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A long‐pulsed neodymium‐doped yttrium aluminum garnet (Nd:YAG) frequency‐doubled laser with no Q‐switch was constructed for optical measurements of high‐velocity phenomena. The laser consists of a doubled‐elliptical pump cavity with a Nd:YAG rod and two xenon flash lamps, an intracavity potassium titanyl phosphate crystal, and a high‐voltage electrical‐pulse source. A narrow‐band‐stimulated emission at the frequency‐doubled 532‐nm wavelength was confirmed by a spectrometer. The delay time from a trigger signal and the effective pulse duration were approximately 40 and 65 μs, respectively. The laser average output power was measured to be larger than 6 kW by a pyroelectric joulemeter. This laser may be used as a flash monowavelength light source, and also as a long‐pulsed single‐mode laser in the visible wavelength region using for example, an intracavity etalon and/or a brewster plate.

We produced a long-pulsed dye laser with no Q-switch for the shock-wave measurement or time-resolved spectroscopy under shock compression of solids. The average output power of this laser was larger than 13 kW (effective pulse duration ; ∼50 μs). This laser has been used as a light source for the Hugoniot measurement of solids by the inclined-mirror method combined with a rotating-mirror type streak camera. It was confirmed that the time resolution of Hugoniot measurement increased to higher than 1 ns.

The high-time-resolution streak photographic system equipped with a powder gun and a two-stage light gas gun has been constructed for the Hugoniot measurement of solids at pressures up to >300 GPa. For this system, a compact rotating-mirror-type streak camera and a long-pulsed dye laser with no Q-switch were produced. A time resolution higher than 1 ns was achieved by using a 2-µm-wide slit of the camera formed using the laser. The shock velocity and particle velocity of steady shock waves of the materials with a shock velocity of ~6 km/s can be measured by the inclined-mirror method with the basic errors of 0.2 and 0.1–0.2%, and 0.2 and 0.35–0.45% for symmetrical and asymmetrical impact, respectively, depending on shock velocity and impact velocity.