A light detection and ranging (LIDAR) system includes an optical source to emit an optical beam, where a local oscillator (LO) signal is generated from a partial reflection of the optical beam from a partially-reflecting surface proximate to the first focal plane, and where a transmitted portion of the optical beam is directed toward a scanned target environment. LIDAR system to focus the LO signal and a target return signal at a second focal plane comprising a conjugate focal plane to the first focal plane. The system may also include a photodetector with a photosensitive surface proximate to the conjugate focal plane to mix the LO signal with the target return signal to generate target information.