Abstract: A bandpass filter is comprised by a plurality of reflection gratings operating in a Wood's anomaly region and arranged in serial relationship. Specifically, the gratings are serially arranged in two substantially parallel rows with the gratings in the first row offset laterally from the gratings in the second row. Further, the input to each grating is at substantially the same angle of incidence such that the output of one grating is the direct input to the next succeeding one of the gratings.

Abstract: Disclosed is an optical bandpass filter for transmitting light in a narrow band around the wavelength .lambda..sub.c, including a first series of layers, each of thickness t, having a refractive index n.sub.1 and a second series of layers, each of thickness t, having a refractive index n.sub.2 and alternating with the first series. The thickness t is selected so that t=.lambda..sub.c /4n.sub.c and .vertline..DELTA..vertline.>.pi..vertline.D-1/.lambda..sub.c .vertline., where ##EQU1## and n.sub.c is the common value of n.sub.1 and n.sub.2 at the wavelength .lambda..sub.c. Also disclosed is a filter with each succeeding layer in the first and second series thicker than the preceding layer. The thickness of the thinnest layer is .lambda..sub.1 /4.sub.n and the thickness of the thickest layer is .lambda..sub.2 /4n Cos .theta., where .lambda..sub.1 is the minimum wavelength to be reflected by the filter, .lambda..sub.2 is the maximum wavelength, n=(n.sub.1 +n.sub.2)/2, and .theta.

Abstract: A nonmagnetic substrate is shown having a magnetic film that has been separated into a grid-like pattern of spaces to form quadrilateral magnetic elements. The spaces are filled with conductors arranged generally in X and Y directions. Each quadrilaterally shaped magnetic post element has a first and second region of low anisotropy material compared to the high anisotropy material of the magnetic film. The first regions of low anisotropy material are located in one corner of the quadrilaterally shaped post elements while the second regions are located in the corner opposite the first regions. Alternate columns of magnetic post elements have the first and second regions of low anisotropy material in opposite corners defined by a first diagonal, while the remaining columns have the low anisotropy material in corners defined by the second diagonal. This arrangement permits redundant switching of each magnetic post element.

Abstract: A projection screen is formed as at least one reflective holograms each of which, when referenced with a projector, reconstructs a defined observation pupil.

Abstract: An improved conductive grid for a magneto-optic display is shown having individual magnetic and transparent post elements separated from one another by an orthogonal grid-like pattern. Conductors are deposited in each vertical separation and every other horizontal separation. A first region of low anisotropy material compared to the high anisotropy material of each post element is located in close proximity to the intersection of each vertical and horizontal conductor.

Abstract: A reflector structure for reflecting light back toward the source thereof and adapted to be secured to an associated support surface, the reflector structure comprising a lens member of light-transmitting synthetic resin having a front face and a rear face. The lens member has a plurality of integrally formed retrodirective reflector elements formed in the rear face and extending outwardly therefrom. Each of the reflector elements in use is individually surrounded by a peripheral wall defining a cell around the individual reflector element. The peripheral walls extend between the plane of the rear face of the lens member and the plane of the associated support surface, the lens member being adapted to be sealed to the associated support surface.

Abstract: An electrochromic display device comprises an electrolyte contained between a pair of spaced-apart substrates. A set of electrodes are disposed on at least one of the substrates in contact with the electrolyte and a layer of electrochromic material is disposed on at least one of the electrodes to define a display electrode. The electrochromic material comprises a color-reversible salt of iron(III) hexacyanoferrate(II) which, depending on its oxidation-reduction state, exhibits different colors. A source of electric charge is connected through circuitry to effect reversible electrochemical oxidation and reduction of the salt of iron(III) hexacyanoferrate(II) to effect a corresponding reversible color change exhibited by the display electrode.

Abstract: Recently, there has been the tendency to increasingly use optical machinery and devices which utilize optical parts made of synthetic resin. Since an antireflection coating film for these synthetic resin optical parts is high in adhesive strength and is hard, it is advantageous to use silicon oxide. Particularly, silicon monoxide (SiO) varies in refractive index by varying the evaporation condition, and therefore, it is possible to make use of such properties to produce a multi-layered antireflection coating film from a single evaporation material by varying the evaporation conditions.

Abstract: An improved grid pattern is shown for increasing the density of magnetic post elements, within a magneto-optic display, for example, wherein the post elements are separated by a grid-like pattern of spaces which are filled with conductive elements arranged generally in the X and Y directions. Each quadrilaterally shaped post element is separated by a diagonal so that the first, third, fifth . . . etc. columns of post elements have diagonals running in one direction while the second, fourth, sixth . . . etc. columns have diagonals running in the opposite direction. A region of low anisotropy material is located in the corner of each triangularly shaped magnetic post element opposite the diagonal which forms the triangular element so as to be as close as possible to all extremes of the element.

Abstract: Disclosed is an optical system used in a spacecraft to observe a remote surface and provide a spatial and spectral image of this surface. The optical system includes aspheric and spherical mirrors aligned to focus at a first focal plane an image of the surface, and a mirror at this first focal plane which reflects light back on to the spherical mirror. This spherical mirror collimates the light and directs it through a prism which disperses it. The dispersed light is then focused on an array of light responsive elements disposed at a second focal plane. The prism is designed such that it disperses light into components of different wavelengths, with the components of shorter wavelengths being dispersed more than the components of longer wavelengths to present at the second focal plane a distribution pattern in which preselected groupings of the components are dispersed over essentially equal spacing intervals.

Abstract: Exposure patterns are formed in photosensitive material by multiple beam laser interferometry by a method which involves exposing said photosensitive material simultaneously to at least three coherent beams of exposing radiation wherein the sources of said beams are arranged substantially symmetrically around an axis perpendicular to the plane of said photosensitive material. Preferably, surface relief patterns are formed by developing said exposed material. Apparatus for providing such multiple coherent beams is also disclosed.

Abstract: An improved, controlled automatic light control device is provided by the e of a hydraulic automatic light control. Hydraulic control avoids inherent problems of mechanical automatic light control devices. A liquid used for light absorption permits the entire iris area to darken without loss of aperture. The uniform extinction without diffraction limitations of mechanically driven automatic light control devices is significantly improved. The use of thermoelectric coolers and heat sinks provides reliability in a large dynamic range environment without warping or other distortion of the system. The device is applicable for visible light to near infrared light.

Abstract: An electrochromic device comprising a solid electrolyte, wherein the electrolyte consists of porous glass impregnated with a solid ion-conductive compound such as an alkali metal salt, is described.

Abstract: In an optical device an objective is moved axially along its optical axis relative to a frame in a parallel guide by means of first electro-magnetic actuating means connected to the objective and second electromagnetic actuating means arranged on the frame, which first and second actuating means co-operate axially with each other by means of a magnetic field which is oriented transversely of the optical axis and transversely of the direction of movement of the objective. In order to suppress vibrations caused by axial reactive forces transmitted from the second actuating means to the frame, axially resilient damping means are arranged between the frame and at least a part of the second actuating means. The movements of the second actuating means do not affect the position of the objective because an axial displacement of the radial magnetic field does not give rise to an axial movement of the objective.

Abstract: A light absorptive film comprising a first sub-film and a second sub-film each including at least one dielectric layer and at least one metallic layer which have anti-reflecting functions even when used independently and arranged oppositely on both sides of another dielectric layer. Said light absorptive film exhibits anti-reflecting effect for light incident on said first sub-film and said second sub-film.

Abstract: A side reflector assembly is provided for mounting on a spoked wheel such as a bicycle. The assembly includes a plate-like reflector means and a cylindrical connector or coupler means to be coaxially fitted in the reflector means. The reflector means is provided at the center portion of its front face with a bottomed round aperture. The aperture is provided in the leading edge of the periphery thereof with a pair of notches for receiving a wheel spoke, and on the inner wall thereof adjacent to said notches with thicker wall portions. The reflector means is modified to have a set of three apertures on both sides thereof to accommodate different spoke arrangements.

Abstract: The present invention includes a rotable disk type of hologram which deflects an incident light beam such as a laser into an intermediate scanning path of a curvilinear configuration. An extended prism provides a variable incident angle surface for refracting the incident curvilinear configuration into substantially a linear scan path on an object surface.

Abstract: A laser protection device comprising a plurality of edge filters for receiving an incident beam and progressively separating the desired optical energy from the laser energy contained in the beam. The first edge filter receives the incident beam and provides a first reflected beam and a first transmitted beam. One of the beams provided by the edge filter comprises a relatively high percent of desired optical energy and the other of the beams provided by the edge filter comprises a relatively high percentage of laser energy. The other edge filters are arranged in series to similarly progressively reduce the percentage of laser energy contained in the beam.

Abstract: Apparatus for illuminating transmission holograms from the rear with an illumination source located in front of the hologram, comprising a reflector and a light trap adapted to be mounted behind the hologram at a location chosen to reflect light from the source through the hologram as though from a source behind the hologram, while reflecting ambient light from the direction of an observer of the hologram into the trap.

Abstract: A variable index-of-refraction optical medium of certain minimum thickness and periodicity with respect to the wavelength of incident light--if it meets certain specified constraints with respect to (1) relative indices-of-refraction of both its internal structure and that of its surroundings and (2) relative values of incident wavelength to periodicity and the relative indices-of-refraction--operates to produce both angularly-dependent subtractive-color filter reflection spectra and subtractive-color filter transmission spectra in accordance with its physical parameters. Such filters are suitable for use as authenticating devices for sheet-material authenticated items.