Twin-image elimination apparatus and method

Abstract

The twin-image elimination apparatus of the present invention comprises (a) a scanning light source for emitting a scanning light beam; (b) an interference device which converts the scanning light beam from the scanning light source into a spherical wave and a plane wave having temporal frequencies different from each other and combines the spherical and plane waves together; (c) a scanner for scanning an object with the combined light beam from the interference device; (d) a photodetector for detecting a scattered wave from the object; (e) a first multiplier which converts an output signal of the photodetector into a cosine-coded holographic information; (f) a second multiplier which converts the output signal of the photodetector into a sine-coded holographic information; and (g) a holographic reconstruction device which converts output signals of the first and second multipliers into a sum signal, in which these output signals are added together with a phase difference of .pi./2+2n.pi. (wherein n is an integer not less than 0), so as to reproduce an image of the object without the presence of its twin image. Hence, at the time of reconstructing a hologram, the virtual image component contained in the output signal of the photodetector can be removed, thereby improving the image quality of the reconstructed image.