Abstract: An imaging optical system includes three reflecting mirrors having first to third reflection surfaces and is configured, such that in an XYZ orthogonal coordinate system using an optical axis at the center of the field of view as Z-axis, the optical axis at the center of the field of view and an optical axis of an image plane are in parallel to each other Assuming that along the path of the beam traveling along the optical axis at the center of the field of view a distance between the second reflection surface and the third reflection surface is L2, a distance between the third reflection surface and the image plane is L3 and fy1 and an equivalent F-number of the imaging optical system is represented as Fno, the relational expression 0.5<Fno(L2/L3)<1.3 is satisfied.

Abstract: An illumination device for planar light sources gives uniform illumination on an illuminated plane. A of lengthwise direction and length of breadthwise direction are different from each other. The illumination device includes a planar light source and an optical element including a light receiving surface for receiving light form the planar light source and a light exiting surface. A shape of the planar light source is symmetric with respect to x-axis and y-axis and a length of the shape in x-axis direction is shorter than length of the shape in y-axis direction; the center of the planar light source is set as the origin and two axes orthogonal to each other are selected as x-axis and y-axis. Assuming that the maximum value of x-coordinate of the planar light source is a and the maximum value of y-coordinate of the planar light source is b, the following relationships hold: h ab = ( h a + a ) - ( h b + b ) ( h a + a ) h ab ? 0.02 .

Abstract: Disclosed is a thin-film type light-absorbing film including multiple layers formed on a substrate. The multiple layers include: an iron oxide layer including triiron tetraoxide; and a dielectric layer including dielectric substance, wherein thickness of the iron oxide layer is 40 nanometers or more and the iron oxide layer and the dielectric layer form an anti-reflecting layer.

Abstract: A filter for a light receiving element, which can sufficiently eliminate disturbance due to sunlight and the like out of doors. The filter for a light receiving element according to one embodiment of the present invention is used for a light receiving element which receives signal light having a known spectral distribution. The filter for a light receiving element according to one embodiment of the present invention is configured so that when the energy density of the ambient light in the light receiving element is represented by N1 and the energy density of the signal light in the light receiving element is represented by N2, N1/(N2)2 is minimized under constraints.

Abstract: A lens used for a line generating optical system is provided, wherein X-axis is defined in longitudinal direction of the generated line, Y-axis is defined in width direction and Z-axis is defined in direction of the optical axis and wherein the lens has an optical surface which does not collimate the light in X-axis direction and which collimates or collects the light in Y-axis direction alone, inclination of direction of transferred tool mark with respect to X-axis being from 40 to 50 degrees in an area of 80% or more of the optical surface.

Abstract: A method for producing an optical element, in which a multi-layered film is provided on a plastic substrate, having a resistance against lights in a wavelength range of 300 nm to 450 nm, is provided. The method for producing the optical element according to the invention, is an method for producing an optical element having a multi-layered film in which a layer made of a low-refractive-index material and a layer made of a high-refractive-index material are alternately formed on a plastic substrate, the optical element being used for light in a wavelength range of 300 nm to 450 nm.

Abstract: A terahertz electromagnetic wave generating element can include a generation layer, and a plurality of pairs of layer structures provided on opposite sides thereof. The layer structures are each provided with a first layer, a second layer on the side of the first layer opposite to the generation layer, and a first grating and a second grating, and having a grating period smaller than the wavelength of the terahertz electromagnetic wave to be used. The first and second gratings are configured so that the refractive index of a medium between the first layer and the second layer continuously varies between a first refractive index and a second refractive index. The thickness of the first and second layers and the grating period, and the grating height are determined so that a terahertz electromagnetic wave having a desired bandwidth with respect to a central wavelength of the terahertz electromagnetic wave generated by the generation layer can be generated.

Abstract: An illuminating device includes a light source and a light receiving surface, first and second light exit surfaces. When a point at the edge of the light emitting surface is P2 and an axis which passes through a center P1 of a light emitting surface and is perpendicular to the light emitting surface is an optical axis, the optical element has a hollow around the optical axis. The first light exit surface is such that x coordinate of a point most distant from the optical axis on the first light exit surface is at least 1.5 times x coordinate of P2, that in 80% or more of an area in which x coordinate of a point is at least the x coordinate of another point P3, an angle of incidence of light emitted at P1 is at least the critical angle and that in 80% or more of an area in which x coordinate of a point is equal to or smaller than x coordinate of another point P4, an angle of incidence of light emitted at P2 is smaller than the critical angle.

Abstract: A vehicular lamp includes a light source, a reflector, a shade, and the projector lens. Light emitted from the light source is reflected by the reflector, and the light is partially blocked by the shade. Light which is not blocked is transmitted through the projector lens, and an object ahead of a vehicle is irradiated with the light. A diffraction grating is provided in a region including an end portion of a light passing region of at least one surface in the projector lens in order to reduce color separation.

Abstract: Disclosed is a filter for a light receiving element, which can sufficiently eliminate disturbance due to sunlight and the like out of doors. A filter for a light receiving element according to one embodiment of the present invention is used for a light receiving element which receives signal light having a known spectral distribution. The filter for a light receiving element according to one embodiment of the present invention is configured so that when the energy density of the ambient light in the light receiving element is represented by N1 and the energy density of the signal light in the light receiving element is represented by N2, N1/(N2)2 is minimized under constraints.

Abstract: A line generator according to the present invention includes a light source, a first lens group, and a second lens group. An optical axis is set to a position of a light beam which travels orthogonal to incidence surfaces of both the first and second lens groups and the first lens group is configured such that light beams from the light source are not collimated in a first direction in a plane orthogonal to the optical axis and are collimated or focused only in a second direction orthogonal to the first direction in the plane orthogonal to the optical axis and the second lens group is configured such that the light beams which have passed through the first group form a line.

Abstract: There is provided an infrared light source that has a simple structure and radiates infrared rays polarized in a specific direction and having a specific wavelength. The infrared light source (100) comprises a heat generator (107) and a latticework (101) in which a dielectric part (105) and a metal part (103) are alternately formed at a constant pitch in a constant direction. The infrared rays are radiated in a direction perpendicular to the surface of the latticework and are polarized in the direction indicated by an arrow A. If the constant pitch is denoted by P, the width of the dielectric part in the constant direction by T, and the specific wavelength by ?, for arbitrary P and T that meet the inequalities 0<P?2.0? and T?0.5P, the depth D of the latticework is so selected that the intensity spectrum of the infrared rays radiated from the infrared light source has the peak at ?.

Abstract: An illuminating device includes a light source (101) and an optical element including a light receiving surface (203), first and second light exit surfaces (205, 207). When the center of a light emitting surface (201) is designated as P1, a point at the edge of the light emitting surface is designated as P2 and an axis which passes through P1 and is perpendicular to the light emitting surface is designated as an optical axis, the optical element has a hollow around the optical axis with respect to the edge.

Abstract: To provide a compact image forming optical system in which an incident angle to an imaging plane of a solid-state imaging device is small and whose chromatic aberration, astigmatism, field curvature, and distortion are reduced. An image forming optical system of a first embodiment of the present invention comprises four lenses arranged from the object side to the imaging plane side in order, that are a first lens that is a double-convex lens, a second lens that is a double-concave lens, a third lens that is a positive meniscus lens that is convex toward an image side, and a fourth lens that is a negative meniscus lens that is convex toward an object side. An aperture is placed closer to the object than the image side surface of the first lens.

Abstract: A line generator according to the present invention includes a light source, a first lens group, and a second lens group. An optical axis is set to a position of a light beam which travels orthogonal to incidence surfaces of both the first and second lens groups and the first lens group is configured such that light beams from the light source are not collimated in a first direction in a plane orthogonal to the optical axis and are collimated or focused only in a second direction orthogonal to the first direction in the plane orthogonal to the optical axis and the second lens group is configured such that the light beams which have passed through the first group form a line.

Abstract: An optical element having a laser damage suppression film which is capable of withstanding high power blue laser and formed on a plastic substrate. Specifically disclosed is an antireflection optical element wherein a multilayer film, which is composed of low refractive index material layers (105) and high refractive index material layers (107) arranged alternately, is formed on a plastic substrate. In this antireflection optical element, the oxygen permeability coefficient is decreased such that variation in laser permeability is 2% or less after being continuously irradiated with blue laser having an energy density of 120 mW/mm2 for 1000 hours at an ambient temperature of 25° C. In one embodiment, the oxygen permeability coefficient is set at 30 cm3·mm m2·24 hr·atm) or less.

Abstract: An imaging optical system includes three reflecting mirrors having first to third reflection surfaces and is configured, such that in an XYZ orthogonal coordinate system using an optical axis at the center of the field of view as Z-axis, the optical axis at the center of the field of view and an optical axis of an image plane are in parallel to each other by changing orientation of the optical axis in a YZ section while maintaining the orientation of the optical axis in an XZ section. At least one of the three reflection surfaces is rotationally asymmetric. Assuming that along the path of the beam traveling along the optical axis at the center of the field of view a distance between the second reflection surface and the third reflection surface is L2, a distance between the third reflection surface and the image plane is L3 and fy1 and an equivalent F-number of the imaging optical system is represented as Fno, the relational expression 0.5<Fno(L2/L3)<1.3 is satisfied.

Abstract: To provide a compact image forming optical system in which an incident angle to an imaging plane of a solid-state imaging device is small and whose chromatic aberration, astigmatism, field curvature, and distortion are reduced. An image forming optical system of a first embodiment of the present invention comprises four lenses arranged from the object side to the imaging plane side in order, that are a first lens that is a double-convex lens, a second lens that is a double-concave lens, a third lens that is a positive meniscus lens that is convex toward an image side, and a fourth lens that is a negative meniscus lens that is convex toward an object side. An aperture is placed closer to the object than the image side surface of the first lens.

Abstract: A wavelength filter, includes a grating in which a first portion extends in X direction on a substrate surface and a second portion extends in the X direction along the first portion and are alternately arranged in Y direction perpendicular to the X direction on the substrate surface at a constant cycle shorter than a wavelength of light to be used. A cross-sectional figure of respective first portions in the Y direction and perpendicular to the substrate surface is provided with at least one protruding portion so as to have the width in the Y direction wider than neighboring portions. Plural waveguide layers parallel to the substrate surface are divided by regions parallel to the substrate surface. Wavelength bands of light reflected from the plural waveguide layers shift while overlapping with each other to reflect a wavelength band broader than that reflected from a single waveguide layer.

Abstract: A polarizing element usable for two wavelengths in a predetermined wavelength region and having a simple structure. The polarizing element has a two-layer structure in which a grid pattern of a constant period ? having a triangular cross-section is formed on a substrate and a film with a refractive index higher than that of the substrate is deposited on the grid pattern. When first and second wavelengths ?1, ?2 satisfy ?1<?2, ? cos ?0<?1 where ?0 is the angle of incidence on the grid surface.