University of Rochester

United States of America As Represented by the Secretary of the Air Force

Kenneth L Marshall

Stephen D Jacobs

Tanya Z Kosc

Stavros G Demos

Anka Trajkovska-Petkoska

Sadeg Mustafa Faris

Le Li

Gerald Philip Cox

Kathleen A Cerqua

Cathy A Fromen

Eric Glowacki

Additive manufacturing systems and methods utilizing an optical light valve configured to spatially modulate the intensity of a laser beam, in conjunction with a writing and erasing sub-system configured to repeatedly write and erase patterns in the optical light valve to repeatedly vary the spatial modulation of the laser beam. In some implementations, the systems and methods may also employ additional laser beams or other energy sources that are not spatially modulated by the optical light valve. In some implementations, the systems and methods may employ additional laser beams or other energy sources configured to reduce surface roughness of the powder or other material being used for additive manufacturing.

Additive manufacturing systems and methods

A beam shaping system including an all-optical liquid crystal beam shaper, the beam shaper including a photoswitchable alignment material including at least one of a PESI-F, SPMA:MMA 1:5, SPMA:MMA 1:9, ora SOMA:SOMA-p:MMA 1:1:6 material, at least some of the liquid crystals of the beam shaper including at least one of a phenylcyclohexane, cyclo-cyclohexane, or a perfluorinated material.

All-optical, optically addressable liquid crystal-based light valve employing photoswitchable alignment layer for high-power and/or large aperture laser applications

Drink holder

Switchable gas permeation membranes in which a photo-switchable low-molecular-weight liquid crystalline (LC) material acts as the active element, and a method of making such membranes. Different LC eutectic mixtures were doped with mesogenic azo dyes and infused into track-etched porous membranes with regular cylindrical pores. Photo-induced isothermal phase changes in the imbibed mesogenic material afforded large, reversible changes in the permeability of the photo-switchable membrane to nitrogen. For example, membranes imbibed with a photo-switchable cyanobiphenyl LC material demonstrated low permeability in the nematic state, while the photo-generated isotropic state demonstrated a 16&#xd7;-greater sorption coefficient. Both states obey a high linear sorption behavior in accordance with Henry's Law. In contrast, membranes imbibed with a photo-switchable phenyl benzoate LC material showed the opposite permeability behavior to the biphenyl-imbibed membrane, along with nonlinear sorption behavior.

Photo-switchable membrane and method

A PCLC flake/fluid host suspension that enables dual-frequency, reverse drive reorientation and relaxation of the PCLC flakes is composed of a fluid host that is a mixture of: 94 to 99.5 wt % of a non-aqueous fluid medium having a dielectric constant value &#x2208;, where 1&#x3c;&#x2208;&#x3c;7, a conductivity value &#x3c3;, where 10&#x3e;&#x3c3;&#x3e;10Siemens per meter (S/m), and a resistivity r, where 10&#x3e;r&#x3e;10ohm-meters (&#x3a9;-m), and which is optically transparent in a selected wavelength range &#x394;&#x3bb;; 0.0025 to 0.25 wt % of an inorganic chloride salt; 0.0475 to 4.75 wt % water; and 0.25 to 2 wt % of an anionic surfactant; and 1 to 5 wt % of PCLC flakes suspended in the fluid host mixture. Various encapsulation forms and methods are disclosed including a Basic test cell, a Microwell, a Microcube, Direct encapsulation (I), Direct encapsulation (II), and Coacervation encapsulation. Applications to display devices are disclosed.

PCLC flake-based apparatus and method

Doped electrically actuatable (electrically addressable or switchable) polymer flakes have enhanced and controllable electric field induced motion by virtue of doping a polymer material that functions as the base flake matrix with either a distribution of insoluble dopant particles or a dopant material that is completely soluble in the base flake matrix. The base flake matrix may be a polymer liquid crystal material, and the dopants generally have higher dielectric permittivity and/or conductivity than the electrically actuatable polymer base flake matrix. The dopant distribution within the base flake matrix may be either homogeneous or non-homogeneous. In the latter case, the non-homogeneous distribution of dopant provides a dielectric permittivity and/or conductivity gradient within the body of the flakes. The dopant can also be a carbon-containing material (either soluble or insoluble in the base flake matrix) that absorbs light so as to reduce the unpolarized scattered light component reflected from the flakes, thereby enhancing the effective intensity of circularly polarized light reflected from the flakes when the flakes are oriented into a light reflecting state. Electro-optic devices contain these doped flakes suspended in a host fluid can be addressed with an applied electric field, thus controlling the orientation of the flakes between a bright reflecting state and a non-reflecting dark state.

Electrically actuatable doped polymer flakes and electrically addressable optical devices using suspensions of doped polymer flakes in a fluid host

Liquid crystal point diffraction interferometer (LCPDI) systems that can provide real-time, phase-shifting interferograms that are useful in the characterization of static optical properties (wavefront aberrations, lensing, or wedge) in optical elements or dynamic, time-resolved events (temperature fluctuations and gradients, motion) in physical systems use improved LCPDI cells that employ a 'structured' substrate or substrates in which the structural features are produced by thin film deposition or photo resist processing to provide a diffractive element that is an integral part of the cell substrate(s). The LC material used in the device may be doped with a 'contrast-compensated' mixture of positive and negative dichroic dyes.

Liquid crystal devices especially for use in liquid crystal point diffraction interferometer systems

Precisely configured, especially of geometric shape, flakes of liquid crystal material are made using a mechanically flexible polymer mold with wells having shapes which are precisely configured by making the mold with a photolithographically manufactured or laser printed master. The polymer liquid crystal is poured into the wells in the flexible mold. When the liquid crystal material has solidified, the flexible mold is bent and the flakes are released and collected for use in making an electrooptical cell utilizing the liquid crystal flakes as the active element therein.

Method for making precisely configured flakes useful in optical devices

Optical devices utilizing flakes (also called platelets) suspended in a host fluid have optical characteristics, such as reflective properties, which are angular dependent in response to an AC field. The reflectivity may be Bragg-like, and the characteristics are obtained through the use of flakes of liquid crystal material, such as polymer liquid crystal (PLC) materials including polymer cholesteric liquid crystal (PCLC) and polymer nematic liquid crystal (PNLC) material or birefringent polymers (BP). The host fluid may be propylene carbonate, poly(ethylene glycol) or other fluids or fluid mixtures having fluid conductivity to support conductivity in the flake/host system. AC field dependent rotation of 90&#xb0; can be obtained at rates and field intensities dependent upon the frequency and magnitude of the AC field. The devices are useful in providing displays, polarizers, filters, spatial light modulators and wherever switchable polarizing, reflecting, and transmission properties are desired.

Optical devices having flakes suspended in a host fluid to provide a flake/fluid system providing flakes with angularly dependent optical properties in response to an alternating current electric field due to the dielectric properties of the system

Composite or layered flakes having a plurality of layers of different materials, which may be dielectric materials, conductive materials, or liquid crystalline materials suspended in a fluid host and subjected to an electric field, provide optical effects dependent upon the angle or orientation of the flakes in the applied electric field. The optical effects depend upon the composition and thickness of the layers, producing reflectance, interference, additive and/or subtractive color effects. The composition of layered flakes may also be selected to enhance and/or alter the dielectric properties of flakes, whereby flake motion in an electric field is also enhanced and/or altered. The devices are useful as active electro-optical displays, polarizers, filters, light modulators, and wherever controllable polarizing, reflecting and transmissive optical properties are desired.

Electrically addressable optical devices using a system of composite layered flakes suspended in a fluid host to obtain angularly dependent optical effects

Flakes or platelets of polymer liquid crystals (PLC) or other birefringent polymers (BP) suspended in a fluid host medium constitute a system that can function as the active element in an electrically switchable optical device when the suspension is either contained between a pair of rigid substrates bearing transparent conductive coatings or dispersed as microcapsules within the body of a flexible host polymer. Optical properties of these flake materials include large effective optical path length, different polarization states and high angular sensitivity in their selective reflection or birefringence. The flakes or platelets of these devices need only a 3-20&deg; rotation about the normal to the cell surface to achieve switching characteristics obtainable with prior devices using particle rotation or translation.

Electrically switchable polymer liquid crystal and polymer birefringent flake in fluid host systems and optical devices utilizing same

The invention provides a series of ferroelectic smectic liquid crystal compounds, FLC, of wide tilt angle and mixtures formulated from them that are useful for high speed modulation or switching of optical radiation. Such FLC mixtures are useful in total internal reflection, TIR switching devices. In such TIR switches, an applied DC voltage rotates the molecules through about a 90.degree. angle which changes the perceived refractive index at the FLC layer and permits rapid optical switching. For an FLC crystal material to be useful in such a device it must possess a value of molecular tilt angle .theta. of approximately 45.degree., since the dipole molecule rotates through an angle of about 2 .theta. upon application of a DC field to the cell. This requirement for a large molecular tilt angle greatly limits the compounds and mixtures thereof which can be employed in such TIR devices. The smectic FLC compounds and mixtures thereof of the present invention provide for TIR switches that exhibit high contrast ratios ( &lt;1,000:1). They can also provide in such switch, 2-position bistable beam deflection. That is, if the electric field of the TIR switches is shut off, the smectic FLC compounds will hold the molecular tilt angle existing at that time without requiring an applied electric field (to hold such pattern) unlike their nematic LC predecessors.

High tilt angle FLC mixture for TIR switching devices

Composite optical devices using polymer liquid crystal materials both as optical and adhesive elements. The devices are made by assembling a heated polymer liquid crystal compound, while in a low viscosity form between optically transparent substrates. The molecules of the polymer are oriented, while in the liquid crystalline state and while above the glass transition temperature (T.sub.g) of the polymer, to provide the desired optical effects, such as polarization, and selective reflection. The liquid crystal polymer cements the substrates together to form an assembly providing the composite optical device.

Growing community of inventors

Rochester, NY, United States of America

Kenneth L Marshall