U.S. Philips Corporation

Koninklijke Philips Corporation N.v.

Howard J Wilson

Peter K Bachmann

Jacques P Warnier

Hans-Jurgen E Hagemann

Peter E Geittner

Detlef Uwe Wiechert

Hans-Jurgen Lydtin

Peter Klaus Bachmann

Dieter Leers

Albrecht Kraus

Bernd Rausenberger

Norbert Braun

Klaus Rademacher

In a capacitively coupled discharge lamp the electrode comprises a dielectric material that during operation is in contact with the discharge. The impedance of the dielectric material is small and its electron affinity is negative. In this way it is realized that the discharge lamp can be operated efficiently at low frequencies (less than 500 KHz).

Discharge lamp having electrode part with negative electron affinity

In an electron-emitting component with a cold cathode comprising a substrate and a cover layer with a diamond-containing material consisting of nano-crystalline diamond having a Raman spectrum with three lines, i.e. at K=1334.+-.4 cm.sup.-1 with a half-width value of 12.+-.6 cm.sup.-1, at K=1140.+-.20 cm.sup.-1 and at K=1470.+-.20 cm.sup.-1, the cold cathode exhibits a low extraction field strength, a stable emission at pressures below 10.sup.-4 mbar, a steep current-voltage characteristic and stable emission currents in excess of 1 microampere/mm.sup.2. The electron emission of the component demonstrates a long-time stability, and a constant intensity of the electron beam across its cross-section.

Electron emitter with nano-crystalline diamond having a Raman spectrum

In the manufacture of optical fibers according to the PCVD method, a method is provided wherein the yield of the method (.eta.), in particular at increased deposition rates (m), is raised by reducing the geometrical taper, without forming optical tapers. This is obtained in that glass is deposited in layers on the inside of a glass tube and, simultaneously, on a glass rod having a circular cross-section, which rod is arranged inside the glass tube, such that its longitudinal axis coincides with that of the glass tube, the radius of the glass rod being adjusted to at most 0.67 times and at least 0.2 times the inner radius of the glass tube, and the glass rod being removed from the glass tube upon completion of the deposition process.

Method of manufacturing optical fibres

Polarization-retaining optical fibres are manufactured according to the PCVD method, in which on the inside of a glass tube and, simultaneously on at least two glass rods which are arranged inside the glass tube such that their longitudinal axes run parallel to the longitudinal axis of the glass tube, glass is deposited in layers and the glass rods are removed from the glass tube upon completion of the glass deposition process. Alternatively, a single glass rod, the radial dimensions of which in two mutually perpendicular directions are in a ratio unequal to one, i.e. elliptical, is arranged in a glass tube such that its longitudinal axis coincides with the longitudinal axis of the glass tube.

Polarization-retaining optical fibres are manufactured according to the PCVD method, in which on the inside of a glass tube (1) and, simultaneously on at least two glass rods (2, 3) which are arranged inside the glass tube such that their longitudinal axes run parallel to the longitudinal axis of the glass tube, glass is deposited in layers and the glass rods are removed from the glass tube upon completion of the glass deposition process. Alternatively, a single glass rod, the radial dimensions of which in two mutually perpendicular directions are in a ratio unequal to one, is arranged in a glass tube such that its longitudinal axis coincides with the longitudinal axis of the glass tube.

Optical fibres whose refractive index profiles show specific peripheral and/or radial and/or axial optical modulation structures are manufactured according to the PCVD method, in which such method parameters are varied which influence:

Method of manufacturing optical fibers

In an optical fiber based on silicon dioxide with fluorine doping which determines its refractive index profile, at least in the light transmitting core a substance is added that increases the thermal expansion coefficient. The added substance is uniformly distributed at least in the light transmitting core, and reduces the influence of the drawing force F.sub.Z (during drawing of the preform) on the Rayleigh scattering .alpha..sub.R and the wavelength-independent 'c term' losses. Even at high fluorine dopant concentrations, low Rayleigh scattering losses in the range of the material-intrinsic losses pure for silicon dioxide are achieved. The OH-contamination level is also further reduced, and cracks in the collapsed preforms are largely avoided.

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Aachen, Germany

Howard J Wilson