The methodology and apparatus are described to perform tunable repetit
ion rate optical spectroscopic measurements using high-power visible d
iode lasers. Here, a train of picosecond pulses interrogates a materia
l, a sample, or a device under test. The response of the sample or dev
ice varies as the pulse repetition frequency changes. Using an rf modu
lated high-power AlGaInP 670-nm diode laser, the pulse train repetitio
n frequency may be smoothly varied from the kHz range up to the GHz ra
nge. The power and the pulse width may be kept constant by adjusting t
he rf power and the dc injection current. This procedure is automated
through computer control. Here we describe the details of our particul
ar setup and present examples of the technique.