Abstract: A variable optical attenuator comprising a separation/combination birefringent element, fixed polarization rotation means, a convex lens, variable polarization rotation means, and a mirror which are arranged in that order. The fixed polarization rotation means has a compensation film Faraday element placed in a cylindrical permanent magnet, and the variable polarization rotation means has a base film Faraday element that is placed outside the cylindrical permanent magnet, and an electromagnet applying a variable magnetic field thereto. Thereby, both the Faraday elements are magnetized in directions different from each other.

Abstract: An optical attenuator with increased dynamic range and reduced temperature-dependence over the dynamic range. The optical attenuator has a Faraday rotational angle variable device which applies an external magnetic field to light polarized by a garnet crystal, and a polarizer and an analyzer disposed at the front and rear of the optical axis of the device. There is an angle x formed between the plane of polarization of the light incident to the garnet crystal and the magnetic field orthogonal to the optical axis, where an angle y is formed between the polarizer and the analyzer, and the angle x is set to satisfy {(?z/2)+90×n}?12<x<{(?z/2)+90×n}+12 (n=0, 1, 2 or 3), where z=y±90; z is the angle of rotation of the plane of polarization caused by the Faraday rotational angle variable device.

Abstract: A variable optical attenuator comprising a separation/combination birefringent element, fixed polarization rotation means, a convex lens, variable polarization rotation means, and a mirror which are arranged in that order. The fixed polarization rotation means has a compensation film Faraday element placed in a cylindrical permanent magnet, and the variable polarization rotation means has a base film Faraday element that is placed outside the cylindrical permanent magnet, and an electromagnet applying a variable magnetic field thereto. Thereby, both the Faraday elements are magnetized in directions different from each other.

Abstract: An electric double layer capacitor has a pair of current collectors, a positive polarizable electrode which is provided on one of the pair of current collectors, includes activated carbon of a weight W+ and has a capacitance C+, a negative polarizable electrode which is provided on the other of the pair of current collectors, includes activated carbon of a weight W? and has a capacitance C?, a separator interposed between the positive and negative polarizable electrodes, and an organic electrolytic solution which impregnates at least the positive and negative polarizable electrodes and the separator, wherein C?/C+=0.6 to 1.0 and W?/W+=1.1 to 2.0. Even when continuously charged at a high applied voltage, the electric double layer capacitor has a high retention of capacitance and a low rise in internal resistance, and thus has an excellent durability.

Abstract: An active material powder mixture for batteries or a carbonaceous material powder mixture for electrical double-layer capacitors is composed of a battery active material or a carbonaceous material in combination with an electrically conductive powder that adheres to the periphery of the active material or carbonaceous material and has an average particle size of 10 nm to 10 ?m. The battery active material powder mixture may be used to make electrodes for secondary batteries. The carbonaceous material powder mixture may be used to make polarizable electrodes for electrical double-layer capacitors. Secondary cells produced using the active material powder mixture can lower an impedance of an electrode and operate at a high capacity and a high current, have a high rate property, and are thus well-suited for use as lithium secondary cells and lithium ion secondary cells.

Abstract: An electric double layer capacitor has a pair of current collectors, a positive polarizable electrode which is provided on one of the pair of current collectors, includes activated carbon of a weight W+ and has a capacitance C+, a negative polarizable electrode which is provided on the other of the pair of current collectors, includes activated carbon of a weight W and has a capacitance C?, a separator interposed between the positive and negative polarizable electrodes, and an organic electrolytic solution which impregnates at least the positive and negative polarizable electrodes and the separator, wherein C?/C+=0.6 to 1.0 and W?/W+=1.1 to 2.0. Even when continuously charged at a high applied voltage, the electric double layer capacitor has a high retention of capacitance and a low rise in internal resistance, and thus has an excellent durability.

Abstract: An active material powder mixture for batteries or a carbonaceous material powder mixture for electrical double-layer capacitors is composed of a battery active material or a carbonaceous material in combination with an electrically conductive powder that adheres to the periphery of the active material or carbonaceous material and has an average particle size of 10 nm to 10 &mgr;pm. The battery active material powder mixture may be used to make electrodes for secondary batteries. The carbonaceous material powder mixture may be used to make polarizable electrodes for electrical double-layer capacitors. Secondary cells produced using the active material powder mixture can lower an impedance of an electrode and operate at a high capacity and a high current, have a high rate property, and are thus well-suited for use as lithium secondary cells and lithium ion secondary cells.