Compact diode laser homodyne vibrometers

We discuss the architecture and performance of compact, robust, alignment-free, homodyne vibrometers using telecom diode lasers as the illumination source. The technical challenges and performance of implementations using conventional macroscopic optical components are compared with ultra-miniature micro-bench components and assembly methods. Focused sensitivity exceeding 4.6 pm/SQRT(Hz) at 1m range, 23 pm/SQRT(Hz) at 5m range, and useful operation to >20m have been demonstrated with COTS 1550 nm sources, 1.5 cm transmit/receive beam diameter and 32 mW transmitted power. Vibrometer measurement bandwidth exceeds 100 kHz with current electronics. Demonstrated performance is suitable for a variety of defense, security, and inspection applications.