Abstract: A display especially for viewing by a night-vision aid has an array of LED's which emit green light. A dichroic filter is located in front of the display and transmits radiation at the peak emission of the diodes but reflects radiation in the range to which the night-vision aid is sensitive. A bandpass filter located in front of the dichroic filter prevents transmission of longer wavelengths, and a circularly polarizing filter in front of the bandpass filter prevents transmission of radiation reflected specularly from surfaces behind it.

Abstract: Color transparencies having more than one imaged dichroic filter, and an imaged neutral density filter, layered on one side of a single glass substrate, and processes for making the same, are disclosed. In one embodiment, the color transparency is produced by a deposition process including the steps of coating a glass substrate with a photoresist and developing an image thereupon, depositing alternating layers of high and low refractive index dielectrics to form a dichroic layer of a primary subtractive color, stripping the photoresist from the glass, preparing at least one additional imaged dichroic filter on the first, and preparing a neutral density filter on the substrate on the side having the layered dichroic filters. A red antihalation coating may be applied to the lower surface of the glass substrate prior to exposing the photoresist to prevent undesirable exposure of additional portions of the photoresist layer.

Abstract: A coating, composed of an optically effective layer system for substrates, whereby the layer system has a high antireflective effect. On a front side of the substrate, facing the observer, in sequence from the front side to the observer, a first layer is arranged on the substrate, functioning as dielectric and comprising metal oxide. Thereupon follows a second layer comprising nitride, preferably TiN.sub.x (x is equal to or greater than 1, preferably x=1.05). A third layer follows functioning as dielectric and comprising metal oxide. Thereupon a fourth layer follows comprising nitride, preferably TiN.sub.x (x is equal to or greater than 1, preferably x=1.05). A fifth layer follows functioning as dielectric comprising metal oxide. On a backside of the substrate a TiN.sub.x -layer (x.gtoreq.1, preferably x=1.05) is arranged.

Abstract: A light sensor comprises optical filters, an interference filter and a photoelectric converting element which receives and photoelectrically converts light which has passed through the optical filters and the interference filter. An incident angle of the incident light on the interference filter can be changed so as to realize a desirable spectral sensitivity in a combination of the optical filters, the interference filter and the photoelectric converting element. The incident angle can be changed by a mounting structure that can rotate about an optical axis.

Abstract: A ghost image eliminating optical system in a transmission optical system including a plurality of transmission optical elements having boundary reflection surfaces, so that a ghost image can be formed by light reflected by at least two specific boundary reflection surfaces, wherein the specific boundary reflection surfaces are coated with at least two anti-reflection coatings having complementary reflection characteristics to eliminate the ghost image.

Abstract: An optical thin film filter for the spatial and spectral separation of two or more transmitting bands of radiant energy. For a two band filter the filter has a substrate substantially transparent to radiant energy in the transmitted bands. On one surface of said substrate is a multilayer interference coating that transmits both wavelength bands of interest. On the other surface of said substrate (or on the same surface) are two sets of non-overlapping butted, parallel stripes with one set being alternately interspersed with the other. The widths of said stripes are varied to provide for precisely defined regions of spatial and spectral delineation. One set of stripes is capable of transmitting one of the bands of interest and reflecting all others, while the second set of stripes is capable of transmitting at least one band different from the one band transmitted by said first set of stripes and reflecting all others.

Abstract: A measuring instrument that must transmit predetermined wavelengths of optical radiation has an optical filter assembly that can be conveniently manufactured. The optical filter assembly can be coated to provide optical coatings on either side of the substrate, and a masking layer can be deposited to encompass the peripheral edges of the optical coatings and exposed portions of the substrate to eliminate the problem of optical noise resulting from optical radiation contact with the edges of the coating layers.

Abstract: A color display device has groups of liquid crystal display elements controlled by respective TFTs, the groups providing respective different color outputs, e.g. red, green and blue, and being either interspersed in a single panel with individual elements associated with color filter elements or in respective separate panels illuminated by differently colored light. The TFTs are of multilayer structure having semiconductor, gate insulator and gate layers. At least one layer thickness of the TFTs is different from group to group and is selected in accordance with the color light to which they are subjected so as to reduce absorption of that light, and consequently photo-induced currents in their semiconductor layers. Significantly reduced absorption is achievable by appropriate choice for example of semiconductor and insulator layer thicknesses based on optical interference considerations. The device can be used as a projection display device.

Abstract: An improved system is provided suitable for use in landing an aircraft (for example, helicopter, RPV, VTOL) on shipboard comprising a support, base, platform or housing, reciprocal from remote a landing area on the deck of a ship to a position proximate the landing area, the housing carrying an upwardly directed light sensor comprising a lens system and a pair of band-pass filters, one filter before the lens system of the sensor and one after the lens system, the filters each passing the identical wavelength of light at its center but which each need not have the same band width as the other, a pulse detector in close proximity to the upwardly directed light sensor, and means for securing the aircraft to the support, housing, base or platform.