Holographic local-oscillator beam multiplexing for array heterodyne detection

Linear holographic gratings have been developed that can be used for amplitude and phase matching of local oscillator (LO) and signal wave fronts in heterodyne detection with infrared imaging arrays. With these holographic gratings the system's signal-to-noise ratio and resolution can be maximized, and the LO power dissipation on the focal plane can be minimized. A holographic surface relief pattern multiplexes the LO beam when a single LO laser beam illuminates it. Each beam of this multiplexed set then has the same amplitude shape as and is collinear with each element of the signal wave front illuminating the array.