Modified Forms for Glan–Thompson and Rochon Prisms*†

Many of the commonly used types of polarizers and polarizing beam splitters consist of two appropriately oriented birefringent crystals (of the same material) which are cemented together. This paper describes modified forms of Glan–Thompson and Rochon prisms in which one of the two calcite (or quartz) halves is replaced by an isotropic material such as glass. In addition to a saving of calcite, these devices have other advantages which add to their usefulness. Two types of modified Glan–Thompson prisms and two types of modified Rochon prisms are described. The modified Glan–Thompson prisms behave as Glan–Thompson prisms for light entering one end, and as Rochon prisms for light entering the other end. The modified Rochon prisms, on the other hand, behave like Rochon prisms regardless of which end light enters. Several commercially available glasses are listed which can be used with calcite or quartz in these devices.