OLIA: an open-source digital lock-in amplifier

TL;DR

OLIA is an open-source, low-cost digital lock-in amplifier built with a microcontroller, offering advanced features comparable to expensive commercial devices, suitable for optical detection and remote control.

Contribution

This paper introduces OLIA, a compact, affordable, open-hardware digital lock-in amplifier with versatile features and open-source design, expanding accessibility for scientific measurements.

Findings

OLIA costs around US$35 and fits on a credit card.

It supports dual-phase lock-in detection up to 50 kHz.

Includes an optical breakout for noise-tolerant detection down to 40 pW.

Abstract

The Open Lock-In Amplifier (OLIA) is a microcontroller-based digital lock-in amplifier built from a small number of inexpensive and easily sourced electronic components. Despite its small credit card-sized form-factor and low build-cost of around US$35, OLIA is a capable instrument that offers many features associated with far costlier commercial devices. Key features include dual-phase lock-in detection at multiple harmonic frequencies up to 50 kHz, internal and external reference modes, adjustable levels of input gain, a choice between low-pass filtering and synchronous filtering, noise estimation, and a comprehensive programming interface for remote software control. OLIA comes with an optional optical breakout board that allows noise-tolerant optical detection down to the 40 pW level. OLIA and its breakout board are released here as open hardware, with technical diagrams, full parts-lists, and source-code for the firmware provided as Supporting Information.