What are the basic conditions of holography? What is the key to the success of this experiment?

In order to meet the interference conditions of light generation, laser with good coherence is usually used as the light source to separate the light and the light illuminating the object from the same laser beam. The photosensitive film is developed into a hologram. Holograms do not directly display images of objects. When the laser beam or monochromatic light is incident in the direction close to the reference light, the image of the original object can be observed at an appropriate angle. This is because the laser beam diffracts on the interference fringes of the hologram and reproduces the original light wave. The reconstructed image is stereoscopic.