Abstract: A flip chip stack of integrated circuits for minimum volume packaging with interconnected chips attached to one or two sides of a flexible circuit board where stacking arrangements for two, five and six chips are disclosed.

Abstract: An optical system for imaging an input beam from an input to an output beam at an output. The system includes a lens adapted for receiving the input beam from the input, and a reflecting device adapted for reflecting the input beam from the lens back to the lens. The lens is adapted for converging the beam reflected by the reflecting device to the output. The input and the output are both located substantially in the focal plane of the lens and off axis, with respect to the optical axis of the lens, on opposing sides from the optical axis of the lens. The reflecting device is located on a side opposite, with respect to the principal plane of the lens, to the side of the input and the output.

Abstract: A system for determining an optical loss of a device under test DUT includes a fiber coupler for receiving an optical input power (Ps) at a first input, coupling out a stimulus signal at a first output derived from the optical input power (Ps), receiving a response signal on the applied stimulus signal, and for providing a returning optical power (P) at a third output derived from the received response signal. For calibration, a reference cable with a reflectivity Rref is coupled to the first output of the fiber coupler and a value Pref of the returning optical power is measured. The reference cable is exchanged for a customer cable, whereby an end of the customer cable is provided in a way that no, or substantially no, reflection occurs, and a value Ppara of the returning optical power is measured. The calibration uses the values Rref, Pref, and Ppara.

Abstract: An optical measuring device includes an optical detector for measuring an incident optical signal coupled to the detector by an optical fiber. The optical fiber and/or the optical detector comprise an interface between optical media with different refractive indices, e.g., a boundary surface, face or facet. The interface is angled with respect to the incident optical signal to reduce reflection in the direction of the incident optical signal. Because light transmitted with a polarization perpendicular to the plane of incidence of the optical signal has an intensity substantially equal to the intensity of light transmitted with a polarization parallel to the plane of incidence of the optical signal, the incident optical signal transmitted through the interface is substantially independent of the polarization direction of the incident optical signal.

Abstract: An optical attenuator for attenuating the intensity of a light beam emerging from an optical fiber comprises a wedge-shaped attenuator disk made of an absorbing material and a transparent disk which is also wedge-shaped and fixed to the absorbing disk. For adjusting different attenuations, the attenuator disk together with the transparent disk are rotated around an axis by a motor. By rotating the disk, the thickness of the absorbing material through which the beam passes and thus the attenuation of the beam can be varied continuously. After passage through the attenuator disk, a corner cube reflects the beam back into the direction where it came from, so that it passes a second time through the transparent plate and the attenuator disk. This second passage occurs at a location which is shifted relative to the location of the first passage (in a direction perpendicular to the plane of the paper). The transmitted beam impinges on a prism from which it is directed via a lens into an optical fiber.

Abstract: A variable optical attenuator includes incoming and outgoing surfaces which are inclined relative to each other so that light reflected at an attenuating coating on one or both surfaces is reflected away from the optical path to avoid interference effects. The attenuating coating varies in density depending upon the angle of rotation of the attenuator. Variable attenuation may be achieved by rotating the attenuator a predetermined amount under microprocessor control.

Abstract: A process and catalyst for the orthomethylation of phenols having at least one free ortho position, wherein the phenols are reacted with methanol in a molar ratio of about 1:1 to 1:10 at about 250.degree.-340.degree. C. in the gaseous phase under a pressure of about 1-4 bar absolute and with rates per unit volume (LHSV) of about 0.05-3 h.sup.-1 in the presence of an iron oxide catalyst. This catalyst consists essentially of (a) iron oxide, (b) molybdenum oxide or tungsten oxide (c) one or several oxides of the elementsmagnesium, calcium, barium, lanthanum, cerium or manganese in a metal-atomic ratio of about (a):(b):(c): of 100:0.2- 10:0.2- 10.