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: A small-sized, lightweight and inexpensive visual display apparatus which enables observation of a full-color image at a wide field angle, which is clear and flat as far as the edges thereof, without using a costly element such as a polarizing element. The visual display apparatus has an image display device (4), and an ocular optical system for projecting an image formed by the image display device (4) and for leading the projected image to an observer's eyeball. The image display device (4) has a louver (10) for limiting the viewing angle. The ocular optical system has two semitransparent surfaces (2 and 3). The second semitransparent surface (3) is a curved surface which is concave toward the observer's eyeball side, so that light rays emanating from the image display device (4) first pass through the second semitransparent curved surface (3), and are reflected by the first semitransparent surface (2).

Abstract: An image display apparatus, e.g. a head-mounted image display apparatus, which is capable of satisfactorily correcting field curvature and other aberrations in an optical system simultaneously, and which enables even an image of high resolution to be sufficiently clearly observed, without forming an intermediate image. The apparatus has an image display device (6) for displaying an image, and an optical system for projecting an image formed by the image display device (6) without forming an intermediate image and for leading the projected image to an observer's eyeball (1). The optical system includes at least one concave mirror (4) having a rotationally asymmetric reflecting surface which is concave toward the observer's eyeball and decentered with respect to an optical axis, and at least one optical element (9) of positive refractive power which is disposed between the concave mirror (4) and the image display device (6).

Abstract: A display apparatus of the type that is fitted to the user's head or face, and having a higher resolution in a first region of the display than that of the remaining area of the display, without increasing the size of the display. As an example, an image of the characters "ABC", for example, are generated or received. However, it might be desired that the center character "B", for example, be displayed at a higher resolution than that of the characters "A C". To accomplish this, the original image "ABC" is divided into an image of "A C" and an image of "B". Then, the image of "B" is electrically distorted and formed on a screen such that the image of "B" is larger in size than the image of "A C". An ocular optical system including an optical element effects a second distortion of the image to correct the electrically created distortion.

Abstract: An image display apparatus designed so that the field angle for observation can be widened without causing the substrate of an image display device to interfere with the observer's head and without increasing the overall size of the apparatus. The apparatus includes a two-dimensional image display device (6), an optical path splitting device (4), and a concave ocular mirror (5). The image display device (6) is used as an object point of the concave ocular mirror (5), and the object point is projected in the air as an enlarged image for an observer (1) without effecting image formation in the optical path. In the image display apparatus, either or both the optical path splitting device (4) and the concave ocular mirror (5) are decentered so that the display center (7) of the two-dimensional image display device (6) can be shifted away from the observer's head with respect to a reference axis (8) which perpendicularly intersects the observer's visual axis (3) lying when he or she sees forward.

Abstract: A compact and lightweight visual display apparatus having high resolution and a large exit pupil diameter, which enables observation of an image that is flat and clear as far as the edges of the visual field at a wide viewing angle of 30.degree. or more using a planar two-dimensional image display device. The apparatus uses a concentric optical system which provides a flat image surface (4) as an ocular optical system. The concentric optical system has at least two semitransparent reflecting surfaces (2 and 3) which have respective centers of curvature disposed in the vicinity of a pupil (1) and which have respective concave surfaces directed toward the pupil. The semitransparent reflecting surfaces are disposed so that each semitransparent reflecting surface transmits light rays at least once and reflects them at least once.

Abstract: An optical system which is usable as either an ocular optical system or an imaging optical system, and which is satisfactorily corrected for both field curvature and comatic aberration for a field angle of up to about 120.degree. and for a pupil diameter of up to about 15 millimeters. The optical system includes a partial optical system (10) having a flat semitransparent surface (1) which is closer to a pupil plane (E), and a concave semitransparent surface (2) which is closer to an image plane (I). A refracting optical element (4) is disposed at the pupil plane (E) or image plane (I) side of the partial optical system (10) with an air spacing provided therebetween. Alternatively, the refracting optical element (4) may be cemented to the partial optical system (10). The refracting optical element (4) has a focal length f.sub.a which satisfies the condition of f.sub.a >0.

Abstract: A concentric optical system usable as either an imaging optical system or an ocular optical system, which enables a clear image to be obtained at a field angle of up to about 90.degree. and with a pupil diameter of up to about 10 millimeters with substantially no chromatic aberration. The concentric optical system includes a first optical component having a first semitransparent reflecting surface (2), and a second optical component having a second semitransparent reflecting surface (3). The first and second semitransparent reflecting surfaces (2 and 3) have respective centers of curvature disposed at approximately the same position (1). The first and second optical components are different in dispersion from each other.

Abstract: A portable visual display which enables observation of an image with minimal distortion includes a two-dimensional display device (7) for displaying an image for observation, and an ocular optical system (6) for projecting an image formed by the two-dimensional display device (7) or a real image thereof in the air as a magnified image and for deviating the optical axis. The ocular optical system (6) is comprised of a concave aspherical mirror. The concave mirror (6) is designed so that the curvature thereof in a direction (X direction) perpendicular to a plane (Y-Z plane) in which the optical axis conventionally increasingly deviates gradually increases in a direction (-Y direction) in which the optical axis is deviated as seen from the observer's eye (1).

Abstract: A visual display apparatus which enables the view angle for observation to be changed between two different levels with a simple arrangement by the observer's intention or according to the kind of image reproduced. The visual display apparatus has a device (5) for displaying an image, a relay optical system (4) for projecting the image displayed on the image display device (5) to form a first image, and an ocular optical system (2) for projecting the first image in an observer's eyeball. The relay optical system (4) has an optical system (4.sub.2) which is movable along an optical axis and enables a magnification to be changed between two different levels by moving the movable optical system (4.sub.2) along the optical axis. When one of magnifications of the movable optical system (4.sub.2) is assumed to be .beta., the other magnification is approximately 1/.beta..

Abstract: An image display apparatus designed so that the field angle for observation can be widened without causing the substrate of an image display device to interfere with the observer's head and without increasing the overall size of the apparatus. The apparatus includes a two-dimensional image display device (6), an optical path splitting device (4), and a concave ocular mirror (5). The image display device (6) is used as an object point of the concave ocular mirror (5), and the object point is projected in the air as an enlarged image for an observer (1) without effecting image formation in the optical path. In the image display apparatus, either or both the optical path splitting device (4) and the concave ocular mirror (5) are decentered so that the display center (7) of the two-dimensional image display device (6) can be shifted away from the observer's head with respect to a reference axis (8) which perpendicularly intersects the observer's visual axis (3) lying when he or she sees forward.

Abstract: A concentric optical system usable as either an imaging optical system or an ocular optical system, which has an F-number of 1.5 to 3 and enables a flat and clear image to be photographed or observed at a view angle of up to 60.degree. or more with substantially no aberration. The concentric optical system includes at least two semitransparent reflecting surfaces (2) and (3) each having a center of curvature disposed in the vicinity of a pupil (1) and a concave surface directed toward the pupil. The semitransparent reflecting surfaces are disposed so that each semitransparent reflecting surface passes each particular bundle of light rays at least once and reflects them at least once, thereby providing a flat image surface (4).

Abstract: A visual display apparatus which enables observation of an image that is flat and clear as far as the edges of visual field at a view angle of 40.degree. or more and which ensures a large exit pupil diameter. The visual display apparatus has a two-dimensional image display device (14) for displaying an image for observation, a relay optical system (15) for projecting in the air a real image of the image display device (14), and an ocular concave reflecting optical system (3) for projecting the real image as an enlarged image in the air and for reflectively bending the optical axis. A decentered correcting optical system (8) which has surfaces decentered with respect to each other is disposed between the relay optical system (15) and the ocular concave reflecting optical system (3). The angle of reflective bending by the ocular concave reflecting optical system (3) is preferably 60.degree. or more.

Abstract: An image display system wearable on the user's head is disclosed for displaying a magnified projected image. The image display system includes an image display element for displaying an image thereon, a right eye ocular optical system for forming a light path leading an image formed on the image display element onto the right eye of the viewer, a left eye ocular optical system for forming a light path leading an image formed on the image display element onto the left eye of the viewer, thereby viewing a spatially enlarged projection of the image by both the right and left eye ocular optical systems. The right eye ocular optical system for leading the image from the LCD 1 to the right eye 5R includes a half-mirror 3R and a convex lens 4R. The left eye ocular optical system for leading the image to the left eye 5L includes a half-mirror 3L and a convex lens. The LCD 1 is placed at a position at substantially equal distance from the right and left eyes.

Abstract: This invention relates to a projection lens system used for transferring circuit or other patterns from masks, etc. on which the circuit patterns are drawn onto semiconductor wafers by projection photolithography, and provides a projection lens system which makes high resolving power of the order of a few micrometers and wide exposure coverages compatible with each other.This projection lens system includes at least two sets of lens groups, each built up of lenses having concave surfaces located opposite to each other, and includes at least one lens surface of positive refractive power between said two sets of lens groups, said two sets of lens groups all satisfying the following conditions:1/L<.vertline..phi..sub.1 <20/L (1)1/L<.vertline..phi..sub.2 <20/L (2)wherein .phi..sub.1 and .phi..sub.2 stand for the respective negative refractive powers of said oppositely located concave surfaces, and L is the distance between object and image.

Abstract: A head- or face-mounted display apparatus which enables observation at a field angle of 40.degree. or more and provides an image which is flat and clear as far as the peripheries thereof. The display apparatus has a two-dimensional image display element (1), a relay optical system (2 and 3) for projecting a two-dimensional image displayed by the two-dimensional image display element (1), and a concaves mirror (4) disposed forwardly of an observer's eyeball (5) to project the two-dimensional image in the air as an enlarged image and to lead the projected image to the observer's eyeball (5). The relay optical system includes a first lens unit (2) including at least one positive lens and having positive or negative refracting power, and a second lens unit (3) including at least one negative lens and having negative refracting power. The relay optical system is decentered so that the front focal surface (8) of the concave mirror (4) coincides with the image surface (7) of the relay optical system.

Abstract: This invention relates to a projection lens system used for transferring circuit or other patterns from masks, etc. on which the circuit patterns are drawn onto semiconductor wafers by projection photolithography, and provides a projection lens system which makes high resolving power of the order of a few micrometers and wide exposure coverages compatible with each other. This projection lens system includes at least two sets of lens groups, each built up of lenses having concave surfaces located opposite to each other, and includes at least one lens surface of positive refractive power between said two sets of lens groups, said two sets of lens groups all satisfying the following conditions:(1) 1/L<.vertline..phi..sub.1 .vertline.<20/L(2) 1/L<.vertline..phi..sub.2 .vertline.<20/Lwherein .phi..sub.1 and .phi..sub.2 stand for the respective negative refractive powers of said oppositely located concave surfaces, and L is the distance between object and image.

Abstract: In order to allow the surgical operator and his assistant to make stereoscopic viewing of the region of surgery with a same magnification and in coaxial relationship, the surgical microscope comprises: a common objective lens; a pair of variable magnification optical systems disposed on the image side of the objective lens; and a pair of light beam splitting members disposed on the image side of the pair of variable magnification optical systems, respectively, wherein arrangement is provided so that paired observational optical paths are to be directed to extend respectively in a plurality of directions each having a predetermined angle relative to a plane containing the optical axes of the pair of variable magnification optical systems, within a plane crossing these optical axes at right angles, respectively. The pair of light beam splitting members are constituted as an optical path splitting unit, and the barrel section and the optical path splitting unit are removably coupled to each other.

Abstract: In order to allow the assistant also to make an observation of the same region of the object as by the surgical operator in the form of a normal and clear stereoscopic image, and to enable the size of the barrel as well as the price to be about the same as that of an ordinary surgical microscope having two optical axes, the surgical microscope of the invention is arranged so that by the employment of two pairs of prisms each having a polarized light beam splitter section and a total reflection surface, a pair of operator's observational optical systems and a pair of assistant's observational optical systems are used partly in common, and one of the polarized beams so split by the polarized beam splitter section is utilized as the operator's observational light, and the other is utilized as the assistant's observational light.

Abstract: An objective lens system for microscopes comprising a first positive lens component, a second positive cemented doublet, a third lens unit comprising at least one cemented lens, a fourth meniscus cemented doublet having a convex surface on the object side and a fifth negative cemented doublet. Said objective lens system has a working distance longer than twice of its focal length and an image surface which is flat over a wide range up to a field number of 27.