Holographic microinterferometry of laser-produced plasmas with frequency-tripled probe pulses

Holographic microinterferometry is used to study plasmas produced by high-intensity subnanosecond pulses from a Nd laser. The probing pulse is frequency tripled to 3547 Å in order to reduce refractive errors due to steep density gradients and to reduce spatial resolution requirements. Measured electron densities as high as one-fourth critical for 1.06 μm are presented. Factors concerning the extension of these measurement to 1021 electrons/cm3 are discussed.