Scanning sensor scans on a circumference and simultaneously a radiation wave is received by scanning sensor to generate received signal Sm(f). A radiation wave is received by a fixed sensor at a position not changed with respect to the center of a circle with the circumference to generate received signal Sr(f). The received signal Sm(f) is made to interfere with the received signal Sr(f) to acquire an interference signal. The interference signal is detected to obtain measured data E(r,&phgr;) at each point on the circumference. Also, evaluation data V(&phgr;′) is calculated to estimate a direction of the radiation wave based on measured data E(r,&phgr;) at each point. A multi-dimensional hologram data processing apparatus consists of N-dimensional data array memory, N-dimensional flag array memory, N-dimensional array address generating unit, and digital signal processing unit. N-dimensional data array memory is written with N-dimensional array data; N-dimensional flag array memory is written with N-dimensional array flag values; N-dimensional array address generating unit generates addresses for the N-dimensional array data; and digital signal processing unit controls N-dimensional array address generating unit, executes an algorithm, and outputs a peak point detection value and an area detection value.