What is the principle of light used in holography?

Interference principle. Holography is based on the interference principle of light, so the light source must have good coherence. The appearance of laser provides an ideal light source for holography. This is because laser has good spatial and temporal coherence. In the experiment, a good hologram can be obtained by shooting small diffuse objects with He-Ne laser.

The following statements are correct: A. Holographic technology uses the interference principle of light.

B-ultrasound instruments use ultrasonic waves instead of ordinary sound waves because ultrasonic waves are easier to diffract.

C the process of electromagnetic oscillation is the process of alternating electric field energy and magnetic field energy.

D the principle of special relativity holds that the laws of physics are the same in any reference system.

Answer: AC. Ultrasonic instrument uses ultrasonic waves instead of ordinary sound waves because ultrasonic waves have good linearity and are not easy to diffract, and B is wrong; The principle of special relativity holds that the physical laws are different in different reference systems, and D is wrong.

Holographic principle 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.