# FreiLaser: Flexible pulse generator for laser control in optogenetic experiments

## TL;DR

FreiLaser is a low-cost, flexible laser control system for optogenetics that offers precise control and a user-friendly interface.

## Contribution

A cost-effective and versatile open-source laser control system for optogenetic experiments.

## Key findings

- FreiLaser generates stable and temporally precise control signals for multiple lasers.
- The system includes a mask controller to prevent behavioral bias in experiments.
- Its open-source design allows adaptability for various experimental needs.

## Abstract

To facilitate optogenetic experiments in neuroscience, we designed a cost-effective (<40 €) and versatile laser control system, FreiLaser, based on the Raspberry Pi Pico microcontroller running CircuitPython. FreiLaser allows precise control over various stimulation parameters for up to four lasers, utilizing both analog and digital signals. It features a user-friendly graphical interface for parameter configuration and real-time visualization, as well as an API for seamless integration with existing experimental setups. The system also includes a built-in mask controller to prevent behavioral bias by synchronizing masking LEDs with laser pulses. Validation tests confirmed that FreiLaser generates stable, temporally precise control signals, suitable for a range of stimulation patterns. The system’s flexibility, ease of use, and low cost make it an invaluable tool for researchers conducting optogenetic and behavioral studies. Our open-source design ensures accessibility and adaptability for a wide range of experimental needs.