Abstract: A variable optical filter comprises a first polarizer, a first phase difference element operable to generate a phase difference, a variable Faraday rotator operable to impart a variable Faraday rotation, a second phase difference element operable to generate a phase difference, and a second polarizer, wherein said polarizers, said variable Faraday rotator, and said phase difference elements are arranged in the mentioned order along the optical axis, and wherein when the angles formed by the optic axes of said first and second phase difference elements and the transmitted polarization azimuth of the first polarizer are assumed respectively to be ?1 and ?2, these ?1 and ?2 are set to different angles.

Abstract: A variable optical attenuator is disclosed which comprises a plane-parallel birefringent element for separation/synthesis which separates light beams having orthogonal polarization directions on the same optical path, the birefringent element synthesizing light beams on different optical paths; a light converging lens disposed adjacent to the birefringent element for separation/synthesis; a reflecting mirror disposed at a focal point of the lens opposite to the birefringent element for separation/synthesis with respect to the lens; a variable polarization rotating device; and an input port and an output port which are disposed at the end of the birefringent element for separation/synthesis; the variable polarization rotating device being disposed at any position between the birefringent element for separation/synthesis and the reflecting mirror, the variable polarization rotating device controlling the rotational angle of the polarization direction of incident light beams from the input port, to thereby contr

Abstract: A novel human IFN-&agr; subtype and its derivative having an unprecedentedly high specific activity, DNA encoding these proteins, an expression vector having said DNA, a transformant transformed with said expression vector, a method of producing the above human IFN-&agr; and its derivative, and medical uses of the above human IFN-&agr; and its derivative.

Abstract: A novel human IFN-&agr; subtype and its derivative having an unprecedentedly high specific activity, DNA encoding these proteins, an expression vector having said DNA, a transformant transformed with said expression vector, a method of producing the above human IFN-&agr; and its derivative, and medical uses of the above human IFN-&agr; and its derivative.

Abstract: A variable optical attenuator is disclosed which comprises a plane-parallel birefringent element for separation/synthesis which separates light beams having orthogonal polarization directions on the same optical path, the birefringent element synthesizing light beams on different optical paths; a light converging lens disposed adjacent to the birefringent element for separation/synthesis; a reflecting mirror disposed at a focal point of the lens opposite to the birefringent element for separation/synthesis with respect to the lens; a variable polarization rotating device; and an input port and an output port which are disposed at the end of the birefringent element for separation/synthesis; the variable polarization rotating device being disposed at any position between the birefringent element for separation/synthesis and the reflecting mirror, the variable polarization rotating device controlling the rotational angle of the polarization direction of incident light beams from the input port, to thereby contr

Abstract: An optical circulator comprises a first birefringent element for separation and synthesis; a first polarization rotation block; a circulator function block; a second polarization rotation block; and a second birefringent element for separation and synthesis; the circulator function block includes a first birefringent element for optical path control; a second birefringent element for optical path control which shifts the optical paths depending on the polarization directions and which has twice the optical path shifting amount of the first birefringent element for optical path control; and a ¼ wave plate and a reflector allowing light beams along peripheral optical paths to bypass and acting on only light beams along central optical paths.

Abstract: A hollow magnetic member includes a plurality of separate magnetic pieces. A parting surface between such pieces is defined by a plane parallel to or defining an angle of not more than forty-five (45) degrees with a center axis of the magnetic member. A holder for supporting a polarizer has such a cross section defined by a part of a cylinder cut away along a plane parallel to or defining an angle of not more than forty-five (45) degrees with the center axis thereof. A notched portion is formed in a cutting surface for containing the polarizer. A jig for assembly includes a base for holding the holder and a plate for positioning optical elements such as the polarizer. The holder is disposed in a recess in the base with the notched portion directed upward. A bonding material is applied to the notched portion prior to installation of the polarizer. The plate is placed on the base by inserting pins through holes, and then a screw is engaged with a tapped hole.