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.