Abstract: A retinal projection display device for projection of an image onto a retina of a wearer wearing an eyeglass-type support is provided. The retinal projection display device includes the eyeglass-type support including a temple; a light source; an optical scanner disposed in the temple and configured to scan light from the light source so as to form the image; a projector configured to project the image formed by the optical scanner onto the retina; an optical deflector disposed in the temple and configured to change a projection direction of the image formed by the optical scanner; and a translation member configured to translate the optical scanner and the optical deflector in a direction in which the temple extends.

Abstract: Provided is a mold manufacturing method that is capable of manufacturing a mold of a complex shape particularly of an optical element with sufficient shape accuracy and within a relatively short time. This mold manufacturing method includes: a step for forming a base made of metal into a first shape through machining; a step for coating the base with a resin layer; a step for forming the resin layer into a second shape; and a step for forming the base into a third shape through dry-etching.

Abstract: Provided is a mold manufacturing method that is capable of manufacturing a mold of a complex shape particularly of an optical element with sufficient shape accuracy and within a relatively short time. This mold manufacturing method includes: a step for forming a base made of metal into a first shape through machining; a step for coating the base with a resin layer; a step for forming the resin layer into a second shape; and a step for forming the base into a third shape through dry-etching.

Abstract: A light-receiving optical system includes a rotating mirror configured to rotate around a rotation axis and having a reflection plane arranged at an angle with the rotation axis; an imaging optical system having an optical axis that coincides with the rotation axis; a multifocal Fresnel lens having sections formed concentrically around the optical axis; and light-receiving elements, wherein the imaging optical system is configured such that rays of light that enter the rotating mirror are converged onto one of the sections depending on an angle of the rays with the optical axis, and the multifocal Fresnel lens is configured such that the rays reach one of the light-receiving elements, which corresponds to the one of the sections so that a light-receiving element that the rays reach is determined depending on the angle of the rays with the optical axis independently of a rotational position of the rotating mirror.

Abstract: A microlens array includes N microlenses arranged in a predetermined direction on an x-y plane. A projection onto the x-y plane of the vertex of each microlens is arranged in the vicinity of a lattice point of a reference lattice on the x-y plane, the lattice spacing of the reference lattice in the predetermined direction being D/M (millimeters) where M is a positive integer. A distance between two sides of a lens facing each other is approximately equal to D, and a distance between the projection onto the x-y plane of the vertex of the lens and the projection onto the x-y plane of a side of the lens is D/2+?i. Letting n represent the refractive index of the material of each microlens and letting f (millimeters) represent the focal length of each microlens, the following relationships are satisfied. 0.0042 D < D 2 ? ? f = D ? ( n - 1 ) 2 ? ? R 0.0048 ? f ? { 1 + ( D / 2 ? ? f ) 2 } < ? < 0.

Abstract: A light-receiving optical system includes a rotating mirror configured to rotate around a rotation axis and having a reflection plane arranged at an angle with the rotation axis; an imaging optical system having an optical axis that coincides with the rotation axis; a multifocal Fresnel lens having sections formed concentrically around the optical axis; and light-receiving elements, wherein the imaging optical system is configured such that rays of light that enter the rotating mirror are converged onto one of the sections depending on an angle of the rays with the optical axis, and the multifocal Fresnel lens is configured such that the rays reach one of the light-receiving elements, which corresponds to the one of the sections so that a light-receiving element that the rays reach is determined depending on the angle of the rays with the optical axis independently of a rotational position of the rotating mirror.

Abstract: An infrared imaging system used for infrared rays of wavelength of 5 micrometers or greater, the system including, from the object side to the image side, an aperture, a lens made of synthetic resin and an imaging element, the object side surface of the lens being convex to the object side in the paraxial area, wherein F-number of the system is 1.4 or smaller.

Abstract: A microlens array includes N microlenses arranged in a predetermined direction on an x-y plane. A projection onto the x-y plane of the vertex of each microlens is arranged in the vicinity of a lattice point of a reference lattice on the x-y plane, the lattice spacing of the reference lattice in the predetermined direction being D/M (millimeters) where M is a positive integer. A distance between two sides of a lens facing each other is approximately equal to D, and a distance between the projection onto the x-y plane of the vertex of the lens and the projection onto the x-y plane of a side of the lens is D/2+?i. Letting n represent the refractive index of the material of each microlens and letting f (millimeters) represent the focal length of each microlens, the following relationships are satisfied. 0.0042 D < D 2 ? ? f = D ? ( n - 1 ) 2 ? ? R 0.0048 ? f ? { 1 + ( D / 2 ? ? f ) 2 } < ? < 0.

Abstract: An infrared imaging system used for infrared rays of wavelength of 5 micrometers or greater, the system including, from the object side to the image side, an aperture, a lens made of synthetic resin and an imaging element, the object side surface of the lens being convex to the object side in the paraxial area, wherein F-number of the system is 1.4 or smaller.

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.

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.