Apparatus and method for measuring characteristics of optical pulses

A method for measuring characteristics of optical pulses in an input light beam comprising the steps of:

• (a) splitting the input beam of optical pulses to be measured into first and second beams,
• b) modulating an optical path length of one of the first and second light beams,
• (c) changing an optical path length of one of the first and second light beams relative to the other of said first and second light beams,
• (d) mixing the first and second light beams,
• (e) detecting a light beam output from said optical mixer, and
• (f) measuring the amplitude of an AC signal output from said optical detector;
• wherein said modulating the optical path length of one of the first and second light beams and said detecting the light beam from the optical mixer performs heterodyne detection in order to measure the AC signal component which is generated by the modulation of the optical path length.

An apparatus for measuring characteristics of optical pulses comprising:

• (a) a beam splitter for splitting an input beam of optical pulses to be measured into a pair of light beams output therefrom;
• (b) means for modulating the optical path length of one of the pair of light beams output from said beam splitter;
• (c) means for changing the optical path length of one of said pair of light beams output from said beam splitter relative to the other of said pair of light beans output from said beam splitter;
• (d) means for chopping one of said pair of light beams output from said beam splitter;
• (e) an optical mixer for mixing the pair of output light beams;
• (f) an optical detector for detecting a light beam from said optical mixer;
• (g) detecting means for detecting the amplitude of an AC signal output from said optical detector;
• and
• (h) synchronous detecting means for detecting the amplitude of the output from said detecting means synchronously with the operation of said light chopping means.

A method for measuring characteristics of optical pulses in an input light beam comprising the steps of:

• (a) splitting the input beam of optical pulses to be measured into first and second beams,
• (b) modulating an optical path length of one of the first and second light beams,
• (c) changing an optical path length of one of said first and second light beams relative to the other of said first and second light beams,
• (d) chopping one of the first and second light beams,
• (e) mixing the first and second light beams,
• (f) detecting a light beam generated by said mixing,
• (g) detecting the amplitude of an AC signal produced from the detecting of the light beam, and
• synchronously detecting the amplitude of an AC modulation component in the detected AC signal from the detecting of the light beam in synchronism with the chopping of one of the first and second light beams;
• wherein said modulating the optical path length of one off the first and second light beams, said chopping of one of said first and second light beams, said detecting of the amplitude of an AC signal produced from the detecting of the light beam and said synchronously detecting the amplitude of an AC modulation component in the detected AC signal from the detecting of the light beam performs heterodyne detection in order to detect and measure the AC modulation component which is generated by the modulation of the optical path length.