Patent ID: 7525712

Claim:
A switchable apochromatic polarization rotator, comprising: a first fixed waveplate having a first principal axis fixed in a first orientation; a second fixed waveplate having a second principal axis fixed in a second orientation, the first and second fixed waveplates being substantially similar; and first and second substantially similar switchable waveplates having principal axes oriented such that electromagnetic radiation transmitted through all of the waveplates has a first rotated polarization, wherein, in response to one or more applied control signals, the principal axes of the switchable waveplates rotate such that the electromagnetic radiation transmitted though all of the waveplates has a second rotated polarization; wherein the first and second orientation being approximately in a range of 3.75 to 82.5 degrees, and further wherein the principal axes of the first and second switchable waveplates being approximately in a range of 7.5 to 82.5 degrees, and being switchable to approximately a range of −60.5 to 97.5 degrees, based upon the control signals applied to the switchable waveplates; and wherein the sequencing of the waveplates is arranged as FSSF, where S represents the first and second switchable waveplates and F represents the first and second fixed waveplates, and the principal axes of these waveplates are approximately configured with control signal 1 as F(7.5°), S(29.5°), S(60.5°), F(82.5°) and control signal 2 as F(7.5°), S(97.5°), S(−7.5°), F(82.5°).