The difference between holographic photography and ordinary photography

Holography is a new photographic technology, which records all the information in the reflected or transmitted light waves of the object being photographed. Ordinary photography uses the principle of lens imaging to record the surface image reflecting the change of light intensity on the surface of the object being photographed on the photosensitive film.

Holography records the intensity of reflected light and the phase of reflected light. This can be achieved by superimposing the reference beam and the reflected beam on the photographic film to produce an interference pattern.

Holography is a kind of photographic record that expresses stereoscopic impression through the cooperation of a group of auxiliary reference beams.

Light wave is an electromagnetic wave, which carries amplitude and phase information in its propagation. Ordinary photography takes photosensitive materials (such as photographic negatives) as the recording medium, and uses lens imaging system (such as camera) to image objects on the photosensitive materials. It only records the intensity distribution image of light waves from objects, that is, amplitude information, but does not include phase information. So ordinary photography can only take two-dimensional (plane) images. In order to record the amplitude and phase information of light waves at the same time, the phase difference between two light waves can be determined by using the optical path difference of object light and reference light with the help of a coherent reference light. Therefore, with the help of reference light, the amplitude and phase information of light waves from objects can be recorded.

Refer to Baidu Encyclopedia Holography