The FST-001-B is a piezo-driven fiber stretcher with an optical delay range of up to 3 mm. The device, including the piezo driver, is packaged in a metal enclosure. Each of the four piezos can be controlled independently, allowing high resolution or large stroke. Piezos can be controlled with an analog signal or a 12-bit TTL signal. Under analog control, the driving circuit acts as a 4-channel voltage amplifier with 30V/V amplification.