Laser beam injecting optical device for optical fiber

Abstract

In a shielding case, a condenser lens condenses a laser beam output by a laser oscillator to inject the laser beam into an entrance end face of an optical fiber disposed posterior to a focusing point of the laser beam. Ventilation of an ambient gas in the shielding case is carried out by ventilating means, and the ambient gas bringing about ionization in the vicinity of the focusing point of the laser beam is eliminated, thereby preventing the outbreak of air breakdown.

Description

[0001] Cross References to Related Applications [0002] This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2006-196715 filed on July 19, 2006, the entire contents of which are hereby incorporated by reference. field of invention [0003] The present invention relates to a laser light incident optical device for an optical fiber that makes laser light incident on an optical fiber. Background technique [0004] Conventionally, in the fields of laser application, laser-induced fluorescence analysis, laser peening, etc., laser light obtained by a giant pulse oscillation system with a peak power of 1 MW or more has been used. [0005] In the transmission of such a high-power laser, it is possible to transmit several kW with a single optical fiber with continuous oscillation light using a step-index optical fiber made of quartz with a core diameter of about 1 mm. However, with a short-pulse laser with a pulse width of abo...

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Problems solved by technology

[0009] However, in order to avoid damage to the incident end face and inside of the optical fiber, in the configuration in which the laser focus generated by the focusing lens is formed on the front of the optical fiber, the pulsed laser beam with a peak power of several MW or more is focused by the focusing lens and incident on the core diameter φ1mm. When the optical fiber is used, although stable laser light can be transmitted after the start of laser oscillation, as time goes by, the air near the focus of the laser light generated by the focusing lens gradually becomes ionized

Therefore, there is a problem that air breakdown occurs frequently, and stable laser light cannot be transmitted due to the influence of plasma generated by air breakdown.

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