Beam Engineering for Advanced Measurements Co.

US Government As Represented by the Secretary of the Army

University of Central Florida Research Foundation, Inc.

Beam Engineering for Advanced Materials Co.

Sarik R Nersisyan

Nelson V Tabirian

Diane Steeves

Brian Kimball

Olena Uskova

David E Roberts

Leonid B Glebov

Vadim Smirnov

Anna Tabirian

Rafael O Vergara

Vasile Rotar

Optical beam steering and focusing systems, devices, and methods that utilize diffractive waveplates are improved to produce high efficiency at large beam deflection angles, particularly around normal incidence, by diffractive waveplate architectures comprising a special combination of liquid crystal polymer diffractive waveplate both layers with internal twisted structure and at a layer with uniform structure.

High-efficiency wide-angle beam steering system

Method for fabrication of vector vortex waveplates of improved quality due to reduced singularity size and widened spectral band, the method comprising creating a boundary condition for vortex orientation pattern of a liquid crystal polymer on a substrate using materials with reversible photoalignment, equalizing exposure energy over the area of the waveplate by redistributing the energy of radiation used for photoalignment from the center of the beam to its peripheries, and using vector vortex waveplate as a linear-to-axial polarization converter. Fabrication of spectrally broadband vector vortex waveplates further comprises two or more liquid crystal polymer layers with opposite sign of twist.

Vector vortex waveplates

Pointing and positioning system of light beams and images including a plurality of cycloidal diffractive waveplates, each waveplate capable of deviating a generally broadband light beam over a predetermined angle. The lateral translation and deviation angles of the light beams are controlled by controlling the relative distance, rotational position, and the diffraction efficiency of at least one in the plurality of waveplates.

Broadband optics for manipulating light beams and images

The objective of the present invention is providing a method for fabricating high quality diffractive waveplates and their arrays that exhibit high diffraction efficiency over large area, the method being capable of inexpensive large volume production. The method uses a polarization converter for converting the polarization of generally non-monochromatic and partially coherent input light beam into a pattern of periodic spatial modulation at the output of said polarization converter. A substrate carrying a photoalignment layer is exposed to said polarization modulation pattern and is coated subsequently with a liquid crystalline material. The high quality diffractive waveplates of the present invention are obtained when the exposure time of said photoalignment layer exceeds by generally an order of magnitude the time period that would be sufficient for producing homogeneous orientation of liquid crystalline materials brought in contact with said photoalignment layer. Compared to holographic techniques, the method is robust with respect to mechanical noises, ambient conditions, and allows inexpensive production via printing while also allowing to double the spatial frequency of optical axis modulation of diffractive waveplates.

Fabrication of high efficiency, high quality, large area diffractive waveplates and arrays

An apparatus and method for fabricating high quality one- or two-dimensional diffractive waveplates and arrays that exhibit high diffraction efficiency and capable of inexpensive large volume production. A generally non-holographic and aperiodic polarization converter for converting the polarization of a coherent input light beam of a visible wavelength into a pattern of continuous spatial modulation at the output of the polarization converter. A photoresponsive material characterized by an anisotropy axis according to polarization of the light beam is exposed to a polarization modulation pattern and coated subsequently with an anisotropic material overlayer with ability of producing an optical axis orientation according to and under the influence of the anisotropy axis of the photoresponsive material layer. The diffractive waveplates are obtained when exposure time of photoresponsive material layer exceeds an order of magnitude the time period that is known to produce spatially homogeneous orientation of the anisotropic overlayer.

Optical systems for controlling with propagation of light beams in lateral and angular space, and through optical apertures. The light beams include laser beams as well as beams with wide spectrum of wavelengths and large divergence angles. The optical systems are based on combination of diffractive waveplates with diffractive properties that can be controlled with the aid of external stimuli such as electrical fields, temperature, optical beams and mechanical means.

A cycloidal diffractive waveplate () comprising first and second substrate layers (), a liquid crystal layer (C,H) provided between the first and second substrate layers, and transparent positive electrodes () and transparent negative electrodes () provided on the first substrate layer. The liquid crystal layer has a diffractive state (C) in which the optical axes of the liquid crystal molecules are periodically rotated across a plane of the waveplate and a non-diffractive state (H) in which the optical axes of the liquid crystal molecules are all orientated in the same direction in the plane of the waveplate. The electrodes () are arranged in an alternating series, such that when an electric voltage is applied to the electrodes an electric field is produced in the plane of the waveplate and the liquid crystal layer is switched from the diffractive state to the non-diffractive state. A method of manufacturing the cycloidal diffractive waveplate is also provided.

Cycloidal diffractive waveplate and method of manufacture

A method of fabricating a liquid crystal polymer film includes providing a support substrate having a surface having a shape arranged to define a form of a liquid crystal polymer film to be fabricated; applying a layer of a photoaligning material over the surface of the support substrate, the photoaligning material having an absorption band; exposing the layer of photoaligning material to a light having a linear polarization and the light comprising a wavelength within the absorption band to convert the layer of photoaligning material into a layer of photoaligned material; applying a layer of a polymerizable liquid crystal over the layer of photoaligned material; performing photopolymerization of the layer of polymerizable liquid crystal to form a liquid crystal polymer film; applying a solvent to the layer of photoaligned material, the solvent formulated to dissolve the photoaligned material to thereby release the liquid crystal polymer film from the support substrate; and removing the liquid crystal polymer film from the support substrate.

Method of fabricating a liquid crystal polymer film

Pointing and positioning system of light beams and images including a plurality of cycloidal diffractive waveplates, each waveplate capable of deviating a generally broadband light beam over a predetermined angle. The lateral translation and deviation angles of the light beams are controlled by controlling the relative distance, rotational position, and the diffractive efficiency of a least one in the plurality of waveplates.

Non-mechanical optical beam steering and switching is produced by optically controlled liquid crystal spatial light modulator with angular magnification by high efficiency volume Bragg gratings recorded in a photosensitive PTR glass. Small angle beam deflection in a photoactive liquid crystal cell is produced by exposing it to a controlling beam from an external source of radiation with predetermined distribution of power density which causes predetermined spatial gradients of a refractive index in a liquid crystal cell and, therefore, refraction of a controlled beam which is made to propagate in the region with spatial gradient of the refractive index. Large angle beam deflection is produced by a volume Bragg grating with angular selectivity adjusted in such way that small angle scanning produced by optically controlled liquid crystal spatial light modulator results in change of diffraction efficiency from zero to 100% for switching the beam for two Bragg angles.

Optical beam steering and switching by optically controlled liquid crystal spatial light modulator with angular magnification by high efficiency PTR Bragg gratings

The objective of the present invention is providing a method and a simple instrument that can be used on a routine basis to accurately and quickly measure the focus position, waist radius, divergence, quality, power and power density of a laser beam. The measurement is performed by scanning a thin film of a nonlinear optical material in the focal region along the propagation direction of the beam and registering the variation of the on-axis intensity of the laser beam by a photodetector.

Growing community of inventors

Maitland, FL, United States of America

Sarik R Nersisyan