Abstract: An optical system which forms an optical image on an image pickup element, comprising in order from an object side, a first lens unit having a positive refractive power, which includes a plurality of lenses, a stop, and a second lens unit which includes a plurality of lenses, wherein the first lens unit includes a first object-side lens which is disposed nearest to an object, and the second lens unit includes a second image-side lens which is disposed nearest to an image, and the first lens unit includes a negative lens, and a positive lens which is disposed on the object side of the negative lens, and the following conditional expressions are satisfied: ???1.1??(15) 0.08<NA??(16) 1.0<WD/BF??(19) 0.5<2×(WD×tan(sin?1NA)+Yobj)/?s<4.0??(20).

Abstract: A communication method using link aggregation, the method includes receiving a transfer frame; calculating, by a first communication device, an identification number of an output port for the transfer frame among a plurality of ports using a hash function, by using a combination of a source address of the transfer frame, a destination address of the transfer frame, and a cyclic number that is generated for every combination of the source address and the destination address and represents an order of the transfer frame as a hash key; and transmitting the transfer frame from the output port.

Abstract: An optical system which forms an optical image on an image pickup element, comprising in order from an object side, a first lens unit having a positive refractive power, which includes a plurality of lenses, a stop, and a second lens unit which includes a plurality of lenses, wherein the first lens unit includes a first object-side lens which is disposed nearest to an object, and the second lens unit includes a second image-side lens which is disposed nearest to an image, and the first lens unit includes a negative lens, and a positive lens which is disposed on the object side of the negative lens, and the following conditional expressions are satisfied: ???1.1??(15) 0.08<NA??(16) 1.0<WD/BF??(19) 0.5<2×(WD×tan(sin?1 NA)+Yobj)/?s<4.

Abstract: An optical system which forms an optical image on an image pickup element, comprising in order from an object side, a first lens unit having a positive refractive power, which includes a plurality of lenses, a stop, and a second lens unit which includes a plurality of lenses, wherein the first lens unit includes a first object-side lens which is disposed nearest to an object, and the second lens unit includes a second image-side lens which is disposed nearest to an image, and the first lens unit includes a negative lens, and a positive lens which is disposed on the object side of the negative lens, and the following conditional expressions are satisfied: ???1.1??(15) 0.08<NA??(16) 1.0<WD/BF??(19) 0.5<2×(WD×tan(sin?1 NA)+Yobj)/?s<4.0??(20).

Abstract: An optical system which forms an optical image on an image pickup element, comprising in order from an object side, a first lens unit having a positive refractive power, which includes a plurality of lenses, a stop, and a second lens unit which includes a plurality of lenses, wherein the first lens unit includes a first object-side lens which is disposed nearest to an object, and the second lens unit includes a second image-side lens which is disposed nearest to an image, and the first lens unit includes a negative lens, and a positive lens which is disposed on the object side of the negative lens, and the following conditional expressions are satisfied: ???1.1??(15) 0.08<NA??(16) 1.0<WD/BF??(19) 0.5<2×(WD×tan(sin?1 NA)+Yobj)/?s<4.

Abstract: An imaging optical system smaller than conventional systems yet with well-corrected aberrations, comprises five lenses L1-L5 having refractive powers, in order from the object side: positive, negative, positive, positive, and negative, with an aperture at an endmost object-side position. In one embodiment, L1 is biconvex, L2's object-side surface is convex, L5's object-side surface is convex, and 1.0?f3/f1?4.9, f1 and f3 being the focal lengths of L1 and L3, respectively. In a variant thereof, L2 is a meniscus lens and L5's object-side surface is concave. In another embodiment, L1 is glass, and ?4.0<(r6+r7)/(r6?r7)<?0.51, r6 and r7 being paraxial curvature radii of L3's object-and image-side surfaces, respectively. In another embodiment, L1 is glass, and ?1.5<f2 /f<?0.73, f2 being the focal length of L2 and f the focal length of the whole optical system. In yet another embodiment, L1 is glass, and ?11.2<r3/f1<?0.9, r3 being the paraxial curvature radius of L1's image-side surface.

Abstract: An image pickup optical system includes in order from an object side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a positive refractive power, and a fifth lens having a negative refractive power. An aperture stop is disposed nearest to the object side, and the first lens has a biconvex shape. An image-side surface of the third lens has in a peripheral portion, an area of which, a refractive power becomes weaker as compared to a refractive power of a central portion thereof. An object-side optical function surface of the fourth lens has a concave shape, and an object-side surface of the fifth lens has a concave shape.

Abstract: A communication method using link aggregation, the method includes receiving a transfer frame; calculating, by a first communication device, an identification number of an output port for the transfer frame among a plurality of ports using a hash function, by using a combination of a source address of the transfer frame, a destination address of the transfer frame, and a cyclic number that is generated for every combination of the source address and the destination address and represents an order of the transfer frame as a hash key; and transmitting the transfer frame from the output port.

Abstract: A zoom lens system according to the present invention includes a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with positive refractive power, and a fourth lens group with negative refractive power which are arranged in turn from the object side toward the image side, and the zoom lens system is formed so that, in performing a zooming operation from the wide angle end position to the telephoto end position, the first lens group keeps still, the distance between the first and second lens groups becomes small, the distance between the second and third lens groups becomes wide, and the distance between the third and fourth lens groups becomes small.

Abstract: A zoom lens system according to the present invention includes a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with positive refractive power, and a fourth lens group with negative refractive power which are arranged in turn from the object side toward the image side, and the zoom lens system is formed so that, in performing a zooming operation from the wide angle end position to the telephoto end position, the first lens group keeps still, the distance between the first and second lens groups becomes small, the distance between the second and third lens groups becomes wide, and the distance between the third and fourth lens groups becomes small.

Abstract: A zoom lens system according to the present invention includes a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with positive refractive power, and a fourth lens group with negative refractive power which are arranged in turn from the object side toward the image side, and the zoom lens system is formed so that, in performing a zooming operation from the wide angle end position to the telephoto end position, the first lens group keeps still, the distance between the first and second lens groups becomes small, the distance between the second and third lens groups becomes wide, and the distance between the third and fourth lens groups becomes small.

Abstract: An image pickup optical system includes in order from an object side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a positive refractive power, and a fifth lens having a negative refractive power. An aperture stop is disposed nearest to the object side, and the first lens has a biconvex shape. An image-side surface of the third lens has in a peripheral portion, an area of which, a refractive power becomes weaker as compared to a refractive power of a central portion thereof. An object-side optical function surface of the fourth lens has a concave shape, and an object-side surface of the fifth lens has a concave shape.

Abstract: An image pickup optical system having five lenses includes in order from an object side, a first lens having a biconvex shape, and a positive refractive power, a second lens having a negative refractive power, a third lens having a meniscus shape with a concave surface thereof directed toward the object side, and a negative refractive power, a fourth lens having a meniscus shape with a concave surface thereof directed toward the object side, and a positive refractive power, and a fifth lens having a negative refractive power. The third lens and the fourth lens are cemented, and the negative refractive power at a central portion of the third lens increases gradually toward a peripheral portion thereof, and the positive refractive power at a central portion of the fourth lens decreases gradually toward a peripheral portion thereof.

Abstract: The imaging optical system of the invention is built up of, in order from its object side, the first lens group G1 having positive refracting power, the stop S, the second lens group G2 having positive refracting power, and the third lens group G3 having negative refracting power. The first lens group G1 comprises a cemented lens consisting of the first lens L1 and the second lens L2. The second lens group G2 comprises the third lens L3. The third lens group G3 comprises the fourth lens L4. The second lens L3 has an object-side surface that is concave on its object side both on and off the optical axis, and an image-side surface being an aspheric surface that is convex on its object side on the optical axis and has one or more off-axis inflection points.

Abstract: An imaging optical system smaller than conventional systems yet with well-corrected aberrations, comprises five lenses L1-L5 having refractive powers, in order from the object side: positive, negative, positive, positive, and, with an aperture at an endmost object-side position. In one embodiment, L1 is biconvex, L2's object-side surface is convex, L5's object-side surface is convex, and 1.0<f3/f1<4.9, f1 and f3 being the focal lengths of L1 and L3, respectively. In a variant thereof, L2 is a meniscus lens and L5's object-side surface is concave. In another embodiment, L1 is glass, and ?4.0<(r6+r7)/(r6?r7)<?0.51, r6 and r7 being paraxial curvature radii of L3's object- and image-side surfaces, respectively. In another embodiment, L1 is glass, and 1.5<f2/f<0.73, f2 being the focal length of L2 and f the focal length of the whole optical system. In yet another embodiment, L1 is glass, and 11.2<r3/f1<0.9, r3 being the paraxial curvature radius of L1's image-side surface.

Abstract: An optical system comprises, in order from the object side, a first lens having a biconvex shape and having a positive refractive power, a second lens having a meniscus shape with a concave surface facing the object side and having a negative refractive power, a third lens having a negative refractive power, a fourth lens having a meniscus shape with a concave surface facing the object side and having a positive refractive power, and a fifth lens having a negative refractive power. The first lens and the second lens are cemented together.

Abstract: A zoom lens system according to the present invention includes a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with positive refractive power, and a fourth lens group with negative refractive power which are arranged in turn from the object side toward the image side, and the zoom lens system is formed so that, in performing a zooming operation from the wide angle end position to the telephoto end position, the first lens group keeps still, the distance between the first and second lens groups becomes small, the distance between the second and third lens groups becomes wide, and the distance between the third and fourth lens groups to becomes small.

Abstract: An image pickup optical system having five lenses includes in order from an object side, a first lens having a biconvex shape, and a positive refractive power, a second lens having a negative refractive power, a third lens having a meniscus shape with a concave surface thereof directed toward the object side, and a negative refractive power, a fourth lens having a meniscus shape with a concave surface thereof directed toward the object side, and a positive refractive power, and a fifth lens having a negative refractive power. The third lens and the fourth lens are cemented, and the negative refractive power at a central portion of the third lens increases gradually toward a peripheral portion thereof, and the positive refractive power at a central portion of the fourth lens decreases gradually toward a peripheral portion thereof.

Abstract: The imaging optical system of the invention is built up of, in order from its object side, the first lens group G1 having positive refracting power, the stop S, the second lens group G2 having positive refracting power, and the third lens group G3 having negative refracting power. The first lens group G1 comprises a cemented lens consisting of the first lens L1 and the second lens L2. The second lens group G2 comprises the third lens L3. The third lens group G3 comprises the fourth lens L4. The second lens L3 has an object-side surface that is concave on its object side both on and off the optical axis, and an image-side surface being an aspheric surface that is convex on its object side on the optical axis and has one or more off-axis inflection points.

Abstract: A switch station including an ATM switch; a memory storing control data for operations of the switch station; an intra-station device, accommodating a subscriber line, performing communication operation on subscriber ATM cell; a control processor generating control information in link access protocol (LAP) format; and an interface unit converting LAP control information into ATM cell to the intra-station device through the ATM switch, wherein the control information is communicated according to LAP, the intra-station device receives the control information and transmits a direct memory access request to obtain control data stored in the memory, the interface unit obtains and converts the data format of the control data into ATM cell to transmit to the intra-station device through the switch, and the intra-station device performs the communication operation on the subscriber ATM cell based on the control data received through the switch.