Double Fresnel rhomb

Figure 9.4 (a) Fresnel rhomb for quarter-wave retardation, (b) Double Fresnel rhomb... 

Thus, the polarization of both the incident and scattered light must be controlled. A typical argon laser produces linearly polarized light. The incident polarization can be adjusted to be either vertical or horizontal with respect to the scattering plane with a double Fresnel rhomb polarization rotator. The scattered light can be analyzed with a Glan-Thomp-son prism polarizer. 

Optical retarder plates, of appropriate thicknesses, made of birefrin-gent material, normally crystalline quartz or mica, can be used to rotate the plane of polarization for linearly polarized light or to produce circularly polarized light. To rotate linearly polarized light by an arbitrary angle, a double Fresnel rhomb is very useful (Fig.6.46). 

The experimental apparatus is depicted in Fig. 3 and is described in detail elsewhere [14]. It consists of a molecular beam scattering chamber, pulsed frequency-doubled dye laser, double fresnel rhomb polarization rotator, fibre bundles to coUect fluorescence from excited states, and time-gated photon counting and boxcar averaging equipment. 

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