The methodology and apparatus are described to perform tunable repetition rate optical spectroscopic measurements using high‐power visible diode lasers. Here, a train of picosecond pulses interrogates a material, a sample, or a device under test. The response of the sample or device varies as the pulse repetition frequency changes. Using an rf modulated high‐power AlGaInP 670‐nm diode laser, the pulse train repetition frequency may be smoothly varied from the kHz range up to the GHz range. The power and the pulse width may be kept constant by adjusting the rf power and the dc injection current. This procedure is automated through computer control. Here we describe the details of our particular setup and present examples of the technique.