Improvement in microscope photometry by voltage to frequency conversion: analogue measurement and digital processing

Abstract

A system for digital measurement of microscope photometric signals, based on Voltage to Frequency Conversion (VFC) and suitable for automatic data processing, has been devised. Advantages and disadvantages are illustrated with special emphasis on the comparison between photocurrent measuring and photon counting techniques. A statistical analysis of the results allows the calibration of VFC net counts versus detected photons. A biological application is reported; this shows the suitability of the system even to low light levels.