Abstract: A transducer (800) is provided where a membrane (830) is formed over a front substrate (615); and a piezoelectric layer (820) is formed over the membrane (830) at an active portion (821) and peripheral portions located adjacent the active portion (821). A patterned conductive layer including first and second electrodes (840, 845) is formed over the piezoelectric layer (820). Further, a back substrate structure is provided having supports (822, 824) located at the peripheral portions adjacent the active portion (821). The height (826) of the supports (822, 824) is greater than a combined height (828) of the patterned piezoelectric layer and the patterned conductive layer. Many transducers may be connected to form an array, where a controller may be provided for controlling the array, such as steering a beam of the array, and processing signals received by the array, for presence or motion detection and/or imaging, for example.

Abstract: A lens system includes a lens (18) and a non-periodic phase structure (16). A temperature-dependence of the spherical aberration of the lens is compensated by a temperature dependence of the spherical aberration of the non-periodic phase structure. A wavelength-dependence of the defocus of the lens is compensated by a wavelength-dependence of the defocus of the non-periodic phase structure. A wavelength-dependence of the spherical aberration of the non-periodic phase structure is compensated by a wavelength-dependence of the spherical aberration of the lens.

Abstract: The illumination system (1) has a substrate (2) and an active layer (3) comprising an electroluminescent material, in which the active layer (3) is present between a first, optically transparent electrode layer (5) and a second electrode layer (7). The illumination system (1) is characterized in that a light-scattering layer (28) comprising a medium having light-scattering properties is present in a forward direction (29) with respect to the active layer (3), in which the non-scattered fraction of a (collimated) light beam, when passed through the light-scattering layer (8) in the forward direction (29), is in the range between 0.05 and 0.8, preferably in the range between 0.1 and 0.5. The light-scattering properties of the medium are preferably stronger as the light is more obliquely incident, as is achieved by using birefringent particles and/or media. A very suitable light-scattering layer (28) is a (half) monolayer of TiO.sub.

Abstract: An optical system includes comprising a polarizing element in the form of a layer which comprises an isotropic material having a refractive index n.sub.i and an anisotropic material having refractive indices n.sub.a,e and n.sub.a,o. The refractive index n.sub.i is substantially equal to n.sub.a,e or n.sub.a,o. The optical system includes a retroflector for back-reflecting the polarization component diffused in the polarizing element.

Abstract: An illumination system (3) includes an optical waveguide (11) and a light source (9) whose light is coupled into the optical waveguide (11) via at least one end face (13) of the optical waveguide (11). The optical waveguide (11) is provided with recesses (19) which are subsequently filled up with a material which is different from that of the optical waveguide (11). One of the two materials is isotropic and has refractive index n.sub.p and the other material is anisotropic and has refractive indices n.sub.o and n.sub.e. For the refractive indices it should hold that n.sub.o or n.sub.e is equal or substantially equal to n.sub.p in order that there is separation of polarization at the interfaces between isotropic and anisotropic material. Further, a flat-panel picture display device includes such an illumination system.