Giant Birefringent Optics in Multilayer Polymer Mirrors

Abstract

Multilayer mirrors that maintain or increase their reflectivity with increasing incidence angle can be constructed using polymers that exhibit large birefringence in their indices of refraction. The most important feature of these multilayer interference stacks is the index difference in the thickness direction (z axis) relative to the in-plane directions of the film. This z-axis refractive index difference provides a variable that determines the existence and value of the Brewster's angle at layer interfaces, and it controls both the interfacial Fresnel reflection coefficient and the phase relations that determine the optics of multilayer stacks. These films can yield optical results that are difficult or impossible to achieve with conventional multilayer optical designs. The materials and processes necessary to fabricate such films are amenable to large-scale manufacturing.

Polarizing optics in a spider eye

“…For obliquely incident light with the plane of incidence in the x-z-plane (Fig. 6b), light polarized along the y−axis corresponds to s-polarization (evector orthogonal to plane of incidence) and the reflection only depends on n y , whereas the reflection of p-polarized light (e-vector parallel to plane of incidence) depends on both n x and n z (Weber et al, 2000). For the orthogonal case, s-polarized light is strongly reflected whereas for p-polarized light reflection is weak.…”

“…Light polarized in the x-z-plane has its electric field parallel to the plane of incidence (Ep) and is called p-polarized light. Adapted from Weber et al (2000). c Schematic drawing of the modeled tapetum used to calculate reflection and polarization.…”

Limits on WIMP dark matter using scintillating CaWO4 cryogenic detectors with active background suppression

“…The prototype detector modules used here [7,9,10] consist of a 300 g cylindrical CaWO 4 crystal with 40 mm diameter and height, and an associated cryogenic light detector. The light detector is mounted close to a flat surface of the CaWO 4 crystal, and both detectors are enclosed in a housing of highly reflective polymeric multilayer foil [11]. An important improvement of the energy resolution of the light channel was achieved by roughening the flat surface of the CaWO 4 facing the light detector to a roughness of about 10 µm.…”

Textured silicon calorimetric light detector

“…The setup (Figure 2), described in detail elsewhere [12,13], consisted of a CaWO 4 scintillating crystal of cylindrical shape (35 mm high with a 40 mm diameter) placed in a concentric 50 mm diameter light collector lined with a polymer reflective foil [14].…”