Fig. 1. Schematic block diagram of the J-KAREN-P laser system.

Fig. 2. Measured pre-pulse contrast in the J-KAREN-P laser system with the plane-parallel plates of (a) approximately 1 mm, (b) approximately 3 mm, (c) approximately 5 mm, (d) approximately 8 mm and (e) approximately 11.8 mm. The green line is for calibration (the plane-parallel plate is placed after the compressor). The blue line, red line and black filled circles are obtained with the output energies of approximately 45, 1.8 and 26 J, respectively. These energies correspond to the B-integrals of approximately 0.037, 0.25 and 0.85 rad, respectively.

Fig. 3. (a) Summary of pre-pulse peak contrast in the J-KAREN-P laser system with plane-parallel plates of approximately 1, 3, 5, 8 and 11.8 mm. The blue, red and black filled circles are obtained with the output energies of approximately 45, 1.8 and 26 J, respectively. These energies correspond to B-integrals of approximately 0.037, 0.25 and 0.85 rad, respectively. (b) Summary of the time delay versus the plane-parallel plate thickness.

Fig. 4. Representative measured artificial and real pre-pulses in the J-KAREN-P laser system by the Ti:sapphire pre-amplifier crystal.

Fig. 5. Typical contrast of the J-KAREN-P laser system (a) before and (b) after employing optical components with a small wedge angle.

Fig. 6. Typical contrast of the J-KAREN-P laser system with the Öffner stretcher convex mirror roughness of (a) 1–2 nm RMS (blue line) and (b) 0.2–0.3 nm RMS (red line).