摘要:

The mutual interference of two beams of a low-coherence source has been demonstrated experimentally in the frequency domain at the output of a Michelson interferometer when the optical path difference (OPD) between both beams exceeds the coherence length of the source. The spectral interference between both beams, which shows up a periodic modulation of the source spectrum with the period dependent on the OPD, serves as an illustration of a technique for measuring both OPDs and displacements in a range dependent on the source spectrum width. Using a high-resolution spectrometer, good agreement between theoretical description of two-beam spectral interference experiment and the measured spectral modulation has been confirmed and the effect of both the spatial and the spectral integration has been resolved.

ISSN:0950-0340    

DOI:10.1080/09500349708232906

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We report a new phenomenon in showing that the rotation sensitivity of Lau fringes depends not only on spatial coherence of the illumination used but also on its convergence or divergence. This finding could be usefully applied to beam collimation and focal length measurement.

ISSN:0950-0340    

DOI:10.1080/09500349708232907

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The free electron model proposed by Rustagi and Ducuing to explain the enhancement of the second-order hyperpolarizabilities of π-con-jugated linear molecules with increasing conjugation length has been extended to two and three dimensions. The sign and magnitude for the linear (α) and third order (γ) polarizabilities as a function of the size and electron density of the systems have been obtained. Some simple general conclusions on the role of dimensionality in the nonlinear response have been obtained.

ISSN:0950-0340    

DOI:10.1080/09500349708232908

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A new type of 1 × 9 multiple-beam splitter making use of two surface relief holographic gratings in stack is reported. The grating periods differ by a factor of three and the zero and ±1 diffraction orders generated by either grating on normal or slightly oblique incidence of a plane wave have nearly identical diffraction efficiencies. The fundamental feature of the design is the quoted ratio between grating periods rather than the specific choice of the profile shape. Splitters which generate nine beams (diffraction orders) bearing about 90% of the total output power with less than 4% non-uniformity in their diffraction efficiencies were achieved. Possible extension to 9 × 9 multiple-beam splitting using a tandem of crossed grating is addressed, too.

ISSN:0950-0340    

DOI:10.1080/09500349708232909

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A technique used to examine the performance of reference lens of interferometer is described. The defects in the reference lens that are primarily due to the manufacturing errors or the assembly errors or both will result in the common focus error of reference lens at the centre of curvature of reference surface, which affects the measurement accuracy. The optical path difference between the reference wave front and the test wave front at the exit pupil is applied to analyse the influence of common focus error of reference lens on the measurement errors. A comparison of the experimental result with the numerical analysis is made.

ISSN:0950-0340    

DOI:10.1080/09500349708232910

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We studied both experimentally and theoretically the transmission and polarization characteristics of a Cr4+: YAG saturable absorber crystal as a function of the intensity and polarization state of an incident laser beam. We found that a birefringent absorption behaviour is induced and we show that the experimental results are well described by a full numerical model which includes excited-state absorption as well as a ground-state cross-absorption term. By using pump-probe measurements we show that a finite cross-saturation of the absorption is achieved along the crystal axes orthogonal to the polarization of the optical radiation. No induced refractive index birefringence is observed.

ISSN:0950-0340    

DOI:10.1080/09500349708232911

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor