Showing papers on "Waveplate published in 1973"

A new ellipsometer its principle, realization and performances

Abstract: In the new ellipsometer which is described in this paper, no quarter wave plate nor compensator are used. The elliptically polarized light under study goes through a Faraday rotator powered by a sinusoidal current of pulsation ω. After this, the ellipse pendulates with the same pulsation. When the principal section of the analyser is perpendicular or parallel to the mean orientation of the axis of the ellipse, the fondamental frequency vanishes in thespectrum of the signal delivered by the radiation detector (photo-multiplier). A critical study is made of the two possible methods of measurement which can be used with the instrument. The conclusion of the study is the choice of a method which, while universally applicable with also give a fair precision in the difficult case when the reflectivity of the surface under study gets very close to unity. Since the accuracy of measurement depends also on the localization in space of the zero plane for angle-measurements, a method is exposed for localization of this zero plane, permitting high precision while remaining easy to use. The paper ends with examples of results obtained in the study of alkali metals: Cesium and Potassium.

Laser angular rate sensor biasing apparatus

Abstract: Electro-optical apparatus for preventing lock-in in a laser angular rate sensor. A Faraday material is placed between two wave plates, the birefringence of each wave plate varying in response to applied electric fields. The two wave plates may be positioned so that the principal axes of their index ellipses are substantially orthogonal to one another. A cyclic voltage of high frequency is applied to each wave plate to rapidly and cyclically vary its birefringence. This achieves biasing apparatus having a longer effective optical path length first in one direction and then in the opposite direction.

Apparatus for laser frequency selection

Abstract: A laser system having a lasing medium positioned between a pair of mirrors defining a resonant cavity. An etalon is positioned within the cavity with its mirrors perpendicular to the axis of the resonant cavity and use is made of the frequency selectivity of the transmission characteristics of the etalon. The output of the laser is linearly polarized and a quarter wave plate is positioned on each side of the etalon within the cavity. The reflected light from the etalon having passed through the one quarter wave plate twice is linearly polarized in a 90* direction to the transmission of the linear polarizer. The light transmitted by the etalon passes through two quarter wave plates twice and is polarized with the proper polarization for transmission through the linear polarizer. A piezoelectric transducer is used to vary the spacing of the etalon mirrors to make the laser frequency selective.

Average form of polarization of partially polarized gaussian light

Abstract: The ratio between the components of the complex amplitudes of a plane, completely polarized, electromagnetic wave describes the state of polarization For partially polarized gaussian light, the average value of this ratio is found to be simply related to the elements of the coherency matrix This average is related to the degree of polarization and the cross-correlation function Its propagation through linear optical systems is discussed

Small-angle scattering of circularly polarized light from an anisotropic sphere

Abstract: A theory of the small-angle scattering of circularly polarized light from an anisotropic sphere has been derived. The validity of the theory has been verified, and a relationship between the structural information thus obtained and the structural information obtained with linearly polarized light has been demonstrated.

Conception, realisation et fonctionnement d'un nouvel ellipsometre

Abstract: SUMMARY A new ellipsometer its principle, realization and performances In the new ellipsometer which is described in this paper, no quarter wave plate nor compensator are used. The elliptically polarized light under study goes through a Faraday rotator powered by a sinusoidal current of pulsation w. Afrer this, the ellipse pendulates with the same pulsation. When the principal section of the analyser is perpendicular or parallel to the mean orientation of the axis of the ellipse, the fondamental frequency vanishes in thespectrum of the signal delivered by the radiation detector (photomultiplier). A critical study is made of the two possible methods of measurement which can be used with the instrument. lle conclusion of the study is the choice of a method which, while universally applicable with also give a fair precision in the difficult case when the reflectivity of the surface under study gets very close to unity. Since the accuracy of measurement depends also on the localization in space of the zero plane for angle-measurements, a method is exposed for localization of this zero plane, permitting high precision while remaining easy to use. The paper ends with examples of results obtained in the study of alkali metals : Cesium and Potassium.