Abstract: An abrasive slurry regeneration method includes: collecting at least a used abrasive slurry containing an abrasive component and a constituent component of a polishing target object discharged from a polishing machine; inactivating a metal ion dissolved in the used abrasive slurry; dispersing the abrasive component and the constituent component of the polishing target object contained in the used abrasive slurry; separating the dispersed abrasive component and constituent component of the polishing target object to remove the constituent component of the polishing target object; and preparing a regenerated abrasive slurry containing the abrasive component.

Abstract: An ion exchange resin member 20 that serves as an impurity remover for removing impurities from fluid F discharged from a fuel cell 100 is placed in a discharge passage for the fluid F to flow through, and a dispersion means for dispersing the fluid F over, and making the fluid F flow to, an entry-side surface 21 of the ion exchange resin member 20 is placed upstream from the ion exchange resin member 20. Also, a gas discharge part and a liquid discharge part are placed downstream from a fluid outlet of the ion exchange resin member 20, and a liquid-movement-preventing means for preventing a liquid in the fluid discharged from the fluid outlet from moving toward the gas discharge part is placed between the ion exchange resin member 20 and at least either the gas discharge part or the liquid discharge part.

Abstract: An ion exchange resin member 20 that serves as an impurity remover for removing impurities from fluid F discharged from a fuel cell 100 is placed in a discharge passage for the fluid F to flow through, and a dispersion means for dispersing the fluid F over, and making the fluid F flow to, an entry-side surface 21 of the ion exchange resin member 20 is placed upstream from the ion exchange resin member 20. Also, a gas discharge part and a liquid discharge part are placed downstream from a fluid outlet of the ion exchange resin member 20, and a liquid-movement-preventing means for preventing a liquid in the fluid discharged from the fluid outlet from moving toward the gas discharge part is placed between the ion exchange resin member 20 and at least either the gas discharge part or the liquid discharge part.

Abstract: A small-sized camera in which while the light emerging from a photographic lens having an optical axis parallel with a photosensitive plane is conducted by first and second mirrors to the photosensitive plane to form a photographic system, the first or second mirror is turned around a predetermined axis to conduct the light to an eyepiece lens to form a finder system. And, a structure of construction for efficiently removing the stray light of this camera is disclosed.

Abstract: A zoom lens is disclosed comprising, from front to rear, a first lens groups of positive power, a second lens group of negative power, a third lens group of positive power, and a fourth lens group, at least two of these four lens groups being moved to effect zooming and the second lens group being moved to effect focusing, and satisfying the following condition:-0.85<.beta.2T<-0.65where .beta.2T is the image magnification for an infinitely distant object of the second lens group in the telephoto end.

Abstract: A zoom lens includes a first lens group having a negative refractive power and having an object-side sub-group stationary during focusing and an image-side sub-group arranged to move for focusing purposes, and a second lens group having a positive refractive power and arranged on the image side of the first lens group, wherein the first lens group and the second lens group move axially at the same time and in differential relation for zooming purposes.

Abstract: A camera having a photographic lens and an eyepiece lens for observing an image formed by the photographic lens, wherein when this camera is used as a telescope, the interval between the image and the eyepiece lens is shortened, while simultaneously changing the focal length of the eyepiece lens, so that the magnification of the finder is increased.

Abstract: A zoom lens is composed of, as counted from the object side of the lens, a first lens unit or group having a positive refractive power, a second lens unit or group having a negative refractive power, a third lens unit or group having a positive refractive power, a fourth lens unit or group having a negative refractive power and a fifth lens unit or group having a positive refractive power. Assuming that, when varying the magnifying power of the lens from a wide angle end to a telephoto end, an air space between an i-th lens unit and an i+l-th lens unit varies to a degree .DELTA.Di, the i-th lens unit has a focal length fi, the focal length of the whole lens system as obtained at the telephoto end is FT, and a space between the first and second lens units varies to a degree .DELTA.E1 between the wide angle end and the telephoto end, the zoom lens is arranged to satisfy the following conditions:.DELTA.D1>0.DELTA.D2<0.DELTA.D3>0.DELTA.D4<00.046<.vertline.f2/FT.vertline.<0.0930.22<.vertline.

Abstract: A zoom lens including, from front to rear, a first lens unit of positive power, a second lens unit of negative power and a third lens unit of positive power, wherein for a standard focal length range at least the first and second lens units move simultaneously and independently of each other, and to obtain a focal length beyond the standard range, at least the second lens unit moves, whereby the locus of movement of the first lens unit bends at an end of the standard range, and as the standard range is exceeded, the first lens unit either remains stationary or moves forward.

Abstract: A telephoto lens comprising, from front to rear, a first lens unit including a lens of negative power with its rear surface concave toward the rear and whose overall power is positive, a second lens unit of negative power axially movable for focusing, and a third lens unit of positive overall refractive power having a negative lens whose front-most lens surface is concave toward the front and at least two positive lenses.

Abstract: A zoom lens comprising, from front to rear, a first zoom section and a second zoom section, the first zoom section having a plurality of movable lens units which simultaneously move to effect zooming, and the second zoom section having a plurality of axially movable lens units, the light beam exiting from the rearmost unit in the first section enters directly the frontmost unit in the second section, and the refractive powers of the front and rear lens units are made positive and negative respectively, whereby the front and rear lens units are simultaneously moved in such a way that the magnifying power of the rear lens unit remains positive when the focal length of the entire system varies.

Abstract: A zoom lens comprising, from front to rear, a first lens unit of negative power, a second lens unit of positive power and a third lens unit, the first and second lens units being axially movable for zooming, and the zoom lens satisfying the following conditions:1.2f.sub.W <.vertline.f.sub.1 .vertline.<1.6f.sub.W0.9f.sub.W <f.sub.2 <1.3f.sub.W-0.35/f.sub.T <1/f.sub.3 <0.3/f.sub.T0.85f.sub.W <l.sub.1W <1.2f.sub.W0<l.sub.2W /f.sub.W <0.30<l.sub.1T /f.sub.W <0.20.7<(l.sub.2T -l.sub.2W)/f.sub.W <1.21.2<.vertline..beta..sub.2T .vertline.<1.1.sqroot.f.sub.T /f.sub.Wwhere F.sub.1, f.sub.2 and f.sub.3 are the focal lengths of the first, second and third lens units respectively, l.sub.1W and l.sub.2W are the first and second separations between the first and second lens units and between the second and third lens units respectively when in the wide angle end, l.sub.1T and l.sub.2T are the first and second separations when in the telephoto end, .beta..sub.

Abstract: A zoom lens having a plurality of lens units with the air separations, at least one of which is varied to effect zooming, the rearmost lens surface of successive two of the lens units and the frontmost lens surface of the rear one being both formed to convex shapes toward the front, whereby when these two lens units axially move at different speeds from each other, a soft-focus effect of varying magnitude is produced on the image.

Abstract: A zoom lens including, from front to rear, a first lens group of positive power, a second lens group of negative power, a third lens group of positive power, a fourth lens group of negative power, and a fifth lens group of positive power. For zooming from the shortest focal length to the longest focal length, the first lens group is moved forward, the air space between the first and second lens groups is increased, the air space between the second and the third lens groups is decreased, the air space between the third and fourth lens groups is increased, and the air space between the fourth and fifth lens groups is decreased. The fifth lens group remains stationary during zooming. This construction and arrangement results in a zoom lens of compact form with a large aperture while still permitting good stability of aberration correction throughout a greatly extended zooming range.

Abstract: The disclosed zoom lens has at least four lens groups with proper refractive powers operating such that while the third lens group counting from front is held stationary, the first and second lens groups and at least one of the fourth lens group and those that follow are moved axially in differential relation to effect zooming. A given range of variation with zooming of the image magnification of the second lens group and a given differential relation for the zooming movement of the first and second lens groups achieve good stability of aberration correction over an extended zooming range.

Abstract: A high relative aperture Gauss type lens comprising, from front to rear, a first lens unit including at least one positive lens, a negative meniscus-shaped second lens convex toward the front, a positive third lens with its front surface of strong convex curvature toward the front, a negative fourth lens with its rear surface of strong concave curvature toward the rear, a negative fifth lens with its front surface of strong concave curvature toward the front, a positive sixth lens with its rear surface of strong convex curvature toward the rear, a negative meniscus-shaped seventh lens convex toward the rear, a positive meniscus-shaped eighth lens convex toward the rear, a positive ninth lens, and a positive meniscus-shaped tenth lens convex toward the front.

Abstract: A zoom lens including, from front to rear, a first lens unit of negative power and a second lens unit of positive power with the separation therebetween being varied to effect zooming. The first lens unit is moved to effect focusing, wherein with the first lens unit focusing a finite object distance on the wide angle side, the second lens unit moves rearward to obtain focal lengths beyond the zooming range.

Abstract: A zoom lens having at least four components of which the 1st counting from the object side is of positive power, the 2nd is of negative power and the 3rd and 4th are of positive or negative power, wherein the 2nd component is made fixed, and the 1st component and at least one of those that follow the 2nd component are made movable for zooming, whereby the bulk and size of the lens system is minimized, while still permitting good correction of aberrations.

Abstract: The disclosed zoom lens includes, from front to rear, a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power, and a fourth lens unit. When zooming, the first and third lens units are axially moved independently of each other, the second lens unit remains stationary, and the fourth lens unit is axially moved but changes the direction of advance at an intermediate point in the zooming range.

Abstract: A zoom lens is constructed, from front to rear, of a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power and a fourth lens unit of positive or negative power. When zooming from the wide angle to the telephoto end, the first and third lens units move forward at the same speed, while the second lens unit moves simultaneously in non-linearly differential relation to the first and third lens unit. The zoom lens satisfies the following conditions:0.4 fT<f1<0.65 fT0.4 fW<.vertline.f2.vertline.<0.25 fT0.12 fT<f3<0.35 fT-0.18<fW/f4fT/f4<0.10.8<.vertline..beta.2T.vertline.<1.0where f1 to f4 are the focal lengths of the first to the fourth lens units, respectively, fW and fT are the shortest and longest focal lengths of the entire zoom lens system, respectively and .beta.2T is the magnifying power of the second lens unit in the telephoto end.