Abstract
The effects of various window functions on spatial filtering characteristics of a spatial filter velocimetry are studied theoretically and experimentally.
Windows which have transmittance distributions of Gaussian, sinusoidal and triangular types are applied to the spatial filter with a periodic transmittance distribution. The relationships between the types of window functions and parameters involved inthem, and various quantities (peak value, selectivity, side lobe and dependency of the peak value on the orthogonal component of the object velocity) which characterize the spatial filtering characteristics are analyzed.
Then, it is shown that such window functions can be realized optically by combination of an object lens and two kinds of apertures and the effects of these windows on power spectrum of the output signal of the spatial filter are confirmed experimentally.
