Hospital operating rooms are equipped with shadowless lights. How is this lamp made? Why is there no shadow when using it?

Careful observation of the light and shadow of the electric lamp shows that the shadow is particularly dark and slightly shallow around. The particularly dark part is called the umbra, and the particularly dark part is called the dark part around the umbra, called the penumbra.

Candles are lit next to the fake cylindrical tea cone placed on the table, and the tea cone casts a clear shadow. Click two candle-shaped overlapping photos next to the tea cone, and there is no light in the overlapping part of the two shadows to take a full black umbra. A candle next to the umbra lights three or even four candles, and the umbra gradually shrinks. The light energy of the electric lamp on the existing umbra layer is formed by the umbra. The light emitted by the electric lamp is limited by the bent filament. It is reasonable to give some light to the object, and it is completely blocked. The more umbra there are, the more candles revolve around the tea cone. The umbra disappears completely. Seeing that scientists make surgical shadow lights according to the principle and arrange the luminous intensity of the lights, the light source with the same angle can illuminate the operating table, which not only ensures that the surgical field of vision is bright enough, but also produces obvious shadows.