  We demonstrate to image asymmetric molecular orbitals via high-order harmonic
generation in a one-color inhomogeneous field. Due to the broken inversion
symmetry of the inhomogeneous field in space, the returning electrons with
energy in a broad range can be forced to recollide from only one direction for
all the orientation angles of molecules, which therefore can be used to
reconstruct asymmetric molecular orbitals. Following the procedure of molecular
orbital tomography, the highest occupied molecular orbital of CO is
satisfactorily reconstructed with high-order harmonic spectra driven by the
inhomogeneous field. This scheme is helpful to relax the requirement of laser
conditions and also applicable to other asymmetric molecules.
