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We report on the construction and characterization of a low-cost Mach–Zehnder optical interferometer in which quadrature signal detection is achieved by means of polarization control. The device incorporates a generic green laser pointer, home-built photodetectors, 3D-printed optical mounts, a circular polarizer extracted from a pair of 3D movie glasses, and a python-enabled microcontroller for analog-to-digital data acquisition. Components fit inside of a [Formula: see text] space and can be assembled on a budget of less than US$500. The device has the potential to make quadrature interferometry accessible and affordable for instructors, students, and enthusiasts alike.
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A compact and open-source microcontroller-based rapid auto-alignment system
Maintaining stable and precise alignment of a laser beam is crucial in many optical setups. In this work, we present a microcontroller-based rapid auto-alignment system that detects and corrects for drifts in a laser beam trajectory using a pair of two-dimensional duo-lateral position sensing detectors (PSDs) and a pair of mirror mounts with piezoelectric actuators. We develop hardware and software for interfacing with the PSDs and for controlling the motion of the piezoelectric mirror mounts. Our auto-alignment strategy—implemented as a state machine on the microcontroller by a real-time operating system kernel from FreeRTOS—is based on a simple linearized geometrical optical model. We benchmark our system using the standard case of coupling laser light efficiently into the guided mode of a single-mode fiber optic patch cable. We can recover the maximum fiber coupling efficiency in ∼10 seconds, even for a laser beam misaligned to the point of zero fiber coupling efficiency.
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- Award ID(s):
- 2120757
- PAR ID:
- 10592925
- Publisher / Repository:
- Review of Scientific Instruments
- Date Published:
- Journal Name:
- Review of Scientific Instruments
- Volume:
- 95
- Issue:
- 9
- ISSN:
- 0034-6748
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1063/5.0211005
