Which intensity is the pulse average during the pulse duration?

• A. Itp
• B. Ita
• C. Ipa
• D. Isptp

Answer: (C)

When a source emits energy in bursts, different ways of measuring intensity capture different parts of the burst cycle. The pulse-average intensity is the average energy delivery per unit area during the actual pulse window. It is defined as the energy in a single pulse divided by the beam area and the pulse duration: I_pa = E_pulse / (A × pulse duration). This focuses on what happens during the pulse itself, ignoring the waiting time between pulses.

In contrast, the time-averaged intensity over the entire exposure includes the off-time as well, so it’s lower by the duty cycle factor. The peak intensity during the pulse is the maximum value inside the pulse, which can be higher than the average during the pulse if the pulse isn’t flat. The spatial-peak temporal-peak measure considers the absolute maximum intensity at the hottest spot and at the moment of its maximum.

Thus, the description that matches “pulse average during the pulse duration” is the pulse-average intensity.