Thesis (doctoral)--Rijksuniversiteit te Utrecht, 1946. / Includes bibliographical references.

A sensitive, wide or narrow band, solid state spectrometer operating at a wavelength of 0.85 cm has been built which is described in detail. The spectrometer is of the crystal detector reflection-cavity-in-magic-Tee-bridge type and can operate from room down to liquid helium temperatures. The cavity Is excited In the TE₁₁₁ mode and the magnetic field modulated at 140 cps. Both large and small field modulations are incorporated for scope presentation of line width varying from about 0.5 to 500 gauss. Signals from single crystals of copper sulphate pentahydrate and polycrystalline 1-1-diphenyl-2-picryl hydrazyl (DPPH) have been obtained. From the latter, a sensitivity limit of about 10⁻⁸ gram is obtained at room temperature for a bandwidth of 1 cps indicating a sensitivity of the order of 10⁻¹¹ gram at 4.2° K. Various methods of improvement were discussed in order to reach the ultimate sensitivity. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

No description available.

Thesis (Ph. D.)--University of Iowa, 1923. / Reprinted from the Journal of the Optical society of America and review of scientific instruments, v. 10, no. 6, June, 1925.

No description available.

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Neste trabalho apresentamos resultados experimentais e teóricos do ruído de intensidade e de fase, e das correspondentes correlações, entre os campos de bombeio e sonda na transparência induzida eletromagneticamente. Experimentalmente, nessa condição, medimos excesso de ruído de intensidade em ambos feixes e correlação e anti-correlação de ruído de intensidade, mostrando claramente que elas dependem tanto da intensidade dos feixes, quanto da frequência de análise em que as medidas são realizadas. Utilizando uma varredura local do feixe sonda, observamos estruturas no espectro de ruído dos campos na transparência induzida e, a partir do ruído da soma e da diferença das intensidades dos feixes, vimos que nessa região há zonas com correlação e anti-correlação de intensidade, intercaladas. Estas estruturas dependem, novamente, da intensidade dos feixes e da frequência de análise. Ainda no campo experimental, com relação ao ruído de fase, medimos excesso de ruído nos nossos feixes e, pela primeira vez, medimos uma correlação desse ruído entre os feixes na condição de transparência induzida. Teoricamente, aprofundamos análises realizadas com um modelo em que átomos e campos são tratados quanticamente e, dadas as limitações constatadas, desenvolvemos um novo modelo semi-clássico. As novas previsões obtidas com esse modelo, em que os campos possuem fases difusivas, mostram um bom acordo qualitativo com os resultados experimentais. O excesso de ruído de intensidade dos feixes, observado na transparência induzida, se deve ao excesso de ruído de fase dos lasers, que é transferido ressonantemente pelos átomos para o ruído de intensidade. / In this work we present experimental and theoretical results of intensity and phase noise, and of the correspondent correlations, between pump and probe fields in electromagnetically induced transparency. Experimentally, in this condition, we measure intensity excess-noise in both beams as well as intensity correlations and anti-correlations, clearly showing that both are dependent on the fields intensities and on the analysis frequency. We also observed structures in the noise spectra of the fields in the induced transparency and that, in a single spectrum, there are zones with correlation and anti-correlation of intensity, interchanged. These structures are dependent, again, on the fields intensities and on the analysis frequency. We also measured excess phase noise in our beams and, for the first time, we measured a phase noise correlation between the beams in the condition of induced transparency. Theoretically, we further developed an analysis with a model in which the atoms and the fields are treated quantum-mechanically. Owing to limitations detected in the application of this model to our experimental situation, we developed a new semi-classical model, in which the fields present phase diffusion. The new predictions obtained show a good qualitative agreement with the experimental result features. The excess noise of intensity of the beams, in the electromagnetically induced transparency, is a result of the resonant transfer of the diode lasers excess phase noise into intensity noise by interaction with the atoms.

Neste trabalho apresentamos resultados experimentais e teóricos do ruído de intensidade e de fase, e das correspondentes correlações, entre os campos de bombeio e sonda na transparência induzida eletromagneticamente. Experimentalmente, nessa condição, medimos excesso de ruído de intensidade em ambos feixes e correlação e anti-correlação de ruído de intensidade, mostrando claramente que elas dependem tanto da intensidade dos feixes, quanto da frequência de análise em que as medidas são realizadas. Utilizando uma varredura local do feixe sonda, observamos estruturas no espectro de ruído dos campos na transparência induzida e, a partir do ruído da soma e da diferença das intensidades dos feixes, vimos que nessa região há zonas com correlação e anti-correlação de intensidade, intercaladas. Estas estruturas dependem, novamente, da intensidade dos feixes e da frequência de análise. Ainda no campo experimental, com relação ao ruído de fase, medimos excesso de ruído nos nossos feixes e, pela primeira vez, medimos uma correlação desse ruído entre os feixes na condição de transparência induzida. Teoricamente, aprofundamos análises realizadas com um modelo em que átomos e campos são tratados quanticamente e, dadas as limitações constatadas, desenvolvemos um novo modelo semi-clássico. As novas previsões obtidas com esse modelo, em que os campos possuem fases difusivas, mostram um bom acordo qualitativo com os resultados experimentais. O excesso de ruído de intensidade dos feixes, observado na transparência induzida, se deve ao excesso de ruído de fase dos lasers, que é transferido ressonantemente pelos átomos para o ruído de intensidade. / In this work we present experimental and theoretical results of intensity and phase noise, and of the correspondent correlations, between pump and probe fields in electromagnetically induced transparency. Experimentally, in this condition, we measure intensity excess-noise in both beams as well as intensity correlations and anti-correlations, clearly showing that both are dependent on the fields intensities and on the analysis frequency. We also observed structures in the noise spectra of the fields in the induced transparency and that, in a single spectrum, there are zones with correlation and anti-correlation of intensity, interchanged. These structures are dependent, again, on the fields intensities and on the analysis frequency. We also measured excess phase noise in our beams and, for the first time, we measured a phase noise correlation between the beams in the condition of induced transparency. Theoretically, we further developed an analysis with a model in which the atoms and the fields are treated quantum-mechanically. Owing to limitations detected in the application of this model to our experimental situation, we developed a new semi-classical model, in which the fields present phase diffusion. The new predictions obtained show a good qualitative agreement with the experimental result features. The excess noise of intensity of the beams, in the electromagnetically induced transparency, is a result of the resonant transfer of the diode lasers excess phase noise into intensity noise by interaction with the atoms.

The major objective of this study was to analytically determine the effects of small transverse solar tracking errors on the concentrated intensity profile generated by a 22-inch wide, f-number one, linear Fresnel model lens. Transverse tracking error is caused by the misalignment of the lens optic axis and the center of the sun in a direction perpendicular to the lens optic axis. The analytical method consisted of extending an earlier theoretical model developed by Cosby3 in which the solar disk was perfectly tracked; thus the tracking error problem is treated as a perturbation of the basic theory. Data was obtained using extensive computer calculations.Results indicated that in the presence of transverse tracking error, lens serrations (upper half serrations) on the same side of the lens optic axis as the sun differ significantly from the lens serrations (lower half serrations) on the opposite side of the lens optic axis in their concentration characteristics. Incident angles of sunlight are greater for upper half serrations causing greater angles of refraction at the second surface. The peak concentration ratio values are observed to shift in the negative intercept direction in a linear relationship with tracking error angle. It was observed that the 90% target width monotonically increased, e.g., by 100% and 700% for transverse tracking errors of 1/2° and 2-1/2°, respectively. It is concluded that the dominant cause for the 90% target width increase is the intensity profile shift itself. Some lesser influence results from increasing intensity profile skewness and profile broadening for IR wavelengths caused by greater IR refraction with increased transverse tracking error.Ball State UniversityMuncie, IN 47306