Radiation losses of optical nanofibers are investigated in assumption of Gaussian statistics of distorted glass/air interface. Nonlinear relationship between the radiated power and roughness power spectrum is established. The losses in the single mode silica nanofibers are estimated for the case of inverse-square law of the roughness power spectrum.
A new adaptive method of wavefront sensing is proposed and demonstrated. The method is based on the Talbot self-imaging effect, which is observed in an illuminating light beam with strong second-order aberration. Compensation of defocus and astigmatism is achieved with an appropriate choice of size of the rectangular unit cell of the diffraction grating, which is performed iteratively. A liquid-crystal spatial light modulator is used for this purpose. Self-imaging of rectangular grating in the astigmatic light beam is demonstrated experimentally. High-order aberrations are detected with respect to the compensated second-order aberration. The comparative results of wavefront sensing with a Shack-Hartmann sensor and the proposed sensor are adduced.
The paper presents improved version of our new method for compression of correlated image sets Optimal Image Coding using Karhunen-Loeve transform(OICKL). It is known that Karhunen-Loeve(KL) transform is most optimal representation for such a purpose. The approach is based on fact that every KL basis function gives maximum possible average contribution in every image and this contribution decreases most quickly among all possible bases. So, we lossy compress every KL basis function by Embedded Zerotree Wavelet(EZW) coding with essentially different loss that depends on the ftmctions' contribution in the images. The paper presents new fast low memory consuming algorithm of KL basis construction for compression of correlated image ensembles that enable our OICKL system to work on common hardware. We also present procedure for determining ofoptimal losses ofKL basic functions caused by compression. It uses modified EZW coder which produce whole PSNR(bitrate) curve during the only compression pass.
One ofthe major limitations of intensity interferometry both in space and time domain is that only the linearly filtered signals could be registered in photon-counting mode. However, this restriction can be removed by a prior processing ofthe registered signal in a simple way before image formation from the field correlation function. This is a typical example of ill-posed inverse problems for non-symmetric transforms. We investigate the implementation of eigenfunction method to the problem of correlation function restoration from the photocount data. The effectiveness of the restoration procedure for the typical examples of astronomic images is investigated by computer simulation, both for symmetric and non-symmetric objects with phase restoration by the application of incoherent reference source.
A holographic wavefront sensor based on the Talbot effect is proposed. Optical wavefronts are measured by sampling the light amplitude distribution with a two-dimensional (2D) precorrected holographic grating. The factors that allow changing an angular measurement range and a spatial resolution of the sensor are discussed. A comparative analysis with the Shack-Hartmann sensor is illustrated with some experimental results.
An analytical method to recover the two-dimensional probability density function (PDF) of a random light field from the PDF of photon counts is presented. Some illustrations of the inversion procedure are given with application to the problem of light intensity interferometry.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.