Abstract: A method for monitoring the interaction of molecular species utilizes a sensor device comprising a substrate (1) with a waveguide (2) formed on the surface thereof. A grating (3) is formed in one of the surfaces of the waveguide (2). A beam of light (6) is incident on the grating (3) and the angle of incidence at which maximum reflection occurs is monitored. A first molecular species is immobilized on the waveguide (2). Changes in the angular position of the reflection maximum provide an indication of interaction of the first molecular species with a second molecular species contained in a sample brought into contact with the sensor device.

Abstract: An apparatus and method for modulating an incident light beam for forming a two-dimensional projection image. The apparatus includes a plurality of elongated elements each having a reflective surface. The elongated elements are suspended substantially parallel to each other above a substrate with their respective ends supported, forming a column of adjacent reflecting surfaces grouped according to display elements. Alternate ones of each group are deformable by a applying a voltage with respect to the substrate. An approximately flat center section of each deformed element is substantially parallel to and a predetermined distance from a center section of each undeformed element. Limiting the predetermined distance avoids hysteresis in deforming the elements and avoids adhesion of the elements to the substrate.

Abstract: Condenser system for use with a ringfield camera in projection lithography where the condenser includes a series of segments of a parent aspheric mirror having one foci at a quasi-point source of radiation and the other foci at the radius of a ringfield have all but one or all of their beams translated and rotated by sets of mirrors such that all of the beams pass through the real entrance pupil of a ringfield camera about one of the beams and fall onto the ringfield radius as a coincident image as an arc of the ringfield. The condenser has a set of correcting mirrors with one of the correcting mirrors of each set, or a mirror that is common to said sets of mirrors, from which the radiation emanates, is a concave mirror that is positioned to shape a beam segment having a chord angle of about 25 to 85 degrees into a second beam segment having a chord angle of about 0 to 60 degrees.

Abstract: A method and an apparatus for stretching an optical pulse and shaping its spectrum. The method includes the step of: providing a an optical fiber element having a first long length fiber Bragg grating having a refractive index perturbation of varying periodicity. The optical pulse is launched into the fiber Bragg grating, wherein the Bragg grating reflects the pulse in a chromatically dispersed output. The reflected output is coupled with an optical modulator programmed to temporally modify the amplitude of the chromatically dispersed output to attenuate selected optical frequencies in a desired pattern. The apparatus for stretching and arbitrarily shaping the spectrum of an optical pulse with a desired wavelength resolution &Dgr;&lgr;res includes a routing optical device and an optical fiber element having a Bragg grating. The routing optical device routs energy between different waveguides, and has an input port to receive the optical pulse.

Abstract: The present invention is related to a system for transferring a beam of electromagnetic radiation having a vacuum wavelength. The system according to the invention includes a first dielectric medium, a second dielectric medium and a dielectric layer in between the first and the second medium. The dielectric layer has a periodicity of the dielectric properties parallel to the layer. The periodicity has a period that is smaller than the wavelength of the electromagnetic radiation in the second dielectric medium.

Abstract: A spatial light modulator pixel comprises a movable reflective surface in which an array of subapertures is formed, wherein each subaperture contains a fixed (non-movable) island reflector. The movable reflector is micromechanically actuated so that the combination of movable and fixed reflectors functions alternately as a plane mirror or as a two-dimensional diffraction grating (i.e., a “bigrating”), depending on the movable reflector's position. The device is useful for applications such as maskless lithography and high-resolution printing.

Abstract: A mechanical grating device for enhancing the reflective properties is presented. A mechanical grating has a plurality of parallel ribbon elements which are suspended above a channel. An incident light beam is modulated by the actuation of selected ribbon elements. The actuation of the ribbon elements, which changes the height of the ribbon elements relative to the substrate, is a result of an applied voltage that produces an electrostatic force. On the top surface of the ribbon elements is a coating of reflective metal upon which is an optical coating is provided. The optical coating is a stack of at least two different materials with different refractive indices. The thickness and the composition of the sequential layers in the stack are chosen to produce certain desired reflective properties. Embodiments are presented for reducing the mechanical effects of the dielectric optical coating.

Abstract: A microscopy and/or lithography system uses a comparatively low-resolution image projection system, which has a very small numerical aperture but large image field, in conjunction with a microlens array comprising miniature lens elements, each of which has a large numerical aperture but very small field. The projection system contains a small aperture stop which is imaged by the microlenses onto an array of diffraction-limited microspots on the microscope sample or printing surface at the microlens focal point positions, and the surface is scanned to build up a complete raster image from the focal point array. The system design thus circumvents the tradeoff between image resolution and field size which is the source of much of the complexity and expense of conventional wide-field, high-NA microscopy and microlithography systems.

Abstract: A method for operating an electro-mechanical grating device comprises the steps of: providing a beam of light; applying a first electrostatic actuation force for a certain amount of time thereby generating a first pattern in each group wherein the pattern comprises N different levels thereby diffracting the incident light beam into a first direction; and applying a second electrostatic actuation force for a certain amount of time thereby generating a second pattern in each group wherein the second pattern comprises N different levels thereby diffracting the incident light beam into a second direction different from the first direction. The electro-mechanical grating device has a plurality of spaced apart deformable ribbon elements disposed parallel to each other in the unactuated state and spanning a channel. The deformable ribbon elements are organized in groups of N elements wherein N is greater than 2.

Abstract: A method and apparatus for converting a beam of light that is substantially coherent and has a coherence length into substantially incoherent radiation. The method has the steps of collimating the beam, delaying a first portion of the beam by a first optical delay by ballistic passage through a first cell of an optical element, and delaying each of a plurality of other portions of the beam by an optical delay different from the first optical delay by an amount exceeding the coherence length of the beam.

Abstract: An overcoat protected diffraction grating. A replica grating having a thin aluminum reflective grating surface is produced by replication of a master grating or a submaster grating. The thin aluminum reflective surface may be cracked or have relatively thick grain boundaries containing oxides and hydroxides of aluminum and typically is also naturally coated with an aluminum oxide film. The grating is subsequently recoated in a vacuum chamber with a thin, pure, dense aluminum overcoat and then also in the vacuum the aluminum overcoat is coated with a thin film of MgF.sub.2. The grating is especially suited for use for wavelength selection in an ArF laser operating producing an ultraviolet laser beam at a wavelength of about 193 nm. The oxygen free aluminum overcoat prevents the ultraviolet light from causing damage by stimulating chemical reactions in grating materials under the aluminum grating surface or in the aluminum oxide film. The MgF.sub.

Abstract: An electromagnetic wave interactive structure is provided for forming a transmitted electromagnetic wave response which is a function of the frequency of the incident wave. A phase transition material selected from the transition-metal oxides, dynamic nonlinear materials, the rare earth monochalcogenides and the organometallics is provided in geometric relationship with a fixed metallic structure. The phase transition material is then switched between a dielectric phase and a metallic phase to alter the response of the composite structure. Thus, an inductive mesh may be switched to a reflective surface (FIG. 8); an inductive band-pass changed to a reflective surface (FIG. 9); a capacitive band-stop response to an inductive band-pass response (FIG. 10); a capacitive band-stop response changed to a reflective surface (FIG. 11); a capacitive mesh response to an inductive band-pass response (FIG. 12); and a capacitive band-stop response switched to an inductive mesh response (FIG. 13).

Abstract: A method is disclosed for actuating electromechanical ribbon elements which are suspended over a channel. The channel defines a bottom surface having a bottom conductive layer formed below said bottom surface. A data generator provides a data stream. The data generator is connected to a modulator for generating from said data stream a modulated bipolar voltage signal whose time average is equal to the time average of a bias voltage applied to the bottom conductive layer. The data generator and the modulator are necessary to carry out the method. The method comprises the steps of: providing a data stream; generating from said data stream a modulated bipolar voltage signal whose time average is equal to the time average of a bias voltage applied to the bottom conductive layer; and applying said modulated bipolar voltage signal to the ribbon elements.

Abstract: One polarizer reflective-type color liquid crystal display has been developed. Reflective-type liquid crystal display have found increasingly important for both direct-view and projection displays. Attractive features such as high contrast ratio, mirror reflection reduced, and clear image of no parallax are demonstrated. This design uses single polarizer to enhanced the brightness and an inner metallic reflector to avoid parallax.

Abstract: A method of fabricating a modulator for modulating an incident beam of light includes a substrate having a cavity formed therein and a plurality of spaced-apart deformable elements formed in the cavity. The deformable elements each has a base layer, a poled magnetic layer formed in the base layer and a first light reflection layer deposited on the magnetic layer for reflecting an incident beam of light. Between adjacent deformable elements on the base of the cavity is arranged a second light reflection layer. A conductive element formed in the substrate electro-magnetically energizes the deformable elements to deflect in the cavity. Incident light passing through each one of the first light reflection layers is caused to destructively interfere with light reflected from the second light reflection layers thereby causing modulation of the incident light.

Abstract: A grating light valve is configured to either reflect or diffract an incident beam of light from a light source. Each grating light valve includes a plurality of deformable reflective ribbon structures. Preferably, the grating light valve is located within a vacuum chamber. A directable low power electron gun is also positioned within the chamber. To form an image the gun is scanned across an array of grating light valves and selectably irradiates predetermined ones of the ribbons to charge each such ribbon to a predetermined level. Depending upon the amount of charge so deposited onto the ribbon, it will deflect a predetermined distance toward an underlying substrate. The ribbons are preferably erased in one of two ways. According to the preferred embodiment, each ribbon includes a path of impedance to allow the charge to bleed into the substrate. The impedance is selected to discharge a fully charged ribbon in a period of a single frame.

Abstract: A spectrally resolved monochromatic light is provided which generally comprises an incoherent small source lamp, a concave grating for spectrally resolving the wavelengths of the light to obtain a particular wavelength, and an optical fiber for collecting and transmitting the particular wavelength. The light source can also have more than one optical fiber output, each having a different monochromatic wavelength. An order sorting device, such as a filter or dichroic mirror can be used to filter out the shorter wavelength radiation resulting from higher grating orders.

Abstract: Condensers having a mirror with a diffraction grating in projection lithography using extreme ultra-violet significantly enhances critical dimension control. The diffraction grating has the effect of smoothing the illumination at the camera's entrance pupil with minimum light loss. Modeling suggests that critical dimension control for 100 nm features can be improved from 3 nm to less than about 0.5 nm.

Abstract: A holographic grating 12 is formed on one surface of a scale substrate 11 in such a manner that a light source is disposed over the other surface of the scale substrate 11. The scale substrate 11 is formed of a transparent material. A reflection film 13 is directly deposited on the grating surface. A protection substrate 15 is adhered to the reflection film 13 on the scale substrate 11 with adhesive agent 14. Thus, a reflection-type hologram scale 1 is accomplished.

Abstract: A method of making a modulator for modulating an incident beam of light uses a substantially planar light reflection surface formed by a light reflection layer associated with a plurality of deformable elements and a light reflection layer associated with a plurality of fixed elements. The fixed and deformable elements are arranged in a cavity of a substrate supporting the modulator. Light is modulated when a current is applied to a conductive element operably associated with the deformable elements causing the light reflective layer associated with the deformable element to deflect towards the base of the cavity from its substantial planar relations with the light reflecting layer of the fixed element.

Abstract: A static diffracting grating display system provides a fixed image representing high digital content information. A plurality of physical diffracting features are fixed into the surface of a substrate. The diffracting features are positioned and oriented to selectively diffract or reflect a first incident beam of light which is then collected by a first display optical system. For color, preferably three light sources, red, green and blue, are used to form three incident beams of light. The period between adjacent ones of the diffracting features can be adjusted to appropriately form full-color image from the collected light. Preferably the diffracting features are formed by embossing a deformable substrate. Where the material of the deformable substrate is not reflective, a reflective coating is then applied. In some circumstances a protective overcoat applied over the reflective surface to obviate scratches or other damage to the diffracting features of the embossed surface.

Abstract: An energy saving window system operates selectively in different seasons and climatic conditions to optimize transfer of the sun's radiation through the window into an interior space. Two sets of diffraction gratings are deployed, with two mode settings--a summer or capture mode and a winter or transmittance mode. In the summer mode, transfer of heat into the interior is undesirable. Unwanted heat rays are redirected to a scupper by additive diffraction through two diffraction gratings in series. The scupper redirects the undesired radiation to a heat sink or back out through the window. In the winter mode, transfer of heat into the interior is desirable. By repositioning the two diffraction gratings so that their deflections are subtractive, the sun's rays are redirected to be essentially undiffracted so as to miss the scupper and enter the room. The essentially undiffracted light rays are acceptable as a view and are effectively unblocked as to solar heat gain.

Abstract: A modulator for modulating an incident beam of light uses a substantially planar light reflection surface formed by a light reflection layer associated with a plurality of deformable elements and a light reflection layer associated with a plurality of fixed elements. The fixed and deformable elements are arranged in a cavity of a substrate supporting the modulator. Light is modulated when a current is applied to a conductive element operably associated with the deformable elements causing the light reflective layer associated with the deformable element to deflect towards the base of the cavity from its substantial planar relations with the light reflecting layer of the fixed element.

Abstract: Optical media is imaged by a combination of components for splitting a coherent beam into two co-propagating optical beams; converging the optical beams to produce a pattern of interference fringes having a pitch; varying the pitch and/or amplitude of the interference pattern fringes; axially rotating the fringes around the media; and axially rotating the co-propagating optical beams so as to maintain rotary synchronism with the axially rotating fringes as the permanent fringes are formed in the media whereby the longitudinal index of refraction is modulated along the media preferably with circular symmetry. The media is positioned as a work piece along a workpiece axis, with some of the system components translated along and/or rotated about the workpiece axis. Independently variable design parameters can, according to the preferred control system, be specified in advance with a high degree of flexibility.

Abstract: A grating modulator array (40) is comprised of a plurality of modulator sites (41). Each modulator site (41) is comprised of a plurality of first poled regions (50) and a plurality of second poled regions (51) alternating with said first poled regions. A first electrode (48a) is attached to a first end of each of the modulator sites and a second electrode (48b) is attached to a second end of each of the modulator sites and each of the electrode pairs establishes a field in the poled regions of the modulator sites which causes a phase shift in polarized light incident on the modulator.

Abstract: Microlenses 3a and 3b are formed on a first surface of a transparent substrate, and an output efficiency control device 2 which modulates a light amount of incident light is provided on a second surface opposing the first surface. Incident light 4 is made to be incident obliquely to an optical axis of the microlens 3a, to be focused on the output efficiency control device 2. The output efficiency control device 2 modulates a light amount of incident light and outputs the light as outgoing light 5 through the microlens 3b. Because of such a structure, the output efficiency control device 2 can be decreased in size, compared with a diameter of a beam and an aperture of a microlens.

Abstract: An echelle grating having a groove facet angle and groove periodicity such that for laser-emitted light of two different wavelengths the highest propagating diffraction order is blazed and the next higher order is non-propagating such that the intensity of each blazed order is enhanced. In an example, the 84th diffraction order of a KrF excimer laser emitting at 248.4 nm and the 108th diffraction order of an ArF excimer laser emitting at 193.3 nm will both be blazed when the groove spacing d is 0.010623 mm, corresponding to a frequency f of 94.13 grooves per mm, and the groove facet angle .theta..sub.g is about 80.degree., whereas the next higher order for each laser, i.e., the 85th and 109th orders, respectively, are non-propagating, and thus both blaze orders are enhanced.

Abstract: The invention relates to a semiconductor optical reflector serving in particular for being disposed facing an integrated laser cavity so as to feed light back into said cavity, and enable it to oscillate continuously. The reflector is made up of a plurality of cascaded Bragg reflector sections. More particularly, said sections are of the same length L and have the same coupling coefficient, and the length L of each pair of sections is given by the following relationship:L=.lambda..sup.2 /[(n.sub.i+1 +n.sub.i).times.1.7(n.sub.i+1 .LAMBDA..sub.i+1 -n.sub.i .LAMBDA..sub.i)]where .lambda. is the mean value of the Bragg wavelengths reflected by the reflector;n.sub.i+1 and n.sub.i are the respective effective refractive indices of said adjacent sections; and.LAMBDA..sub.i+1 and .LAMBDA..sub.i are the respective periods of said adjacent sections.The reflector of the invention has a wide spectrum band independent of the value of the coupling coefficient.

Abstract: An optical assembly utilizing a novel optical element. The assembly includes a tunable source of input radiation; an optical element that can receive at least a portion of the input radiation and comprises a manifold having at least two independent surfaces, in which at least a portion of each independent surface is selected from the group consisting of a reflective structure and a diffractive structure, and the independent surfaces are geometrically configured so that a portion of incident radiation to the manifold is diffracted at least twice in an angular sense that can increase a tuning sensitivity of an angular deviation of the incident radiation exiting the manifold; and, a scanner means which can accept and redirect a portion of the radiation output by the optical element for producing an illumination pattern.

Abstract: A special record format used for commanding light pattern shapes and addressable light pattern shape generator. The command format includes a first part which commands a specified gobo and second parts which command the characteristics of that gobo. The gobo is formed by making a default gobo based on the type and modifying that default gobo to fit the characteristics.

Abstract: A diffractive structure (100) has a substantially planar substrate (1). A set of facets (2) is formed in or on said substrate (1), the plane or planes in which the facets (2) lie being arranged at a non-zero angle to the plane of the substrate (1). Each facet (2) has a diffraction grating (5) formed thereon. The diffractive structure (100) will produce color over a wide range of viewing and illumination angles.

Abstract: A method is disclosed for actuating electro-mechanical ribbon elements which are suspended over a channel. The channel defines a bottom surface and having a bottom conductive layer formed below said bottom surface. A data generator provides a data stream. The data generator is connected to a modulator. Additionally, an actuation voltage generator, connected to the modulator, produces a periodic high frequency voltage signal that has a frequency close to mechanical resonant frequency .function..sub.R of the ribbon elements. The signal from the modulator is applied to the ribbon elements 31 of the electro-mechanical grating device.

Abstract: A multi-line continuous wideband tunable laser (1) utilizes a symmetric or asymmetric grating (5) and a plurality of optical fibers (3), each of which forms a part of a respective laser cavity optical axis. By simultaneously altering both the periodicity of the intersections of the grating (5) with the plurality of optical axes established by the plurality of optical fibers (3) and the effective cavity length of each laser (1), a single-line spectral output is achieved at any desired point in the operating band.

Abstract: A semiconductor Bragg reflector and to a method of fabricating it. The reflector comprises a plurality of stacked layers on a substrate of a III-V type material, one of the stacked layers forming a holographic grating. The layer forming the grating comprises an alternating succession of air pockets and of III-V type material. Such a reflector is particularly suitable for use in laser devices.

Abstract: A modulator (10) for modulating an incident beam of light includes a substrate (14) having a cavity (32) formed therein and a plurality of spaced-apart deformable elements (12) formed in the cavity (32). The deformable elements (12) each has a base layer (16), a poled magnetic layer (18) formed in the base layer (16) and a first light reflection layer (20) deposited on the magnetic layer (18) for reflecting an incident beam of light. Between adjacent deformable elements on the base (12) of the cavity (32) is arranged a second light reflection layer (36). A conductive element (22, 24) formed in the substrate (14) electro-magnetically energizes the deformable elements (12) to deflect in the cavity (32). Incident light passing through each one of the first light reflection layers (20) is caused to destructively interfere with light reflected from the second light reflection layers (36) thereby causing modulation of the incident light.

Abstract: An improved micro machine has at least a first element which is moveable relative to a second element such that the first and second elements can be in contact with each other. The contacting portions of both the first and second elements are protected with a long-lasting lubricant to prevent the elements from sticking or adhering to each other. The lubricant is a polar low molecular weight compound preferably applied as a vapor. This class of low molecular weight lubricants consists of acetone, ethanol, ethylene glycol, glycerol, isopropanol, methanol, and water. According to the disclosure a lubricant has a low molecular weight if its molecular weight is less than .about.100 amu, or has a vapor pressure .gtoreq.5 Torr at room temperature. The preferred micro machine is a GLV wherein the bottom of the deformable ribbon contacts the landing electrode when the reflector is in a down position (close to the substrate).

Abstract: An optical element is formed as a body having two layers, at least on of which is transmissive to a selected wavelength of a light of illumination. One layer is formed with a first surface relief optical formation as a boundary thereof, and the other layer is formed on the boundary so as to have an adjacent boundary that is a second surface relief optical formation that is the conjugate of the first surface relief optical formation. The other layer also has further optical features on a surface opposite the adjacent boundary. The formation and features are preferably diffractive. The further optical features opposite the adjacent boundary is preferably a compensated conjugate of the formation at the adjacent boundary.

Abstract: The hologram card generates a hologram image in response to an illumination light beam. The hologram card comprises a substrate of a first plastic material having a first refractive index. The substrate has a contoured surface. The contoured surface is formed to include localized topological features constituting a diffractive optical element. The diffractive optical element is structured to generate a hologram image when illuminated by the illumination light beam. The hologram card also comprises a protective layer of a second plastic material having a second refractive index that differs from the first refractive index by less than 0.2. The protective layer covers the contoured surface of the substrate. The protective layer is chemically bonded to, and directly contacts, at least the topological features constituting the diffractive optical element.

Abstract: A reconfigurable compound diffraction grating is fabricated using microelectomechanical systems (MEMS) technology. The compound grating structure can be viewed as the superposition of two separately configured gratings. A common lower electrode is placed beneath selected beam elements, known as deflectable beams, to achieve the desired grating configuration (i.e. every other, every third, every fifth, etc.) of the beams in the primary grating. These deflectable beams alone comprise a secondary, lower resolution grating structure. The beam elements are linked to a common upper electrode. Voltage applied across the electrodes creates an electrostatic force that pulls the selected beams down toward the underlying electrode. Changing the vertical position of the selected beams with respect to the other stationary beams presents a different ruling spacing distribution to the incoming radiation. By changing this distribution, the diffracted power among individual diffraction orders of the wavelengths is altered.

Abstract: An extra step for a conventional replica forming process for diffraction gratings used in lasers is described herein. Applicant has discovered that the deterioration of a replica diffraction grating, when used with intense laser light, is accelerated due to small quantities of the radiation leaking through minute fractures in the aluminum reflective coating. Applicant has identified the source of this problem as occurring during the removal of the replica from the master grating. Applicant's improvement to this conventional process is to deposit a thin reflective overcoat of aluminum on the surface of the replica after the replica has been removed from the master and cleaned. The overcoating is performed in a vacuum chamber by sputtering or evaporation. This overcoat is not subjected to any subsequent destructive forces and hence remains relatively opaque. A typical thickness of the overcoat is around 100 nm. An oxide layer is formed over the aluminum and a third layer of aluminum is formed over the oxide.

Abstract: A method of making a light modulator (10) for modulating an incident beam of light includes a substrate (14) having a cavity (32)formed therein and a plurality of spaced-apart deformable elements (12) formed in the cavity (32). The deformable elements (12) each has a base layer (16), a poled magnetic layer (18) formed in the base layer (16) and a first light reflection layer (20)deposited on the magnetic layer (18) for reflecting an incident beam of light. Between adjacent deformable elements on the base (12) of the cavity (32) is arranged a second light reflection layer (36). A conductive element (22, 24) formed in the substrate (14) electro-magnetically energizes the deformable elements (12) to deflect in the cavity (32). Incident light passing through each one of the first light reflection layers (20) is caused to destructively interfere with light reflected from the second light reflection layers (36) thereby causing modulation of the incident light.

Abstract: This invention comprises a novel apparatus for recording a holographic groove pattern on a diffraction grating blank. The recording apparatus is configured using newly developed groups of analytical equations. The invention further comprises the novel holographic diffraction grating made with the inventive recording apparatus. The invention additionally comprises monochromators and spectrometers equipped with the inventive holographic diffraction grating. Further, the invention comprises a monochromator configured to reduce aberrations using a newly developed group of analytical equations. Additionally, the invention comprises a method to reduce aberrations in monochromators and spectrometers using newly developed groups of analytical equations.

Abstract: A surface pattern has two surface portions with microscopically fine, light-diffracting relief structures. The relief structures are in the form of grating structures GS1 and GS2, respectively, which are composed of at least two superimposed gratings G1 and G2, G3 and G4, respectively. The light-diffracting properties of the gratings G1 to G4 are so selected in accordance with various criteria that novel optical effects which cannot be holographically copied can be achieved with the grating structures GS1 and GS2. Such surface patterns are suitable as optical security elements for documents or articles of all kinds as well as packing foils.

Abstract: An all-reflective pulse stretcher for laser systems employing chirped-pulse amplification enables on-axis use of the focusing mirror which results in ease of use, significantly decreased sensitivity to alignment and near aberration-free performance. By using a new type of diffraction grating which contains a mirror incorporated into the grating, the stretcher contains only three elements: 1) the grating, 2) a spherical or parabolic focusing mirror, and 3) a flat mirror. Addition of a fourth component, a retro-reflector, enables multiple passes of the same stretcher resulting in stretching ratios beyond the current state of the art in a simple and compact design. The pulse stretcher has been used to stretch pulses from 20 fsec to over 600 psec (a stretching ratio in excess of 30,000).

Abstract: In an infra-red imaging system, infra-red radiation from a scene is optically collected and directed to form an infra-red image of the scene on an array of bi-state diffraction grating elements. Each bi-state diffraction grating element has an activated state providing diffraction of incident infra-red radiation at a predetermined angle from the incident direction and an alternative inactivated state providing no such diffraction at the predetermined angle. Scanning apparatus sequentially activates the bi-state diffraction grating elements temporarily from their inactivated states to their activated states to produce a scanned infra-red image of the scene in IR radiation diffracted by the elements at the predetermined angle, which is collected and directed to an infra-red detector. The detector provides a coded electrical representation of the scanned infra-red image of the scene to further apparatus which generates therefrom a human-detectable signal.

Abstract: A reflective grating for the optical diffraction of light rays comprises k juxtaposed, grooved, plane sub-gratings, the planes of the sub-gratings being offset in terms of height with respect to one another along the normal to the plane of the reflective surface of the grooves, enabling the difference in optical path of the grating to be reduced to the difference in optical path between the two ends of a sub-grating.

Abstract: The diffractive optical modulator of the invention includes: a plate having a portion functioning as a first electrode; a spacer layer formed on the plate; and a grating consisting of a plurality of beams having a portion functioning as a second electrode, both ends of the beams being supported on the spacer layer. In the diffractive optical modulator, by adjusting a voltage applied between the first electrode and the second electrode, a distance between the beams and the plate is varied, thereby controlling the diffraction efficiency. An insulating layer is further provided between the plate and the plurality of beams.

Abstract: Holographic test structures on a semiconductor wafer are used to provide real-time analysis of upstream fabrication processing parameters. The test structures comprise reflective segments within multiple cells on the test structure. The size and placement of the reflective segments within the cells are determined by diffraction theory in such a way that a desired image is projected from the test structure. The intensity, sharpness, and shape of the image is used as a direct measure of the upstream fabrication process parameters.

Abstract: An optical device reads the information such as bar codes on an object. A light-emitting element emits a read-beam. A lens cover has an inclined surface that is at an angle with the read-beam and reflects the read-beam toward a bar code, the read-beam emerging as a reflected-beam after reflection from the surface of the bar code. The reflected-beam contains a component directly reflected from the bar code and a component randomly reflected by the white and black areas of the bar code. An optical system in the form of a lens is arranged between the lens cover and the light-emitting element, and converges the read-beam to the bar code. The inclined surface is also at an angle with the reflected-beam and reflects the reflected-beam toward a second optical system in the form of a lens which in turn converges the reflected-beam emerging from the inclined surface to a light-sensing element. The light-sensing element detects the reflected-beam.

Abstract: Diffractive indicia for a surface (1) comprising a plurality of small separate diffractive elements (2) and means for a adhering the diffractive elements to the surface. Each diffractive element has a diffractive surface relief structure and is not separately resolvable to the human eye. The appearance of the diffractive indicia, when applied to the surface, changes when the viewing angle and/or angle of illumination relative to the surface changes. In preferred arrangements, the diffractive indicia, are incorporated in an ink or a transfer medium. A palette of diffractive indicia with different characteristic colours and other optical properties may be provided.