Patent ID: 7907280

Claim:
A method of constructing a multiple element retarder system for introducing a relative phase retardation between orthogonal components of a polarized beam of electromagnetic radiation entered thereinto, said multiple element retarder system comprising at least two similar elements which are sequentially secured with respect to one another such that a beam of electromagnetic radiation entered to the first thereof undergoes internal reflection at least once in each of the at least two elements, and exits the second thereof along a locus which is not angularly deviated or laterally offset from that of said entered beam by more than acceptable amounts; said method comprising the steps of: practicing steps a and b in either order, said steps a and b being: a) providing a multiplicity of similar elements; b) defining acceptable beam angular deviation and lateral offset values; said method further comprising: c) from said multiplicity of similar elements selecting two thereof and securing them in a sequential system, then experimentally monitoring angular deviation entered to a beam of electromagnetic radiation entered to a first thereof, so that it undergoes internal reflection at least once in each of the at least two elements, and then exits the second thereof; d) determining if the beam angular deviation experimentally monitored in step c is acceptable under the criteria defined in step b, and performing a selection from the group consisting of: accepting the said sequential system if said defined angular deviation criteria is met and proceeding to step e; and rejecting said sequential system and repeating step c if said defined angular deviation criteria is not met; e) if practice of step d results in accepting said sequential system, proceeding to determine if a lateral offset exists between the beam entered to the first element and that exiting the second element, and if so performing at least one selection from the group consisting of: changing the relative orientation of said selected elements with respect to one another; and rotating said system of the two selected elements as said unit about an axis not parallel to the electromagnetic beam; until said lateral offset entered to said beam of electromagnetic radiation is determined to be acceptable under the criteria defined in step b; f) optionally experimentally re-checking if the angular deviation entered to said beam of electromagnetic radiation is still acceptable after practice of step e; and accepting said sequential system only if both the angular deviation and lateral offset entered to said beam of electromagnetic radiation are then acceptable under the criteria of step b.