Abstract: A multi-wavelength etalon comprises at least two regions with different indices of refraction. The change in refractive index alters the wavelengths of incident light, and thus the number of wavelengths between the reflective surfaces of the etalon, and therefore the etalon's transmission characteristics. By selecting specific indices of refraction, an etalon can be provided which produces peaks and troughs at preselected wavelengths in each region. The transition between two adjacent regions with different indices of refraction can be graded to reduce optical interference which may result from an abrupt transition.

Abstract: An anti-reflection with high conductivity and transmission controlled multi-layer coating for Flat CRT products is provided which includes five layers coating by vacuum sputtering and one layer coating by conventional wet process. The first layer is formed by an oxide material. The second layer is arranged on an underlying first layer and is formed by a metal. The third layer is arranged on an underlying second layer and is coated by vacuum sputtering. The third layer provides high conductivity thin film with resistance as low as 102 &OHgr;/square. The fourth layer is arranged on an underlying third layer and is formed by an oxide material. The fifth layer is formed by an oxide material. The fourth layer and fifth layer are coated by vacuum sputtering. The sixth layer is deposited on the top surface and is formed by a wet silica coating process.

Abstract: An exemplary embodiment of the invention is an optical filter including a mirror including a plurality of first dielectric layers having a first index of refraction and a plurality of second dielectric layers having a second index of refraction. A plurality of the first dielectric layers have an integer quarter wave optical thickness and at least one of the first dielectric layers has a non-integer quarter wave optical thickness. A plurality of the second dielectric layers have an integer quarter wave optical thickness and at least one of the second dielectric layers has a non-integer quarter wave optical thickness. In an exemplary embodiment, the non-integer quarter wave optical thickness first layer and the non-integer quarter wave optical thickness second layer are determined so as to enhance transmission at a predetermined wavelength.

Abstract: An optical multilayer structure material has a structure such that, on a substrate, a conductive layer in contact with the substrate, a gap portion having a size that enables an interference phenomenon to occur and can be changed, and an optical thin film are formed in this order. The circumference of a movable portion in the optical thin film is uniformly supported by supporting portions, suppressing generation of strain due to an internal stress. Through holes are formed in the movable portion to allow an etchant to easily reach a sacrifice layer when forming a gap portion by etching for sacrifice layer. There is provided an optical multilayer structure material having a simple construction, which can suppress generation of strain due to an internal stress and can be advantageously used in an image display apparatus.

Abstract: A vehicle lamp assembly includes a housing and an LED lamp carried in the housing. A signal mirror, includes a mirror; and an LED lamp. The LED lamp includes a heat extraction member.

Abstract: High-density polyethylene (HDPE) is used as a coating for optical elements operating in transmission in the infrared spectrum, which are made up of a material other than polyethylene, such as hygroscopic salt, semiconductor materials, fluorides, chalcogenides, silver halides, and others, so as to exploit the optical properties of HDPE, at the same time keeping the thickness reduced.

Abstract: An anti-reflection with high conductivity and transmission controlled multi-layer coating for Flat CRT products is provided which includes five layers coating by vacuum sputtering and one layer coating by conventional wet process. The first layer is formed by an oxide material. The second layer is arranged on an underlying first layer and is formed by a metal. The third layer is arranged on an underlying second layer and is coated by vacuum sputtering. The third layer provides high conductivity thin film with resistance as low as 102 &OHgr;/square. The fourth layer is arranged on an underlying third layer and is formed by an oxide material. The fifth layer is formed by an oxide material. The fourth layer and fifth layer are coated by vacuum sputtering. The sixth layer is deposited on the top surface and is formed by a wet silica coating process.

Abstract: A UV-absorbing filter absorbs a UV component of incoming light to reduce an amount of the UV component of transmitted light. The UV-absorbing filter comprises a transparent UV-absorbing glass plate which contains a UV-absorbing substance; a transparent first and second heat-resistant glass plates which face respective surfaces of the UV-absorbing glass plate; a first and second distance pieces which are made of heat-resistant resin and which are respectively interposed between the UV-absorbing glass plate and the first and second heat-resistant glass plates, in the vicinity of an outer edge of the UV-absorbing glass plate, so as to form a space between them.

Abstract: A polymeric photonic band gap structure can be defined by a block copolymeric species, a mixture of homopolymers, or a combination optionally with appropriate dielectric contrast enhancing additives. The structure includes periodic, phase-separated microdomains alternating in refractive index, the domains sized to provide a photonic band gap in the UV-visible spectrum. A method of the invention involves creating a defect in a polymeric article including a periodic structure of a plurality occuring separate domains. The defect can be created by inserting into the material a plane of a material different from materials defining the polymeric article. According to another method of the invention, a defect is created in a polymeric article, including a periodic structure of a plurality of periodically occuring separate domains, by altering polymeric material in the article.

Abstract: A colored anti-fog mirror includes a substrate, a metal reflecting film formed on a front surface of the substrate, and a hydrophilic function layer having a hydrophilic function and containing photocatalytic substance provided on the metal reflecting film. The thickness of the hydrophilic function layer is set in such a manner that wavelength of reflected light has a peak of reflectance within a range from 400 nm to 510 nm and a mirror surface thereby exhibits a bluish color.

Abstract: A graded anti-reflective coating (ARC) with one or more layers has a bottom layer that is highly absorbing at the lithographic wavelength, and one or more layers between the substrate and the resist layer having inhomogeneous optical constants. The refractive indices are matched across layer interfaces, and the optical constants vary smoothly through the layer thicknesses. In each layer the extinction coefficient and the refractive index have independently selectable values and gradients. This ARC structure provides almost total absorption in the bottom layer and near-zero reflection at the resist interface and all other intermediate interfaces. Layers are preferably of inorganic materials, typically SiOxNy. Because of its highly absorbing bottom layer, an ARC according to an embodiment of the present invention works effectively over diverse substrate materials for a variety of lithographic wavelengths. It provides great latitude of manufacturing tolerances for thicknesses and optical constants.

Abstract: A sunlight shielding translucent glass panel has a transparent glass sheet, an absorbing layer disposed on the transparent glass sheet, and transparent dielectric films and mainly Ag films that are alternately arranged on the absorbing layer.

Abstract: For prevention of ghost images from occurring on head-up displays, a glass surface is ground, and a reflecting surface with a wedge-shaped cross section is formed. Furthermore, in order to reduce optical distortion at the edge portion of the reflecting surface, a ground surface contacting the reflecting surface with an angle between 150° and 210° is formed. In accordance with the enlargement of the reflecting surface accompanied by the tendency of head-up displays becoming larger, the reflecting surface is divided into at least two regions, and the angle of the reflecting surface is optimized for each region.

Abstract: A laser microscope according to the present invention is characterized by comprising a laser light source configured to emit an ultra-short pulse laser beam, a storage unit configured to store at least one of dispersion data and chirp amounts of a plurality of optical members inserted in an optical path, a pulse width adjuster configured to adjust a pulse width of the ultra-short pulse laser beam, and a controller configured to control the pulse width adjuster based on at least one of the dispersion data and the chirp amounts of at least one of a laser wavelength of the laser light source and at least one optical member so that the pulse width is shortened on a sample surface.

Abstract: A solid state device used to modulate the intensity of reflected or transmitted light by modulating with an external voltage the optical thickness of a thin film ferroelectric placed in an etalon cavity is disclosed. The device is constructed by selecting a generally planar supporting substrate, preferably silicon or sapphire in order to be compatible with silicon integrated circuits. A dielectric stack consisting of alternating layers of different index of refraction materials, also specifically selected to be compatible with later growth of the thin film ferroelectric, is deposited thereon to form a partially reflective and partially transmitting mirror, followed by a transparent electrically conductive layer. The thin film ferroelectric is deposited on the conductive layer, followed by a second transparent conductive layer and a second dielectric stack. Leads are connected to the conductive layers and in turn to a voltage generator.

Abstract: An optical wavelength selective control apparatus has a plurality of wavelength selective optical filters connected to one another to extract an optical signal at an arbitrary wavelength from wavelength division multiplexed signals according to a frequency signal for selecting a wavelength, and a frequency oscillator for outputting a signal at a frequency corresponding to a wavelength of the optical signal to be extracted to each of the wavelength selective optical filters as a frequency signal for selecting a wavelength, thereby performing a wavelength selecting process highly accurately with the wavelength selective optical filter.

Abstract: Described are articles having a photochromic poly(meth)acrylic coating The coatings exhibit a Fischer microhardness of from 50 to 150 Newtons per mm2 and improved photochromic performance properties, i.e., the formation of darker activated colors and faster rates of photochromic activation and fade when irradiated with ultraviolet light.

Abstract: The present invention provides a wavelength selective optical filter device (240) for receiving input radiation and outputting corresponding filtered output radiation, characterized in that the filter device (240) includes a plurality of at least partially mutually coupled Fabry-Perot optical resonators (330, 340, 360; 360, 400, 430) for filtering the input radiation to generate the output radiation, the filter device (240) being tunable from a first radiation wavelength to a second radiation wavelength by mutually detuning the resonators in a period where the resonators are being retuned from the first wavelength (&lgr;1) to the second wavelength (&lgr;2) so that the filter device (240) is substantially in a non-responsive state during the period. The resonators incorporate freely suspended mirrors (360, 430) which are electrostatically actuated to affect tuning of the resonators (330, 340, 360; 360, 400, 430).

Abstract: An electronic projection system that includes specularly reflective optical components made of a multilayered polymeric material with a reflectivity of at least 96% from about 400 nm to about 700 nm, and a method for enhancing the optical quality of a projected image in a projection display device comprising the step of incorporating at least one specular mirror component in the optical train of the device.

Abstract: An optical switch element is described, which includes a fixed layer disposed outwardly from a substrate and a movable mirror assembly disposed outwardly from the fixed layer. The moveable mirror assembly is operable to move relative to the fixed layer responsive to a voltage applied to the movable mirror assembly. In a particular embodiment, the movable mirror assembly includes an inner strip spaced apart from the fixed layer by a first distance and an outer strip disposed approximately adjacent to the inner strip and spaced apart from the fixed layer by a second distance which is greater than the first distance. The optical transmission of the optical switch element changes depending on the position of the movable mirror assembly.

Abstract: A dual-band optical filter is disclosed which has two transmission bands. The first band is relatively narrow (about 1 nm) and encompasses a wavelength of about 1550 nm, while the second band is relatively broad (greater than 50 nm) to transmit wavelengths in a range of 1300-1400 nm. Accordingly, the filter can be used in wavelength division multiplexed communication systems to simultaneously select a payload channel having a wavelength of approximately 1550 nm, and a 1310 nm service channel.

Abstract: A projection type display device constructed so that light source beams via a polarization beam splitter are separated of colors by a color separating/synthesizing optical system and enter light valves disposed for every color light, the light beams exiting from the respective light valves are synthesized by the color separating/synthesizing optical system, the synthesized light beams exit, the polarization beam splitter analyzes the synthesized light beams and takes out the analyzed light beams, and the analyzed light beams are projected on a screen through a projection lens. A normal line of an outgoing surface of the polarization beam splitter with respect to the light source beams exiting toward the color separating/synthesizing optical system from the polarization beam splitter, has a predetermined angle larger than zero degree with respect to an optical axis of the light source beams.

Abstract: A multi layer interference coating comprising at least one multi layer stack deposited on a reflective layer (9), wherein each multi layer stack comprises a first dielectric layer (11), a layer of asbsorbing material (10) and a second layer of dielectric material (11) arranged in series and having a reflectance spectrum in the infrared region comprising at least one maximum. The dielectric layers are of equal optical thickness and typically are of the same material. The multi layer structure of the coating is such that incident electromagnetic radition, for which odd multiples of half wavelengths correspond to the optical thickness of the multi layer coating at the incident wavelength do not propagate within the coating and reflection at these wavelengths, is suppressed. Coatings may therefore be designed to have a near satured color in the visible wavelength spectrum. The reflective layer may be a metal or a conducting oxide, a conducting nitride, a conducting silicide or a conducting sulphide.

Abstract: An ultraviolet microscope optical system includes a light source emitting light in a region of wavelengths shorter than 300 nm; an illumination optical system; an objective lens system; an imaging optical system; and a photographing device.

Abstract: The antireflection film of the present invention comprises an alternately multi-layered film of 10 layers formed on a base member and having antireflection characteristics in two wavelength regions including a first wavelength (&lgr;1) of 248 nm and a second wavelength (&lgr;2) of 633 nm as central wavelengths, respectively, the multi-layered film of 10 layers comprising: low-refractive index layers arranged at odd-numbered positions from a side opposite to the base member and having a refractive index of 1.45 to 1.52 at the first wavelength (&lgr;1); and high-refractive index layers arranged at even-numbered positions from the side opposite to the base member and having a refractive index of 1.65 to 1.80 at the first wavelength (&lgr;1), wherein layers arranged at the first, second and third positions from the side opposite to the base member each have an optical thickness ranging from 0.21&lgr;1 to 0.28&lgr;1.

Abstract: The photonic band gap (PBG) dual-spectrum sensor utilizes the frequency-selective properties of a photonic band gap device constructed in accordance with this invention to separate incident electromagnetic wave into two frequency bands. The parameters of the PBG device are chosen so that one frequency band is transmitted through the device with low attenuation while the second band is reflected with low attenuation from the front face of the device. This separation of the two frequency bands allows separate detection processes to be performed to recover the information content of the two signals before the information is fused in subsequent signal processing operation. Such a PBG device would be useful in missile seekers that seek to distinguish a target object from its background.

Abstract: An apparatus and associated method are provided to compensate for temperature-induced drift in the center wavelength of an optical filter, such as an interference filter or an etalon filter. Interference filters can be used to filter out one among a number of narrow, closely-spaced channels in an optical wavelength division multiplexed (WDM) communications system. Etalon filters can be used to lock the output wavelength of distributed feedback lasers and in other related applications. The center wavelength of interference filters and etalon filters changes with both temperature and the angle of incidence of the optical beam. The apparatus and associated method of the invention use a positioner with a different coefficient of thermal expansion to adjust the angle of incidence of the filter as the temperature changes, thereby offsetting the temperature-induced center wavelength change.

Abstract: An amorphous diamond coating applied onto mirrored optics in an infrared motion sensor to block specific wavelengths of energy from a “white light” source like a halogen lamp, without reducing the reflectivity of the mirror surface in the Mid-Infrared wavelengths. A specific thickness of diamond-like-coating is applied on top of the reflective metal surface of a mirrored part, thereby reducing the mirror's reflectivity at visible and near-Infrared wavelengths known to be problematic for IR motion sensors, such as those emitted from halogen lamps. The coating has no significant detrimental effect on mid-infrared reflectivity, so the IR motion sensor's performance is otherwise unaffected.

Abstract: A distributed matrix switch comprises a number of collimators each comprising a ferrule and a GRIN lens. A partially reflective coating is provided at the GRIN lens surface to pass a portion of an incoming light beam and to reflect the remainder. If the reflected portion is conveyed by means of an optical path to another collimators of similar construction, selected percentages of an incoming beam may be distributed along two or more optical paths. A receiving channel is then moved to different positions for receiving the portion of the light that is passed by one of the collimators to accomplish switching.

Abstract: A multilayer polymer film has an optical stack including a plurality of alternating polymer layers with skin layers having mechanical, optical, or chemical properties differing from those of the layers in the optical stack, wherein the refractive indices in the in-plane direction nx and ny, and the refractive index in the thickness direction nz for each layer are all selected to obtain optical effects such as reflection, transmission, and/or polarization.

Abstract: A multilayered polymer film includes a first set of optical layers and a second set of optical layers. The first set of optical layers is made from a polyester which is often birefringent. The polyesters of the first set of optical layers typically have a composition in which 70-100 mol % of the carboxylate subunits are first carboxylate subunits and 0-30 mol % are comonomer carboxylate subunits and 70 to 100 mol % of the glycol subunits are first glycol subunits and 0 to 30 mol % of the glycol subunits are comonomer glycol subunits, where at least 0.5 mol % of the combined carboxylate and glycol subunits are comonomer carboxylate or comonomer glycol subunits. The second set of optical layers comprise copolyesters wherein 0.01 to 2.5 mol % of the combined carboxylate and glycol subunits are carboxylate subunits derived from compounds having three or more carboxylate or ester functionalities, glycol subunits derived from compounds having three or more hydroxyl functionalities, or combinations thereof.

Abstract: A variable optical wavelength filter for making it possible to control the movement of an optical wavelength filter during a momentary loss of the optical input signal in the same way as when the optical input signal is present. Even when the input of the second direct current signal to an integrator is interrupted because of the momentary loss of the optical input signal, the integrator is able to place a dielectric multilayer filter at the position directly before the momentary loss of the optical input signal because of sustaining the voltage from directly before the momentary loss of the optical input signal.

Abstract: A vehicular rearview mirror system includes an interior rearview mirror system having an electrochromic reflective element, a digital electrochromic drive circuit supplying a drive signal to the reflective element and a garage door opener. The garage door opener includes a transmitter and logic circuit. The logic circuit supplies signals to the transmitter for transmitting garage door opening signals. A microcontroller is provided which defines, at least in part, the digital drive circuit and logic circuit. In this manner, the digital electrochromic mirror system and the garage door opener have at least some components in common. The microcontroller communicates over a vehicle network with at least one module performing at least one other vehicle function. The vehicle network may have at least wired interconnections and may further have wireless interconnections.

Abstract: A dielectric interference filter system with at least filter elements of different spectral characteristics on the same carrier substrate is provided. The filter elements have the same height and/or adjoin each other without gaps. The system is used for, inter alia, interference color filter systems in the form of an LCD-display or CCD-arrangement. A process for manufacturing the system includes preparing at least one filter element by coating and subsequent etching, and preparing at least one subsequent filter element by coating and subsequent structuring utilizing lift-off in which the etching mask is used as the lift-off mask.

Abstract: Methods and apparatuses for filtering optical channels to provide, for example, an interleaver, or a deinterleaver. A multi-plate comb filter is used to separate subsets of channels and for mixing subsets of channels. Interleavers and deinterleavers having one or more multi-plate comb filters can be used to increase the bandwidth of an optical network. The interleavers and deinterleavers can be used to interface components designed for a first channel spacing to components designed for a second channel spacing.

Abstract: This patent describes a device that enhances the perception of a stationary white object such as a golf ball to improve the performance of the user in locating such objects during a round of golf. The device uses an optical filter that attenuates light transmission for light of wavelengths longer than approximately 500 &mgr;m (from the trees and grass) and transmits light having shorter wavelengths (from the ball). The filter is worn in an eyeglass type holder. These glasses are inexpensive, light and portable. They assist the user in avoiding costs, penalty strokes, and wasted time due to lost balls. To improve golf course efficiency through the reduction of round times.

Abstract: A cassette has a first bar code disposed on a lid thereof for being used for the user to register ID information and a second bar code disposed on a positioning reference surface of the cassette for being used to read ID information through a loading apparatus. The first and second bar codes are effective to determine whether a stimulable phosphor sheet housed in the cassette is either a single-sided sheet or a double-sided sheet.

Abstract: The present invention has an object to provide a manufacturing method of readily realizing an optical filter having a flat transmission characteristic and a superior cutoff characteristic relative to adjacent bands. To this end, with the manufacturing method of the present invention, a bandpass filter consisting of a dielectric multilayer coating is formed on one plane of a transparent substrate, and an antireflection coating is formed on the other plane of the substrate. The substrate is then divided into a plurality of segments, and adjacent two segments are selected and adhered to each other by a transparent adhesive with band-pass filter surfaces of these segments facing to each other, while interposing a glass spacer between the band-pass filter surfaces, to thereby obtain an optical filter.

Abstract: An optical interference coating on a refractory substrate, the coating being comprised of alternating layers of silicon dioxide and zirconium dioxide. The coating can be in the form of an optical filter where a substrate bearing the coating can be repeatedly cycled between room temperature and a temperature of at least 1000° C. without significant degradation of its optical or mechanical properties.

Abstract: A multi-wavelength etalon suitable for tuning and maintaining the operating frequency of a laser used in an optical communication system is disclosed. The communication system has a representative channel wavelength and a channel spacing. The etalon has a plurality of steps on one of the sides with a step size that is a fraction of the channel spacing. The nominal thickness of the etalon is chosen so that a transmission peak occurs at a wavelength substantially equal to the representative channel wavelength and a next peak occurs at the wavelength of an adjacent channel. The step size is a fraction of the channel separation and is substantially optimized so that a peak or trough in the transmission curve in the region of one step overlaps a steep portion of the transmission curve for one or more other steps.

Abstract: An electromagnetic wave filter for a plasma display panel which is effective in preventing incorrect actions of a remote control of appliances, comprising a transparent substrate, a light transmitting electromagnetic wave shield film, and a resin protective film, wherein the electromagnetic wave shield film is a 7-layered laminate in which a dielectric layer and a metal layer containing silver as the principal ingredient are laminated alternately with the dielectric layer being the first to be provided on the transparent substrate, the dielectric layer has a refractive index of 1.6 to 2.8 at 550 nm, and the metal layer containing silver as the principal ingredient contains 0.1 atomic % or more and less than 0.5 atomic % of palladium based on silver and has a thickness of 5 to 25 nm, whereby the electromagnetic wave shield film has a sheet resistance of 3 &OHgr;/□ or lower and a near infrared transmission of 20% or lower at 850 nm.

Abstract: An optical interference filter having high transmissivity at first and second passbands. The interference filter includes a first stack having a plurality of dielectric layers, a second stack having a plurality of dielectric layers, and a spacer interposed between the first and second stacks. Each of the dielectric layers included in the first and second stacks have optical thicknesses which vary quadratically. The dielectric layers have alternating high and low refractive indices.

Abstract: A wavelength division multiplexing device which can easily utilize existing optical fibers for increasing the transmission capacity by approximately several fold mainly in a short-range information communication network, comprising, as essential elements, a pair of 1×N optical couplers (2≦N≦16), N light emission devices in which one of peak wavelengths thereof differs from every other one by at least 30 nm and N light receivers having optical filters having light-transmission wavelength bands adjusted to correspond to said peak wavelengths, wherein the light emission devices and the light receivers having optical filters corresponding to peak wavelengths of the light emission devices form pairs, and said light emission devices of said light receivers are optically connected to N-port-side ports of one of the 1×N optical couplers.

Abstract: Data loss is reduced and bandwidth efficiency improved while tuning an optical add/drop device comprising a hitless wavelength-tunable optical filter. The hitless wavelength-tunable optical filter includes a broadband reflective surface and a tunable filter surface, the reflective surface and filter surface positioned adjacent to each other. Hitless tuning of the device is accomplished by changing the point at which an optical beam strikes the filter surface along a constant wavelength channel track whenever the beam is incident to the filter surface region. Realignment to a position associated with a new wavelength channel track is performed with the optical beam incident to the reflective surface region. Repositioning the optical beam to the filter region occurs at a location corresponding to the new wavelength to be added/dropped and subsequent optical beam realignment within the filter region is along the new wavelength channel track.

Abstract: A elemental mirror for vehicles having a luminous reflectance of at least about 30% includes a substrate coated with a thin layer of elemental semiconductor having an index of refraction of at least 3 and an optical thickness of at least about 275 angstroms. Preferably, the elemental semiconductor coating is sputter coated silicon or germanium and a light absorbing coating is included therebehind. The mirror is spectrally nonselective with elemental semiconductor optical thicknesses of about 275 to 2400 angstroms on the front substrate surface. Spectrally selective mirrors are provided by adding an interference coating to the elemental semiconductor layer coating, preferably of a dielectric such as silicon dioxide or silicon nitride, on either the front or rear substrate surface, or by using a thicker, single elemental semiconductor layer. Instead of an absorbing coating behind the mirror, additional elemental semiconductor and dielectric thin layers may be included to reduce secondary reflections.

Abstract: Disclosed is an antireflection film used to be stuck on the surface of a glass panel of a CRT, which can be inexpensively manufactured at a high productivity while satisfying all of requirements regarding its adhesive strength, reflectance characteristic, electric resistance and total light transmittance. The antireflection film is formed by stacking silicon oxide films and indium tin oxide films on a base film in multilevels, wherein the thickness of the uppermost silicon oxide film of the antireflection film is thicker than the indium tin oxide film directly under the uppermost silicon oxide film, and the lowermost silicon oxide film, positioned at the interface with the base film, of the antireflection film is a SiOx film where the value x is in a range of 0.5 to 1.9.

Abstract: Four and five-layer antireflection coatings are disclosed suitable for use on optical parts such as lenses and prisms in which layers of thin films are formed on the surfaces of the optical parts by a process such as vacuum evaporation. By selecting the materials for the layers based on the refractive index of the materials, as well as based on the refractive index of the substrate, reflectance of the s-polarized component of incident light can be reduced over a large range of incident angle up to a range of approximately 45 degrees.

Abstract: An optical element has a plurality of reflective surfaces formed integrally so as to reflect light incident thereto successively and thereafter guide it out of the optical element. The optical element is provided with a member for preventing light of a predetermined wavelength band from emerging from the optical element.

Abstract: An optical filter including a plurality of dielectric layers is provided on a quartz substrate. Quartz is advantageous as a substrate material because it has relatively low loss at wavelengths commonly used in telecommunication systems. Moreover, it is thermally and chemically stable, and has good adhesion to most dielectric films used as quarter and half wave layers. Further, quartz is mechanically tough, relatively inexpensive and readily available. The quartz substrate is cut from a crystal and has an orientation with reduced birefringence. In addition, the thickness of the quartz substrate is selected to reduce temperature-related shifts in the center wavelength of the filter.