The Challenge of Evidence-Based Medicine and Standardization in Health Care

A twin beam photometer using a discharge tube, the radiating flux of which is modulated by magnetic means. The photometer selects from this modulated radiating flux two radiating beams, the distance from each other being determined by the amplitude of the radiating flux. Measuring cells are placed in the track of each radiating beam; the radiation from both radiating beams is received in a radiation detector.