14 September 1994 New method for the determination of the G factor for a spectrophotofluorometer
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Abstract
In modem spectrophotofluorometers diffraction gratings are used to select the excitation and emission wavelengths of fluorescent solutions, respectively. Diffraction gratings, however, are polarization sensitive. In a spectrophotofluorometer the polarization contribution ofthe emission diffraction grating (known as the grating or G factor) must be known. In this paper an analysis of the measurement of the G factor is made using the formalism of the Stokes polarization parameters and the Mueller matrix calculus. The analysis shows that the current method for determining the spectral polarization behavior of the emission diffraction grating (the G factor) assumes the optical source in the cuvette chamber, e.g., a tungsten lamp or a fluorescent solution is unpolarized. In practice, these sources are usually partially polarized. Consequently, for this and other reasons we have developed a new method for obtaining G using a right angle prism placed in the cuvette chamber of the spectrophotofluorometer. The right angle prism has the unique property that it behaves as a perfect retarder and when incident polarized light is reflected from the diagonal surface of the prism the Stokes parameter s is zero. By setting the incident polarizer to +45and then setting the analyzer to the horizontal and vertical directions, respectively, the correct G factor can be determined. In the final part of the paper we describe the
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Edward Collett, Enrique Homar, "New method for the determination of the G factor for a spectrophotofluorometer", Proc. SPIE 2265, Polarization Analysis and Measurement II, (14 September 1994); doi: 10.1117/12.186654; https://doi.org/10.1117/12.186654
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