Wavelength Swept Lasers
In optical interferometric metrology, the wavelength of light serves as a reference for length. At a given optical wavelength, an interference signal varies as a sinusoidal function of distance with a period equal to the wavelength. Although this approach offers unrivaled precision, the periodic signal results in a 2π ambiguity for measurement of lengths greater than one wavelength. In optical coherence tomography (OCT), one wishes to determine light scattering distances and distribution within a sample, but without the ambiguity. To accomplish this, OCT is based on interferometry using many optical wavelengths, each serving as a “ruler” with different periodicity. OCT traditionally has used broadband light sources providing a wide range of wavelengths, all simultaneously. Alternatively, a tunable light source emitting one wavelength at a time, rapidly swept over a broad spectral range, can also be used to achieve the absolute ranging capability in OCT.
KeywordsOptical Coherence Tomography Intensity Noise Cavity Length Tuning Range Gain Medium
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