A method and apparatus is provided to calibrate a LiDAR using a reflect array calibration target having a spatially varying spectral reflectance profile. A frequency modulated continuous wave LiDAR emits a beam that spans a range of wavelengths, and, therefore, spatially varying spectral features in the reflectance profile can be used as indicia of where the LiDAR beam hits the calibration target. For example, the center has one absorption wavelength and the periphery has another, such that alignment is achieved by changing the alignment direction to maximize the spectral feature at the one absorption wavelength while minimizing the spectral feature at the other absorption wavelength. Alternatively, at least one spectral feature can have a center wavelength that changes as a function of space. Thus, the LiDAR is aligned by changing the beam direction to shift the center wavelength to a value corresponding to the target center.