A new hybrid optical device that is capable of splitting a monochromatic laser beam into an arbitrary number of lines over a wide angle is presented. It consists of a binary surface-relief computer-generated phase hologram and a continuous parabolic surface-relief grating. In this device the phase hologram serves to generate three small, parallel lines while the continuous parabolic surface-relief phase grating acts as an array of diverging parabolic lenses to widen these lines. The binary surface-relief was generated into one side of a quartz substrate through a plasma-etching process, and the parabolic profile was generated into a thick photoresist deposited on the other side of the quartz substrate. Calculations showed that a diverging parabolic lens with a f-number of 0.5 would deliver the desired optical pattern of multiple beams distributed over 90 degrees . A surface-relief depth of 6.0 mum was calculated with consideration of the phase distributions of such lens. The parabolic profiles were fabricated in a 10-mum-thick photoresist, by use of a contact exposure through a mask with a space pattern of repetitive 4- and 6-mum lines. He-Ne laser light was passed through a device that generated three parallel lines over a 90 degrees angle. The resulting diffraction patterns were characterized, and a satisfying result was obtained. The resulting multiple-line pattern can be used in robot vision and other applications.

High image quality and complex, refractive optical systems, as those used in remote sensing applications, are, in general, very difficult to be manufactured with the required performance. This can be charged to the high sensitivity of such systems to the fabrication tolerances, mainly concerning the relative alignment of the optical components with respect to each other. When the system does not achieve the expected quality, the puzzle is to identify where the problems lies. This is even worsened when the number of optical elements becomes high. Due to these facts, some misalignment characterization and estimation techniques based on Bayesian estimators and wavefront measurements have been proposed in the literature. This paper is the result of a deep study and investigation of these techniques, with emphasis on an application to an intentionally simple system for the sake of illustration that highlights conceptual issues that could be extended to more realistic, complex optical systems. With this purpose, the sensitivity of the wavefront Zernike coefficients to the misalignment parameters, its use in a parameter estimator design that includes nonlinear terms, the study of the system observability, and a statistical analysis of the estimator performance considering the observation noise are addressed in details. Numerical simulation results for the simple system are shown. We also present insights on how to apply the technique to the alignment of a 11-lens optical system used in the Brazilian remote sensing camera MUX, that will fly on-board the upcoming Sino-Brazilian satellites CBERS 3&4.

A hybrid diffractive optical element (HDOE) capable of splitting a monochromatic laser beam into an arbitrary number of lines over high angle is presented. The element is formed by a continuous parabolic surface-relief phase grating and a binary surface-relief computer generated phase hologram. The parabolic profile was generated into a thick photo resist and the binary surface-relief was generated into a quartz substrate.

Misalignments always occur in real optical systems. These misalignments do not generate new aberration forms, but they change the aberration field dependence. Two-mirror telescopes have been used in several applications. We analyze a two-mirror telescope configuration that has negligible sensitivity to decenter misalignments. By applying the wave aberration theory for plane-symmetric optical systems it is shown that the asphericity in the secondary mirror, if properly chosen, can compensate for any decenter perturbation allowing third-order coma unchanged across the field of view. For any two-mirror system it is possible to find a configuration in which decenter misalignments do not generate fielduniform coma.

Introdu~ao Como e possivel medir a espessura de um material mole, deformavel, estando este em movimento, sem que 0 processo de medida altere 0 seu valor? Como e possivel, por exemplo, verificar as dimensoes de uma peya em movimento, ao mesmo tempo em que esta sendo trabalhada? Como verificar se um conjunto foi posicionado corretamente em relayao a outro, estando ambos em movimento? AMm destas situayoes, poderia-se enumerar uma serie de casos em que as tecnicas de mediyao ja estabelecidas nao se aplicam com a eficiencia desejavel. Por outro lado, ja saD de conhecimento, dito cientifico, uma serie de tecnicas que poderiam ser aplicadas, mas que, por diversas razoes, ainda nao 0 foram.