Abstract: The invention provides an optical system which is well corrected in terms of both curvature of field and coma at a field angle of about 120.degree. and a pupil diameter of about 15 mm and may be applied to both image pickup and ocular systems. Dioptric elements 11 are located the pupil plane side E and/or image plane side I of a concentric element 12 including two semitransparent surfaces 121 and 122, said two semitransparent surfaces 121 and 122 being concave on the pupil plane side E and located such that they transmit light at least once and reflect light at least once.

Abstract: A head-mounted visual display apparatus which uses two or more two-dimensional display devices and which is compact, lightweight and enables an image which is clear as far as the periphery of the observation image field to be observed at a wide field angle and high resolution. The apparatus has a first two-dimensional display device (4) and a second two-dimensional display device (5). An ocular optical system (3) includes a first surface (11) having both reflecting and transmitting actions, a second surface (12) having at least reflecting action, and a third surface (13) having at least reflecting action. The first surface (11) is disposed to face an observer's eyeball (6). The second surface (12) is disposed to face the first surface (11). The third surface (13) is disposed to face the first surface (11) in a side-by-side relation to the second surface (12). Thus, images displayed by the first and second two-dimensional display devices (4 and 5) are led to the observer's eyeball (6).

Abstract: The invention relates to an image-forming optical system which is compact and light in weight with well corrected aberrations, and is suitable for use on an image display device designed to form no intermediate image, and an optical system. This optical system comprises a prism member and a diffraction optical element that are mutually decentered. The prism member comprises at least three juxtaposed optical surfaces, at least one of which is constructed of a curved surface. Between the optical surfaces, at least two reflections occur. Spaces between the optical surfaces arc filled with a medium having a refractive index greater than 1.

Abstract: A prism optical system for use as an ocular optical system of a visual display apparatus, which has a compact size as a whole, causes a minimal reduction of the light intensity in the ocular optical system, provides a wide field angle and a large exit pupil diameter, and is effectively corrected for off-axis aberrations. The prism optical system has two transparent surfaces (6 and 7), and two reflecting surfaces (2 and 3). The space between the first transparent surface (6) and the second transparent surface (7) is filled with a medium having a refractive index not smaller than 1.3.

Abstract: A visual display apparatus, for example, a head-mounted display apparatus, which enables an image to be observed at a wide field angle and high resolution. The apparatus includes a pair of two-dimensional display devices (4 and 5) disposed with their display surfaces facing each other, and two half-mirrors (6 and 7) which are paired with the display devices (4 and 5) and combined to each other in the shape of a V. The apparatus further includes a concave mirror (8) having a center axis coincident with the center axis of the half-mirrors (6 and 7) combined in a V shape. The two-dimensional display devices (4 and 5) are adapted to display images (11 and 10) each including an overlap region (9) and having an area wider than one half of the image for observation. The images (11 and 10) are combined together into one continuous image by the two half-mirrors (6 and 7) combined in a V shape.

Abstract: A variable-magnification image-forming optical system having at least four lens units including a decentered optical system. The decentered optical system has at least one curved surface with a rotationally asymmetric surface configuration having no axis of rotational symmetry in nor out of the surface. Rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface configuration. A magnification change is effected by changing at least one of the spacings between the four lens units.

Abstract: A head-mounted image display apparatus capable of providing an observation image which is clear and has minimal distortion even at a wide field angle. The apparatus has an image display device (6), and an ocular optical system (7) for leading an image formed by the image display device (6) to an observer's eyeball position without forming an intermediate image so that the image can be observed as a virtual image. The ocular optical system (7) has at least one reflecting surface (4) having reflecting action. The at least one reflecting surface (4) has a surface configuration defined by a plane-symmetry three-dimensional surface which has no axis of rotational symmetry in the surface nor out of the surface, and which has only one plane of symmetry.

Abstract: A compact image-forming optical apparatus which is free from moire fringes and capable of providing an aberration-free, clear image of minimal distortion even at a wide field angle. The image-forming optical apparatus has an objective optical system (104) and an electronic image pickup device (108). The objective optical system (104) has at least one reflecting surface (106, 107) decentered such that the whole surface is tilted with respect to the axial principal ray. The reflecting surface has a rotationally asymmetric surface configuration that corrects rotationally asymmetric decentration aberrations caused by decentration. A low-pass member (103) is disposed in the vicinity of a pupil plane (101) closer to the object than the reflecting surface. The low-pass member cuts off a high-frequency component concerning the object image in a bundle of rays led to the electronic image pickup device (108).

Abstract: A compact image display apparatus having a wide exit pupil diameter, which enables observation of an image that is flat and clear as far as the edges of visual field at a field angle of 40.degree. or more. The apparatus includes an image display device (8) for displaying an image, a relay optical system (7) for relaying the image to form a relay image, and an ocular optical system having a reflecting surface (2) that bends a bundle of light rays emanating from the relay optical system (7) and forming an exit pupil (1) of the relay image. The ocular optical system has an entrance-side optical surface (6) provided in an optical path extending from the relay optical system (7) to the reflecting surface (2), and an exit-side optical surface (5) provided in an optical path along which the ray bundle bent by the reflecting surface travels to reach the exit pupil (1) and having a power different from that of the entrance-side optical surface (6).

Abstract: An optical system capable of correcting aberrations due to three-dimensional decentration by using a rotationally asymmetric surface having no plane of symmetry. The optical system includes, from the ray bundle entrance sides, a first surface (3) serving as both a first transmitting surface and a second reflecting surfaces a second surface (4) as a first reflecting surfaces and a third surface (5) as a second transmitting surface. The space between these surfaces is filled with a medium having a refractive index larger than 1. The first surface (3) is a three-dimensional surface having no plane of symmetry.

Abstract: A compact endoscope optical system capable of providing a clear image of minimal distortion even at a wide field angle. The endoscope optical system includes an objective optical system for forming an object image. The objective optical system has a prism member (3) having reflecting surfaces (5, 6) for bending an optical path. The endoscope optical system further includes an image transfer system for leading the object image formed by the objective optical system to an observation apparatus along the direction of a major axis. The objective optical system has a configuration producing decentration aberration by bending the optical path. The prism member (3) has at least one curved surface (4 to 7) having an optical action in the optical path. The curved surface is such a non-rotationally symmetric surface having no axis of rotational symmetry in nor out of the surface as to correct the decentration aberration.

Abstract: An image display apparatus corrected for distortions, particularly, a distortion which is asymmetric with respect to the center of the image field. The apparatus includes an image display device (8), and an ocular optical system (42) having a rotationally asymmetric optical surface or a decentered optical surface having a power. The apparatus satisfies the condition of .vertline.tan .THETA..sub.1 -tan .THETA..sub.2 .vertline./tan .THETA..sub.1 <0.1, where .THETA..sub.1 is an angle made between a light ray emitted from an arbitrary point (44) on the image display device (8) and passing through the center of an exit pupil (40) and a visual axis (41), that is, a straight line connecting the center of an observer's pupil and the center of a projected image of the image display device (8), and .THETA..sub.

Abstract: The present invention provides a head-mount image display apparatus which is maximumly reduced in size so as to arrange eyepiece optical systems in limited spaces such that the eyepiece optical systems do not touch the user's nose. The head-mount image display apparatus comprises LCD for displaying images for left and right eyes, eyepiece optical systems for guiding the images for left and right eyes displayed on the LCD to left and right eyeballs, body of the display apparatus for supporting the LCDs and the eyepiece optical systems for the left and right eyes such that the LCD and the eyepiece optical system for the right eyepiece is arranged at a predetermined distance from the LCD and the eyepiece optical system for the left eye, wherein corners of the eyepiece optical systems, at least which face a user's nose, are each provided with a chamfered portion planed off so as not to touch the user's nose.

Abstract: The present invention provides a head-mount image display apparatus which is maximumly reduced in size so as to arrange eyepiece optical systems in limited spaces such that the eyepiece optical systems do not touch the user's nose. The head-mount image display apparatus comprises LCD for displaying images for left and right eyes, eyepiece optical systems for guiding the images for left and right eyes displayed on the LCD to left and right eyeballs, body of the display apparatus for supporting the LCDs and the eyepiece optical systems for the left and right eyes such that the LCD and the eyepiece optical system for the right eyepiece is arranged at a predetermined distance from the LCD and the eyepiece optical system for the left eye, wherein corners of the eyepiece optical systems, at least which face a user's nose, are each provided with a chamfered portion planed off so as not to touch the user's nose.

Abstract: The invention provides an optical system which is well corrected in terms of both curvature of field and coma at a field angle of about 120.degree. and a pupil diameter of about 15 mm and may be applied to both image pickup and ocular systems. Dioptric elements 11 are located the pupil plane side E and/or image plane side I of a concentric element 12 including two semitransparent surfaces 121 and 122, said two semitransparent surfaces 121 and 122 being concave on the pupil plane side E and located such that they transmit light at least once and reflect light at least once.

Abstract: The invention relates to an optical system which is compact and light in weight with well corrected aberrations, and is suitable for use on an image display device designed to form no intermediate image, and an optical system best usable as an ocular optical system for use on a head- or face-mounted image display device. This optical system comprises an optical element 7 and a diffraction optical element 8 that are mutually decentered. Optical element 7 comprises at least three juxtaposed optical surfaces, at least one of which is constructed of a curved surface. Between the optical surfaces at least two reflections occur. Spaces between the optical surfaces are filled with a medium having a refractive index greater than 1.

Abstract: The invention relates to an ocular optics system which forms no intermediate image, is reduced in terms of size and weight with well-corrected aberrations, and is best suited for use on face- or head-mounted image display devices, and provides an ocular optics system 7 comprising three juxtaposed optical surfaces 3, 4 and 5, wherein a space defined by three optical surfaces 3, 4 and 5 is filled with a transparent medium having a refractive index greater than 1, at least two optical surfaces 3 and 4 of these three optical surfaces are defined by curved surfaces concave on a pupil position side of the optics system, and at least four reflections occur between curved surfaces 3 and 4.

Abstract: An optical system which is compact, lightweight and satisfactorily corrected for aberrations and may be suitably used as an imaging optical system or an ocular optical system for a head- or face-mounted image display apparatus which forms no intermediate image. The optical system includes an optical member (7) and a diffraction optical element (8), which are decentered with respect to each other. The optical member (7) has at least three adjacent optical surfaces, at least one of which is a curved surface. At least two reflections take place between the optical surfaces. The space between the optical surfaces is filled with a medium having a refractive index larger than 1. Light rays emitted from an image display device (6) enter the optical member (7) through a first transmitting surface (5) disposed to face the image display device (6) and are reflected by a first reflecting surface (3).

Abstract: A head-mounted image display apparatus (HMD) including an ocular optical system, which has an F-number of 1.5 to 3 and enables a flat and clear image to be observed at a view angle of up to 60.degree. or more with substantially no aberration. The HMD has at least two, surfaces and each having a concave surface directed toward the pupil. The two surfaces are disposed so that light rays from an image display device are reflected by the first surface, and the reflected light rays are reflected by the second surface and pass through the first surface to enter an observer's eyeball.

Abstract: A head-mounted image display apparatus having an exit pupil that is enlarged without causing an increase in the size of a relay optical system or a reduction in the size of a projected image. The head-mounted image display apparatus has an image display device (1) having a display surface for displaying an image, a relay optical system (2) for transmitting the image displayed on the display surface of the image display device (1) to form an image of the display surface, and an ocular optical system (4) for projecting the image transmitted by the relay optical system inside an observer's eyeball as an enlarged image. A numerical aperture (NA) enlarging element is disposed at a position conjugated with the display surface with respect to the relay optical system (2). Thus, pupil alignment is facilitated without causing an increase in the size of the relay optical system (2) or a reduction in the size of the projected image.