Patent ID: 7830526

Claim:
A method for optical frequency measurement for measuring the frequency of a laser under measurement (LUM), comprising steps of: operating two frequency-stabilized mode-locked laser combs at a first repetition rate and a second repetition rate, and mixing said frequency-stabilized mode-locked laser combs with the LUM to generate a first beat frequency and a second beat frequency, respectively; using a dispersion device to measure an approximate frequency of the LUM and calculating an approximate ordinal comb number according to the approximate frequency, the first repetition rate, and the second repetition rate; calculating the ordinal comb number difference where the first beat frequency and the second beat frequency are generated according to the first repetition rate, the second repetition rate, the offset frequencies, the first beat frequency, the second beat frequency and the approximate ordinal comb number; calculating an ordinal comb number of the comb lines, which generates said first beat frequency or said second beat frequency, from said ordinal comb number difference; and calculating the frequency of the LUM according to the repetition rate, the offset frequency, the beat frequency, and the ordinal comb number.