An imaging apparatus adjusts the polarization directions of irradiation beams (to a diffraction grating) corresponding to first and second beams respectively which have different polarization directions (for example, by adjusting a relative angle formed between light-emitting ends of respective polarization maintaining fibers) so that the spectral characteristics of the irradiation beams at the diffraction grating coincide with each other. Then, the imaging apparatus acquires a tomographic image indicating polarization information for a object based on beams (that come from the diffraction grating for splitting and diffracting a beam from the adjustment unit) corresponding to the first and second beams respectively which have different polarization directions.
