Which parameter change increases the spot size?

• A. Decreasing spot size (mm)
• B. Increasing spot size (mm)
• C. Decreasing energy (J/cm2)
• D. Decreasing repetition rate (Hz)

Answer: (B)

Spot size is the diameter of the laser beam as it hits the skin. To increase the spot size, you adjust the system to produce a larger beam diameter, which expands the area treated with each pulse. This means you can cover more skin per pulse and treatment can be faster. Keep in mind that energy density (fluence) will drop if the pulse energy stays the same, since the same energy is spread over a bigger area; you’d need to increase energy to maintain the same dose. The other parameter changes don’t change the beam’s width—they affect how much energy per pulse or how often pulses occur, not how wide the beam is. So the action that increases the footprint on the skin is increasing the spot size itself.