Quarter wavelength plate

A larger frequency shift is possible if the laser is placed in longitudinal or transverse magnetic fields which cause a Zeeman splitting of the upper and lower laser level. With polarizers and quarter wavelength plates one can select the shifted a+ or a- component... 

Some attention has to be given to the degree of circular polarization y and thus to the creation of cpl. Two experimental principles are common the use of a quarter wavelength plate and the use of a Fresnel rhomb or a Solcil-Babinet compensator in a few experiments, radiation from a cyclotron after passage through a polarizing undulator was used. The degree of circular polarization is easily jeopardized when a X/4 plate is employed, as this is an interference device... 

The basic optical components of an ellipsometer are a source (L), a polarizer (P), an analyser (A) and a detector (D). Some additional components, like compensators (C, e. g. quarter-wavelength plate) and modulators (M, e. g. photoelastic modulator) are added in some configurations. Typical configurations are PCSA or PSCA, where S is the sample. 

Half wave plates are used to rotate the principal axis of the polarization ellipse (see section 2.4.2). Half wave plates for applications involving single wavelengths can be fabricated in precisely the same manner as quarter wave plates, but with thicknesses that are twice those specified by equation (9.1). 

Figure 3. The sequence of optical hardware needed to view a specimen between crossed circular polars. A quarter wave plate typically introduces a path difference in the range 0.15pm to 0.16pm (approximately 1/4 of the wavelength of Nao light) between the slow and fast rays. The use of crossed circular polars to identify regions of zero birefringence unambiguously is most sensitive if the illumination has a wavelength of exactly four times the path difference introduced by the quarter wave plates.

Figure 13. Producing circularly polarized light by means of a quarter wavelength retarder. A, Two beams, plane polarized at right angles, traverse a birefringent plate. B, On emerging the two beams are 90° (one quarter of a wavelength) out of phase. C, Shows the two beams recombined. The result is perfectly circularly polarized light. See text for discussion. Reproduced, with permission, from [4].

Figure 9.25 Wavelength dependence of orientation birefringence for (open circles) CTA, (closed circles) CTA/TCP (95/5) and (closed diamonds) CTA/TCP (90/10), stretched at a draw ratio of 1.5. In the figure, the straight dotted line represents the ideal wavelength dispersion for a multi-band quarter-wave plate with a thickness of 400 pm. Reproduced with permission from M. E. A. Manaf, M. Tsuji, Y. Shiro3 ma, and M. Yamaguchi, Macromolecules, 2011, 44, 10, 3942. 2011, ACS Publications [36].

A reflection system consists of a linear polarizer on the top, a quarter-wave plate in the middle, and a mirror at the bottom. Calculate the reflection spectrum of the system in the wavelength region from 400 nm to 700 nm. (a) The quarter-wave plate is a regular quarter-wave plate with its principal axis at 45° with respect to the transmission axis of the polarizer, (b) The quarter-wave plate is the broadband quarter-wave plate as shown in Figure 3.8(b). 

T. Ishinabe, T. Miyashita, T. Uchida, and Y. Fujimura, A wide viewing angle polarizer and a quarter-wave plate with a wide wavelength range for extremely high quality LCDs, Proc. 2P Int l Display Research Conference (Asia Display/IDW Ol), 485 (2001). 

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