Patent ID: 7330272

Claim:
An interferometer assembly, comprising: a polarizing beam splitter sub-assembly comprising at least a first external face a having at least one polarizing beam splitter interface located therewithin; a first discrete quarter wave plate comprising a suitable birefringent material and having a first front surface and a first rear surface, the first front surface and first rear surface being substantially parallel to one another, a highly reflective first coating being disposed on the first rear surface, and first interface surface being defined by the intersection of the first rear surface with the first coating, and a second discrete quarter wave plate comprising suitable birefringent material and having a second front surface and a second rear surface, the second front surface and the second rear surface being substantially parallel to one another, a highly reflective second coating being disposed on the second rear surface, a second interface surface being defined by the intersection of the second rear surface with the second coating; wherein an angular difference between a first imaginary pointing vector positioned normal to the first interface surface and a second imaginary pointing vector positioned normal to the second interface surface is less than or equal to about seven micro-radians, and wherein a light beam reflected from said polarizing beam splitter sub-assembly is reflected by both said first and second interface surfaces prior to exiting said polarizing beam splitter sub-assembly.