Selective extraction of a two-dimensional optical image by synthesis of the coherence function.

We propose a novel manner for optical ranging and imaging by adopting a synthesis of the optical coherence function. The optical coherence function with a periodic delta-function-like shape can be synthesized in the sense of time averaging by modulating the laser frequency with an appropriate waveform, in which the direct frequency-modulation characteristic of a semiconductor laser diode is used. This method does not require either mechanically driven references or Fourier-transform calculations. Selective extraction of a two-dimensional image from an object was successfully performed in a basic experiment.