Semiconductor Inspection And Metrology System Using Laser Pulse Multiplier

摘要

A pulse multiplier includes a beam splitter and one or more mirrors. The beam splitter receives a series of input laser pulses and directs part of the energy of each pulse into a ring cavity. After circulating around the ring cavity, part of the pulse energy leaves the ring cavity through the beam splitter and part of the energy is recirculated. By selecting the ring cavity optical path length, the repetition rate of an output series of laser pulses can be made to be a multiple of the input repetition rate. The relative energies of the output pulses can be controlled by choosing the transmission and reflection coefficients of the beam splitter. This pulse multiplier can inexpensively reduce the peak power per pulse while increasing the number of pulses per second with minimal total power loss.

主权项

1. A pulse multiplier comprising:
a first ring cavity including:
a first beam splitter;a set of one or more mirrors; and a second ring cavity including:
a second beam splitter; anda second set of one or more mirrors;wherein the first beam splitter directs a first fraction of each input laser pulse to the second beam splitter, and directs a second fraction of each input laser pulse into the first ring cavity, andwherein the second beam splitter directs a third fraction of each pulse incident on it to an output of the pulse multiplier, and directs a fourth fraction of energy of each pulse incident on it into the second ring cavity.