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The design and development of an efficient high average power dye laser oscillator-amplifier system developed at the Laser & Plasma Technology Division, Bhabha Atomic Research Centre, is reported. The dye laser is pumped by a 6.5-kHz repetition rate copper vapor laser. The signal beam to the dye amplifier is obtained from an efficient narrow-band grazing incidence grating (GIG) dye laser oscillator incorporating a multiple prism beam expander. Amplifier extraction efficiency up to 40% was obtained in a single amplifier stage, using rhodamine 6G (Rh6G) in ethanol. We have also demonstrated simultaneous amplification of two laser beams at different wavelengths in the same dye amplifier cell.

A large number of autoionization resonances have been observed in uranium in the energy range 50,590–51,560cm−1 by two-step three-photon ionization technique, using two copper vapor laser pumped dye lasers. A Rydberg series converging to the ionization limit of UII at 1749cm−1 (6 L 13/2) has been identified. Some of these resonances are very narrow with a fwhm of 0.1cm−1. Possible origins of these are discussed.

Using two pulsed tunable dye lasers, a two colour multiphoton ionization process has been utilised to explore the higher energy levels of uranium. One hundred and thirty eight new UI levels have been observed in the 37540–38420 cm−1 region. J assignments of these levels have been suggested on the basis of their excitation from intermediate levels with known and contiguous J values. In eight cases the J assignments are unique.

An active wavelength stabilization and scanning system is described which reduces the dye laser wavelength fluctuation under feedback by detecting the changes in the fringe diameter of a temperature‐stabilized Fabry–Perot interferometer with the help of two photodiodes. An estimate of the wavelength drift due to thermal effects is made. Short‐ and long‐term fluctuations in the wavelength, monitored by recording iodine fluorescence are reported. The system response to a sudden external disturbance to the wavelength was studied.