To measure light intensity, it is essential to understand that intensity relates to the power of the light source and the area over which it is measured. Photodiodes are commonly used for measuring light intensity, as they convert incoming photons into an electrical current, which correlates with the number of photons hitting the device. For varying intensities, one can either measure total power over an area for an average intensity or use an array of detectors to create a detailed intensity map. Calibration of detectors is crucial, often involving known reference points, such as a standard light bulb, to establish a relationship between current output and light intensity. Overall, understanding the principles of light intensity measurement is vital for accurate readings in optics.