AQT90 FLEX Service Training Optical Unit 21/04/2019 RADIOMETER A/S RADIOMETER PRESENTATION 21-04-2019

21/04/2019 RADIOMETER PRESENTATION Photometer Photodiode measures actual excitation energy, used for correction of measured counts

Measurement Cycle MEASUREMENT CYCLE 21/04/2019 RADIOMETER PRESENTATION Measurement Cycle MEASUREMENT CYCLE UV light pulse is focused onto the sample Europium is excited Europium relaxes and emits red light Red emission is focused onto the detector through a narrow band pass filter Typically 1000-3000 cycles per measurement MEASUREMENT CHARACTERISTICS Lowest light about 1 fW Lowest count ~500-1000 Dynamic range 14.000 Precision is limited by the number of photons counted CRITICAL ISSUES Sensitivity Background phosphorescence Dark counts

21/04/2019 RADIOMETER PRESENTATION Measuring

21/04/2019 RADIOMETER PRESENTATION Measuring - Reference During this measurement the photo count is high (>550.000) requiring fewer cycles (=1000) to obtain a precise result. After excitation the europium emits light with a decreasing intensity as shown. The time constant for the decay, Tau, must be in the range [800 ; 1200] for measurements on the reference cup

21/04/2019 RADIOMETER PRESENTATION Measuring - Dark During this measurement the photo count is very low (<20) requiring a large number of cycles (=3000) to obtain a precise result. The flashlight is off (low integrator value). The output is constant (except for noise). Since there is no decay, Tau should in principle be indefinite, which it is here (“NaN” means “Not a Number”). However, the low number of counts and the noise decreases the accuracy of the calculation, so almost any number could appear here.

Optical Unit RADIOMETER PRESENTATION End of session Optical Unit 21/04/2019 RADIOMETER A/S RADIOMETER PRESENTATION 21-04-2019