Abstract: A photochromic plastic has been discovered which is useful in the manufacture of protective eyeglasses. The photochromic plastic comprises a host polymer material and a dopant. The plastic exhibits photochromic properties due to excited state absorption which occurs when the material is exposed to UV light. The eyeglasses function as protection against radiation from the sun as well as from industrial and other sources. The dynamic range and response time of this novel photochromic plastic may be tailored in accordance with the particular use or application desired.

Abstract: An apparatus and method for teaching a language includes an audio visual medium for displaying a story on a screen in visual form accompanied by a sound track of said story in a language to be learned. A text is provided containing the story in written form with successive short segments of said story identified by means of sequential identifying indicia. The screen is provided with subtitles displaying each segment in written form in the language to be learned. Each of the subtitles is provided with sequential identifying indicia corresponding to those of the written text. Controls are provided to start, stop, and reverse the audio visual medium to permit a user to locate and repeat a particular segment repeatedly as desired.

Abstract: A solid state laser in which molecules containing transition metal ions form the lasing medium. More particularly, the electronic states of molecular complexes containing transition metal ions, which are in closed shell configurations, are pumped by an ultraviolet source to emit coherent radiation.

Abstract: Apparatus employing a light beam to affect another light beam. A primary beam of linearly polarized monochromatic light is directed on an element of chromium chalcogenide spinel magnetic semiconductor, specifically single crystal CdCr.sub.2 Se.sub.4. A control beam of monochromatic light is selectively elliptically polarized and directed at the element. As the light beams traverse the same path through the element the circularly polarized control beam interacts with the element thereby changing the effect of the element on the linearly polarized primary beam to rotate the plane of linear polarization of the primary beam. A linear polarization analyzer receives the primary beam from the element and passes, blocks, or diverts light depending upon the plane of linear polarization of the incident light.

Abstract: A laser medium includes an ordered perovskite crystal of the general formula: A.sub.2 B Cr.sub.y B'.sub.1-y X.sub.6. A and B are alkali metal ions with the ionic radius of A greater than B. B' is an ion selected from the group consisting of Y.sup.3+, La.sup.3+, Gd.sup.3+, Lu.sup.3+, Sc.sup.3+, Al.sup.3+, Ga.sup.3+, and In.sup.3+. X is an ion selected from the group consisting of F.sup.-, Cl.sup.-, and Br.sup.-. A can be an ion selected from the group consisting of K.sup.+, Na.sup.+,Cs.sup.+, and Rb.sup.+. B can be an ion selected from the group consisting of K.sup.+-, Na.sup.+, and Li.sup.+. The chromium can be represented by Cr.sup.+3 ions. The laser media can be ordered perovskite polycrystalline compounds of the formulae: CsNaCr.sub.0.01 Y.sub.0.99 Cl.sub.6 ; KLi Cr.sub.y Sc.sub.1-y F.sub.6 (where y equals 0.01 and 0.10); K.sub.2 NaCr.sub.y Sc.sub.1-y F.sub.6 (where 0.01 .ltoreq.y.ltoreq.0.40).

Abstract: Miniature lasers comprise a high neodymium content aluminophosphate glass composition as the active lasing medium, disposed in an optical cavity defined by a first totally reflective mirror and a second partially transmissive mirror, and an optical pumping means which can be either a flashlamp or a light emitting diode.The aluminophosphate glass laser material consists essentially of from 0.01 to 13 mole percent neodymium oxide, from 25 to 35 mole percent aluminum oxide, and from 60 to 70 mole percent phosphorus pentoxide.

Abstract: A high gain stoichiometric neodymium laser medium of the general formula K.sub.5 Nd.sub.x M.sub.(1-x) Li.sub.2 F.sub.10 where x takes on a non-zero positive value less than or equal to one, and M is a metal selected from the group consisting of lanthanum, cerium, and gadolinium.Minilasers employing a laser medium of the general formula K.sub.5 Nd.sub.x M.sub.(1-x) Li.sub.2 F.sub.10 are provided in which the optical pumping is provided by at least one light emitting diode or laser diode.

Abstract: A white light source is described in which a trivalent metallic ultraphosphate is irradiated with a low voltage electron beam. The metallic ions are generally restricted to the lanthanide rare earth ions and yttrium. The material so irradiated emits light in a spectral continuum centered in the visible portion of the electro-magnetic spectrum. This emission is, however, in addition to any narrow bandwidth light emission of the type generally associated with a transition of the metallic ion involving the electrons of the 4f shell.

Abstract: A optical logic device is described in which binary logic functions are accomplished by use of a laser, such as a dye laser, whose output has a polarization direction which is determinable by the direction of polarization of an input excitation laser pumping pulse. An optical component, such as a birefringent element, establishes a pair of bistable polarization directions representative of the binary logic levels. Bistable polarization operation is achieved by requiring a greater intensity of an input laser pumping signal to establish one polarization direction when compared with the input intensity required to establish the other polarization direction. A Brewster plate may be employed to establish the bistable operation of the laser medium.