Abstract: Polymerisable optically active compounds have the general formula: ##STR1## where: W.sup.1 denotes a polymerisable residue,S.sup.1 denotes a spacer unit,Y.sup.1 denotes a single bond, or one of the groups --O--, --COO--, --OOC--, --OCOO--, --S--, --CONH-- or --NHCO--,M denotes a divalent mesogenic group, andR.sup.1 and R.sup.2 denote straight chain, branched or cyclic alkyl groups with up to 8 carbon atom.

Abstract: The invention relates to a method of welding weld studs to a workpiece, in particular of aluminum in each case, by the stroke ignition method, in which the stroke height(s) of the weld stud (1) is altered as a function of the measured arc voltage and optionally of the arc firing time. In particular, the stroke height(s) of the stud (1) can be increased during the occurrence of short circuits, i.e. during a sudden drop in the arc voltage, preferably in predetermined steps. The weld stud is immersed into a pool of melt after a predetermined period of time of between 5 and 10 ms after the welding current has been switched off. The polarity of the stud or of the workpiece is changed at least once during the welding process. The welding current is interrupted for a predetermined period of time for this purpose. The method leads to an improved, readily reproducible quality of weld.

Abstract: In liquid crystal display cells comprising a liquid crystal (7) disposed between two substrate plates (1,2) provided with drive electrodes (3,4), the orientation layer (5,6) on the inner sides of the plates where the electrodes are disposed comprises an oriented photopolymer layer. This layer is formed by irradiating photopolymer layer. This layer is formed by irradiating photoreactive material with linear polarized light.

Abstract: The image-producing device comprises a liquid crystal cell with a liquid crystal (10, 21, 44) between two plates provided with drive electrodes (2, 6; 24, 25; 42, 46) and wall orientation layer (3, 7; 26,27; 43, 45) and an optically anisotropic polymeric additional element (9, 31, 52). The additional element, which can be a separate element or in the form of a coating or a foil stuck directly to the cell, comprises an oriented photopolymer.

Abstract: The present invention is concerned with optically active, ferroelectric, smectic, photo-cross linkable compounds of the formula ##STR1## wherein A.sup.1 and A.sup.2 may both signify residues of the formula ##STR2## and be the same or different, while A.sup.3 may signify a residue of the formula ##STR3## as well as liquid crystalline mixtures which contain such compounds and their use in the cross-linked state in optical components.

Abstract: An optical component includes an anisotropic layer of cross-linked liquid crystal monomers with varying local orientation of the liquid crystal molecules. The liquid crystal layer is in contact with an orientation layer comprising a photo-orientable polymer network (PPN). A method of making includes orienting the liquid crystal monomers by the interaction with the PPN layer and subsequently fixing the molecules by cross-linking.

Abstract: An apparatus for providing a vacuum in a segmented tire mold includes an upper sidewall assembly and lower sidewall assembly, a plurality of radially moveable tread mold segments operable with the upper sidewall assembly and lower sidewall assembly to define a tire mold cavity. A conical actuating ring assembly surrounds the tire mold segments and engages the mold segments to provide radial movement of the mold segments. The apparatus includes a first seal between the conical actuating ring assembly and the lower mold assembly, as well as a second seal between the conical actuating ring and the upper sidewall assembly, thereby sealing the space defined by the tire mold so that a vacuum can be drawn on the tire mold cavity upon the closing of the mold.

Abstract: The present invention is concerned with photo cross-linkable liquid crystals of the formula ##STR1## wherein A is a cross-linkable mesogenic residue;X is a single bond, --COO--, --CH.sub.2 O--, --CONH-- or --C.dbd.N--; andQ is n-alkylene, c-alkylene, 1,4-phenylene, 4,4'-biphenylene or 2,6-naphthylene;liquid crystalline mixtures which contain such compounds as well as their use in the cross-linked state for optical building elements.

Abstract: The invention is concerned with linear and cyclic polymers or oligomers having a photoreactive ethene group. The polymers are of the formula ##STR1## wherein M.sub.a, M.sub.b, M.sub.c are monomer units for homo- or copolymers;x, y, z are mole fractions of the copolymers, whereby in each case 0<x.ltoreq.1; 0.ltoreq.y.ltoreq.1 and 0.ltoreq.z<1;S.sub.a, S.sub.b are spacer units;Z.sub.a, Z.sub.b are molecule units which can undergo photochemical isomerization/dimerization;n is a magnitude of 4-100 000 andm is 0 or 1,The compounds are used as an orientating layer for liquid crystals.

Abstract: A stent for the splinting and/or for the holding open of a hollow organ is comprised from filaments 11 which are formed together into a tubular and self-expanding netting. In the collapsed state the stent 10 is stretched in an axial direction and in an extended state the stent is fore-shortened in the axial direction. The filaments 11 are formed with rectangular cross-section and the crossing-points 12 are securely attached to another at the free ends 14 and 15.

Abstract: A tracheal stent 1 is comprised from a plastic shaft 2 and metal clasps 5 which grasp the plastic shaft 2 ventrolaterally. The plastic shaft 2 is, cranially, lengthwise oval in cross section and, caudally, squarish-oval. It is comprised from thin highly-elastic and stable sheet and from clasps 5, whereby the clasps 5 are bound to the sheet. The clasps 5 can, in a first manifestation, be sufficiently compressed together over their free ends 6, 7 that the plastic shaft 2 is given as small an outer circumference as possible. In a second manifestation, the clasps 5 can be spread out by, for example, being heat activated. A stably-shaped and, in section 7', highly-elastic lumen 8 is formed in plastic shaft 2 which largely corresponds to the size of a lumen of a natural trachea.

Abstract: Polymeric coatings having optically non-linear or optically anisotropic properties in selected areas and of any arbitrary shape including a pattern. These zones are sharply defined from surfaces having centro-symmetrical or isotropic configurations or from surfaces with different optically non-linear or anisotropic properties. The polymeric coating has optically non-linear and/or mesogenic side chains, selected surface areas of which are cross-linked by the action of light, the zones which have optically non-linear or anisotropic properties being subjected to the influence or orienting fields or forces during the cross-linking process. The distances between optically different zones are limited to typically about 1 .mu.m.

Abstract: An oriented photopolymer is a polymer where photomodification is initiated by irradiation with plane-polarized light and where the molecular configuration has a preferred orientation as a result of linear polarization. These polymers have optically anisotropic and other novel properties.

Abstract: An apparatus for the isotropic irradiation of cavity walls includes in a first channel of a catheter a light conducting fiber which has a cortically shaped tip for deflecting a light beam radially outwardly through a transparent portion of the catheter and a resiliently expandable sleeve tightly disposed around the catheter and having its interior in communication by a second channel with a fluid supply for expanding the sleeve so as form a light scattering structure whose scattering characteristics are adjustable dependent on the degree of sleeve expansion.

Abstract: An optical frequency conversion element has a wave-guiding layer which consists of a .chi..sup.(2) -active ferroelectric liquid crystal. The monomeric or polymeric liquid crystal material has a periodic structure which permits the so-called quasi phase matching of a guided laser beam. The period length of the structure is equal to twice the coherence length l.sub.c =.pi./.DELTA..beta. of the material, whereby .DELTA..beta.=.beta..sub.o (2.omega.)-2.beta..sub.o (.omega.), with .omega.=angular frequency of the fundamental wave, 0=zero-order mode and .beta.=propagation constant of the mode.

Abstract: The polarizer comprises a layer of cholesteric liquid crystal with Grandjean structure disposed in the path of the light and in which the light in a given wavelength range is reflected with selective and circular polarization or is transmitted with reversed direction of rotation, and a mirror which reversed the direction of rotation of the circular-polarized light. The component reflected by the mirror is also transmitted. If the liquid crystal layer is concentric with the source of natural light and the mirror is spherical, the result is a source of circular polarized light. A projection system is obtained by a combination of two of the aforementioned polarizers, one serving as a polarizer and one as an analyzer, and an interposed liquid crystal display cell for modulating the intensity of the polarized light.

Abstract: At a tube shaft 2 a tracheal tube 1 has a blocking cuff 4 made of a material which has the structure of a synthetic caoutchouc mixed polymer. A blocking cuff 4 designed in such a way is not permeable to anesthesia gas and may be manufactured to have one layer. Preferably the blocking cuff 4 is made of butadiene acrylnitrile mixed polymer.

Abstract: The polarizer comprises a layer of cholesteric liquid crystal with Grandjean structure disposed in the path of the light and in which the light in a given wavelength range is reflected with selective and circular polarization or is transmitted with reversed direction of rotation, and a mirror which reversed the direction of rotation of the circular- polarized light. The component reflected by the mirror is also transmitted. If the liquid crystal layer is concentric with the source of natural light and the mirror is spherical, the result is a source of circular polarized light. A projection system is obtained by a combination of two of the aforementioned polarizers, one serving as a polarizer and one as an analyzer, and an interposed liquid crystal display cell for modulating the intensity of the polarized light.

Abstract: A medical instrument consists of a relatively rigid shaft (1) and a flexible tip (3) that is attached to one end of the shaft (1) as an extension thereof. Fastened to its outer end at points opposite each other are tension cables (5, 6), which are guided in a tubular sheath parallel to the tip (3) and to the shaft (1) to its other end, and at the other end of the shaft are joined to an adjusting wheel (8) that allows shortening of one and equal lengthening of the other of the two oppositely located tension cables (5, 6) in order to impart to the tip (3) a selectable curvature in the direction of the shortened tension cable. The invention has as its object a simplification of known instruments which simultaneously allows a reduction in dimensions.

Abstract: In a heart catheter which consists of a hose having a sonde with an electrode structure for locating pathological areas arranged at its distal end, a light transmitting fiber is movably disposed in the hose and the hose has sensors associated therewith so as to be movable together with the fiber out of the distal end of the hose for engagement with the tissue of the pathological area for positioning the distal end of the hose at a predetermined distance and location relative to the pathological area in order to provide for appropriate irradiation of the pathological area by radiation energy supplied through the light transmitting fiber.