Holographic Wavefront Correction for ShADOE LIDAR Receivers, Phase II

Current shared aperture diffractive optical elements (ShADOE) have intrinsic residual wavefront errors on the order of 50 waves which limits the angular resolution of the LIDAR application to about 300 micro-radians. We have reduced these aberrations by constructing a secondary holographic correction plate using the aberrated wave from the ShADOE as one of the two construction waves. The other construction wave was collimated. All six overlapping apertures require individually constructed plates, we delivered only 2 thus far. This method of correction requires the use of the final playback wavelength for construction and so is useful for 532 and 355nm but not for 2054 nm. Computed diffractive optics can be used for 2054 nm using measured aberrations at the same wavelength. This proposal deals just with a continuation of fabrication and test of the 2 inch 355 nm holographic correction plates (HCP) to bring resolution well under 50 micro radians. Secondarily we propose to make and measure a small 2054 nm ShaDOE and demonstrate a digitally mastered HCP that will approach diffraction limited performance as required at that wavelength. More »