Borysow Jacek, Kostinski Alexander, Fink Manfred
Department of Physics, Michigan Technological University, Houghton, Michigan 49931, USA.
Appl Opt. 2011 Oct 20;50(30):5812-5. doi: 10.1364/AO.50.005812.
We ask whether it is possible to restore a multipass system alignment after a gas cell is inserted in the central region. Indeed, it is possible, and we report on a remarkably simple rearrangement of a laser multipass system, composed of two spherical mirrors and a gas cell with flat windows in the middle. For example, for a window of thickness d and refractive index of n, adjusting the mirror separation by ≈2d(1-1/n) is sufficient to preserve the laser beam alignment and tracing. This expression is in agreement with ray-tracing computations and our laboratory experiment. Insofar as our solution corrects for spherical aberrations, it may also find applications in microscopy.
