Abstract: This infrared optical system using the wavelength range of 3 to 5 ?m comprises, in the order from an object side, a first lens having a negative power and formed with a convex meniscus toward an object, a second lens that is convex on both sides, and a cold aperture. A bandpass filter is provided between the second lens and the image surface. The first and second lenses are configured with silicon or germanium with each provided with an aspheric surface at least on one side. The infrared optical system satisfies the conditional expressions: 0.1 ?m<?2??1<1 ?m, 3 ?m<?1<5 ?m, and 3 ?m<?2<5 ?m. (Where ?1 and ?2 respectively represent a wavelength near the shorter wavelengths and a wavelength near the longer wavelengths in a half width of the transmission wavelength region of the bandpass filter).

Abstract: This aerial image display device is provided with an optical plate having a plurality of reflective surfaces orthogonal to each other in plan view, a projection device, a specular mirror, and a screen. The mirror includes a counter mirror disposed spaced apart from the optical plate at the opposite side of a focused image M across the optical plate. The projection device and the screen sandwich a light path between the counter mirror and the optical plate at the opposite side of the focused image (M) across the optical plate. The projection light emitted from the projection device is incident on the screen after reflecting from the counter mirror, and then incident on the optical plate after reflecting from the screen and then from the same counter mirror.

Abstract: This aerial image display device is provided with an optical plate having a plurality of reflective surfaces orthogonal to each other in plan view, a projection device, a specular mirror, and a screen. The mirror includes a counter mirror disposed spaced apart from the optical plate at the opposite side of a focused image M across the optical plate. The projection device and the screen sandwich a light path between the counter mirror and the optical plate at the opposite side of the focused image (M) across the optical plate. The projection light emitted from the projection device is incident on the screen after reflecting from the counter mirror, and then incident on the optical plate after reflecting from the screen and then from the same counter mirror.

Abstract: This infrared optical system using the wavelength range of 3 to 5 ?m comprises, in the order from an object side, a first lens having a negative power and formed with a convex meniscus toward an object, a second lens that is convex on both sides, and a cold aperture. A bandpass filter is provided between the second lens and the image surface. The first and second lenses are configured with silicon or germanium with each provided with an aspheric surface at least on one side. The infrared optical system satisfies the conditional expressions: 0.1 ?m<?2??1<1 ?m, 3 ?m<?1<5 ?m, and 3 ?m<?2<5 ?m.

Abstract: A variable-magnification observation optical system includes an objective system, an erecting system, and an eyepiece system. The objective system includes a positive first group, a positive second group, and a negative third group in order from the object side. The eyepiece system includes a positive fourth group and a positive fifth group in order from the object side. The erecting system is located between the first group and the second group. The fifth group includes in order from the object side a negative meniscus lens and a positive lens with an air gap therebetween wherein the negative meniscus lens has a concave surface facing the object. The fifth group has at least one aspheric surface.

Abstract: These variable-magnification observation optical systems are provided with an objective system, an erecting system, and an eyepiece system. In order from the object side, the objective system has a positive first lens group, a positive second lens group, and a negative third lens group. In order from the object side, the eyepiece system has a positive fourth lens group and a positive fifth lens group. The erecting system is located between the first and second lens groups. In order from the object side, the fifth lens group has the following, with air gaps in between: a negative meniscus lens element, the concave surface of which faces the object side; a negative meniscus lens element, the convex surface of which faces the object side; and a biconvex positive lens element.

Abstract: A compound eye optical system forms a plurality of images with different fields of view for connecting the plurality of images with the different fields of view and outputting one composite image. The system includes: a plurality of individual eye optical systems forming the plurality of images with different fields of view on an imaging surface; and an overall optical system forming an image with a field of view incorporating the entire fields of view obtained by the plurality of individual eye optical systems on the imaging surface, wherein the individual eye optical systems and the overall optical system are configured by a lens array plate having a plurality of lenses integrally formed.

Abstract: These variable-magnification observation optical systems are provided with an objective system, an erecting system, and an eyepiece system. In order from the object side, the objective system has a positive first lens group, a positive second lens group, and a negative third lens group. In order from the object side, the eyepiece system has a positive fourth lens group and a positive fifth lens group. The erecting system is located between the first and second lens groups. In order from the object side, the fifth lens group has the following, with air gaps in between: a negative meniscus lens element, the concave surface of which faces the object side; a negative meniscus lens element, the convex surface of which faces the object side; and a biconvex positive lens element.

Abstract: A variable-magnification observation optical system includes an objective system, an erecting system, and an eyepiece system. The objective system includes a positive first group, a positive second group, and a negative third group in order from the object side. The eyepiece system includes a positive fourth group and a positive fifth group in order from the object side. The erecting system is located between the first group and the second group. The fifth group includes in order from the object side a negative meniscus lens and a positive lens with an air gap therebetween wherein the negative meniscus lens has a concave surface facing the object. The fifth group has at least one aspheric surface.

Abstract: Provided is a compound optical system that can obtain high-resolution images by solving the problem of aberration in a field-of-view separation-type optical system, and that enables a super thin image pickup device to be achieved. Also provided is an image pickup device using the compound optical system. With respect to the image pickup range of a central individual-eye lens, by narrowing the image pickup range of a peripheral individual-eye lens, the field curvature amount at the image pickup region can be reduced, and therefore, the eccentricity amount of the lens surface (or the lens group) can be reduced. As a result, an individual-eye lens with little defocus and good image forming characteristics can be obtained, and a compound optical system with favorable image forming characteristics can be configured.

Abstract: A compound eye optical system forms a plurality of images with different fields of view for connecting the plurality of images with the different fields of view and outputting one composite image. The system includes: a plurality of individual eye optical systems forming the plurality of images with different fields of view on an imaging surface; and an overall optical system forming an image with a field of view incorporating the entire fields of view obtained by the plurality of individual eye optical systems on the imaging surface, wherein the individual eye optical systems and the overall optical system are configured by a lens array plate having a plurality of lenses integrally formed.

Abstract: The present invention provides a wide-angle optical system constituted of, in order from the object side to the image side, front group 11, stop 12, and rear group 13. The front group 11 is constituted, in order from the object side to the image side, of first lens 111 having negative optical power, second lens 112 having negative optical power, and third lens 113 having positive optical power. The rear group 13 is constituted, in order from the object side to the image side, of fourth lens 131 having positive optical power, and fifth lens 132 having negative optical power. The opposite surface from the stop of each of the paired lenses 113 and 131 arranged at the both sides of the stop 12 is a convex surface.

Abstract: The present invention provides a wide-angle optical system constituted of, in order from the object side to the image side, front group 11, stop 12, and rear group 13. The front group 11 is constituted, in order from the object side to the image side, of first lens 111 having negative optical power, second lens 112 having negative optical power, and third lens 113 having positive optical power. The rear group 13 is constituted, in order from the object side to the image side, of fourth lens 131 having positive optical power, and fifth lens 132 having negative optical power. The opposite surface from the stop of each of the paired lenses 113 and 131 arranged at the both sides of the stop 12 is a convex surface.

Abstract: An optical unit for forming an object image according to the present invention includes: a reflection member for bending an optical axis of the optical unit; a front lens group arranged closer to an object side of the optical unit than the reflection member; a rear lens group arranged closer to an image forming side of the optical unit than the reflection member; and a driver for driving the optical unit. The driver drives the reflection member and the front lens group in a predefined first direction and in a predefined second direction.

Abstract: A zoom optical system according to the present invention is provided with, in order from an object side thereof: a first lens group having a negative refractive power; a second lens group having a positive refractive power; a third lens group having a negative refractive power; and a fourth lens group having a positive refractive power. The zoom optical system moves at least the second lens group and the third lens group for zooming operation from a wide-angle end to a telephoto end. The zoom optical system moves the third lens group for a focusing operation. The first lens group is provided with, in order from the object side of the zoom optical system, a meniscus lens having a negative refractive power whose concave surface faces an image side of the zoom optical system, a reflective optical element, and at least one lens.

Abstract: An optical unit for forming an object image according to the present invention comprises: a reflection member for banding an optical axis of the optical unit; a front lens group arranged closer to an object side of the optical unit than the reflection member; a rear lens group arranged closer to an image forming side of the optical unit than the reflection member; and a driver for driving the optical unit. The driver drives the reflection member and the front lens group in a predefined first direction and in a predefined second direction.

Abstract: A zoom optical system according to the present invention is provided with, in order from an object side thereof: a first lens group having a negative refractive power; a second lens group having a positive refractive power; a third lens group having a negative refractive power; and a fourth lens group having a positive refractive power. The zoom optical system moves at least the second lens group and the third lens group for zooming operation from a wide-angle end to a telephoto end. The zoom optical system moves the third lens group for a focusing operation. The first lens group is provided with, in order from the object side of the zoom optical system, a meniscus lens having a negative refractive power whose concave surface faces an image side of the zoom optical system, a reflective optical element, and at least one lens.

Abstract: A variable magnification optical system for forming an optical image of an object on the light-receiving surface of an image sensor with variable magnification includes: from an object side, a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, a fourth lens unit having a positive optical power, and a fifth lens unit. In magnification variation from the wide-angle end to the telephoto end, the first lens unit, the third lens unit, and the fifth lens unit are kept in fixed positions whereas the second lens unit and the fourth lens unit move. The third lens unit includes, from the object side, a positive lens element having a biconvex form, and a negative lens element having a form concave to an image side. The negative lens element has an aspherical surface.