Detectors respond to radiation by producing various physical effects which can be measured.
Some detectors will emit light pulses in response to radiation and by counting the pulses the intensity of the radiation can be found. Others will store the effects of radiation over a long periods and can then yield the information at a later time. Instruments can be designed to indicate either the rate at which the radiation is being received, or the integrated amount over a certain time. In practice it is difficult to realise such a device and most dose measuring instruments are compromises with some limitations on what type or energy of radiation they can measure. Accurate over a wide range of intensities.