Device used to visualise and record the course of physical processes which change over time, and particularly those involving oscillation. The following distinction is made in terms of functionality:
- The fluid-jet oscilloscope, which uses a nib or ink jet to write on graph paper and is suitable for processes of up to around 1 Hz.
- The light-beam oscilloscope mainly uses UV light, which is deflected by a fine mirror secured to a wire frame. A surrounding polygonal mirror allows things to be represented on light-sensitive paper and on a screen. The light-beam oscilloscope is suitable for frequencies of up to around 10 kHz.
- The cathode ray oscilloscope deflects the beam from a cathode ray tube (Braun tube) in proportion to the input signal and time. With a cathode ray oscilloscope, it is possible to represent things on the screen, set things down on paper and save curves. In addition, since the cathode ray oscilloscope can process signals of up to around 100 MHz, it has now largely eclipsed the other principles.