The master thesis presents the design and development of an optical instrument laser harp, which is meant for free-space optical playing. As the product is not widely available on the market, the development of the instrument was carried out using widely available low-cost components. Using these and the knowledge acquired during the study of electrical engineering, it is possible to produce a product that is comparable to the ones available on the market but at a much lower price.
A working prototype of a laser harp has been produced using the method of rapid home workshop printed circuit board (PCB) prototyping. Laser harp is a musical instrument that projects laser beams through the air instead of using metal string and consist of three main parts, which are a laser fan, a dedicated optical receiver and a microcontroller unit. The microcontroller unit was programmed using low-level programming in the C programming language without the use of dedicated libraries. The microcontroller unit performs all the logic operations required to detect the touch of a string, produce the laser fan and communicate with the sound player. The laser fan consists of a single laser which is directed around the room by a galvanometer with an attached mirror. The touch of a string is detected by a dedicated optical receiver which uses a photoresistor that changes its resistance if the reflection of a laser beam shines on to it when the string is touched. For the sake of simplicity and lower cost the tone is produced by a computer to which the microcontroller unit forwards data via serial RS-232 and USB communication. A Python script running on the computer then digitally processes the received data and plays the tone corresponding to the touched string.
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