ULTRAVIOLET RECORDER

Typical Number in Hospital: 3

Cost Bands: 4,5

References:

Signals which change rapidly (e.g. above 50 Hz maximum frequency) may not be accurately recorded using a pen recorder. This problem can be overcome by using a low-inertia galvanometer system. In the ultraviolet recorder ultraviolet light is directed through a slit and lens system on to a tiny mirror mounted within a small galvanometer coil in a narrow tube placed in a strong magnetic field. As the current in the coil varies in time with the signal to be measured the mirror swings so directing the beam of ultraviolet light on to a moving paper strip. A number of different signals may be recorded simultaneously but this may cause problems of identification of each channel if they cross over.

Ultraviolet recorders may be used wherever high-speed operation is required. They are sometimes used to record electromyograms (EMG).