Laser wavelength selection.
The advent of multiwavelength lasers has stimulated considerable interest in wavelength selection, i.e., methods of selecting for various applications one or more of the available wavelengths from a given laser. This paper describes a technique for parallel wavelength separation or recombination of laser beams external to laser cavities. The device used is based on the optical activity of quartz crystals and on the polarization dependent reflection of birefringent calcite crystals.
Total internal reflection light deflector.
A digital electrooptic light deflector is described whose deflection elements are an isotropic plate and an optically birefringent plate immersed in a refractive index matching oil. Total internal reflection or complete transmission takes place at the birefringent plate according to the linear polarization state of the light beam. The deflector is suited for large deflections and a broad band of wavelengths.
B.S.T.J. briefs: The use of wollaston prisms for a high-capacity digital light deflector
A digital light deflcctor was recently proposed by T. J. Nelsonl1 in which n optical modulators and n uniaxial crystals were used to provide 2n positions of the beam. Each uniaxial crystal was used to deflect a beam of light into either of two beams, with the light at the output remaining parallel to the input but displaced by an amount proportional to the thickness of the crystal. For a large number of positions it was found that a lens had to be employed in order to focus the beam into a smail spot. The lise of the lens requircs that converging or diverging light must pass through the uni ax ial crystal. In this brief we point out that this converging beam, when passing through the crystal as an extraordinary ray, is subjected to an index of refraction which varies rapidly with angle. The digital light deflector using this type of deflection therefore has appreciable image distortion, and the limiting spot densities that can be achieved are less than would be predicted if only diffraction were important.