beam into an array of beams in parallel or fan arrangement. Playing the actual sound is usually handled by connecting the laser harp to a synthesizer, sampler or computer. This frameless design is more elaborate than the framed style, relying on reflecting the light back to a single photodiode. The fan of laser beams is actually a single beam scanned into a fan pattern. By matching the timing of the reflected beam, the instrument can determine which beam the player is blocking and sound the corresponding note. Alternative designs use multiple lasers. In these designs, each laser can be independently controlled (pulsed on and off) to Several techniques generate more control data, such as a continuous range of values like those in typical MIDI controllers: An infrared or ultrasonic rangefinder attached to the instrument that determines the position of the hand that blocks a beam A laser-based rangefinder that determines the distance from the hand to the laser's starting or ending point (and possibly using this laser itself as the string)—or a variation of this that uses the intensity of the sensor signal itself A camera that tracks position and motion of the laser dot on the hand, or length of the exposed beam if visible, then calculates a continuous value based upon a reference The first of these is relatively inexpensive and straightforward to implement, and can use the same micro-controller that drives the lasers and reads the detectors. The advantage of a dedicated sensor mechanism is that the instrument can be self-contained, as opposed to requiring a computer to control it with input from an ILDA interface and USB camera. The PC-based approach, however, offers more flexibility and can be constructed with mostly off-the-shelf hardware. Unframed laser harps benefit from the use of higher-power lasers, as they facilitate easier detection by the sensor system. As the sensor is exposed to all ambient light, it can be swamped by stage lighting behind the artist if the sensitivity is too high. To avoid this, the system can use ambient light sensors to reject ambient light. The player may use white or light-coloured gloves to improve performance by scattering more light off the player's hands to provide the sensor with a higher signal-to-noise ratio with respect to ambient light. Furthermore, the gloves protect the player's skin from potentially hazardous laser radiation and give audiences a more visual impression of the instrument.