Is it easy to learn to play the harp? Probing Google reveals that many musically inclined individuals are looking to answer similar questions about musical instruments. This searcher’s quest ended midway through an online forum in which users were exploring the topic, “On a scale from kazoo to violin, how hard is it to learn to play the lute?” The only conclusions achieved from this search are that (a) the harp is one of the more difficult instruments to learn, and (b) adding semiconductor laser diodes to the task is unlikely to simplify the task. Courtesy of iStock.com/hepjam. Neither of these factors deterred a few gifted electronics engineers, all former students from the Southern Alberta Institute of Technology (SAIT), who were also musically inclined. In November 2020, Kathryn Talabucon, Jahziel Ortega, and Rohnin Menezes introduced an instrument they called the “laser harp.” Rather than physical strings, the instrument features eight semiconductor diode lasers aimed at a corresponding number of photoresistors. To produce notes, players selectively block each laser’s beam — which, much like on a conventional harp, can be achieved with a stroke of the finger. Depiction of the Laser Harp, featuring a volume adjustment option and a foot petal. The strings in the system are laser diodes. Courtesy of Kathryn Talabucon via Calico Communications. “Each laser is pointing at a photoresistor to send a signal on the microcontroller and produce a sound,” Talabucon said. An LCD readout informs players of the precise note they are making as they work their way either through a demonstration or the concerto of their choice. Completed in early 2020, the all-digital harp went largely unheard until later in the year, due to the pandemic. However, the instrument eventually earned its three developers — who met virtually and built the pieces separately — third prize in the Technology Accreditation Canada’s 2020 Technology Report Contest. Talabucon told Photonics Media that the team designed the digital harp to power its laser diodes without risk of overheating — using 20-mA current and 5 V. She said semiconductor laser diodes were optimal because they are safe, power-efficient, inexpensive, and easy to fit in any possible design. Front View of the Laser Harp. Courtesy of Kathryn Talabucon via Calico Communications. The finished laser harp sounds more like an electric guitar, though it offers a few intangible benefits. Since there are no strings, at least not in the conventional sense, there are no physical parts that could rust or break. The harp also acts as its own recording device, enabling players to record the music they make, as well as change octaves and control volume. None of the team members are classically trained musicians. They are, however, practical engineers. Talabucon said a critical element of the project involved purchasing pre-made laser diodes that cost less than the individual components needed to build and assemble them. The team’s previous experiences with lasers were limited. Talabucon said she had worked with laser diodes as part of a lab project she participated in at SAIT. She and her classmates had used them to determine the behavior of a motor operating at various speeds and powers. At her current workplace, she said, an orthotic technician uses similar diodes for test and measurement purposes. Her team’s award-winning laser harp instrument, though, is an impressive feat of engineering and ingenuity. In other words, something to harp on.