Andrew J. Harvie and John C. de Mello have created OLIA, an open-source digital lock-in amplifier. Digital lock-in is a method for isolating weak signals to facilitate measurement amongst background noise, which is processed away via digital signal processing (DSP).

The Open Lock-In Amplifier (OLIA) is a Teensy 4.0-based system that can outperform far more expensive commercial devices for around $35. OLIA offers dual-phase lock-in detection at multiple harmonic frequencies up to 50KHz, adjustable levels of input gain, and a comprehensive API for remote control. An optional breakout board allows optical detection down to 40 pW. Complete details about the project, as well as firmware, schematics, and BOM can be found in the original research paper.