• I. Yamane
  KEK, Ibaraki
• M. Nakamura, H. Okuno
  RIKEN Nishina Center, Wako

An asym­met­ri­cal con-fo­cal cav­i­ty is com­posed of tow con­cave mir­rors with dif­fer­ent focal length, placed face to face, and their axes and focal points co­in­cide. When a laser beam is in­ject­ed in par­al­lel with the mir­ror axis, from back­ward of and just out­side of the mir­ror with the small­er focal length, the laser beam is trapped in the cav­i­ty and re­peats re­flec­tion by mir­rors. Then, the beam re­flect­ed by the mir­ror with the larg­er focal length pass­es every time the focal point and the pe­ri­od by which puls­es re­turn to the focal point is con­stant. There­fore, if the rep­e­ti­tion pe­ri­od of the in­ject­ed laser pulse is equal to the rep­e­ti­tion pe­ri­od in the cav­i­ty, all laser puls­es comes to the focal point at the same time and the beam in­ten­si­ty is stacked up. Cal­cu­la­tion on the per­for­mance of an asym­met­ri­cal con-fo­cal cav­i­ty shows that a laser pulse can be re­cy­cled more than a few tens turns and the beam in­ten­si­ty can be stacked to more than a few tens times of the orig­i­nal beam in­ten­si­ty when the laser beam is a Gaus­sian beam and the re­flectance of the mir­rors is 100%. Re­sults of cal­cu­la­tion is ex­am­ined using a He-Ne laser and a pair of high re­flec­tion mir­rors.