Patent ID: 8456640

Claim:
An apparatus for measuring a reflectance of an optical laser component, the apparatus comprising: a function generation unit configured to generate a square-wave signal; a semiconductor laser whose excitation current/voltage is modulated by the square-wave signal from the function generation unit; a beam splitter splitting a laser beam from the semiconductor laser into a reference laser beam and a probe laser beam; an optical ring-down cavity having at least three mirrors, wherein the optical laser component is placed inside the optical ring-down cavity; a first detector measuring a power of the probe laser beam exiting the optical ring-down cavity, and transforming the power into a first electrical signal; a second detector measuring a power of the reference laser beam, and transforming the power into a second electrical signal; first and second optical lenses or lens sets focusing the probe laser beam and the reference laser beam into the first and second detectors, respectively; a data acquisition unit acquiring and recording the first and second electrical signals from the first and second detectors; and a computer controlling the function generation unit and data acquisition unit, and processing the first and second electrical signals from the first and second detectors to determine the reflectance of the optical laser component.