Methods and apparatus for accurately determining wavelength by compensating a time delay using a bidirectional wavelength scan are provided. One example method generally includes introducing first wavelength-swept light into an optical waveguide according to a first sweep function having a first wavelength sweep direction; interrogating one or more optical elements, having characteristic wavelengths, with the first wavelength-swept light to produce a first set of optical signals, wherein the optical elements are disposed along the optical waveguide; introducing second wavelength-swept light into the optical waveguide according to a second sweep function having a second wavelength sweep direction, wherein the second wavelength sweep direction is opposite the first wavelength sweep direction; interrogating the optical elements with the second wavelength-swept light to produce a second set of optical signals; and determining a parameter associated with at least one of the optical elements based on the first and second sets of optical signals.