From Phase Conjugate Laser Optics   Pointing stability   As demonstrated by the measured beam quality of
the laser output, SBS phase conjugation effectively corrects both the passive optical
figure errors in the transport optics and the thermally induced aberrations in the glass
amplifier. A very valuable aspect of this correction is also the cancellation of the
first-order aberration of tilt in the amplifier system resulting from vibration, air
disturbances, and long-term alignment drift. For precision, long-range illumination
applications, it is critical that the laser system maintain reproducible shot-to-shot
pointing. We have demonstrated that the incorporation of the SBS phase conjugate
mirror is key to maintaining very tight beam pointing control. Rigorous relay-
imaging through the amplifier system allows small drifts in pointing of the many
optical components in the beam train without introducing aperture clipping in the
amplifier. SBS phase conjugation then cancels these errors so that the output

pointing stability of the high-power laser system is determined only by that of the
low-power injection laser.

Figure 5.24 illustrates a measurement of the shot-to-shot pointing stability over
the course of 100 full-energy laser pulses at 3 Hz. The RMS pointing error in each
dimension is ~ 8% of the 2λ / D...

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Lasers are devices that produce intense beams of monochromatic, coherent radiation. The word "laser" is an acronym for Light Amplification by Stimulated Emission of Radiation.
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Diode lasers use light-emitting diodes to produce stimulated emissions in the form of coherent light output. They are also known as laser diodes.
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Ion lasers function by stimulating the emission of radiation between two levels of an ionized gas. They provide moderate to high continuous-wave output of typically 1 mW to 10 W.
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Helium neon (HeNe) lasers have an emission that is determined by neon atoms by virtue of a resonant transfer of excitation of helium. They operate continuously in the red, infrared and far-infrared regions and emit highly monochromatic radiation.
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Helium cadmium (HeCd) lasers are relatively economical, continuous-wave sources for violet (442 nm) and ultraviolet (325 nm) output. They are used for 3-D stereolithography applications, as well as for exposing holographs.

Topics of Interest   Coherence length   An important motivation behind the generation of long-duration, high-energy pulses from this laser system was provided by coherent imaging applications that...   Phase-locked pointing stability   The mechanical isolation of the injection laser system from the amplifier optical bench was expected to provide significantly increased pointing...

C. BRENT DANE and LLOYD A. HACKEL Lawrence Livermore National Laboratory, Livermore, California 94550, USA 5.1   INTRODUCTION There are a number of important applications that require both high...   Injection laser mechanical isolation   The long-range illumination application for which this laser system is intended demands very high beam point stability. As previously...   Operation with an SBS phase conjugator   By replacing the Pockels cell in the regenerative amplifier ring with a 90o quartz rotator as depicted in Fig. 5.5, an injected pulse from...