US 6,606,181 B2 · Optical power limiting control

Abstract

A controllable phase plate has numerous domains that are randomized as to the orientation of their birefringence and can be used in a power limiting control to produces an electrically controllable diffraction pattern having a portion, especially the zero mode axial spot of the pattern, that is directed onto an output aperture such as a pinhole or an optical fiber end. Controlling the phase plate produces an interference peak or null (or an intermediate level) of light, coupled into the output aperture. The phase plate preferably comprises a liquid crystal with controllable birefringence. The domains have paired orthogonal orientations, which is a condition that is met in randomized domains. The paired orthogonal orientations make the device polarization insensitive. In a controllable attenuating device, collimating lenses are placed before and after the phase plate along a beam path to focus a clear interference pattern on a screen containing the output aperture. Several variations are disclosed including an electrically controllable phase plate arrangement using liquid crystal controllably birefringent material prepared in a polarization insensitive manner in zones, or preferably by providing random director orientation in a plane.

Claims36

Dependent claims

An optical device, comprising:

an optical element to be placed along a propagation path of light, the optical element defining a plurality of individual domains forming local parts of an area of the optical element such that at least more than two of the domains intersect part of the path of the light;
wherein each one of said domains has optical properties that can be different along two mutually perpendicular axes, said two axes for each said domain defining a given orientation of said domain;
wherein the given orientations for said domains vary across the area of the optical element such that any first one of said domains can be paired with a second one of said domains wherein the optical properties of the second one of said domains are substantially equal to the first one but are orthogonal to the first one.

A method of controlling light transmission along a propagation path between an input and an output for an incident light beam that is directed along a light transmission axis, comprising the steps of:

providing an output structure defining at least one aperture placed for passing light to the output, in a material that otherwise blocks light from reaching the output;
providing a controllable phase interference element along the transmission path leading to the output;
directing the incident light along the transmission axis toward the output, through the phase interference element, so as to produce an interference pattern containing peaks and nulls over an area that is larger than the aperture;
controlling the phase interference element to vary the interference pattern such that more or less of the light energy is aligned to one or more of the peaks and nulls that corresponds to the aperture, thereby controlling an extent of coupling between the input for the beam and the output.

1 more element

Dependencies are inferred from the claim text.

Optical power limiting control

Life of this patent

Optical power limiting control

Life of this patent

Abstract

Claims36