1, surrounded on three sides, without adding a bottom surface.

2. The side length is 7cm and the angle is 60.

Holographic projection production method

1. Draw a circle with a compass. The compass should be sharp when you buy it. You can draw with a top-notch refill.

2. Draw five radii with sharp objects, that is, draw four corners, each of which is 70 degrees.

Draw a string with the central angle to form four triangles with the top angle of 70 degrees, and then cut them out.

4. Glue it with transparent glue to get a quadrangular pyramid.

5. For the next holographic projection video, the screen of the projection device should be similar to a pyramid.

6. Adjust the position of the projection device so that the top of the pyramid is in the center of the video.

Extended data

Principle of holographic projection technology

Using the principle of interference to record the light wave information of the object, this is the shooting process: the photographed object forms a diffuser beam under laser irradiation; The other part of the laser beam, as a reference beam, hits the holographic negative and interferes with the object light beam, converting the phase and amplitude of each point on the object light wave into spatially varying intensity, thus recording all the information of the object light wave by using the contrast and interval between interference fringes.

Negative recording interference fringes become holograms, or holograms, after being developed and fixed.