Convergence delay calculation manner and its device null for real-time digital

摘要

PROBLEM TO BE SOLVED: To calculate focusing delay distance of a next focusing point, by using next- focusing-point's delay variable derived from focusing reference distance, integer focusing delay distance, and determining variable of a certain focusing point, deriving integer focusing delay distance and determining variable of the next focusing point, and adding delay variable to the integer focusing delay distance. ;SOLUTION: A delay variable calculator 30 calculates delay variable corresponding to an individual convergence element of n+1-th focusing point using focusing reference distance, integer focusing delay distance, and determining variable corresponding to an individual convergence element of n-th focusing point. An update part 40 calculates integer focusing delay distance, and determining variable corresponding to the individual convergence element of n+1-th focusing point using the delay variable calculated by the calculator 30. By adding integer focusing delay distance calculated by the update part 40 to the delay variable calculated by the delay variable calculator 30, focusing reference distance corresponding to the individual convergence element of n+1-th focusing point is calculated. Thus, only addition of a simple hardware allows focusing delay distance to be calculated accurately.;COPYRIGHT: (C)1998,JPO