Which parameters only need to be filled out for pulse lasers during a survey?

The correct choice focuses on parameters that are specifically relevant to pulse lasers during a survey, emphasizing the unique characteristics of pulsed laser operation.

Energy per pulse is critical because it quantifies the amount of energy delivered in each pulse, influencing potential risk levels and the design of safety measures. Pulse width describes the duration of each pulse, which can affect the laser's interaction with materials and biological tissues, thereby impacting safety assessments. Beam distribution is also vital as it refers to how the energy is spread out in the space, which is essential for understanding exposure risks and determining appropriate control measures.

In contrast, the other options incorporate parameters that may not be specifically relevant to pulse lasers. For example, power density relates more to continuous wave (CW) lasers, where the measure of energy delivered over an area is a priority. Similarly, source size can be more indicative of the overall configuration of the laser setup rather than specific characteristics tied to pulsed operation. Control measures, while always necessary, do not pertain specifically to the survey of pulse lasers in the same detailed manner as the specified parameters in the correct answer. Focusing on the specific operational characteristics of pulse lasers allows for better risk assessment and safety implementation tailored to the unique nature of these devices.