63results about How to "Long back focus" patented technology

The present invention comprises a compact optical see-through head-mounted display capable of combining, a see-through image path with a virtual image path such that the opaqueness of the see-through image path can be modulated and the virtual image occludes parts of the see-through image and vice versa.

An optical imaging system including an illumination system, a Cartesian PBS, and a prism assembly. The illumination system provides a beam of light, the illumination system having an f / # less than or equal to 2.5. The Cartesian polarizing beam-splitter has a first tilt axis, oriented to receive the beam of light. A first polarized beam of light having one polarization direction is folded by the Cartesian polarizing beam splitter and a second polarized beam of light having a second polarization direction is transmitted by the Cartesian polarizing beam splitter. The Cartesian polarizing beam splitter nominally polarizes the beam of light with respect to the Cartesian beam-splitter to yield the first polarized beam in the first polarization direction. The color separation and recombination prism is optically aligned to receive the first polarized beam. The prism has a second tilt axis, a plurality of color separating surfaces, and a plurality of exit surfaces. The second tilt axis maybe oriented perpendicularly to the first tilt axis of the Cartesian polarizing beam-splitter so that the polarized beam is nominally polarization rotated into the second polarization direction with respect to the color separating surfaces and a respective beam of colored light exits through each of the exit surfaces. Each imager is placed at one of the exit surface of the color separating and recombining prism to receive one of the respective beams of colored light, wherein each imager can separately modulate the polarization state of the beam of colored light.

The present invention provides a projection lens for projecting light from a light source onto a screen to form a magnified image, including two joined lenses, each of which includes a negative lens and a positive lens. The difference in the refractive index and the Abbe number between the negative lens and the positive lens in each of the joined lenses and the partial dispersion ratio of the negative lens and the positive lens of the second joined lens are specified. Thus, a large angle of view and a long back focal length can be achieved while satisfying distortion aberrations, telecentric properties and magnification chromatic aberrations.

A wide-angle imaging optical system includes a refractive optical system (3), a reflective optical system, and an image-forming optical system (5). The reflective optical system includes a first reflection surface (1) that directly reflects rays of light from an object, and a second reflection surface (2) that reflects rays of light from the first reflection surface (1). An open portion is provided between the first reflection surface (1) and the second reflection surface (2), and rays of light from the object enter the open portion. A light-transmitting portion (2a) is provided in the second reflection surface (2) and transmits rays of light that have entered the refractive optical system (3). An aperture (1a) is provided in the first reflection surface (1) and allows rays of light from the second reflection surface (2) and the refractive optical system (3) to enter the image-forming optical system (5).

The invention discloses an optical imaging lens group, comprising five lenses of refractive power which consist of a first lens, a second lens, a third lens, a fourth lens and a fifth lens in sequence from an object side to an image side, wherein the first lens has positive refractive power, and the surface of the object side of the first lens adopts a convex surface; the second lens has negative refractive power; the third lens has negative refractive power; the fourth lens has negative refractive power, and at least one of the surfaces of the object side and the image side of the fourth lens adopts a non-spherical surface; and the surface of the image side of the fifth lens adopts a concave surface, at least one of the surfaces of the object side and the image side of the fifth lens adopts the non-spherical surface, and the fifth lens is made of plastic. With the configuration mode of the optical imaging lens group, the sensitivity of the optical system and the lens size can be reduced, aberration and astigmatism of the system can be effectively corrected, and resolving power with high quality can be obtained.

A small size photographic lens for the photographic unit of a device such as a camera or a camera phone. The photographic lens includes: a first lens having positive refractive power; a second lens having negative refractive power and a convex surface facing the object side; a third lens having positive refractive power; and a fourth lens having negative refractive power at the center portion, in which the negative refractive power becomes weaker from the center portion toward the peripheral portion of the fourth lens, and having a positive refractive power at the peripheral portion thereof, the lenses being numbered in order of location from the object.

A wide-angle imaging optical system includes a refractive optical system (3), a reflective optical system, and an image-forming optical system (5). The reflective optical system includes a first reflection surface (1) that directly reflects rays of light from an object, and a second reflection surface (2) that reflects rays of light from the first reflection surface (1). An open portion is provided between the first reflection surface (1) and the second reflection surface (2), and rays of light from the object enter the open portion. A light-transmitting portion (2a) is provided in the second reflection surface (2) and transmits rays of light that have entered the refractive optical system (3). An aperture (1a) is provided in the first reflection surface (1) and allows rays of light from the second reflection surface (2) and the refractive optical system (3) to enter the image-forming optical system (5).

A folded camera that includes two light folding elements such as prisms and an independent lens system, located between the two prisms, which includes an aperture stop and a lens stack. The lens system may be moved on one or more axes independently of the prisms to provide autofocus and / or optical image stabilization for the camera. The shapes, materials, and arrangements of the refractive lens elements in the lens stack may be selected to capture high resolution, high quality images while providing a sufficiently long back focal length to accommodate the second prism.

Providing an optical system having a large aperture ratio, a long back focal length, high optical performance with excellently correcting various aberrations, and an optical apparatus equipped with the optical system. The system includes, in order from an object along an optical axis of the optical system, a first lens group G1 having positive refractive power, and a second lens group G2 having positive refractive power. The second lens group G2 includes a negative lens L21, a first positive lens L22, and a second positive lens L23, and the optical system includes a compound type aspherical lens L2L constructed by a glass material and a resin material.

A single focus lens system and a photographing apparatus including the single focus lens system are disclosed. A single focus lens system is provided that includes a first lens group having a negative refractive power, a stop, and a second lens group having a positive refractive power, sequentially arranged in order from an object side, wherein the first lens group comprises first and second air lenses having a negative refractive power, a meniscus shape and a convex surface toward the object side, and the second lens group comprises a lens that has a positive refractive power, is disposed closest to the object side, and has a convex surface toward the object side.

An imaging optical system for cameras comprising a stop, a first lens, a second lens, and a third lens in order from object side to image side. The first lens is convex at the object side, and has positive refractive power and both surfaces of which are aspherical. The second lens is convex at the image side and has negative refractive power. The third lens has a concave surface at its central portion facing the image side and a convex surface at its peripheral portions facing the image side. The imaging optical system satisfies the conditions of the following Inequalities:0.8<L2Y<10.5<flf<0.86where L denotes the distance from the stop to the image focal point, 2Y denotes the diagonal length of the effective image surface, f denotes the overall focal distance of the imaging optical system, and f1 denotes the focal distance of the first lens.

An imaging lens includes, in order from an object side, a first lens group having a positive power, an aperture diaphragm, and a second lens group having a positive or negative power. The first lens group includes, in order from the object side, a first lens which is a biconcave lens, a second lens that has a positive power and includes a convex image-side surface, and a third lens that has a positive power and includes a convex object-side surface. The second lens group includes, in order from the object side, a fourth lens that has a negative power and includes a concave image-side surface, and a fifth lens which is a biconvex lens. Each of the first to fifth lenses is a single spherical glass lens.

An imaging lens includes, in order from an object side, a positive first lens group, a stop, and a positive second lens group. The first lens group includes, in order from the object side, a first lens, which is a negative meniscus lens having a convex object-side surface, and a second lens having a positive power and including a convex image-side surface. The second lens group includes, in order from the object side, a third lens having a negative power and including a concave object-side surface, a fourth lens having a positive power and including a convex image-side surface, a fifth lens, which is a biconvex lens, and a sixth lens, which is a meniscus lens having a negative power and including a convex surface facing an image side. Each of the first to sixth lenses is a single spherical glass lens.

A projection optical unit has two lens groups. A first projection optical unit disposed closest to an image display element, temporarily forms a first enlarged image (magnification: M1) at the image display element side, rather than at a second projection optical unit. The first enlarged image is subsequently projected in an enlarged form (magnification: M2, wherein M2>M1) onto a screen via the second projection optical unit. A field lens group having positive refractive power is disposed between the first projection optical unit and the second projection optical unit. Consequently, the relationship between F2, which is the F-value of the second projection optical unit, and F1, which is the F-value of the first projection optical unit, becomes F2=F1 / M1, whereby it is possible to realize very-wide-angle imaging at a field angle exceeding 90 degrees.

A projection lens includes a first lens having at least an aspheric surface, a second lens having a concave surface facing the reduction side of the projection lens, and having negative refractive power, a third lens, a fourth lens, a fifth lens, a sixth lens having a convex surface facing the reduction side, and having positive refractive power, and the like, which are sequentially arranged from the magnification side of the projection lens. Further, the following formulas (1) and (2) are satisfied:3.5<Bf / f<7.5  (1); and1.2<|fa / f|<2.0  (2), wheref: focal length of the entire system of the projection lens,Bf: back focus in air of the entire system, andfa: combined focal length of lenses from the second lens to a most-reduction-side lens.

An optical imaging system including an illumination system, a Cartesian PBS, and a prism assembly. The illumination system provides a beam of light, the illumination system having an f / # less than or equal to 2.5. The Cartesian polarizing beam splitter has a first tilt axis, oriented to receive the beam of light. A first polarized beam of light having one polarization direction is folded by the Cartesian polarizing beam splitter and a second polarized beam of light having a second polarization direction is transmitted by the Cartesian polarizing beam splitter. The Cartesian polarizing beam splitter nominally polarizes the beam of light with respect to the Cartesian beam splitter to yield the first polarized beam in the first polarization direction. The color separation and recombination prism is optically aligned to receive the first polarized beam. The prism has a second tilt axis, a plurality of color separating surfaces, and a plurality of exit surfaces. The second tilt axis may be oriented perpendicularly to the first tilt axis of the Cartesian polarizing beam splitter so that the polarized beam is nominally polarization rotated into the second polarization direction with respect to the color separating surfaces and a respective beam of colored light exits through each of the exit surfaces. Each imager is placed at one of the exit surface of the color separating and recombining prism to receive one of the respective beams of colored light, wherein each imager can separately modulate the polarization state of the beam of colored light.

The imaging lens system includes a negative first lens disposed on a most object side, having a concave surface directed toward the object side and having a meniscus shape, a cemented lens LC disposed on a most image side and having a convex surface on its most object side, and an aperture diaphragm disposed just in front of the object side of the cemented lens. The system satisfies the following conditional expressions:0.05<(R2−R1) / (R1+R2)<0.25vd1−vd2>15whereR1 and R2 denote radius of curvatures of object side and image side surfaces of the first lens, respectively, andvd1 and vd2 denote Abbe numbers of lenses, which are located on the most object side and on the most image side among lenses constituting the cemented lens, at the d-line, respectively.

An endoscope objective lens is provided and has a front-group divergent lens system, an aperture stop, and a rear-group convergent lens system in this order from the object side. The back focal length Bf of the whole system is longer than 2.5 times the combined focal length f of the whole system. The rear-group convergent lens system includes a cemented lens. The endoscope objective lens satisfies the specific formula.

A wide-angle lens system includes a negative first lens group, a negative second lens group, and a positive third lens group. The negative first lens group includes at least two negative meniscus lens elements each having the convex surface facing toward the object, and a positive lens element provided on the image-side of the two negative meniscus lens elements. The negative second lens group includes cemented lens elements and a negative meniscus lens element having the convex surface facing toward the object. The wide-angle lens system satisfies the following conditions: f2-3 / f>1.6  (1) f3 / f>1.5  (2) (f2-3 / f) / (f3 / f)>1.0  (3) wherein f2-3 designates the combined focal length of the negative second lens group and the positive third lens group; f designates the focal length of the entire wide-angle lens system; and f3 designates the focal length of the positive third lens group.