High-order achromatic quarterwave combination plates and tuners.
Achromatic quarterwave combination plates are formed from two high-order birefringent plates having even and odd multiples of quarterwave retardation at some nominal wavelength. Eleventh- and twelfth-order plates at 1315 nm combined with their axes 77 degrees apart are shown to have 90 +/- 0.25 degrees of retardation between 1275 and 1355 nm. They can be used to construct two- and four-waveplate tuners for birefringent filters.
Achromatic devices in polarization optics
Retarders or waveplates are tools for polarization modification in bulk optical systems. These devices usually have a strong wavelength dependence in their performance, making them suitable for use over a wavelength band on the order of a few percent of the center wavelength for which they are made. Display and tunable laser applications are examples that can require consistent polarization modification over a much broader wavelength range. We discuss new methods and designs for dramatically increasing range of performance and review older methods as well. We show examples of achievable performance using modern polymer and liquid crystal materials.
Philip Roth’s Great Books: A Reading of The Human Stain
Philip Roth belongs to the first generation of American novelists for whom a university education in the liberal arts was the norm. This essay charts Roth’s developing acquaintance with classical literature, the starting point for Great Books courses in the 1950s, and the implications for his fiction of his understanding of the difference in scope and purpose between the two representative classical genres. It focuses on The Human Stain (2000), the novel in which he reflects most directly upon what tragedy and epic once did, and what might happen to novels if they became more like the one or the other.