An optical component for an interferometric imaging device, which comprises: an object arm, including a first planar waveguide and a first diffraction grating formed in the first planar waveguide and capable of extracting light from the object arm; a reference arm, comprising a second planar waveguide and a second diffraction grating formed in the second planar waveguide and capable of extracting light from the reference arm; wherein the optical component is configured such that, in use with an optically reflective surface extending parallel to the plane of the optical component between the object arm and the reference arm, at least part of the light extracted from the object arm interferes with at least part of the light extracted from the reference arm.