InterPI-A Python open-source project for laser interferometry using a Raspberry PI-Part 1: Hardware Control

Abstract

This MSc thesis describes the implementation of an open-source Signal Processing Unit, required in any laser interferometer, using low-cost and widely accessible hardware, more concretely, on a Raspberry Pi and on a compatible audio card. The primary concern of this project is to interface with the audio card in such a way that there is a predictable latency between modulation and demodulation, as this is a necessity for the signal processing approach. This project forms part of an open-source initiative by Engineering Photonics at Cranfield University to widen the usage of laser interferometry, in this case by drastically reducing the prices of the Signal Processing Unit, to perform optical displacement measurements at nanometre levels or optical fibre sensor interrogation.