Lens arrangements for varying numerical aperture in laser delivery systems
AssigneePanasonic Intellectual Property Management Co., Ltd.
InventorsWang-Long Zhou, Francisco Villarreal-Saucedo
Life of this patent
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Abstract
In various embodiments, one or more optical elements are utilized to alter the numerical aperture of a radiation beam received from an optical fiber in order to accommodate the properties of a downstream collimator within a laser delivery head.
Claims19
A laser delivery system for directing optical radiation onto a workpiece, the system comprising:
- an optical fiber configured to emit, at a fiber exit plane, a radiation beam having a numerical aperture ranging from a first numerical aperture to a second numerical aperture larger than the first numerical aperture;
- coupled to the optical fiber, a laser delivery head configured to receive the radiation beam and containing a collimator having a third numerical aperture less than the second numerical aperture;
- and
- disposed optically downstream of the fiber exit plane and optically upstream of the collimator, an optical element having positive optical power and configured to reduce the numerical aperture of the radiation beam to a value less than the third numerical aperture.
A laser delivery system for receiving and altering a numerical aperture of a radiation beam emitted by a beam source and focusing the radiation with the altered numerical aperture onto a workpiece, the system comprising:
- an optical fiber for transmitting the radiation beam from the beam source to a fiber exit plane;
- disposed at the fiber exit plane, an end cap for receiving the radiation beam from the optical fiber, the end cap having a flat entrance surface and a flat exit surface opposed to and spaced apart from the entrance surface;
- a lens distinct from and disposed optically downstream of the exit surface of the end cap, the lens having a positive optical power;
- and
- a laser delivery head positioned to receive the radiation beam, the laser delivery head comprising (i) a collimator for collimating the radiation beam, and (ii) disposed optically downstream of and distinct from the collimator, focusing optics for focusing the radiation beam onto the workpiece.
A method of modifying a laser delivery system comprising (i) an optical fiber for transmitting a radiation beam emitted by a beam source to a fiber exit plane, and (ii) a laser delivery head for receiving the radiation beam from the optical fiber, the laser delivery head comprising a collimator for collimating the radiation beam, wherein (A) the laser delivery head is configured to accept a radiation beam having a numerical aperture no greater than a maximum numerical aperture, and (B) the beam source is configured to supply a radiation beam having a numerical aperture greater than the maximum numerical aperture, the method comprising:
- without replacing the collimator in the laser delivery head, disposing a lens optically downstream of the end cap, the lens (i) having a positive optical power, (ii) having a center thickness larger than approximately 5 mm, and (iii) being configured to receive the radiation beam and reduce the numerical aperture thereof to a numerical aperture no greater than the maximum numerical aperture;
- and
- within the laser delivery head, maintaining an optical distance between the collimator and the fiber exit surface substantially unchanged notwithstanding the reduction of the numerical aperture of the radiation beam and the presence of the lens.
Dependencies are inferred from the claim text.