Abstract: In a diffractive optical element and a polarization separation element using this diffractive optical element, incident light can be effectively separated for the respective polarization directions over the entire used wavelength range. The diffractive optical element is arranged such that the diffractive optical element has a grating structure in which at least two blazed type grating potions are overlapped with each other, and in at least one grating potion of the two blazed type grating portions, structures smaller than a used wavelength are arranged in a periodic manner on all of light incident surfaces thereof.

Abstract: In a diffractive optical element composed of three or more laminated layers and having a diffraction grating at each interface between adjacent layers, each even-number-th layer has a uniform thickness.

Abstract: A diffractive optical element includes a pair of diffraction gratings. The pair of diffraction gratings differ in dispersion from each other and confront each other through a space of a refractive index of 1. A maximum optical path length difference occurring in the pair of diffraction gratings with respect to each of at least two wavelengths is integer times the associated wavelength. Further, peak portions and valley portions of the pair of diffraction gratings are chamfered.

Abstract: A diffractive optical element includes a plurality of laminated diffraction grating surfaces. Each of the diffraction grating surfaces is formed to have a sufficiently small grating thickness as compared with a grating pitch thereof.

Abstract: In a projection display apparatus, light from a light source is separated into a plurality of beams having different wavelength regions, a plurality of image display elements (123r, 123g, 123b) are inserted in the optical paths of the respective separated beams so as to be illuminated by the beams. A color combiner (XDP) is provided for combining the beams emerging from the plurality of image display elements. The beams combined by the color combiner are projected on a projection surface. A diffraction optical element (124) is inserted in at least one of a plurality of optical paths between the plurality of image display elements and the color combiner.

Abstract: In a diffractive optical element, first and second diffraction gratings of 10 &mgr;m or less in thickness made from materials of respective different Abbe numbers are laminated through an air layer. The grating thickness of the first diffraction grating is made to be 7.5 &mgr;m, and the grating thickness of the second diffraction grating is made to be 6.54 &mgr;m. Glass of the Abbe number of 63.8 is used for the material of the first diffraction grating, and an ultraviolet curable polymer of the Abbe number of 23.0 is used for the material of the second diffraction grating. Accordingly, the diffraction efficiency of the diffractive optical element is improved to 97% or higher throughout the entire visible spectrum.

Abstract: In a diffractive optical element composed of three or more laminated layers and having a diffraction grating at each interface between adjacent layers, each even-number-th layer has a uniform thickness.

Abstract: In a diffractive optical element composed of three or more laminated layers and having a diffraction grating at each interface between adjacent layers, each even-number-th layer has a uniform thickness.

Abstract: An image processor includes a first reader which obtains a first signal corresponding to visible information read on an original, and a second reader which obtains a second signal corresponding to invisible information on the original. A comparator compares the first and second signals to discriminate a predetermined pattern on the original.

Abstract: An invisible information detection apparatus includes parts that irradiate a light onto a medium, detect infrared light generated from the medium, and judge a specific pattern consisting of a combination of two areas on the medium in accordance with the detection result. One of the areas represents higher reflectance than the reflectance of the medium in substantially the same infrared wavelength region, and the other area represents lower reflectance than that of the medium. An invisible information detection method comprises an irradiation step, a detection step and a judgment step. The judgment step judges a specific pattern of a combination of two areas on the medium in accordance with the result from the detection step. One of the areas represents higher reflectance, and the other area represents lower reflectance, as compared to the reflectance of the medium, in substantially the same infrared wavelength region.

Abstract: In a diffractive optical element, which is formed by laminating at least three layers of diffraction gratings made of at least three kinds of materials which differ in dispersion, at least three design wavelengths are set.

Abstract: This invention provides an image reading device capable of precise detection of the optical signal over a wide wavelength range, by forming a photoelectric converting unit for converting the visible light into an electrical signal and a photoelectric converting unit for converting the invisible light into an electrical signal, in monolithic manner on a single semiconductor chip.

Abstract: An object of the present invention is to provide an image processing apparatus and an image processing method both offering a high-precision and general-purpose capability of identifying an image and performing appropriate processing depending on whether identification is effected. In the image processing apparatus and image processing method, image data is detected in visible and invisible light reflected from each of a target pixel and surrounding pixels. Based on the image data detected in visible and invisible light, a specific pattern is identified. The specific pattern appears substantially the same in color as a surrounding area under visible light but different in characteristic therefrom under invisible light, which is identified using the image data of the target pixel and surrounding pixels provided by a detector. The image processing apparatus is controlled depending on whether the identification is effected.

Abstract: Visible information of the document sheet and information other the visible information are efficiently read by an image sensing apparatus including a first line sensor for reading the visible information of the document sheet and a second line sensor for reading the information other than the visible information.

Abstract: A color image reading apparatus is provided wherein a color picture image is read out by a monolithic three line sensor through a reflection type one-dimensional blazed diffraction grating acting as a color separating means. The diffraction grating is concavely curved forward the line sensor, and a light beam, diverging after being focused by an image forming optical element having a predetermined refracting power only in a sub-scan cross section, is color-separated into three color light components by the diffraction grating and re-imaged on the surface of the three line sensors located at a predetermined position. As a result, the blur of .+-.1 order diffracted lights in a sub-scanning direction can be prevented which is due to the deviation of a reflective diffraction angle resulting from the difference in an incident angle of respective lights on the grating surface in the sub-scan cross section.

Abstract: A method and apparatus for processing a medium on which an identification mark is formed using a plurality of recording materials having fluorescent characteristics in wavelength regions almost overlapping with each other and having maximum absorbing characteristics at different wavelengths. The method and apparatus include the features of detecting, on the medium, the identification mark which is comprised of the plurality of recording materials and controlling an operation of a processing apparatus in accordance with a result of the detecting of the identification mark.

Abstract: An optical modulator includes a first diffraction grating for separating a light flux of a wide wavelength band into light fluxes of given wavelength bands. The optical modulator further includes an optical modulation element for modulating the separated light fluxes through corresponding picture elements, respectively, and outputting them. The optical modulator further includes a second diffraction grating for synthesizing the modulated light fluxes outputted from the optical modulation element, wherein the first diffraction grating, the optical modulation element and the second diffraction grating are integrally structured.

Abstract: To properly cut light except for visible light and improve read precision, there is provided an image reading apparatus having a plurality of photoelectric conversion elements. The image reading apparatus includes an image information detecting unit in which the photoelectric conversion elements are arranged on a single chip, a first light-shielding unit, arranged near the photoelectric conversion elements, for transmitting specific visible light, and a second light-shielding unit, arranged near the photoelectric conversion elements at a position different from that of the first light-shielding unit, for partially shielding light except for the visible light.

Abstract: An image reading apparatus includes, as an arrangement for discriminating a specific image with high precision, first illumination means for illuminating an object image so as to perform a normal reading operation, second illumination means for illuminating the object image with light having characteristics different from those of the light from the first illumination means so as to discriminate whether or not the object image is a specific image, and means for adjusting the quantity of light emitted from the first and second illumination means.

Abstract: A specified original that is not supposed to be copied is marked with a pattern that is formed by infrared reflected light. A copying apparatus includes a detecting unit for detecting the pattern and determines that an original is the specified original in accordance with the detection by the detecting unit. A copying operation is controlled in accordance with the determination of whether the original is the specified original that is not supposed to be copied.