RESUMEN
Electrostatic electron lenses have been evaluated in terms of their image transfer characteristics. The effect of polychromatic radiation with different spectral energy distributions on the performance of an electron emitter-lens combination has been studied.
RESUMEN
The distortion in a 2-D scan pattern generated by a system of a plane mirror and a regular polygon scanner was investigated using the matrix formulation of reflection by plane mirrors. A particular configuration involving the two scan elements was identified which does not introduce any distortion in its 2-D scan pattern.
RESUMEN
A method for correcting spherical aberration and coma in fast two-element objectives using high-index materials is discussed. It involves use of an aplanatic lens with a single lens having a minimum spherical aberration and no coma. The method deals only with monochromatic designs. It can be effective in designing high-aperture aplanatic IR objectives. Optical data and performance characteristics of germanium and silicon two-lens systems designed by the proposed method are given.
RESUMEN
The polarization of a scattered beam from any object depends on the nature of the surface of the object. Depolarization of the laser beam can occur as a result of reflections from metallic and dielectric surfaces; it can also be due to multiple scattering in some of the medialike aerosol particles when the laser beam passes through them. While recording a hologram this fact is altogether ignored, and it is assumed that object and reference beams are polarized linearly and parallel to each other. We have studied the variation of diffraction efficiency of a hologram with the degree of polarization of the object beam. There is a 43% decrease in the efficiency value when the degree of polarization falls from 1 to 0.9. A method for minimizing the effects of depolarization is suggested.
RESUMEN
Third-, fifth-, and seventh-order aberrations have been analyzed for in-line and off-axis holographic lenses of different f/No. The seventh-order wave aberrations and the corresponding aberration coefficients are reported here for the first time. It has been concluded that when the holograms are to be used as optical elements, fifth- and seventh-order aberrations should also be considered along with the third order to achieve ideal imagery as both the chromatic and nonchromatic aberrations are quite large even when only small deviations from the recording geometry are present in the reconstruction step.
RESUMEN
A two-layer quarter-quarter antireflection coating with a homogeneous mixture of ZnS and MgF(2) as the inner layer and MgF(2) as the outer layer was fabricated. Its transmittance was measured and found to be comparable with that of a less stable CeF(3)-MgF(2) coating. Measured peak transmittance values agree well with theoretical values.
RESUMEN
Double-layer quarter-half AR coatings effective at two wavelengths simultaneously in the visible region have been fabricated by depositing a homogeneous ZnS-MgF(2) mixture as the inner layer and MgF(2) as the outer layer. The results obtained agree well with those predicted theoretically.
RESUMEN
Laser images and holographic reconstructions are highly affected by dust and imperfections present in various optical components of the imaging system, which create noiselike structures in the final images. To reduce this speckle noise, a phase plate based on a frequency-modulated zone plate is proposed. It can be fabricated by holographic techniques, and it does not require a separate Fourier transforming lens. Experimental results are presented showing the capabilities of the phase plate.
