Three-dimensional transparent objects recognition based on the digital holography and fractional correlator

A novel three-dimensional (3-D) transparent object-recognition method is proposed. It combines the digital holographic technique with the fractional Fourier transform. The complex amplitude distribution of the 3-D transparent object can be recorded by use of the phase-shifting interferometry, and its bidimensional (2-D) Fresnel transform contents the entire information of the 3-D object, such as shape, orientation and location. By use of the fractional Fourier transform, the 3-D transparent objects can be recognized efficiently with the obtained 2-D information. An opto-electronic hybrid implementation has been also suggested.