REDUCING THE SENSITIVITY TO VIBRATION IN NDIR DOUBLE BEAM PHOTOMETERS

摘要

According to an embodiment of the invention, the chopper disc for a non-dispersive infrared double beam photometer for gas analysis has two cut-outs through which light can be irradiated alternately into a reference side and a measuring side of the gas measuring cell. The size of the cut-outs is selected such that during a first time period light is irradiated substantially only into the measuring side and that during a second time period light is irradiated substantially only into the reference side of the gas measuring cell, wherein the first time period is longer than the second time period.