ABSTRACT
Imaging is an optical phenomenon that everyone is familiar with. However, not everyone knows that imaging is an interference phenomenon, and perhaps, even fewer people understand that a camera produced image under sunlight is the result of a single-photon interference: a photon interfering with the photon itself. To prepare the background knowledge for imaging, people start from diffraction and field propagation. In quantum optics, diffraction and imaging are regarded as the transverse behavior of a photon, or a subfield. The use of the pinhole is to simulate a point radiation source. The lens system introduces appropriate phase delays to the spherical wavefront originated from the point source and turns it into a “flat” wavefront. The spherical radiation then becomes a well collimated plane-wave like light beam. Far-field observation of a point-like source is also a good approximation to simulate plane-wave.
