A resolution criterion of general validity is given, and the dependence of autoradiographic resolution on all essential parameters is calculated.The effects of geometric factors (thickness of the emulsion, thickness, size, and number of radioactive objects, and the interspace between the emulsion and the object) and of beta energy on resolution are described first, with the simplifying assumption of linear autoradiographic transfer.The totality of factors influencing resolution can be understood only by considering nonlinear autoradiographic transfer. Here the exposure, the properties of emulsion (sensitivity; maximum number of grains per unit volume of emulsion; diameter of grains; background grain density) and the conditions of observation (autoradiographic “signal-to-noise ratio”; area of measurement) are considered. Increasing the exposure leads to an optimal value of autoradiographic resolution at the beginning of nonlinear transfer; overexposure decreases resolution again.The maximum resolution equals twice the diameter of grains. This parameter is not contained in the basic model and must be considered separately.This theoretical treatment of the resolution problem explains the experimental results quoted in literature in at least a semi-quantitative manner. Possible improvements of the model are discussed.
Geometric factors influencing the diet of vertebrate predators in marine and terrestrial environments