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Sinusoidal wavelength-scanning superluminescent diode interferometer for two-dimensional step-profile measurement

Two-dimensional step-profile measurement is carried out with a sinusoidal wavelength-scanning interferometer where a large scanning width of 41 nm is easily achieved using a superluminescent laser diode of a wide spectral bandwidth of 46 nm. To detect a time-varying interference signal with a short integration time of 118 μs, a shutter function of a two-dimensional CCD image sensor is utilized. A step profile with a step height of 1 μm is measured with an error less than a few nanometers. A Step profile with a step height of 20 μm is also measured with a scanning width of 23 nm.