Abstract: The present invention relates to a compact and high-performance prism optical system having, in order in which light rays pass from the object side, a first transmitting surface (4), a first reflecting surface (5), a second reflecting surface (6), a third reflecting surface (7), and a second transmitting surface (8). When an axial principal ray (1) is projected onto a plane defined by three points at which the axial principal ray (1) impinges on the first transmitting surface (4), the first reflecting surface (5) and the second reflecting surface (6), the projected axial principal ray forms an optical path that bends at two consecutive reflecting surfaces (5, 6) in the same direction with respect to the direction of travel of the rays and bends at the other reflecting surface (7) in a direction different from the direction of bending at the two reflecting surfaces. At least one of the three reflecting surfaces is a rotationally asymmetric surface.

Abstract: An image display element 1 and an observation optical system 2 which forms an exit pupil 4 for observation of an image displayed on the image display element are included, wherein the observation optical system 2 has at least one surface 21 that has a lens function, and the following condition (1) is satisfied:

Abstract: An optical element includes an incidence surface, one or more reflecting surfaces reflecting light from the incident surface, an emergence surface, and off-axial curved surfaces causing the light to emerge from the emergence surface. At least one of the incidence surface, the emergence surface and the one or more reflecting surfaces is a surface having diffracting action. The surface having the diffracting action is a curved surface.

Abstract: The object is to display an image projected by a display device, installed in a vehicle dashboard, for displaying an information data in the optimum field of vision for a driver and to make a driver recognize visually.

Abstract: A prism (1) comprises a first inner surface (114A) that performs total reflection of all rays (20) entering from the exterior and allows ON light (21) to pass therethrough; a second inner surface (122) that allows the rays (20) and the ON light (21) to pass therethrough and performs total reflection of OFF light (22); and a third inner surface (134) that allows the ON light (21) to pass therethrough. A first end (1E1) of the first inner surface (114A) is located in proximity to and above a predetermined point (P) in the second inner surface (122). The prism (1) is regarded as a plane parallel plate having a second outer surface (121) and a third outer surface (133).

Abstract: A projector is disposed at a position that is optically conjugated to a position of eyes of an observer. The projector projects an image to a screen that has retroreflection function so as to provide information of virtual space to the observer. If a real object such as a tactile sense provision device that is to be shielded by the virtual space exists, a part or the whole of the real object is optically hidden from the projection of the projector by a shielding member having retroreflection function, for example, by placing a shielding screen on which a retroreflection material is coated, or by coating the retroreflection material.

Abstract: The present invention relates to a compact and high-performance prism optical system having, in order in which rays pass from the object side, a first transmitting surface (4), a first reflecting surface (5), a second reflecting surface (6), a third reflecting surface (7), a fourth reflecting surface (8), and a second transmitting surface (9). The first transmitting surface (4) and the second reflecting surface (6) are formed from the identical surface, and the second transmitting surface (9) and the third reflecting surface (7) are formed from the identical surface. The first reflecting surface (5) and the fourth reflecting surface (8) are formed from surfaces independent of the first transmitting surface (4) and the second transmitting surface (9). At least one of the reflecting surfaces is formed from a rotationally asymmetric surface. At least one of the second reflecting surface (6) and the third reflecting surface (7) has a power.

Abstract: A compact, lightweight and bright image display apparatus which uses a non-telecentric optical system, or a decentered optical system and a reflection-type image display device, such as a reflection-type LCD, to have high optical performance. The image display apparatus comprises an image display device, and an ocular optical system which leads an image formed by the image display device to an eye point of an observer without forming an intermediate image so that the image can be observed as a virtual image. The ocular optical system comprises a decentered optical system having at least one decentered back-coated reflecting surface. The image display device is a reflection-type image display device which displays an image by reflection of illumination light. An illumination means for forming the illumination light is arranged outside an optical path between the reflection-type image display device and the eye point of the observer.

Abstract: An optical prism 100 for reflecting light incident on its light incidence surface 12 suited for incidence of light from an LCD 20 at least twice within itself and emitting the reflected light as emitted light from a light emission surface 14 to the outside. The optical prism is coupled in use with a display element support 30 adapted to suit it. The side surfaces of the optical prism crossing the light incidence surface 12 and light emission surface 14 have projections 90L and 90R for mounting the optical prism on the display element support.

Abstract: A high-performance and low-cost image-forming optical system having a minimal number of constituent optical elements and made compact and thin by folding an optical path using reflecting surfaces arranged to minimize the number of reflections. The image-forming optical system has a first prism, a stop, and a second prism. The first prism has a first transmitting surface, a first reflecting surface, a second reflecting surface of positive power, and a second transmitting surface. The second prism has a first transmitting surface, a first reflecting surface, a second reflecting surface of positive power, and a second transmitting surface. The first transmitting surface and second reflecting surface of the first prism are the identical surface, and the first reflecting surface and second transmitting surface of the second prism are the identical surface. The image-forming optical system is approximately telecentric on the image side.

Abstract: An optical system includes an optical element having a plurality of reflective surfaces integrally formed, at least one reflective surface out of the plurality of reflective surfaces of the optical element being a curved surface a normal to which at an intersecting point with a reference axis does not coincide with the reference axis, an image pickup element to which light successively reflected by the plurality of reflective surfaces is incident, and an optical member for making at least part of the light that ought to enter the image pickup element, travel in an optical path different from an optical path toward the image pickup element. The light made to travel in the different optical path by the optical member is utilized for a purpose other than image pickup by said image pickup element.

Abstract: A display device for presenting a virtual image of a product. The device supports an object whose virtual image is to be presented at a point on one side of the device, and an optical system having a transparent member mounted in the manner of a conventional store window. The optical system projects an image of the object in virtual space towards an observer on the opposite side of said device. The device is also equipped with a means for directing an odor towards the image. The odor is scented according to the image being produced. The device is positioned adjacent to a place frequented by potential consumers of the product, such as a street in a shopping area of a town or mall.

Abstract: The present invention is an optical apparatus, e.g. an image display apparatus, which enables observation of a clear image at a wide field angle with substantially no reduction in the brightness of the observation image, and which is extremely small in size and light in weight and hence unlikely to cause the observer to be fatigued. The optical apparatus has an image display device (6), and an ocular optical system (7) for leading an image of the image display device (6) to an observer's eyeball (1). The ocular optical system (7) includes, in order from the image side, a third surface (5) which forms an entrance surface, a first surface (3) which forms both a reflecting surface and an exit surface, and a second surface (4) which forms a reflecting surface. The first to third surfaces (3 to 5) are integrally formed with a medium put therebetween which has a refractive index larger than 1.

Abstract: An optical system for an ocular optical system or a projection optical system, in which a plurality of illuminating light sources of different colors can be placed in a side-by-side relation to each other, and which makes it possible to reduce the overall size and weight of an apparatus such as a head-mounted image display apparatus or a color film projection apparatus. The optical system has an image-forming optical system (1) that projects a real image or virtual image of an object placed in an image plane (3). The image-forming optical system (1) has an entrance pupil (5) at a position on the side of the image plane (3) remote from the image-forming optical system. An exit pupil (4) is located in a conjugate relation to the entrance pupil (5) with respect to the image-forming optical system (1). A chromatic aberration producing device (6) is provided between the entrance pupil (5) and the exit pupil (4).

Abstract: A viewing optical system and image-forming optical system in which an intermediate image is formed once and two decentered prisms, i.e. first and second prisms, are arranged to correct each other's decentration aberrations, thereby attaining a wide viewing field angle and a short focal length. The second prism is placed closer to the object side than the first prism and has three optical surfaces, of which a first surface is an entrance surface also serving as a reflecting surface, a second surface is a reflecting surface, and a third surface is an exit surface. At least one of the first and second surfaces has a rotationally asymmetric surface configuration that gives a power to a light beam and corrects aberrations due to decentration. The first prism has a reflecting surface, an entrance surface, and an exit surface. The reflecting surface has a rotationally asymmetric surface configuration that gives a power to a light beam and corrects aberrations due to decentration.

Abstract: An image viewing apparatus has a stop for limiting light from an original image, and a viewing optical system for guiding the light from the original image, limited by the stop, to the eye of a viewer. The viewing optical system has a prism body including an entrance surface into which the light from the original image is incident, a reflecting surface for reflecting the incident light, and an exit surface from which the reflected light emerges. At least one of the entrance surface, reflecting surface, and exit surface is a curved surface, which is a rotationally asymmetric, aspherical surface. The apparatus satisfies the following condition: 3.

Abstract: An optical apparatus includes an optical unit including a light entrance surface, light reflecting surfaces and a light exit surface all of which are integrally formed of transparent material, and the optical unit has in its interior an internal refracting surface for refracting light. Since a light beam passes through the optical unit from the light entrance surface to the light exit surface via the internal refracting surface and the light reflecting surfaces along a bent optical path, the optical apparatus is reduced in size and improved in optical performance, particularly, well corrected in chromatic aberration. Another disclosed optical apparatus is arranged to achieve zooming by using a plurality of optical units each of which is similar to the aforesaid optical unit.

Abstract: Optical system for directing an auxiliary image towards an observer so as to be superimposed on to a main image. The optical system comprises a pentagonal prism having a first surface for intercepting the auxiliary image and directing an auxiliary image beam toward an opposing second surface so as to be internally reflected by the second surface towards a third surface so as to be internally reflected by the third surface and propagated out of the pentagonal prism through a fourth surface opposite the third surface towards the observer. At least one of the surfaces of the pentagonal prism is aspeheric and a directing optics constituted by a wedge proximate and external to the third surface directs a main image beam derived from the main image through the third surface into the pentagonal prism and out of the fourth surface thereof towards the observer.

Abstract: An image enhancement system for scaled viewing of surrounding objects at night or other vision impairing conditions such as dust, smoke, rain, fog, any combination of these conditions or other adverse weather conditions. The system includes a set of glasses or “headset”, which a user wears in a manner similar to a pair of sun or prescription glasses. Affixed to the headset is a camera system which matches a lens element with high speed electronic circuitry to provide an enhanced image of a viewed object, in true scale and range, on LCD screens in front of the user's eyes. Audio is optionally provided. A high intensity wave form illuminator is used to further illuminate the object being viewed, and is preferably attached to the headset. The user has full control over optical properties of the viewed enhanced image, and the system can be activated by switch, by voice or by motion.

Abstract: The present invention provides a method and system for dispersion compensation for a composite optical signal in an optical fiber transmission system. The composite optical signal includes a plurality of channels, each of the plurality of channels includes a band of wavelengths, where the bands of wavelengths have unwanted dispersion and dispersion slope. The present invention includes propagating the composite optical signal in a forward direction; separating the wavelengths in the band of wavelengths in each of the plurality of channels, where the each of the wavelengths in the band is spatially distinguishable from the other wavelengths in the band; spatially separating each band of wavelengths in the plurality of channels; and reflecting the spatially separated bands of wavelengths toward a return direction, where dispersion is added to the reflected bands of wavelengths such that the unwanted dispersion and dispersion slope are compensated.

Abstract: A beamsplitter, including numerous reflecting surface segments, by which a predetermined portion of an incident radiation is coupled-out, the reflecting surface segments being arranged at an angle to the incident radiation, wherein partially reflecting surface segments are provided as the reflecting surface segments, and are aligned mutually parallel and are arranged laterally displaced from each other in a plane arranged perpendicular to the incident radiation.

Abstract: A display system has light source, display panel, conic mirror, and polarized reflector. The light from the light source is filtered by a diffuse reflective polarizer to contain light in a first linear polarization (for example, s-polarized light). That light is directed by the conic mirror toward the polarized reflector, and is reflected toward the display panel displaying images. The conic mirror and the polarized reflector is shaped such that the light telecentrically and uniformly illuminates the display panel. The light is reflected from the display panel being patterned by the image and rotated into a second linear polarization (for example, p-polarized light). The rotated light passes through the polarized reflector for viewing.

Abstract: An image pickup optical system has an optical element of a transparent, optical material including an entrance surface, at least one reflective surface, and an exit surface. The optical element has an optical power, the image pickup optical system has an image pickup element including a plurality of pixels. On the image pickup element an image is formed by light from an object through the optical element. The optical material is a material having an index change amount &Dgr;n from an absolute dry condition at the temperature of 50° C. to saturation under a circumstance of the temperature being 50° C.

Abstract: The invention provides a prism optical system which has an image-forming action and provides a clear yet substantially undistorted image at a wide field angle. In a prism optical system 5 comprising an aperture 1 and having an action on erecting an image formed by an objective, there are provided reflecting surfaces 31, 32, 33, 41, 42, and 43 for image inversion, each of which is constructed of a curved surface having a power, and is in an irrotationally symmetric plane shape having no rotationally symmetric axis both within and outside the surface, so that decentering aberration produced by reflection of light at the curved surfaces can be corrected.

Abstract: This invention relates to an optical reflector receiving an input beam (22) and transmitting a retroreflected reciprocal output beam (28), comprising a beam splitter (20) giving a first secondary beam (27) and a second secondary beam (28), parallel to one another as well as retroreflecting means (21) each redirecting secondary beams toward the beam splitter and forming a Sagnac interferometer,.

Abstract: A polymer dispersed liquid crystal (PDLC) display element for use in an electronic apparatus wherein the display element operates in a PDLC mode or reverse PDLC mode providing for reduction of visual display haze, improved display contrast. The particular medium includes a liquid crystal portion and a polymer portion and may include a chiral component. In cases where visual display haze and contract is a particular problem in the utility of the reverse PDLC display element, such as in the case where the display element is combined with a solar battery, a sufficient amount of dichroic dye is added to the liquid crystal portion of the medium, and, further, a compound showing no fluorescence emission with respect to a liquid crystal portion, or a polymer or a chiral polymer precursor portion of the medium, is employed.

Abstract: A system that provides a head-up display for an operator of a vehicle includes a collection device that can collect infrared energy and an image source coupled to the collection device. The image source can generate a visual image based on the collected infrared energy. The system also includes a lens through which the visual image passes before presentation to the operator of the vehicle and a reflector that can reflect the visual image before presentation to the operator of the vehicle.

Abstract: The invention provides a real-image type finder optical system which is reduced in size in general and thickness in particular. In order from an object side of the system, the system comprises an objective optical subsystem having a positive refracting power, an image-inversion component for erecting a real image formed by the objective optical subsystem having only one image-formation action to an erect image and an ocular optical subsystem having a positive refracting power, with at least one of reflecting surfaces being defined by a roof surface. The objective optical subsystem comprises at least two reflecting surfaces of reflecting surfaces 12 to 14, each defined by a rotationally asymmetric surface with power imparted thereto.

Abstract: A semi-spherical system holding mechanism 8 such as to cover the head portion of the user is provided in the upper portion of a user holding mechanism 9 such as chair, sofa, or the like. A display apparatus 7 is fixed in the system holding mechanism 8. In the display apparatus 7, a video image displayed on a display panel 14 is enlarged by a lens 13, so that a virtual image is formed. The virtual images which are observed by the right and left eyes of the user are arranged at the same position in a space.

Abstract: Optical reflector for receiving an input beam and transmitting a retro-reflected reciprocal output beam. The optical reflector includes a beam splitter for splitting the input beam into first and second secondary beams. The first and second secondary beams being parallel to one another. A reflecting system is also included for redirecting the first and second secondary beams toward the beam splitter. The reflecting system including a total reflector. The beam splitter and the reflecting system are self-aligned.

Abstract: A semi-spherical system holding mechanism 8 such as to cover the head portion of the user is provided in the upper portion of a user holding mechanisms 9 such as chair, sofa, or the like. A display apparatus 7 is fixed in the system holding mechanism 8. In the display apparatus 7, a video image displayed on a display panel 14 is enlarged by a lens 13, so that a virtual image is formed. The virtual images which are observed by the right and left eyes of the user are arranged at the same position in a space.

Abstract: A composite display apparatus has a display device for displaying image information, a display optical system for guiding light from the display device to the eye of an observer, and an image pickup optical system for focusing light from the outside on an image pickup device. An optical axis of the image pickup optical system is substantially aligned with an axis that is an extension of the eye-ball optical axis in an optical path of the display optical system. The apparatus further has an optical path separating element for separating an optical path of the image pickup optical system from the optical path of the display optical system. Each of the display optical system and the image pickup optical system has a plurality of decentered reflective surfaces having curvature. The light from the display device is alternately folded in directions along the eye-ball optical axis by the plurality of reflective surfaces of the display optical system to be guided to the eye.

Abstract: A virtual image display system is provided which comprises a non-emissive, reflective microdisplay which forms a source object; an optical system which forms a magnified, virtual image of the source object from light reflected off the microdisplay; a light source system which produces light to illuminate the display system; and an illumination system which forms at least two virtual light sources to illuminate the display system.

Abstract: A secondary image formation type view finder comprising an objective optical system, a first mirror for folding an optical axis, a relay lens system and a second mirror for folding the optical axis, wherein an optical axis of the relay lens system is disposed so as to be included in a plane nearly perpendicular to an optical axis of the objective optical system, and the first mirror and the second mirror and disposed nearly in parallel with each other, thereby reducing a space to be occupied by the view finder.

Abstract: Low-cost plastic optics allow biocular viewing of video images with a single electro-optic display device. Folded and unfolded dual off-axis configurations use collimated illumination and intermediate imaging optics to fill both eyepieces from a single display device without requiring beamsplitters. Multiple illumination schemes provide either monochrome or color, either two-dimensional or time-sequential true stereographic presentation. Light from multicolor sources is superimposed using dichroic mirrors. A display field lens proximate to the display surface collimates the illumination beam. A shaping lens provides substantially uniform illumination of the display surface. An aperture stop improves image quality by blending sub-pixel higher order spatial harmonics from the display device. Offsetting color over- and under-correction of individual optical elements provides overall chromatic correction with minimal optical complexity.

Abstract: An optical element integrally has an optically acting surface, which is a rotationally asymmetric, aspherical surface, and a monitor surface for evaluation of whether the optical element is defective or not. The monitor surface is provided in a portion effecting no optical action, except for the optically acting surface.

Abstract: A head-mountable image display system provides an image to a user's eye separate from ambient light. The system includes an optical relay having an optical pathway to receive light from a display element. The optical relay also permits passage of ambient light toward the user's eye. An eyepiece assembly is disposed to redirect light on the optical pathway to the user's eye. The system is highly compact, allowing the integration of the display system with eyeglasses, a face mask, such as a diver's mask, a head set, or the like.

Abstract: A miniature display system uses a reflective micro-display that reflects light perpendicular to the surface of the display to generate an image. Light from an off-axis light source is polarized and reflected by a prism to provide on-axis illumination light for the display. The prism uses total internal reflection and/or a polarizer as a beam splitting surface so as to increase the brightness of the image generated by the display. The optical system provides a virtual image with a large field of view so that the small display system can be used in portable, hand-held or head mounted systems to display a large amount of information to the user.

Abstract: The present invention is an optical apparatus, e.g. an image display apparatus, which enables observation of a clear image at a wide field angle with substantially no reduction in the brightness of the observation image, and which is extremely small in size and light in weight and hence unlikely to cause the observer to be fatigued. The optical apparatus has an image display device (6), and an ocular optical system (7) for leading an image of the image display device (6) to an observer's eyeball (1). The ocular optical system (7) includes, in order from the image side, a third surface (5) which forms an entrance surface, a first surface (3) which forms both a reflecting surface and an exit surface, and a second surface (4) which forms a reflecting surface. The first to third surfaces (3 to 5) are integrally formed with a medium put therebetween which has a refractive index larger than 1.

Abstract: A head-mounted image display apparatus capable of displaying an image with dynamic presence even if the observation field angle is not wide, and which is easy to view and unlikely to cause the observer's eye to be fatigued. An image display device (1) is disposed on one side of a projection lens (5′) at approximately the focal point of the lens (5′), and a stop (8) is disposed on the other side of the lens (5′) at approximately the focal point of the lens (5′), thereby projecting the image of the image display device (1). If the refracting power at the peripheral portion of the projection lens (5′) is larger than that at the principal (central) area thereof, the image-formation characteristics of the projected image are deteriorated at the periphery. Consequently, the projected image is blurred at the periphery thereof. Thus, it is possible to project an image in which the edges of the image, which hinder an improvement in dynamic presence, are not clearly displayed.

Abstract: A high-performance image-forming optical system made compact and thin by folding an optical path using reflecting surfaces arranged to minimize the number of reflections. The image-forming optical system has a first prism placed on the object side and a second prism placed on the image side and does not form an intermediate image. The first and second prisms each have a first surface through which a light beam enters the prism, a second surface reflecting the incident light beam in the prism, a third surface reflecting the reflected light beam in the prism, and a fourth surface through which the light beam exits from the prism. At least one of the second and third surfaces has a rotationally asymmetric curved surface configuration that gives a power to a light beam and corrects aberrations due to decentration. Any optical element that gives a refracting power contributing to the image-forming action of a light beam is not placed between the second prism and an image formed by the image-forming optical system.

Abstract: A high-performance image-forming optical system made compact and thin with a minimal number of constituent optical elements and particularly suitable for use in a camera. A first prism is placed on the object side of a second prism. The first prism has a first transmitting surface, a first reflecting surface, a second reflecting surface, a third reflecting surface, and a second transmitting surface. The first transmitting surface and the third reflecting surface are the identical surface, and the first reflecting surface and the second transmitting surface are the identical surface. The second prism has an entrance surface, at least one reflecting surface, and an exit surface. The first prism and the second prism each have at least one reflecting surface with a rotationally asymmetric surface configuration that corrects decentration aberrations.

Abstract: An object of the invention is to provide a compact yet high-performance finder optical system comprising an image inversion optical subsystem having a decentered reflecting surface, which enables a bright, distortion-free image to be observed. This object is achieved by locating a rotationally asymmetric surface in the image inversion optical subsystem forming part of the finder optical system.

Abstract: A multiview three-dimensional image display system comprises an image projection screen, two image generation components, a bifold mirror, an spatial light modulator, and projection optics. Each of the image generation components generates successive finite time sequences of time-multiplexed multiview images and thus form a channel of multiview images. Each of the reflecting surfaces of the bifold mirror reflects a different one of the two channels of multiview images. The spatial light modulator comprises a plurality of strip-like shutters, each of which transmits a different one of the finite time sequences of time-multiplexed multiview images. The projection optics projects the images through the spatial light modulator onto the image projection screen, where the spatial light modulator is imaged to make a single viewing zone.

Abstract: A viewfinder optical system for conducting light from an object to an observer includes a plurality of reflecting surfaces having optical powers. Optical paths of each ray of a light flux reflected successively by the plurality of reflecting surfaces intersect each other at least twice, and the light from the object forms an image at least twice when passing through the viewfinder optical system.

Abstract: A high-performance image-forming optical system made compact and thin by folding an optical path using reflecting surfaces arranged to minimize the number of reflections. The image-forming optical system has a first prism placed on the object side and a second prism placed on the image side and does not form an intermediate image. The first prism has a first surface through which a light beam enters the first prism, a second surface reflecting the incident light beam in the prism, a third surface reflecting the reflected light beam in the prism, and a fourth surface through which the light beam exits from the prism. At least one of the second and third surfaces has a rotationally asymmetric curved surface configuration that gives a power to a light beam and corrects aberrations due to decentration. The second prism has at least one reflecting surface that reflects a light beam in the prism.

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 image display apparatus which enables observation of a clear image at a wide field angle with substantially no reduction in the brightness of the image, and which is extremely small in size and light in weight and hence unlikely to cause the observer to be fatigued. The apparatus includes an image display device (6) and an ocular optical system (9) for leading an image of the display device (6) to an observer's eyeball (1). The ocular optical system (9) has a first optical element (7) and a second optical element (8). The first optical element (7) has three surfaces, and a space formed by the surfaces is filled with a medium having a refractive index larger than 1.

Abstract: An image display apparatus which enables observation of a clear image at a wide field angle with substantially no reduction in the brightness of the observation image, and which is extremely small in size and light in weight. The image display apparatus has an image display device (7) and an ocular optical system (8) for projecting the image of the image display device (7) and leading the projected image to an observer's eyeball (1). The ocular optical system (8) has at least three optical surfaces, and a space formed by these surfaces is filled with a medium having a refractive index larger than 1. The three optical surfaces are defined as a first surface (3), a second surface (4), and a third surface (5), respectively, in the order in which light rays pass in backward ray tracing from the observer's eyeball (1) to the image display device (7).

Abstract: An image display apparatus which enables observation of a clear image at a wide field angle with substantially no reduction in the brightness of the observation image, and which is extremely small in size and fight in weight and hence unlikely to cause the observer to be fatigued. The image display apparatus includes an image display device and an ocular optical system for projecting an image formed by the image display device and for leading the projected image to an observer's eyeball. The ocular optical system (3) has three surfaces, and a space formed by the three surfaces is filled with a medium having a refractive index larger than 1.