LIRIC calibration based on multiphoton excitation

A system for forming subsurface optical structures within an ophthalmic lens, the system comprising:

• a laser pulse source operable to generate a sequence of laser pulses;
• a laser pulse power control assembly operable to selectively control an energy of respective laser pulses of the sequence of laser pulses;
• a scanning assembly controllable to focus the sequence of laser pulses onto sub-volumes of the ophthalmic lens;
• a detector configured to generate a feedback signal indicative of an energy absorbed by the ophthalmic lens from a first laser pulse of the sequence of laser pulses;
• and
• a control unit operatively coupled with the laser pulse power control assembly and the detector, wherein the control unit is configured to control operation of the laser pulse power control assembly to selectively control an energy of a second laser pulse of the sequence of laser pulses based on a selected energy of the second laser pulse, a selected energy of the first laser pulse and the feedback signal.