Abstract: A retainer for holding a rotationally symmetrical optical element, includes a retaining member that holds the optical element via three support parts arranged at approximately 120° intervals, and a joint member that joints the optical element with the retaining member, wherein |(zb−0.6wb)−(zg+1.2)|≦1 is met, where zg is a coordinate of a gravity center of the optical element, zb is a coordinate of a center position of a width of said joint member in the z axis direction by which said joint member contacts the optical element, and wb is the width of said joint member in the z axis direction by which said joint member contacts the optical element.

Abstract: A retainer for holding a rotationally symmetrical optical element, includes a retaining member that holds the optical element via three support parts arranged at approximately 120° intervals, and a joint member that joints the optical element with the retaining member, wherein |(zb−0.6wb)−(zg+1.2)|≦1 is met, where zg is a coordinate of a gravity center of the optical element, zb is a coordinate of a center position of a width of said joint member in the z axis direction by which said joint member contacts the optical element, and wb is the width of said joint member in the z axis direction by which said joint member contacts the optical element.

Abstract: In an optical filter configured by serially connecting three Mach-Zehnder interferometers, an amount of a change in the optical path to be assigned to two optical path change units to control the filter extinction ratio of the optical filter is set based on an equation indicating the relationship among the filter average insertion loss and the filter extinction ratio of the optical filter and the amount of a change in the optical path provided for the two optical path change units.

Abstract: The present invention has an object of providing a variable optical filter that can move its periodic filter characteristic over a wide range in parallel to an optical frequency axis direction. To this end, the variable optical filter of the present invention comprises: first and second filter sections connected in series via an optical path, and a control section for controlling the periodic filter characteristic of each of the first and second filter sections. The control section, when the filter characteristic of one of the first and second filter sections is required to move in parallel to the optical frequency axis direction to exceed a variable range, relatively controls the filter characteristic of each of the first and second filter sections such that the switching is performed from one filter section to the other filter section, provided that the filter characteristic of the overall variable optical filters becomes constant.

Abstract: In an optical unit having a holding structure which brings a junk ring or the like into contact with an optical surface of a lens, the optical surface suffers from a serious elastic deformation leading to deterioration of optical performance. Upon holding the lens, therefore, a face other than the optical surface is provided on the lens so that the lens is held by applying a force to the face from element holding members.

Abstract: By connecting a plurality of VIPA type wavelength dispersion compensators, each compensating for wavelength dispersion of a different order by a plurality of optical circulators and sequentially inputting input light to each VIPA type wavelength dispersion compensator, light, even the higher-order wavelength dispersion of which is compensated for, is outputted as output light.

Abstract: A lens moving mechanism for finely moving at least a lens portion of an objective lens in a direction of an optical axis of the objective lens. The lens moving mechanism includes a holding member holding the lens portion and a disc-like disc cam member provided with a cam surface, which lies in a peripheral portion of the disc-like disc cam member. The disc cam member is rotated to thereby move the holding member on a track conforming to the cam surface.

Abstract: A novel lithium-manganese oxide composition suitable for use in lithium secondary batteries as an active material for positive electrodes, said oxide having a spinel type crystal structure, an Li:Mn molar ratio of 0.9-1.10:2.00, a mean Mn oxidation number of 3.40-3.60 valencies, and a BET specific surface area of at least 1 m.sup.2 /g, substantially all the primary particles of said oxide being less than 1 .mu.m; a process for preparing such an oxide and a lithium secondary battery containing such an oxide are also disclosed.

Abstract: The present invention relates to an apparatus for controlling the lens position of a zoom lens. The zoom lens comprises a plurality of lens units movable along the optical axis for zooming, a focal length setting unit for setting the focal length of the zoom lens, an object distance setting unit for setting an object distance, a store containing a plurality of inherent coefficients and an arithmetic logic unit which specifies focal length information and object distance information as variables, and uses the coefficients in calculating a position to which a lens unit should move.

Abstract: A lubricating oil composition comprising a base oil and, incorporated therein, a phosphoric acid ester, phosphorous acid ester, phosphoric acid ester amine salt or phosphorous acid ester amine salt, an aliphatic dicarboxylic acid compound, and an alkylamine compound and/or primary zinc thiophosphate, succinimide or perbasic magnesium or calcium sulfonate. The change with the lapse of time of the friction coefficient of this lubricating oil composition is small and the friction coefficient is stable, and the change of the friction coefficient by the change of the oil temperature is small. By dint of such excellent characteristics, this lubricating oil composition is especially valuable as a lubricating oil for an automatic transmission of an automobile.

Abstract: A diaphragm device of reduced diameter in the entirety comprising a base plate having a substantially round central opening, first diaphragm blades whose one ends are supported about respective pivot pins on the base plate, a first member arranged to turn all the first diaphragm blades about the pivot pins, the same number of second diaphragm blades as that of the first diaphragm blades arranged in confronting relation to the first diaphragm blades and whose one ends are supported about respective pivot pins on the base plate, and a second member arranged to turn all the second diaphragm blades about the pivot pins.