Can the frequency of holography be expanded and how to realize white light holography?

The frequency of holography can be expanded, and the conditions for realizing white light holography are:

White light holography uses monochromatic light, and the recording process is basically the same as that of ordinary holography. Different from ordinary holography, the recording medium has a certain thickness, usually around several to dozens of wavelengths.

A photographic method that can record and reproduce three-dimensional (stereoscopic) images of objects without a lens. It is a technology that can record the amplitude and phase information of light wave front from objects and reproduce this light wave when necessary.

Light wave is an electromagnetic wave, which carries amplitude and phase information in its propagation. Ordinary photography uses photosensitive materials (such as photographic negatives) as recording media, 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.

The salient features and advantages of holography are as follows:

1. The reconstructed stereoscopic image is beneficial to the preservation and collection of precious artworks.

2. When shooting, every point is recorded on any point of the hologram, and it doesn't matter if the photo is damaged.

3. Holograms have strong stereoscopic impression and vivid images, and can be displayed in various exhibitions with the help of lasers, which will get very good results.