Abstract: The invention discloses a projection optical system for projecting an original image onto a projection surface. The projection optical system comprises a plurality of aspherical curved mirrors, which reflects image light from the original image in sequence and then forms an image on the projection surface. The projection optical system forms a projected image on the projection surface at an aspect ratio different from that of the original image by a combination of reflective actions of the image light on the aspherical surfaces of the plurality of aspherical curved mirrors. Even in a projection optical system having a wide angle of view and a short distance of projection, it is possible to implement a projection optical system that is capable of suppressing distortion and performing an optical aspect conversion.

Abstract: An image forming lens for forming an image of an original document includes a front side lens group arranged at an object side and a rear side lens group arranged at an image forming side. The front side lens group includes from 2 to 4 lenses including at least one positive lens, and the rear side lens group includes one negative lens. The back-focus of the image forming lens when in use is equal to or smaller than 25% of an entire length of the image forming lens, and the open space between the front side lens group and the rear side lens group is equal to or greater than 50% of the entire length of the image forming lens. The front side lens group lens can include two, three or four pieces of lenses. By configuring an image forming lens with at least three lenses, correction of aberration is easy and high performance can be realized.

Abstract: Performance improved spectacle-mounted ocular display apparatus, where the addition of a movable relay mirror mounting assembly provides for image focusing and placement, framing, and orientation/alignment by permitting both translational and rotational movement of the relay mirror. This movement of the relay mirror mounting assembly in turn causes an optical change in the distance of the image from the eye. The performance improvement results from the ability to change the distance between image source and the relay mirror thereby providing a means for increasing the range of image placement and focus adjustment.

Abstract: To generate elastic force in temples and to hold a head with pressing force generated by this elastic force so as to make eyeglasses fit more comfortably. An end of an endpiece to be mounted to a lens is bent, and an endpiece part in a polygonal shape is rotatably mounted to the end. A central portion of the endpiece is pressed against one side of the endpiece part in a normal state. An end of the temple in contact with a user's head is fixed to the endpiece part. As the temple is opened, the endpiece part rotates and the one side then turns from the state of being in contact with the central portion of the endpiece, generating working force so as to return to the initial state and then generating the elastic force in the temple thereby.

Abstract: A projection zoom lens system of the present invention having telecentric incident side is suitable for a projector apparatus using LCD or DMD with prism. The projection zoom lens system of this invention comprises five lens groups having, from the screen side, negative, positive, positive, negative and positive power. In addition to this arrangement, since the lens located closest to the screen is a screen side convex negative meniscus lens, wide-angled and bright zoom lens system can be realized. Further, by designing the distribution of power of the first lens group located closest to the screen, the projection zoom lens provides further improved aberration correction. As the condition for realizing the aforementioned projection zoom lens system, it is preferable that a focal length f1 of the first lens group and a focal length at a wide-angle end fw satisfy the following condition:-1.9<f1/fw<-0.9 (A).

Abstract: Eyewear which provides a visual stimulation to the wearer while permitting the wearer to maintain a degree of normal sight. The eyewear may include a frame securing a first viewing zone which is responsive to an external signal for modulation of a visual characteristic thereof and a second viewing zone which permits the wearer to maintain a degree of normal sight through that zone. Alternatively, a single zone is responsive to an external signal while nevertheless permitting the wearer to maintain an degree of normal sight.

Abstract: In a non-collinear type acousto-optic tunable filter, a source light beam is made off-perpendicularly incident on a crystal body, so that the cross section of the source light beam is narrowed within the crystal body. As a result, the receiving angular aperture becomes large to increase the amount of light collected into the crystal body. Consequently, highly accurate spectrometry can be performed even if the intensity of the source light beam is low. Further, the non-diffraction part of the crystal body can be eliminated by the off-perpendicular incidence of the source light beam, so that the sufficient diffraction length of acoustic and optic waves can be obtained.

Abstract: A zoom lens system comprising, in order from an enlargement side, a first lens unit of a positive power, a second lens unit of a positive power, a third lens unit of a negative power, and a fourth lens unit of a positive power. During a magnification varying operation from a longest focal length condition to a shortest focal length condition, the first lens unit, the third lens unit and the fourth lens unit are movable simply from the enlargement side to a reduction side. The second lens unit is closest to the third lens unit in the longest focal length condition, and closest to the first lens unit in the shortest focal length condition. This zoom lens system satisfies the following conditions:42=<f.sub.L /f.sub.I =<54=<f.sub.L /.vertline.f.sub.III .vertline.=<13where f.sub.L is a focal length of the entire system in the longest focal length condition, f.sub.I is a focal length of the first lens unit, and f.sub.III is a focal length of the third lens unit.