Scientists at Jaeri have demonstrated gain saturation of nickel-like ion x-ray lasers at wavelengths of 13.9 and 12.0nm using a compact chirped pulse amplification Nd:glass laser
Using a series of high precision optics supplied by Optical Surfaces, the Japan Atomic Energy Research Institute (Jaeri) in Kyoto (Japan) has demonstrated the possibility of a compact pumping system for x-ray lasers in the shorter wavelength region. Scientists at Jaeri have demonstrated gain saturation of nickel-like ion x-ray lasers at wavelengths of 13.9 and 12.0nm using a compact chirped pulse amplification Nd:glass laser with an input energy of c14J.
Employing a quasitravelling-wave pumping system using a special six-step mirror enabled the pumping energy to achieve gain saturation to be reduced to 2.5J/mm.
The result demonstrates the possibility of a compact pumping system for x-ray lasers in the shorter wavelength region.
High precision optics from Optical Surfaces were used for two critical elements of the experimental design.
To generate a quasitraveling wave Optical Surfaces produced a complex step mirror consisting of six blocks, each connected to a base plate by optical contact.
Using proprietary manufacturing techniques Optical Surfaces overcame the effects of both bending of the high-power laser coating and the probability of bending during optical contacting to achieve the target of lambda/5 flatness.
The blocks were manufactured parallel to each other with an accuracy of 0.05mrad in the vertical direction and of 0.1mrad in the horizontal position.
The size of the blocks was 25mm wide, 150mm high and the difference of thickness between the neighbouring blocks 600µm.
Using an angle of incidence of 11deg with respect to the surface normal produced an optical delay of 4.07ps between the laser beams reflected from neighbouring blocks.
To provide the precise beam focusing required placed great demands on the quality of the optical components, a 150mm diameter off-axis paraboloid (772mm focal length) and a 203mm diameter off-axis spherical mirror (curvature of 1000mm).
Based upon flexible lapping technology and its uniquely stabilised production environment, Optical Surfaces was able to produce superbly smooth optics fully mounted and tested to have better than lambda/10 flatness across the working surface.
