Abstract: A polarization illumination device and projector having the polarization illumination device are provided. An example of the polarization illumination device comprises an illuminator and a polarized including a polarization splitting surface and a reflecting surface, the splitting surface and the reflecting surface form an inverted V shape. The splitting surface splits part of the light into a transmitted component and a reflected component and directs the former in a first direction and the latter toward the reflecting surface. The reflecting surface reflects a remaining part of the light and directs it toward the splitting surface. The splitting surface splits the remaining part of the light into a transmitted component and a reflected component. The former directed toward a second direction different from the first direction, and the latter is returned to the illuminator.

Abstract: A polarization conversion unit is disclosed. In the unit, a definitely polarized light emitted from a light source is divided into a pair of lights differing in polarized state and are caused to be incident on the optical components including the polarizing beam splitter. The plane of polarization of one of the paired polarized light is rotated to be coincident with the plane of polarization of the other light by the optical components, so that the paired lights with the same plane of polarization are caused to be separately emitted. The optical component has a plano-convex lens which has a positive power and which is arranged at an exit side where the paired lights are separately emitted. The lens has a focal point at a position further than the position of the surface to be illuminated.

Abstract: A silica glass powder suitable for the production of a silica glass body product of a low silanol content, which is obtained by baking a dried silica gel powder obtained by a sol-gel method, at a temperature of from 1,000.degree. to 1,400.degree. C., wherein during the baking period, the silica gel powder is baked in a gas atmosphere containing from 10 to 100% by volume of steam for at least 5 hours.

Abstract: A prilled ammonium nitrate containing 2 to 5 percent by weight water obtained by prilling an aqueous solution of 93 to 98 percent by weight ammonium nitrate is dried by: lowering the drying temperature of the ammonium nitrate to a temperature less than the III--IV crystalline transition temperature of ammonium nitrate at least once when the water content of the prilled ammonium nitrate is 0.3 to 1.5 percent by weight in the drying step; further drying at a temperature higher than the III--IV transition temperature; and adding an anti-caking agent to the dried prilled ammonium nitrate. The dried, prilled ammonium nitrate obtained is useful as an ammonium nitrate fuel oil explosive.