In the last 30 days

• Open/close Application of the Richardson-Lucy algorithm to the deconvolution of two-fold probability density functions

  G Ricort et al 1993 Pure Appl. Opt. 2 125 Tag this article

  Article References Full text PDF (1.14 MB)

  The authors use the Richardson-Lucy algorithm to deconvolve a set of images which are grey level representations of slices of two-fold probability density functions (PDF). These PDFs are computed from the one-dimensional signal obtained with the ESO slit-scanning infrared specklograph. In these conditions, it is shown that the PDF of the true signal is blurred by the PDF of the noise. The deconvolution is first performed on simulated data, for two levels of additive noise, i.e. for two different widths of the blurring function. These images are linked to one another, and they check the goodness of the deconvolution procedure by verifying that the properties of the image power spectrum (a quantity that can be derived from the whole set of PDF) are well conserved during the deconvolution. They discuss the quality of the result, which depends on the number of iterations. An application is made to real physical data.

• Open/close Coupling gratings as waveguide functional elements

  Olivier Parriaux et al 1996 Pure Appl. Opt. 5 453 Tag this article

  Article References Full text PDF (209 KB)

  Waveguide grating couplers allow the essential function of waveguide access to be integrated together with optical processing functions on a monolithic planar substrate. Grating coupling technology is topologically and, to a large extent, technologically compatible with the planar processes which define the optical processing waveguide circuit. Poor coupling efficiency, highly dispersive character, absence of user-friendly modelling tools and fabrication difficulties have long prevented this technology from being implemented into practical sensors and microsystems. This paper makes a review of the points where decisive technological progress has been made, illustrates some useful features of waveguide coupling gratings and underlines some of the difficulties which the designer may encounter.

• Open/close Approximate calculation of the reflection coefficient from a stratified medium

  C J R Sheppard 1995 Pure Appl. Opt. 4 665 Tag this article

  Article References Full text PDF (165 KB)

  An approximate method for calculating the reflection coefficient of stratified media is discussed. An analytic expression is given for the reflection coefficient for a multi-layer antireflecting stack, with elements of arbitrary thickness and oblique illumination.

• Open/close Film mode matching: a versatile numerical method for vector mode field calculations in dielectric waveguides

  A Sv Sudbo 1993 Pure Appl. Opt. 2 211 Tag this article

  Article References Full text PDF (1.21 MB)

  The old film mode matching or transverse resonance method for calculating mode fields in dielectric waveguides is given a new formulation that makes it an efficient, accurate, and general numerical method, ready to exploit standard computer libraries for numerical linear algebra. Both the scalar and the vector field cases are treated for a rather general class of waveguide cross sections, where the method (like the method of lines) is more accurate and more efficient than sophisticated finite-element and finite-difference methods.

• Open/close Optical characterization of chloroaluminium phthalocyanine (ClAlPc) thin films

  M E Azim-Araghi and A Krier 1997 Pure Appl. Opt. 6 443 Tag this article

  Article References Full text PDF (238 KB)

  Thin films of ClAlPc of 100 - 300 nm thickness were sublimed onto glass substrates in high vacuum. Studies of the molecular structure of ClAlPc have been made using films deposited at various temperatures and films annealed after deposition at room temperature. The optical properties in both monoclinic and triclinic forms are reported. Optical data have been obtained from both absorption and reflectivity spectra over the wavelength range 350 - 800 nm. Monoclinic films show two absorption bands, an exciton absorption on the low-energy side of the transparent band and a fundamental absorption above 2.55 eV. A direct allowed transition at 3.05 eV was observed. A doublet of energies in the absorption spectra of the monoclinic form at 1.74 and 1.9 eV was also observed in good agreement with previous findings for other metal phthalocyanines, including CuPc, PbPc, NiPc and CoPc.