DITP 0.5 Micron Imaging Ladar Target Speckle Statistics and their Impact on Discrimination

The direct detection 3D imaging laser radar developed by BMDO under the DITP effort and currently being integrated for a demonstration test flight in FY2001 has the capability of significantly improving the P(K) of an interceptor by providing substantially enhanced discrimination. This is especially true for threats of high interest where closely spaced objects defeat the capability of passive sensors to discriminate based on intensity modulation due to coning. The DITP 3D ladar can easily resolve such CSO's it also has an inherent advantage in that the same amount of coning will result in 3 times as much modulation as the passive sensor would observe. The 3D ladar can also observe the actual object orientation once it is angularly resolved. This can cut through confusion the passive sensor could experience where different combinations of aspect and coning angle can yield the same modulation amplitude. The ability of the 3D ladar to deliver such benefits hinges on the accuracy of its intensity measurements. This paper will present analysis backed by experiments which indicates that while speckle is a potential problem the intensity fluctuations it introduces can be mitigated by multi-pulse averaging. Sufficient engagement timeline exists for such an approach when proper trades between pulse energy rep rate and beam profile are made. Such trades will be presented in detail as will the proper method for estimating the extent of speckle expected for an overall target individual range bin or single angle-angle pixel within a range bin.