Team Name
Laser Harp Team
Timeline
Summer 2025 – Fall 2025
Students
- Dylan Nguyen – Computer Engineering
- Raul Salas – Computer Engineering
- Caleb Smith – Computer Engineering
- Aisosa Okunbor – Computer Engineering
- Jacob Shelton – Computer Engineering
- Ja’Kera Wilson – Computer Engineering
Sponsor
Dr. Shawn Gieser
Abstract
The Laser Harp is an electronic instrument built with 13 laser emitters paired with phototransistors. Each laser forms a beam aimed at a corresponding sensor, and when a beam is interrupted, the system detects the change and plays a programmed note through external speakers. The harp is constructed on a rigid frame made from metal extrusions, with a central PCB responsible for sensor inputs and note-to-beam mapping.
Additional PCBs mounted at the top of the frame handle laser alignment, mounting, and electrical connections. The design is completed with a wooden exterior that improves aesthetics while also adding stability and balance to the overall structure.
Background
A Laser Harp is an electronic instrument that replaces physical strings with laser beams and sensors. When a beam is interrupted, a phototransistor detects the change and sends a signal to our central PCB that triggers the corresponding musical note through the speakers. Ambient light, electrical noise, and precise laser alignment so that beam breaks are detected reliably without false triggers must be taken into account. This project uses multiple beams to sensor pairs, a note mapping system, and a stable frame
to create a playable instrument.
Project Requirements
- Interactive Laser-To-Note Functionality. The system must recognize when a user breaks a laser beam and play a corresponding musical note through an audio output device.
- Educational STEM Engagement Design. The instrument must support easy and intuitive interaction for K–12 students, encouraging learning through hands-on exploration.
- Modular Three-Piece Physical Structure. The harp must be delivered as three wooden components: laser housing, electronics enclosure, and support beam, packaged safely with pre-installed software.
- Rapid System Startup Capability. The system must become fully operational and ready to detect notes within 60 seconds of power-on, ideally within 5 seconds.
- Low-Latency Beam Detection Response. A beam interruption must be detected and transmitted as a MIDI event within 10 milliseconds to support real-time musical playback
- High-Speed MIDI Output Performance. The system must send MIDI Note On/Off messages over USB with minimal delay and support rapidly repeated hand movements.
- Dual Power Configuration Support. The harp must support both battery and wall-powered operation, with at least one hour of continuous runtime.
- Laser Safety Compliance. The system must use low-powered laser diodes and comply with ANSI Z136.1 and IEC 60825-1 safety standards.
- Electrical Safety and Wiring Compliance. All wiring must meet National Electric Code (NEC) standards, including grounding and over-current protection.
- Modular Repairability & Maintenance Access. The system must be repairable via modular subassemblies, labeled connectors, and accessible interior layout without soldering.
Design Constraints
- Safety & Welfare. The Laser Harp must use low-power lasers and safe electrical wiring to ensure it is safe for K–12 students to interact with.
- Constructability / Manufacturability. The device must be constructed using tools and materials available in the Senior Design lab and assembled using simple, repeatable methods.
- Cost / Economic Constraints. All components and materials must remain within the project budget while still meeting technical and safety requirements.
- Maintainability. The system must be designed with modular, easily accessible components that allow fast repairs and replacements without specialized equipment.
- Usability. The Laser Harp must be intuitive, responsive, and simple enough for students and teachers to use without prior training.
- Environmental Constraints. The system must operate reliably in different school environments with varying lighting, temperature, and ambient conditions.
Engineering Standards
- ANSI Z136.1 for Safe Use of Lasers
- IEC 60825-1 (Laser Safety Standard)
- NFPA 70 Standard for safe electrical design and installation
- IPC-A-610 (Acceptability of Electronic Assemblies)
- ISO 10303-21 (CAD data exchange for part documentation)
System Overview
The Laser Harp system is designed to create a virtual string instrument using a series of carefully aligned laser emitters and photodiodes. These components work together to form the appearance of strings. When a user interacts with the system by placing their hand or body in front of one of the laser beams, it interrupts the light path. This interruption is detected by the Raspberry Pi Pico to capture the signal. Based on which beam was interrupted, the Pico identifies which virtual string was activated. It then sends a specific digital signal to another Raspberry Pi. This second Raspberry Pi is responsible for mapping each of these signals to a particular musical note. It uses a SoundFont-based audio engine to process the note and generate the corresponding sound. The resulting audio is then played out through an external speaker, providing an instant musical response to the user’s interaction. All these elements combine to create an interactive and educational instrument that allows users to explore the principles of optics, embedded systems, and digital sound synthesis practically and engagingly.
Results
The Laser Harp system detects when a user interrupts laser beams and sends these signals through the Raspberry Pi Pico for processing. The Pico converts each interaction into a digital event that the Raspberry Pi maps to musical notes and plays through a SoundFont audio engine. Together, the hardware and software create a real-time, interactive musical experience designed for STEM education
Future Work
- Expandable Beam Count. Redesigning the frame to support more beams would allow full-scale musical performance and more complex demonstrations.
- Refine Physical Design. Redesign the wooden frame for better durability, easier transport, and a more professional, instrument-like appearance.
- Increase Laser Visibility. Make the laser beams more visible and visually engaging during demonstrations.
Project Files
Project Charter
System Requirements Specification
Architectural Design Specification
Detailed Design Specification
Color-Coded Wiring Schematic
Poster
Closeout Materials
