M140: Pulsed or constant current ? which is the best pulse frequency ?

hi,

what is the best use with a nichia M140 diode - pulsed or constant ?

if pulsed, which frequency is recommended ? Signal type ? (Rectangular or Sinus pulse)
in the datasheet i can not find a pulse width value.



the same question for a NDV4542
this is a 100mW 405nm laserdiode
CW = max 200mW
pulse = max 400mW

here i have found a pulsewidth 30ns (WOW 33,3MHz ???) , but which signal type ?

can i increase the lifetime, if i adjust the output to 200mW pulsed ?

thanks to this great community