Method of preventing post pulsing of Q-switched laser

• US 3,982,203 A
• Filed: 12/28/1973
• Issued: 09/21/1976
• Est. Priority Date: 12/28/1973
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: de Wit, Michiel
• Primary Examiner(s): Webster, Robert J.
• Application Number:
  US05/429,474
• Time in Patent Office: 998 Days
• Field of Search: 331/94.5, 330/4.3
• US Class Current: 372/13
• CPC Class Codes: H01S 3/117 using intracavity acousto-optic devices

Abstract

An improved optically pumped, acousto-optically Q-switched laser is disclosed, capable of significantly increased output energy. Optical coatings, with their inherent limitations on maximum energy of the output pulse, are completely eliminated. At the reflecting surfaces, Porro prisms replace the mirrors conventionally used. At the non-reflecting or transmitting surfaces, conventional, anti-reflective coatings are eliminated by placing the respective elements at the Brewster angle for the dominant polarization of the Q-switching material. Optimum output coupling is achieved by adjustment of the Q-switch drive. In order to prevent undesired second pulses in the output, which normally limit the maximum attainable output energy, a filtering shield of material opaque to the operating frequency is placed in the laser cavity, between the flash pump and the laser rod, to minimize the possibility of a second-pulse buildup due to random emission before the Q-switch is turned fully off. The wavelength of the output radiation may be sequentially selected from among the various spectral lines of the lasing material, by appropriate selection of the RF frequency applied to the acousto-optic element.

Claims

1. A method of preventing post pulsing of an acousto-optically Q-switched laser system comprising a laser cavity which includes therein a laser rod, first reflecting means mounted along the optical axis of said rod, feedback reflecting means mounted on the opposite side of said rod from said first reflecting means at an angle to said axis, optical pumping means for exciting the laser rod, and an acousto-optic Q-switch mounted on the optical axis of the laser rod between the laser rod and the feedback reflecting means and energizable for deflecting radiation from said laser rod to said feedback reflecting means to provide lasing action as a Q-switched pulse of lasing energy, said method comprising:

placing a filtering material within the laser cavity between said laser rod and said optical pumping means wherein the filtering material is substantially transparent to pumping radiation and substantially opaque to radiation at the lasing wavelength, and

preventing residual radiation emitted in random directions from the laser rod at the lasing wavelength from being deflected into the rod into directions near enough to the axial direction to be regeneratively amplified, by absorption of said radiation in the filtering material during periods when the acousto-optic Q-switch is energized and following the generation of the Q-switched pulse of lasing energy.