公开(公告)号：GB1275024A

公开(公告)日：1972-05-24

申请号：GB2097171

申请日：1971-04-19

Applicant: IBM

Inventor： DAKSS MARK LUDMER ,  GARWIN RICHARD LAWRENCE ,  POLE ROBERT VLADIMIR

IPC: G02F1/03 ,  H01S3/101

Abstract: 1275024 Lasers INTERNATIONAL BUSINESS MACHINES CORP 19 April 1971 [19 Feb 1970] 20971/71 Heading H1C A laser cavity contains a fly's eye lens and an electro-optic system for transverse mode selection. In Fig. 2, the resonator comprises reflectors 15 1 and 32 1 , and contains lenses 16 1 , 30 1 , and the fly's eye lens 100 1 . The latter is an array of small converging lenses which may be stamped from a single glass or plastics sheet. The lenses 16 1 , 30 1 and 100 1 are positioned so that discrete modes such as 20 1 may be resonated. The active medium produces linearly polarized light due to its Brewster angle ends, and this in combination with a further polarizer 28 1 and an electro-optic KDP sheet 34 1 normally prevents resonator action. When a local field is produced in the KDP sheet by an electron beam 55 1 one of the transverse modes such as 20 1 is resonated because it is no longer attenuated by the polarizing system. Any one of a number of transverse modes corresponding to the lenslets of the fly's eye lens may thus be selected. In Fig. 3, the fly's eye lens is the other side of the KDP layer, and has its surface nearest the electron beam gun reflective to light; its action is as before. Suitable active media are an argon ion laser, a Nd doped YAG, or a hollow cathode ionized mercury laser. The latter comprises a glass tube containing a hollow cathode with a tantalum anode wire at each end. The Brewster windows may be replaced by a separate polarizer. The fly's eye lens avoids the need for focusing the resonated beam on to the KDP, and surface irregularities in the KDP are not important. It is stated that other mode selection devices such as the Kerr-Babinet scanlaser may also use the fly's eye lens in like manner.