing the HT shape descriptors but also act as a coherent optical preprocessor for the implementation of multidimensional convolution, correlation, and spectral analysis using 1-D acoustooptical signal processing devices. Several different coherent optical FRT architectures are presented. Experimental results using conventional coherent Fourier transform configuration are given. The relationship between the coherent optical implementation of the FRT and the inverse Radon transform, an important tool in computed tomography, is also detailed.

Observation of optical chaos in a phase-conjugate resonator.

Abstract: The outcoupled power of a phase-conjugate resonator that uses four-wave mixing in BaTiO(3) is observed to undergo transitions from steady to periodic and from periodic to chaotic behavior as a function of time. Period doubling, period-three cycles, and period-five cycles are observed. Control parameters for the transitions are the diameter of an intracavity pinhole aperture, the length of the resonator, and the radius of curvature of the outcoupling mirror.