Application of a dithered sampling technique to increase the spatial resolution of singlet oxygen images

Singlet molecular oxygen (a1Δg) is an intermediate in many important oxidative reactions in heterogeneous biological and polymeric systems. By using a custom-made microscope to detect the 1270nm phosphorescence of singlet oxygen (a1Δg→X3Σg−), singlet oxygen images of such systems can be created. The microscope uses an InGaAs linear photodiode array to detect this extremely weak near infrared phosphorescence. In this article, the effects of the microscope’s modulation transfer function and the detector’s spatial sampling frequency on the resolution of the images are examined. It is shown that a dithered sampling technique can increase the accessible resolution. In this approach, data are repeatedly acquired from the sample after it has been systematically moved on the microscope stage.