Reference Diode in PDA/UV

who knows how to explain the role of reference diode in the PDA/TUV? Thanks


  • Basically the reference diode in the PDA measures the light intensity from the lamp directly, and it will adjust the exposure time to give the same energy output from the lamp during the lifetime of the lamp. The reference diode in the TUV is used to measure the light before it enters the flow cell, so the absorbance measured is the difference between the sample diode and the reference diode. So the reference diode has very different functions in the PDA and the TUV.