Designing a probe beam and an ultraviolet holographic microinterferometer for plasma probing.

The requirements and techniques for time- and space-resolved picosecond probing of laser-produced plasmas are reviewed. The design and limitations of a holographic microinterferometer are discussed, and optical pulse techniques are presented. This technique can provide significant data for understanding the absorption of energy within laser-produced plasmas. The primary requirements are to measure the electron densities in the 10(20)-10(21)-e/cc range, with density contour velocities of 10(6) to 10(7) cm/sec and spatial resolution of 1 microm or better. For these velocities one requires a probe pulse duration of 3-30 psec, an UV wavelength as short as feasible, and large numerical aperture optics corrected for spherical aberration. Interferograms of laser-produced plasmas obtained at 2660 A with a combined resolution of 1 microm and 15 psec are presented.