Displaytech, Inc.

Micron Technology Incorporated

Michael J O'Callaghan

Mark A Handschy

Christopher Morgan Walker

William N Thurmes

A holographic data storage system that includes a write head that includes a pixellated spatial light modulator and a separate or integral phase mask that varies the phase depending on the location in the phase mask that light passes through. The phase variation can be changed over time in a random, pseudo-random, or predetermined fashion. The spatial light modulator and phase mask can be implemented in a liquid crystal SLM (nematic, ferroeleletric, or other), in a DMD SLM, in a magneto-optical SLM, or in any other suitable manner.

Spatial light modulators with changeable phase masks for use in holographic data storage

A spatial light modulator (SLM) having a phase mask that is provided as an internal component thereof. The phase mask can be provided as a multilevel surface of relatively higher index of refraction material on an inner surface of a transmissive cover window or as a separate transmissive window between the cover window and the pixels of the SLM. If the phase mask is to be used with a liquid crystal SLM, then it may be desirable to planarize the surface of the cover window contacting the liquid crystal by providing a layer of relatively lower index of refraction material adjacent the multilevel surface. The phase mask can also be provided on the transmissive cover window by patterned ion deposition, exposing patterned light to a photopolymeric material, or in some other suitable fashion. Arranging for the pixel electrodes to be at one of multiple levels rather than lying in an exactly planar relationship can also effectively create the phase mask.

Phase masks for use in holographic data storage

A holographic data storage system that includes a write head that includes a pixellated spatial light modulator and a separate or integral phase mask that varies the phase depending on the location in the phase mask that light passes through. The phase variation can be changed over time in a random, pseudo-random, or predetermined fashion. The spatial light modulator and phase mask can be implemented in a liquid crystal SLM (nematic, ferroelectric, or other), in a DMD SLM, in a magneto-optical SLM, or in any other suitable manner.

A liquid crystal infrared light chopper includes a polarizer that receives and polarizes incoming infrared light, a layer of ferroelectric liquid crystal material switchable between at least two states, a pair of IR transparent, conductive substrates positioned on either side of the liquid crystal layer and an analyzer that blocks IR light of one polarization state and passes IR light of an opposite polarization state. The liquid crystal layer acts on polarized IR light by changing its polarization if the liquid crystal is in a first state and by not changing its polarization if the liquid crystal is in a second state. Voltages applied to the conductive substrates drive the liquid crystal layer to one of the two states. The analyzer blocks IR light when the liquid crystal layer is in one of the states and passes IR light when the liquid crystal layer is in the second state.

Ferroelectric liquid crystal infrared chopper

A display system includes a spatial light modulator having an array of individually controlled pixels switchable between a first and a second state for producing modulated light having gray scale during a given period of time. The system generates a reference signal that varies in a predetermined way during the given period of time. The system also generates analog pixel image signals associated with each of the pixels for the given period of time. The analog pixel image signal representing a desired gray scale level for each associated pixel during the given period of time. Each of the pixels includes an arrangement for receiving the reference signal and an arrangement for receiving the analog pixel image signal associated with that pixel. A comparator within each pixel compares the reference signal and the analog pixel image signal associated with that pixel and outputs a signal for switching the pixel between the first and the second state when the reference signal reaches a predetermined level relative to the analog pixel image signal. In a display system that uses a light modulating medium that requires DC-field balancing, the pixel may further include an inverter arrangement for inverting the output of the comparator for purposes of DC-field balancing.

Miniature display apparatus and method

An optical correlator includes a first reflective mode spatial light modulator for inputting an input image and a second reflective mode spatial light modulator for inputting a reference image for comparing with the input image. The optical correlator also includes an optics arrangement for (i) directing light into the first spatial light modulator, (ii) directing light along a first optical path from the first spatial light modulator into the second spatial light modulator, and (iii) directing light along a second optical path from the second spatial light modulator into an image plane. The optics arrangement includes a first lens having a focal length f1 and a second lens having a focal length f2. The first lens is positioned substantially adjacent the first spatial light modulator and the second lens is positioned substantially adjacent the second spatial light modulator. In one aspect of the invention, the spatial light modulators have their individual respective backplanes formed as two separate portions of a single integrated circuit die. In another aspect of the invention, the optics arrangement is configured such that the optical correlator does not need to be configured as a optical correlator with the length of the first optical path from the first lens to the second spatial light modulator being substantially equal to the length of the second optical path from the second lens to the image plane.

Optical correlator having multiple active components formed on a single integrated circuit

An optical correlator includes a compound electro-optical component having a first and a second reflective spatial light modulator for forming electro-optical patterns of light. Each spatial light modulator has a reflective backplane with the reflective backplanes of the spatial light modulators being substantially coplanar. The spatial light modulators having their individual respective backplanes formed as two separate portions of a single integrated circuit die. The optical correlator may also include an imager for imaging the output of the optical correlator that is substantially coplanar with the spatial light modulators. The compound electro-optical component may include at least a part of the imager that is formed as a separate portion of the single integrated circuit die that contains the backplanes of the two spatial light modulators.

An arrangement (apparatus and method) for selectively modulating incident unpolarized light passing through a birefringent material, such as ferroelectric crystal. The apparatus includes a plate having one or more birefringent layers corresponding to first and second alignment regions. The birefringent layer corresponding to the first alignment region has a first optic axis selectably set in a first orientation and a second orientation. The birefringent layer corresponding to the second alignment region has a second optic axis selectably set in a third orientation and a fourth orientation. A switching means controls the optical axis states of the birefringent material by applying switching voltages to the areas of the birefringent layer. Light having passed through the birefringent layer at locations having the first orientation has a different phase from, and same polarization as, light having passed through locations with the third orientation, independent of a polarization state of the incident light. As a result, the birefringent material has a uniform state at locations where the corresponding optic axes between the first and second alignment regions are parallel, and a diffracting state produced by an interaction between the light having passed through areas having the first orientation and the light having passed through areas having the second orientation. The arrangement is effective for reflective modulators, multilayer modulators or polarization-preserving modulators, and has applications for intensity modulation, blurring modulation and beam steering.

Diffractive light modulator

An arrangement (apparatus and method) for selectively modulating incident unpolarized light passing through a birefringent material, such as ferroelectric crystal. The apparatus includes a plate having one or more birefringent layers. The birefringent layer has an optic axis selectably set in a first orientation and a second orientation. A switching means controls the optical axis state of voltages to the areas of the birefringent layer. Light having passed through the birefringent layer at locations having the first orientation have a different phase from, and same polarization as, light having passed through locations with the second orientation, independent of a polarization state of the incident light. As a result, the birefringent material has a uniform state at locations where the correspon

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Louisville, CO, United States of America

Michael J O'Callaghan