Pre-Amplifier

Technical contact: Udo Eisenbarth

The Pre-Amplifier system uses two flashlamp-pumped Nd:glass amplifiers with free apertures of 19 mm and 45 mm, operating in a double-pass mode. The input beam, sourced from either the femtosecond or nanosecond frontend, is gradually expanded by Kepler telescopes to a maximum diameter of 70 mm, ensuring fluence levels remain safely below the damage threshold.

Wavefront aberrations are actively corrected by a deformable mirror, which operates in a closed-loop control system with a Shack-Hartmann sensor. Positioned at the end of the laser chain, this sensor allows the deformable mirror to precompensate for wavefront aberrations introduced in the main amplifier.

Additionally, the Pre-Amplifier employs a serrated aperture alongside a spatial filter (pinhole) to produce round or elliptical beam shapes with a near top-hat intensity profile. The apertures are made with lithographically patterned aluminum masks on glass substrates..

Key parameters are:

Maximum output energy (fs pulses):

8J

Maximum output energy (ns pulses):

15J

Cool down between shots:

3 min

Maximum gain (depending on spectral width):

>600 (dep. on the spectral range and beam shape)


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