Patent ID: 7519256

Claim:
A method for manufacturing an optical preform via an internal vapor deposition process, wherein use is made of an energy source and a substrate tube having a supply side and a discharge side, wherein the energy source is movable over the length of the substrate tube between a supply-side point of reversal and a discharge-side point of reversal, wherein one or more glass-forming precursors are supplied to the interior of the substrate tube at the supply side of the substrate tube, and wherein components that have not been deposited on the interior of the substrate tube are discharged at the discharge side of the substrate tube, wherein such conditions are created in the interior of the substrate tube that deposition of glass layers on the interior of the substrate tube takes place, wherein first an outer cladding is deposited and then an inner cladding is deposited, and wherein the velocity profile of the energy source is set so that the acceleration of the energy source near the supply-side point of reversal for depositing the inner cladding is greater than the acceleration of the energy source near the supply-side point of reversal for depositing the outer cladding.