A photon momentum sensor includes: a reflector plate that includes: a central disk including a mirror; an annular member; a plurality of spring legs interposed between the central disk and the annular member, such that: the spring legs are interleaved; neighboring spring legs are spaced apart; and the spring legs individually are arranged in an Archimedean spiral that provides orthogonal motion of the central disk relative to the plane of the annular member; and a bias plate disposed opposing the reflector plate such that: the central disk of the reflector plate moves orthogonally to a plane of the bias plate in response to reflection of laser light, and the central disk and the bias plate are arranged spaced apart as a capacitive structure.